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Background: Pitch counts are only one measure of the true workload of baseball pitchers. Newer research indicates that workload measurement and prevention of injury must include additional factors. Thus, current monitoring systems gauging pitcher workload may be considered inadequate. Purpose/Hypothesis: The purpose of this study was to develop a novel method to determine workload in baseball pitchers and improve processes for prevention of throwing-related injuries. It was hypothesized that our pitching workload model would better predict throwing-related injuries occurring throughout the baseball season than a standard pitch count model. Study Design: Cohort study; Level of evidence, 2. Methods: This prospective observational study was conducted at an academic medical center and community baseball fields during the 2019 to 2023 seasons. Pitchers aged 13 to 18 years were monitored for pitching-related injuries and workload (which included pitching velocity; intensity, using preseason and in-season velocity as a marker of effort; and pitch counts). Results: A total of 71 pitchers had 313 recorded pitcher outings, 11 pitching-related injuries, and 24,228 pitches thrown. Gameday pitch counts for all pitchers ranged from 19 to 219 (mean, 77.5 ± 41.0). Velocity ranged from 46.8 to 85.7 mph (mean, 71.3 ± 5.8 mph). Intensity ranged from 0.7 to 1.3 (mean, 1.0 ± 0.08). The mean workload was 74.7 ± 40.1 for all pitchers. Risk factors significant for injury included throwing at a higher velocity in game (P =.001), increased intensity (eg, an increase in mean velocity thrown from preseason to in-season; P <.001), and being an older pitcher (P =.014). No differences were found for workload between injured and noninjured pitchers because the analysis was underpowered. Conclusion: Our workload model indicated that throwing at a higher velocity, throwing at a higher intensity, and older age were risk factors for injury. Thus, this novel workload model should be considered as a means to identify pitchers who may be at greater risk for injury. [ABSTRACT FROM AUTHOR]

Background: Even though arthroscopic rotator cuff repair is recognized as a standard treatment option, the risk of postoperative retear is a major concern. Purpose: To evaluate the effect of porcine-derived absorbable patch-type atelocollagen during arthroscopic rotator cuff repair. Study Design: Randomized controlled trial; Level of evidence, 1. Methods: A total of 64 patients with rotator cuff tears diagnosed on magnetic resonance imaging (MRI) were enrolled prospectively from November 2020 to December 2021. Both groups had repairs using the suture bridge technique. For the atelocollagen group, before securing the lateral anchors, we inserted porcine-derived absorbable patch-type atelocollagen between the footprint and the tendon. On postoperative day 2, the patients underwent MRI to confirm containment of the patch-type atelocollagen. At 6 months and 1 year postoperatively, the signal intensity of the repaired tendon was assessed using MRI. Patients were evaluated using the Constant score as the primary outcome, along with the visual analog scale for pain; range of motion; American Shoulder and Elbow Surgeons score; University of California, Los Angeles, score; and Korean Shoulder Score preoperatively and at 2, 3, 6, and 12 months postoperatively. Results: No significant changes in the Constant score as primary outcome, pain or other functional scores, and range of motion were observed between the groups at 1 year postoperatively. The patch-type atelocollagen was confirmed to be contained by the time-zero MRI scan taken 2 days postoperatively. Among the 55 patients included in final analysis, 12 retear cases were recorded (21.8% retear rate). A significantly lower retear rate was found in the atelocollagen group, as 3 cases were observed in this group (10.3%) and 9 cases were observed in the conventional repair group (34.6%) (P =.048). Conclusion: The Constant score was not different between the groups. The retear rate after rotator cuff repair was significantly lower in the group that received porcine-derived absorbable patch-type atelocollagen compared with in the conventional group. Registration: KCT0005184 (Clinical Research Information Service [CRIS]; https://cris.nih.go.kr). [ABSTRACT FROM AUTHOR]

Background: There is little evidence of the biomechanical performance of medial collateral ligament (MCL) reconstructions for restoring stability to the MCL-deficient knee regarding valgus, external rotation (ER), and anteromedial rotatory instability (AMRI). Hypothesis: A short isometric reconstruction will better restore stability than a longer superficial MCL (sMCL) reconstruction, and an additional deep MCL (dMCL) graft will better control ER and AMRI than single-strand reconstructions. Study Design: Controlled laboratory study. Methods: Nine cadaveric human knees were tested in a kinematics rig that allowed tibial loading while the knee was flexed-extended 0° to 100°. Optical markers were placed on the femur and tibia and displacements were measured using a stereo camera system. The knee was tested intact, and then after MCL (sMCL + dMCL) transection, and loaded in anterior tibial translation (ATT), ER, varus-valgus, and combined ATT + ER (AMRI loading). Five different isometric MCL reconstructions were tested: isolated long sMCL, a short construct, each with and without dMCL addition, and isolated dMCL reconstruction, using an 8 mm–wide synthetic graft. Results: MCL deficiency caused an increase in ER of 4° at 0° of flexion (P =.271) up to 14° at 100° of flexion (P =.002), and valgus laxity increased by 5° to 8° between 0° and 100° of flexion (P <.024 at 0°-90°). ATT did not increase significantly in isolated MCL deficiency (P >.999). All 5 reconstructions restored native stability across the arc of flexion apart from the isolated long sMCL, which demonstrated residual ER instability (P ≤.047 vs other reconstructions). Conclusion: All tested techniques apart from the isolated long sMCL graft are satisfactory in the context of restoring the valgus, ER, and AMRI stability to the MCL-deficient knee in a cadaveric model. Clinical Relevance: Contemporary MCL reconstruction techniques fail to control ER and therefore AMRI as they use a long sMCL graft and do not address the dMCL. This study compares 5 MCL reconstruction techniques. Both long and short isometric constructs other than the long sMCL achieved native stability in valgus and ER/AMRI. Double-strand reconstructions (sMCL + dMCL) tended to provide more stability. This study shows which reconstructions demonstrate the best biomechanical performance, informs surgical reconstruction techniques for AMRI, and questions the efficacy of current popular techniques. [ABSTRACT FROM AUTHOR]

Background: Timely and appropriate medical care after concussion presents a difficult public health problem. Concussion identification and treatment rely heavily on self-report, but more than half of concussions go unreported or are reported after a delay. If incomplete self-report increases exposure to harm, blood biomarkers may objectively indicate this neurobiological dysfunction. Purpose/Hypothesis: The purpose of this study was to compare postconcussion biomarker levels between individuals with different previous concussion diagnosis statuses and care-seeking statuses. It was hypothesized that individuals with undiagnosed concussions and poorer care seeking would show altered biomarker profiles. Study Design: Cohort study; Level of evidence, 3. Methods: Blood samples were collected from 287 military academy cadets and collegiate athletes diagnosed with concussion in the Advanced Research Core of the Concussion Assessment, Research and Education Consortium. The authors extracted each participant's self-reported previous concussion diagnosis status (no history, all diagnosed, ≥1 undiagnosed) and whether they had delayed or immediate symptom onset, symptom reporting, and removal from activity after the incident concussion. The authors compared the following blood biomarkers associated with neural injury between previous concussion diagnosis status groups and care-seeking groups: glial fibrillary acidic protein, ubiquitin c-terminal hydrolase-L1 (UCH-L1), neurofilament light chain (NF-L), and tau protein, captured at baseline, 24 to 48 hours, asymptomatic, and 7 days after unrestricted return to activity using tests of parallel profiles. Results: The undiagnosed previous concussion group (n = 21) had higher levels of NF-L at 24- to 48-hour and asymptomatic time points relative to all diagnosed (n = 72) or no previous concussion (n = 194) groups. For those with delayed removal from activity (n = 127), UCH-L1 was lower at 7 days after return to activity than that for athletes immediately removed from activity (n = 131). No other biomarker differences were observed. Conclusion: Individuals with previous undiagnosed concussions or delayed removal from activity showed some different biomarker levels after concussion and after clinical recovery, despite a lack of baseline differences. This may indicate that poorer care seeking can create neurobiological differences in the concussed brain. [ABSTRACT FROM AUTHOR]

Background: In baseball, youth athletes play on smaller fields with shorter distances between bases, shorter pitching distances, and smaller mounds. Despite this, youth athletes use baseballs weighing the same amount as those used at the professional level, possibly predisposing youth baseball players to injuries. Purpose: (1) To determine the effects of throwing a smaller, lighter, and both smaller and lighter baseball on throwing arm stress in youth athletes and (2) to also investigate how changing the ball size and weight would affect elbow varus torque, shoulder distraction force, and throwing arm internal rotation velocity during the throwing motion. Study Design: Cross-sectional study; Level of evidence, 3. Methods: This cross-sectional cohort study analyzed the kinematics and kinetics of 38 youth baseball players (mean age, 8.3 ± 0.8 years) throwing a baseball modified in size and weight. Three-dimensional motion data were collected using a retroreflective marker set and a 12-camera motion analysis system. Full-body kinematics and kinetics were calculated using commercial software. Participants threw 5 different types of baseballs 3 times each, in random order, with full effort from a pitching mound to a target 14 m away. The balls used were a 5-oz regular baseball, 5-oz (0.142-kg) baseball with a 5% reduced circumference, 4-oz (0.113-kg) baseball, 4-oz baseball with a 5% reduced circumference, and 3-oz (0.085-kg) baseball. Analysis of variance was used to determine statistical differences in elbow varus torque, shoulder distraction force, and throwing arm internal rotation velocity among baseball types. The Tukey post hoc test was used to further investigate differences between the ball groups, considering P <.05 to be significant. Results: Analysis of variance detected a significant difference in elbow varus torque among ball groups (P =.024). The Tukey post hoc test revealed a moderate difference in elbow varus torque between the 5-oz baseball (4.73 ± 1.06 percentage body weight × height [%BW × H]) and 3-oz baseball (4.06 ± 0.83 %BW × H) (P =.017; d = 0.677 [95% CI, 0.08-1.27]). No significant differences were found in shoulder distraction force or throwing arm internal rotation velocity among ball groups. Conclusion: Compared with a 5-oz baseball, throwing a 3-oz baseball resulted in decreased elbow varus torque with a moderate effect size. [ABSTRACT FROM AUTHOR]

Background: Intra-articular (IA) platelet-rich plasma (PRP) and bone marrow aspirate concentrate (BMAC) injections have shown efficacy and safety in treating osteoarthritis (OA). However, the effectiveness and mechanisms of combined intraosseous (IO) administration of these orthobiologics have yet to be explored. Purpose/Hypothesis: The purpose of this study was to evaluate the effect on pain, cartilage, synovium/infrapatellar fat pad (IFP), and subchondral bone in rat knee OA, comparing isolated IA with combined IA and IO (IA+IO) injections of PRP or BMAC. It was hypothesized that combined injections would be superior to sole IA injections. Study Design: Controlled laboratory study. Methods: A total of 48 rats were divided into 6 groups: sham (only joint puncture during OA induction with IA+IO saline injection treatment) and 5 groups with OA induction, control (IA+IO saline injection), PRP (IA PRP+IO saline injection), BMAC IA (IA BMAC+IO saline injection), PRP IA+IO (IA+IO PRP injection), and BMAC IA+IO (IA+IO BMAC injection). OA was induced by IA injection of monosodium iodoacetate (MIA). Rats were administered different orthobiologics according to their grouping 3 weeks after the MIA injection. Pain changes were evaluated using the weightbearing ratio assay at weeks 3, 4, 5, 7, and 9 after OA induction. Rats were euthanized at week 9 for gross, radiological, histological, immunohistochemical, and immunofluorescence assessments of cartilage, synovium, and subchondral bone. Results: Compared with the control group, all orthobiologics injection groups had reduced joint pain. Compared with IA injection, IA+IO injections provided superior pain relief by suppressing calcitonin gene-related peptide and substance P in both the synovium/IFP and subchondral bone. IA+IO injections slowed the progression of subchondral bone lesions by inhibiting CD31hiEmcnhi vessel formation and excessive osteoclast and osteoblast turnover while preserving subchondral bone microarchitecture, slowing cartilage degeneration. However, IA+IO injections did not outperform isolated IA injections in reducing synovitis and synovium/IFP fibrosis. Compared with PRP, BMAC exhibited superior inhibition of pain-related mediators, but no significant differences were observed in synovitis suppression, infrapatellar fat pad fibrosis, and subchondral bone protection. Conclusion: IA+IO injections of orthobiologics were more effective in relieving pain, slowing cartilage degeneration, and inhibiting abnormal vascularization and remodeling compared with isolated IA injections. BMAC showed superior pain relief in the synovium/IFP and subchondral bone compared with PRP. Further research is needed to optimize PRP and BMAC components for enhanced efficacy in OA management. Clinical Relevance: Our findings contribute to advancing the understanding of pain relief mechanisms and support the endorsement of IO injection of orthobiologics for the treatment of OA and joint pain. [ABSTRACT FROM AUTHOR]

Background: Anterior cruciate ligament (ACL) injury increases risks for osteoarthritis (OA), a poorly modifiable and disabling condition. Joint changes of potentially reversible pre-OA have been described just 2 years after ACL reconstruction (ACLR) when early bone shape changes have also been reported. Purpose: This study evaluates relationships between interlimb differences in tibiofemoral bone shape derived from statistical shape modeling (SSM) of magnetic resonance imaging (MRI) and participant factors on patient-reported outcomes 2 years after unilateral ACLR. Study Design: Cross-sectional study; Level of evidence, 3. Methods: SSM-derived tibiofemoral bone shape and subchondral bone area were assessed from bilateral knee MRI scans of 72 participants with unilateral ACLR (mean age, 34 ± 11 years; 32 women) and compared with a reference cohort of 398 older individuals without OA (mean age, 50 ± 3 years; 213 women). Multivariable logistic regression models examined relationships between participant and surgical factors with interlimb differences in bone shapes or subchondral bone areas. Relationships between patient-reported outcomes and the interlimb differences in bone shape and subchondral area were examined using similar models. Results: Bone shape scores and subchondral bone areas were greater (more OA-like) in ACLR knees than uninjured contralateral knees in every bone metric tested (P ≤.001). Interlimb differences in femur shape scores of participants with ACLR were 65% greater (P <.001) than those of the significantly older reference cohort. Taller height, medial meniscal tears, and decreasing age were associated with larger interlimb differences in shape scores and subchondral areas (P <.05). Bone–patellar tendon–bone (BPTB) autograft recipients demonstrated greater interlimb subchondral area differences compared with allograft recipients (P <.05). Interlimb differences for hamstring autograft recipients did not differ from those with BPTB or allograft. Greater interlimb differences in medial femur subchondral areas were associated with worse patient-reported Knee injury and Osteoarthritis Outcome Score Symptoms (R = 0.27; P =.040). Conclusion: Even in the absence of radiographic OA, just 2 years after unilateral ACLR patients showed greater bone shape scores and subchondral areas consistent with pre-OA in their ACLR knees. Furthermore, greater medial femur bone areas were weakly associated with worse symptoms. Patients who are younger, are taller, have meniscal tears, or have BPTB grafts may be at increased risk for bony asymmetries 2 years after ACLR. [ABSTRACT FROM AUTHOR]

Background: Hinge fractures are considered risk factors for delayed or nonunion of the osteotomy gap in distal femoral osteotomies (DFOs). Limited evidence exists regarding the treatment of hinge fractures after DFO, which could improve stability and thus bone healing. Purpose: To (1) examine the effect of hinge fractures on the biomechanical properties of the bone-implant construct, (2) evaluate the biomechanical advantages of an additional fixation of a hinge fracture, and (3) test the biomechanical properties of different types of varisation DFOs. Study Design: Controlled laboratory study. Methods: A total of 32 fresh-frozen human distal femora equally underwent medial closing wedge DFO or lateral opening wedge DFO using a unilateral locking compression plate. The following conditions were serially tested: (1) preserved hinge; (2) hinge fracture along the osteotomy plane; (3) screw fixation of the hinge fracture; and (4) locking T-plate fixation of the hinge fracture. Using a servo-hydraulic materials testing machine, we subjected each construct to 15 cycles of axial compression (400 N; 20 N/s) and internal and external rotational loads (10 N·m; 0.5 N·m/s) to evaluate the stiffness. The axial and torsional hinge displacement was recorded using a 3-dimensional optical measuring system. Repeated-measures 1-way analysis of variance and post hoc Bonferroni correction were used for multiple comparisons. Statistical significance was set at P <.05. Results: Independent from the type of osteotomy, a fractured hinge significantly (P <.001) increased rotational displacement and reduced stiffness of the bone-implant construct, resulting in ≥1.92 mm increased displacement and ≥70% reduced stiffness in each rotational direction, while the axial stiffness remained unchanged. For both procedures, neither a screw nor a plate could restore intact rotational stiffness (P <.01), while only the plate was able to restore intact rotational displacement. However, the plate always performed better compared with the screw, with significantly higher and lower values for stiffness (+38% to +53%; P <.05) and displacement (–55% to −72%; P <.01), respectively, in ≥1 rotational direction. At the same time, the type of osteotomy did not significantly affect axial and torsional stability. Conclusion: Hinge fractures after medial closing wedge DFO and lateral opening wedge DFO caused decreased bone-implant construct rotational stiffness and increased fracture-site displacement. In contrast, the axial stiffness remained unchanged in the cadaveric model. Clinical Relevance: When considering an osteosynthesis of a hinge fracture in a DFO, an additional plate fixation was the construct with the highest stiffness and least displacement, which could restore intact hinge rotational displacement. [ABSTRACT FROM AUTHOR]

Background: Rotator cuff repair is a common orthopaedic procedure, yet the rate of failure to heal after surgery is high. Repair site rupture is due to poor tendon-to-bone healing and lack of regeneration of the native fibrocartilaginous enthesis. During development, the enthesis is formed and mineralized by a pool of progenitors activated by hedgehog signaling. Furthermore, hedgehog signaling drives regenerative enthesis healing in young animals, in contrast to older animals, in which enthesis injuries heal via fibrovascular scar and without participation of hedgehog signaling. Hypothesis: Hedgehog activation improves tendon-to-bone healing in an animal model of rotator cuff repair. Study Design: Controlled laboratory study. Methods: A total of 78 adult Sprague-Dawley rats were used. Supraspinatus tendon injury and repair were completed bilaterally, with microsphere-encapsulated hedgehog agonist administered to right shoulders and control microspheres administered to left shoulders. Animals were sacrificed after 3, 14, 28, or 56 days. Gene expression and histological, biomechanical, and bone morphometric analyses were conducted. Results: At 3 days, hedgehog signaling pathway genes Gli1 (1.70; P =.029) and Smo (2.06; P =.0173), as well as Runx2 (1.69; P =.0386), a transcription factor of osteogenesis, were upregulated in treated relative to control repairs. At 14 days, transcription factors of tenogenesis, Scx (4.00; P =.041), and chondrogenesis, Sox9 (2.95; P =.010), and mineralized fibrocartilage genes Col2 (3.18; P =.031) and Colx (1.85; P =.006), were upregulated in treated relative to control repairs. Treatment promoted fibrocartilage formation at the healing interface by 28 days, with improvements in tendon-bone maturity, organization, and continuity. Treatment led to improved biomechanical properties. The material property strength (2.43 vs 1.89 N/m2; P =.046) and the structural property work to failure (29.01 vs 18.09 mJ; P =.030) were increased in treated relative to control repairs at 28 days and 56 days, respectively. Treatment had a marginal effect on bone morphometry underlying the repair. Trabecular thickness (0.08 vs 0.07 mm; P =.035) was increased at 28 days. Conclusion: Hedgehog agonist treatment activated hedgehog signaling at the tendon-to-bone repair site and prompted increased mineralized fibrocartilage production. This extracellular matrix production and mineralization resulted in improved biomechanical properties, demonstrating the therapeutic potential of hedgehog agonism for improving tendon-to-bone healing after rotator cuff repair. Clinical Relevance: This study demonstrates the therapeutic potential of hedgehog agonist treatment for improving tendon-to-bone healing after rotator cuff injury and repair. [ABSTRACT FROM AUTHOR]

Background: Various muscle contraction modalities have differing effects on the musculoskeletal system. To understand the magnitude of these effects, the authors investigated the effects of eccentric and concentric contractions on the bone-tendon interface after rotator cuff repair in mice. Hypothesis: Eccentric contraction promotes healing of the bone-tendon interface after rotator cuff repair in mice better than other muscle contraction patterns. Study Design: Controlled laboratory study. Methods: The authors performed acute supraspinatus tendon repair of the right shoulder in 104 C57BL/6 mice. Animals were randomized into 4 groups postoperatively: control group (Con group), horizontal running group (Horz group), +15° uphill running group (Up group), and −15° downhill running group (Down group), with 26 animals in each group. At 4 and 8 weeks postoperatively, the authors removed the eyeball, collected blood samples, and extracted the supraspinatus tendon–humerus complex for histological, immunological, bone morphological, and biomechanical tests. Results: At 4 and 8 weeks postoperatively, the Down group exhibited a better collagen cell arrangement and fibrocartilage layer than the other 3 groups. At 4 weeks postoperatively, anti-inflammatory macrophages (M2 macrophages) were observed at the repair site in all groups except for the Con group. At 8 weeks postoperatively, M2 macrophages were withdrawn from the tendon site in all groups. The transforming growth factor β1 concentration in the Down group was greater than that in the other 3 groups at 4 weeks postoperatively, and it was higher than that in the Con group at 8 weeks postoperatively. The bone volume fraction, number of trabeculae, and thickness of trabeculae at the repair site in the Down group, as well as the ultimate strength and failure load in the biomechanical tests, were greater than those in the other 3 groups at 8 weeks postoperatively. Conclusion: Eccentric contraction promotes healing of the bone-tendon interface after rotator cuff repair in mice better than other muscle contraction patterns. Clinical Relevance: After clinical rotator cuff repair, patients can be rehabilitated by eccentric training to speed up the functional recovery of the shoulder joint. [ABSTRACT FROM AUTHOR]

Background: During the early evolution of femoroacetabular impingement (FAI) treatment, undercorrection of femoral deformity was a leading cause of hip arthroscopy failures. As the pendulum has swung, overresection of femoral deformity has increased in prevalence as a cause of persistent hip pain after arthroscopy. Computed tomography (CT) scans are increasingly being used in hip arthroscopy for preoperative planning purposes and may allow for improved 3-dimensional (3D) assessment of complex femoral deformities after previous femoroplasty. Purpose: To assess whether CT scans provide additional utility over standard radiographs in understanding proximal femoral morphology in patients being evaluated for revision hip arthroscopy after previous femoroplasty in the setting of FAI. Study Design: Cohort study (Diagnosis); Level of evidence, 3. Methods: Preoperative CT scans and standard radiographs were obtained in 80 patients who underwent revision hip arthroscopy for FAI. The anteroposterior and Dunn radiographic views were used to assess patients for residual proximal femoral deformity and were compared with the CT scan views using a commercially available software program. Determinations of underresection were made using alpha angle, while overresection was determined according to a previously described technique. Chi-square tests were performed to determine statistical significance between radiographic and CT classifications of overresection, underresection, and concomitant over- and underresection. A kappa value was calculated to determine the agreement between measurements on the radiographs and CT scans. Results: There were 30 patients (37.5%) for whom the CT scans revealed information about femoral morphology that was not detected on the radiographs. The kappa value of agreement was 0.28 between CT and radiographic measurements. Underresected cams were detected in 30 patients (37.5%) on CT scans versus 17 patients (21.3%) on radiographs (P =.024). Overresected cams were detected in 31 patients (38.8%) on CT scans versus 14 patients (17.5%) on radiographs (P =.0049). Concomitant areas of under- and overresection were detected in 12 patients (15.0%) on CT scans versus 3 patients (3.8%) on radiographs (P =.027). Conclusion: CT scans with 3D planning software may be more sensitive than traditional radiographic views at detecting aberrant proximal femoral anatomy in the setting of failed FAI surgery. The use of 3D planning software may be considered as an adjunctive tool to better understand complex deformity in the proximal femur for the planning of revision hip arthroscopy. [ABSTRACT FROM AUTHOR]

Background: Sports function and psychological readiness to return to sports (RTS) are important outcomes when evaluating rehabilitation after anterior cruciate ligament reconstruction (ACLR). It is, however, unclear which specific factors contribute most to these outcomes. Purpose: To determine associations between demographic characteristics, objective measurements of physical function, patient-reported outcome measure scores, sports-related function assessed with the Knee injury and Osteoarthritis Outcome Score (KOOS) Sport and Recreation subscale, and psychological readiness to RTS assessed with the Anterior Cruciate Ligament–Return to Sport after Injury (ACL-RSI) scale at 1 year after ACLR. Study Design: Cross-sectional study; Level of evidence, 3. Methods: At a mean of 12.5 ± 2.0 months after ACLR, 143 participants (50.3% female), with a mean age of 25.0 ± 5.7 years, were assessed for demographic characteristics, physical factors (hop performance, muscle strength, ankle and hip range of motion), and psychological factors (KOOS Pain and Symptoms subscales, Perceived Stress Scale, fear of reinjury) as well as the KOOS Sport and Recreation subscale and ACL-RSI scale. Backward linear regression models were used to evaluate factors associated with sports function and psychological readiness to RTS. Results: Lower isokinetic knee extension peak torque (limb symmetry index) (B = 18.38 [95% CI, 3.01-33.75]), lower preinjury activity level (B = 2.00 [95% CI, 0.87-3.14]), greater knee pain (B = 0.90 [95% CI, 0.70-1.10]), shorter time between injury and reconstruction (B = 0.16 [95% CI, 0.05-0.26]), and greater fear of reinjury (B = 0.11 [95% CI, 0.01-0.20]) were associated with a worse KOOS Sport and Recreation subscore (R 2 = 0.683). A shorter hop distance (B = 0.15 [95% CI, 0.00-0.29]) was associated with a lower ACL-RSI score (R 2 = 0.245). Conclusion: A combination of knee muscle strength, activity level, knee pain, timing of surgery, and fear of reinjury accounted for approximately 70% of the variation in sports function at 1 year after ACLR. In contrast, there was only 1 weak association between physical function and psychological readiness to RTS at this time point. Thus, factors associated with current sports function are much better known than features related to psychological readiness to RTS. [ABSTRACT FROM AUTHOR]

Background: The incidence of rotator cuff tears is rapidly increasing, and operative techniques for rotator cuff repair have been developed. However, the rates of postoperative retear remain high. Purpose/Hypothesis: The purpose was to determine the effects of human dermal fibroblasts (HDFs) with hyaluronic acid (HA) on tendon-to-bone healing in a rabbit model of chronic rotator cuff tear injury. It was hypothesized that HA would enhance HDF proliferation and that a combination of HA and HDFs would produce a synergistic effect on the healing of repaired rotator cuff tendons of rabbits. Study Design: Controlled laboratory study. Methods: For in vitro study, HDFs were plated on a 24-well plate. After 1 day, 2 wells were designated as the test group and treated with 0.75% HA in phenol red–free Dulbecco's modified Eagle medium (DMEM). An other 2 wells served as control groups and were treated with the same volume of phenol red–free DMEM without HA. Each group was duplicated, resulting in a total of 4 wells, with 2 wells in each group for replication purposes. The cells were incubated for 24 hours, followed by 72-hour cultivation. Absorbance ratios at 96 and 24 hours were compared to evaluate cell proliferation. For the in vivo study, a total of 24 rabbits were randomly allocated to groups A, B, and C (n = 8 each). Supraspinatus tendons were detached bilaterally and left for 6 weeks to establish a chronic rotator tear model. Torn tendons were subsequently repaired using the following injections: group A, 0.5 × 106 HDFs with HA; group B, HA only; and group C, saline only. At 12 weeks after repair, biomechanical tests and histological evaluation were performed. Results: In vitro study showed that HDF proliferation significantly increased with HA (HDFs with HA vs HDFs without HA; 3.96 ± 0.09 vs 2.53 ± 0.15; P <.01). In vivo, group A showed significantly higher load-to-failure values than the other groups (53.8 ± 6.9 N/kg for group A, 30.6 ± 6.4 N/kg for group B, and 24.3 ± 7.6 N/kg for group C; P <.001). Histological evaluation confirmed that group A showed higher collagen fiber density and better collagen fiber continuity, tendon-to-bone interface maturation, and nuclear shape than the other groups (all P <.05). Conclusion: This controlled laboratory study verified the potential of the combination of HDFs and HA in enhancing healing in a chronic rotator cuff tear rabbit model. Clinical Relevance: A potential synergistic effect on rotator cuff tendon healing may be expected from a combination of HDFs and HA. [ABSTRACT FROM AUTHOR]

Background: Osteoarthritis (OA) is the most prevalent chronic degenerative joint disease among the aged population. However, current treatments for OA are limited to alleviating symptoms, with no therapies that prevent and regenerate cartilage deterioration. Purpose: To assess the effects of platelet-derived exosomes (Plt-exos) on OA and then to explore the potential molecular mechanism. Study Design: Controlled laboratory study. Methods: Exosomes derived from human apheresis platelets were isolated and identified. The effects of Plt-exos in protecting chondrocytes under interleukin 1β stimulation were evaluated by analyzing the proliferation and migration in human primary chondrocytes. RNA sequencing was later performed in vitro for primary chondrocytes to reveal the underlying mechanisms of Plt-exo treatment. Anterior cruciate ligament transection was used to construct an OA mice model, and intra-articular injection of Plt-exos was given once a week for 6 weeks. Mice were sacrificed 4 weeks after the last injection. Histologic and immunohistochemistry staining and micro–computed tomography analysis were performed to assess alterations of articular cartilage and subchondral bone. Results: Plt-exos significantly promoted proliferation and migration of chondrocytes within a dose-dependent manner, as well as dramatically promoted cartilage regeneration and attenuated abnormal tibial subchondral bone remodeling, thus slowing the progression of OA. After being treated with Plt-exos, 1797 genes were differentially expressed in chondrocytes (923 upregulated and 874 downregulated genes). Functional enrichment results and hub genes were mainly involved in anti-inflammatory effects, mediating cell adhesion, stimulating cartilage repair, promoting anabolism, and inhibiting catabolism. Conclusion: Our results demonstrated that Plt-exos promoted chondrocyte proliferation and migration in vitro, as well as attenuated cartilage degeneration, improved the microarchitecture of subchondral bone, and retarded OA progression in vivo. Clinical Relevance: Our study illustrated that the administered Plt-exos could alleviate knee OA by attenuating cartilage degeneration and subchondral bone loss, possibly serving as a novel promising treatment for OA in the future. [ABSTRACT FROM AUTHOR]

Background: Anterior cruciate ligament (ACL) repair (ACL-Rp) is known to be a valuable alternative to ACL reconstruction (ACL-Rc) in selected indications. The majority of the ACL-Rp techniques recommend the use of a synthetic brace. The use of the gracilis allows both a biological internal brace and anterolateral ligament reconstruction (ALR). Purpose: The primary objective was to compare the early ability to return to sports between patients who underwent ACL-Rp using a gracilis autograft as an internal brace augmentation with ALR and patients who underwent the conventional ACL-Rc with ALR technique sacrificing both the gracilis and the semitendinosus. The secondary objective was to compare the failure rate, clinical scores, and return to sports at a minimum follow-up of 2 years. Study design: Cohort study; Level of evidence, 3. Methods: A retrospective analysis was undertaken. A total of 49 patients who underwent ACL-Rp with ALR between December 2018 and May 2019 were propensity matched at a 1:1 ratio to those who underwent ACL-Rc with ALR during the same period. The decision to perform ACL-Rp with ALR was based on preoperative selection and intraoperative arthroscopic findings: proximal avulsion tear, partial ACL tear, low- to midlevel sports participation, and good tissue quality. The ability to return to sports was assessed using isokinetic tests and the Knee Santy Athletic Return to Sport test functional test at 6 months postoperatively. At the final follow-up, knee laxity parameters, return to sports, and clinical outcome (Lysholm score, Tegner Activity Scale score, International Knee Documentation Committee score, Knee injury and Osteoarthritis Outcome Score, and Anterior Cruciate Ligament–Return to Sport after Injury score) were recorded. Results: The ACL-Rp group had significantly less hamstring strength deficit when compared with their counterparts who underwent ACL-Rc (0.2% vs 10.2% in concentric, P <.001; 2.5% vs 14% in eccentric, P <.001). The mean Knee Santy Athletic Return to Sport test score was significantly higher in the ACL-Rc group (69.7% ± 16.6% [range, 19%-100%] vs 61% ± 16.8% [range, 19%-100%]; P =.001). In the ACL-Rp group, 61% (30/49) of the patients were authorized to return to pivot sports versus 41% (20/49) in the ACL-Rc group (P =.04). At a mean final follow-up of 31.4 ± 3.5 months, no significant differences were demonstrated between groups with respect to clinical scores and knee laxity parameters. There was a trend for a higher failure rate in the ACL-Rp group without any significance (ACL-Rp: 6.1% [3/49] vs ACL-Rc: 0%; P =.08). Conclusion: At 6 months after operation, harvesting only the gracilis with this ACL-Rp and augmentation with ALR technique was linked to a better early ability to return to sports compared with the ACL-Rc with ALR technique harvesting both the gracilis and semitendinosus. This technique had a limited effect on early flexion strength and provided a satisfactory rerupture rate. [ABSTRACT FROM AUTHOR]

Background: Studies suggest that similar clinical results are achieved via arthroscopic and open biceps tenodesis (BT) techniques. Purpose: To quantify the postoperative migration of the BT construct between arthroscopic suprapectoral BT (ASPBT) and open subpectoral BT (OSPBT) techniques via interference screw (IS) or single-suture suture anchor (SSSA) fixation using radiostereometric analysis. Study Design: Cohort study; Level of evidence, 2. Methods: Distal migration of the biceps tendon after OSPBT with a polyetheretherketone IS, OSPBT with 1 SSSA, ASPBT with polyetheretherketone IS, and ASPBT with 2 SSSAs was measured prospectively. Patients with symptomatic biceps tendinopathy and preoperative patient-reported outcome measures (PROMs) including Constant-Murley subjective, Single Assessment Numeric Evaluation, or Patient-Reported Outcomes Measurement Information System–Upper Extremity scores were included. A tantalum bead was sutured on the proximal end of the long head of the biceps tendon before fixation of tendon tissue. Anteroposterior radiographs were performed immediately postoperatively, at 1 week, and at 3 months. Bead migration was measured, and preoperative PROMs were compared with those at latest follow-up. Results: Of 115 patients, 94 (82%) were available for final follow-up. IS fixation yielded the least tendon migration with no difference between the open and arthroscopic approaches (4.31 vs 5.04 mm; P =.70). Fixation with 1 suture anchor demonstrated significantly greater migration than that achieved with an IS at both 1 week (6.47 vs 0.1 mm, 6.47 vs 1.75 mm, P <.001;) and 3 months (14.76 vs 4.31 mm, 14.76 vs 5.04 mm, P <.001) postoperatively. Two-suture anchor fixation yielded significantly greater migration than IS fixation at 1 week (7.02 vs 0.1 mm, P <.001; 7.02 vs 1.75 mm, P =.003) but not 3 months postoperatively (8.06 vs 4.31 mm, P =.10; 8.06 vs 5.04 mm, P =.07). Four patients with suture anchor fixation (3 patients in the OSPBT 1 SSSA group, 9.4%, and 1 patient in the ASPBT 2 SSSAs group, 3.8%) developed a Popeye deformity, whereas no Popeye deformities occurred in the IS groups. Mean 3-month bead migration in patients with and without a Popeye deformity was 60.8 and 11.2 mm, respectively (P <.0001). PROMs did not differ among groups at final follow-up. Conclusion: Interference screw fixation yielded the least tendon migration whether achieved arthroscopically or open. The available data indicated that fixation with 1 SSSA but not 2 SSSAs resulted in significantly greater migration than that achieved with an IS. Despite variations in tendon migration, PROMs were similar among all groups. When SSSAs are used, tendon migration may be minimized by using ≥2 anchors. [ABSTRACT FROM AUTHOR]

Background: The amount of glenoid width that must be restored with a Latarjet procedure in order to reestablish glenohumeral stability has not been determined. Purpose/Hypothesis: The purpose of this article was to determine the percentage of glenoid width restoration necessary for glenohumeral stability after Latarjet by measuring anterior humeral head translation and force distribution on the coracoid graft. The hypothesis was that at least 100% of glenoid width restoration with Latarjet would be required to maintain glenohumeral stability. Study Design: Controlled laboratory study. Methods: Nine cadaveric shoulders were prepared and mounted on an established shoulder simulator. A lesser tuberosity osteotomy (LTO) was performed to allow accurate removal of glenoid bone. Coracoid osteotomy was performed, and the coracoid graft was sized to a depth of 10 mm. Glenoid bone was sequentially removed, and Latarjet was performed using 2 screws to reestablish 110%, 100%, 90%, and 80% of native glenoid width. The graft was passed through a subscapularis muscle split, and the LTO was repaired. A motion tracking system recorded glenohumeral translations, and force distribution was recorded using a TekScan pressure sensor secured to the glenoid face and coracoid graft. Testing conditions included native; LTO; Bankart tear; and 110%, 100%, 90%, and 80% of glenoid width restoration with Latarjet. Glenohumeral translations were recorded while applying an anteroinferior load of 44 N at 90° of humerothoracic abduction and 0° or 45° of glenohumeral external rotation. Force distribution was recorded without an anteroinferior load. Results: Anterior humeral head translation progressively increased as the proportion of glenoid width restored decreased. A marked increase in anterior humeral head translation was found with 90% versus 100% glenoid width restoration (10.8 ± 3.0 vs 4.1 ± 2.6 mm, respectively; P <.001). Greater glenoid bone loss also led to increased force on the coracoid graft relative to the native glenoid bone after Latarjet. A pronounced increase in force on the coracoid graft was seen with 90% versus 100% glenoid width restoration (P <.001). Conclusion: Anterior humeral head translation and force distribution on the coracoid graft dramatically increased when <100% of the native glenoid width was restored with a Latarjet procedure. Clinical Relevance: If a Latarjet is unable to fully restore the native glenoid width, surgeons should consider alternative graft sources to minimize the risk of recurrent instability or coracoid overload. [ABSTRACT FROM AUTHOR]

Background: The healing capacity of the human glenoid labrum varies by tear location. Current evidence suggests that the healing capacity of meniscal and cartilage injuries relates to cellular composition and vascularity. However, little is known about the histological characteristics of the glenoid labrum and how they may affect healing potential in specific anatomic regions. Hypothesis: Regenerative characteristics of the glenoid labrum differ based on the anatomic region. Study Design: Descriptive laboratory study. Methods: Human glenoid labra from fresh unpreserved cadavers were transversely sectioned in different anatomic regions. Masson trichrome stain was used to determine dense and loose extracellular matrix regions and vessel densities. Hematoxylin and eosin, Ki-67+, and CD90+/CD105+ stains were performed to determine total, proliferative, and progenitor cell densities, respectively. Regression models demonstrated relationships between vascular area, progenitor cell quantity, and probability of successful operation. Results: Among all labral aspects, the superior glenoid labrum had the highest percentage (56.8% ± 6.9%) of dense extracellular matrix or avascular tissue (P <.1). The vascular region of the superior labrum had the fewest total cells (321 ± 135 cells/mm2; P <.01) and progenitor cells (20 ± 4 cells/mm2; P <.001). Vascular area was directly correlated with progenitor cell quantity (P =.006002). An increase in probability of successful operation was associated with a linear increase in vascular area (R 2 = 0.765) and an exponential increase in progenitor cell quantity (R 2 = 0.795). Subsequently, quadratic models of vascularity and progenitor cell quantity around the labral clock were used to assess relative healing potential. Quadratic models for percentage vascular area (P = 6.35e-07) and weighted progenitor cell density (P = 3.03e-05) around the labral clock showed that percentage vascular area and progenitor cell quantity increased as labral tissue neared the inferior aspect and diminished near the superior aspect. Conclusion: Anatomic regions of the glenoid labrum differ in extracellular matrix composition, vascularity, and cell composition. The superior glenoid labrum is deficient in vascularity and progenitor cells, which may explain the high failure rates for repairs in this location. Clinical Relevance: Improved understanding of the composition of distinct glenoid labral positions may help to improve therapeutic strategies for labral pathology. [ABSTRACT FROM AUTHOR]

Background: Although the infection rates for bone–patellar tendon–bone autograft (BTB), hamstring tendon autograft (HT), and allograft have been reported previously, there are limited data available for a large cohort of individuals undergoing anterior cruciate ligament (ACL) reconstruction (ACLR) using quadriceps tendon autograft (QT). Purpose: The aims of this study are (1) to compare rates of septic arthritis after primary and revision ACLR with QT, BTB, HT, and allograft and (2) to evaluate the association between an infection after ACLR and potential risk factors in a large single-system analysis. Study Design: Cohort study; Level of evidence, 3. Methods: All ACLR cases performed by 10 high-volume sports medicine fellowship–trained ACL surgeons between January 2000 and January 2022 were retrospectively analyzed. Minimum follow-up was 90 days after ACLR, and all multiligament reconstructions were excluded. Demographic information, surgical variables, infection characteristics, and rate of ACL graft retention were collected for all included patients. Independent samples t test, chi-square test, or Fisher exact tests with adjusted Benjamini-Hochberg post hoc procedure were used for group comparisons. Results: In total, 6652 patients were included in this study. The most commonly used graft was allograft (n = 2491; 37.4%), followed by HT (n = 1743; 26.2%), BTB (n = 1478; 22.2%), and QT (n = 940; 14.1%). The overall postoperative rate of septic arthritis was 0.34% (n = 23). Septic arthritis rates based on graft type were 0.74% (n = 13) for HT, 0.24% (n = 6) for allograft, 0.20% (n = 3) for BTB, and 0.10% (n = 1) for QT. While a statistically significant difference with regard to graft type (P =.01) was observed, no significant relationships were found between postoperative septic arthritis and age, sex, revision ACLR, ACLR surgical technique, and accompanying intra-articular procedures for all septic arthritis patients (P >.05). The average time from the onset of the symptoms of infection to surgical irrigation and debridement (I&D) was 2 days (minimum, 0; maximum, 6). ACL grafts were retained during I&D procedures in all patients with postoperative septic arthritis. Conclusion: The postoperative rate of septic arthritis was 0.1% after use of the QT autograft. While graft choice may affect rates of septic arthritis after ACLR, patient characteristics, ACLR technique, revision ACLR, and accompanying intra-articular procedures during ACLR were not associated with postoperative septic arthritis with the numbers available for analysis. [ABSTRACT FROM AUTHOR]

Background: Mechanical loading and alendronate (ALN) can be used as noninvasive physical therapy methods for osteoarthritis (OA). However, the timing and efficacy for treatments are unknown. Purpose: To determine whether the timing of mechanical loading and ALN influences the pathobiological changes of OA. Study Design: Controlled laboratory study. Methods: Mice with OA induced by anterior cruciate ligament transection were subjected to early (1-3 weeks) or late (5-7 weeks) axial compressive dynamic load or intraperitoneal injection of ALN. Changes in gait were analyzed using gait analysis system, pathobiological changes in subchondral bone, cartilage, osteophyte, and synovitis were assessed using micro–computed tomography, tartrate-resistant acid phosphatase staining, pathologic section staining, and immunohistochemistry at 1, 2, 4, and 8 weeks. Results: At 1, 2, and 4 weeks, the OA limb had lower mean footprint pressure intensity, lower bone volume per tissue volume (BV/TV) in the subchondral bone, and more osteoclasts. At 4 weeks, the early loading, ALN, and load + ALN treatments induced less cartilage destruction, with a corresponding reduction in Osteoarthritis Research Society International score and increased hyaline cartilage thickness. The treatments also resulted in fewer osteoclasts and higher BV/TV and bone mineral density of subchondral bone and suppressed inflammation and interleukin 1β– and tumor necrosis factor α-positive cells in synovium. At 8 weeks, early loading or load + ALN improved the mean footprint pressure intensity and knee flexion. At 8 weeks, early load + ALN had a synergistic effect on protecting hyaline cartilage and proteoglycans. Footprint pressure intensity and cartilage destruction were worse in late loading limbs, and no differences in BV/TV, bone mineral density, osteophyte formation, and synovium inflammation were found between the late load, ALN, and load + ALN groups and the anterior cruciate ligament transection group. Conclusion: Dynamic axial mechanical loading or ALN in the early stages of knee trauma protected against OA by suppressing subchondral bone remodeling. However, late loading promoted cartilage degeneration in advanced OA, indicating that reduced loading should be performed in the late stages of OA to avoid the acceleration of OA. Clinical Relevance: Early low-level functional exercise or antiosteoporotic drugs could clearly slow or prevent the progression of early OA. For patients with mild to severe OA, loading reduction via brace protection or maintenance of joint stability via early ligament reconstruction surgery may ameliorate OA exacerbation. [ABSTRACT FROM AUTHOR]

Background: Return to sport is essential information when an athlete contemplates surgical intervention. Young athletes, <30 years of age, may undergo complex cartilage procedures or femoral/tibial osteotomies to successfully treat single-compartment knee osteoarthritis. Unicompartmental knee arthroplasty (UKA) may offer an attractive alternative option to middle-aged/older athletes with timely return to the same sport without a lengthy rehabilitation. Purpose: The purpose of this study was to determine if athletes are able to return to the same level of vigorous and moderate sports after fixed-bearing intramedullary nonrobotic UKA and the specific sports activities that these athletes continued to participate in at a minimum of 5 years. We hypothesized that UKA in the appropriately selected middle-aged/older athlete would yield high return to sport after UKA with high patient satisfaction. We also hypothesized that UKA would allow athletes to return to their sports of choice. Study Design: Cohort study; Level of evidence, 3. Methods: We identified 245 patients who underwent a UKA by a single surgeon between 2003 and 2017. Athletes were included if they participated in vigorous or moderate sports, as defined by the American College of Sports Medicine, and had minimum 5-year follow-up. The primary outcome was return to vigorous or moderate sports after UKA. Secondary outcomes included the Knee injury and Osteoarthritis Outcome Score (KOOS) Activities of Daily Living score, KOOS Sport and Recreation score, Lysholm score, Patient Acceptable Symptom State (PASS) analysis, and radiographic analysis. Results: An overall 169 athletes met the inclusion criteria and were evaluated for return to sports. A total of 98% (165/169) returned to vigorous or moderate sports participation. The mean ± SD time to return to sport was 5.2 ± 2.3 months in the 39- to 50-year-old cohort, 5.8 ± 3.2 months in athletes aged 51 to 64 years, and 5.2 ± 3.0 months in athletes aged ≥65 years. A total of 143 athletes had minimum 5-year clinical and radiographic follow-up (mean, 10 years; range, 5-19 years). Maintenance of vigorous and moderate sport was seen in 99% (142/143) of athletes at a mean 10 years. In athletes who participated in vigorous sports, the mean Lysholm score was 85 ± 17, and 83% reached the PASS for KOOS Sport and Recreation. Radiographic analysis revealed no evidence of implant loosening (ie, subsidence, radiolucency) or osteolysis, and limb alignment and posterior slope of the implant were within normal limits. Conclusion: Athletes returned to sport at a mean 5 months after UKA implantation, with 98% (165/169) participating in vigorous or moderate sports. UKA is recommended as an alternative procedure in middle-aged and older athletes with single-compartment osteoarthritis who are contemplating a return to vigorous or moderate sport. [ABSTRACT FROM AUTHOR]

Background: The Knee injury and Osteoarthritis Outcomes Score (KOOS) is a widely used region-specific outcome measure for assessing patients of all ages with a variety of knee conditions. Use of the KOOS for young active patients with anterior cruciate ligament (ACL) tear has been called into question regarding its relevance and interpretability for this specific population. Furthermore, the KOOS does not have adequate structural validity for use in high-functioning patients with ACL deficiency. Purpose: To develop a condition-specific short form version of the KOOS that is appropriate for the young active population with ACL deficiency: the KOOS-ACL. Study Design: Cohort study (diagnosis); Level of evidence, 2. Methods: A baseline data set of 618 young patients (≤25 years old) with ACL tears was divided into development and validation samples. Exploratory factor analyses were conducted in the development sample to identify the underlying factor structure and to reduce the number of items based on statistical and conceptual indicators. Confirmatory factor analyses were conducted to check fit indices of the proposed KOOS-ACL model in both samples. Psychometric properties of the KOOS-ACL were assessed using the same data set, expanded to include patient data from 5 time points (baseline and postoperative 3, 6, 12, and 24 months). Internal consistency reliability, structural validity, convergent validity, responsiveness to change, floor/ceiling effects, and detection of treatment effects between surgical interventions (ACL reconstruction alone vs ACL reconstruction + lateral extra-articular tenodesis) were assessed. Results: A 2-factor structure was deemed most appropriate for the KOOS-ACL. Of 42 items, 30 were removed from the full-length KOOS. The final KOOS-ACL model showed acceptable internal consistency reliability (α =.79-.90), structural validity (comparative fit index and Tucker-Lewis index = 0.98-0.99; root mean square error of approximation and standardized root mean square residual = 0.04-0.07), convergent validity (Spearman correlation with International Knee Documentation Committee subjective knee form = 0.61-0.83), and responsiveness across time (significant small to large effects; P <.05). Conclusion: The new KOOS-ACL questionnaire contains 12 items and 2 subscales—Function (8 items) and Sport (4 items)—relevant to young active patients with an ACL tear. Use of this short form would reduce patient burden by more than two-thirds; it provides improved structural validity as compared with the full-length KOOS for our population of interest; and it demonstrates adequate psychometric properties in our sample of young active patients undergoing ACL reconstruction. [ABSTRACT FROM AUTHOR]

Background: Infiltration of cluster of differentiation (CD) 3+ (CD3+) T cells into the synovium and synovial fluid occurs in most patients with posttraumatic osteoarthritis. During disease progression, proinflammatory T helper 17 cells and anti-inflammatory regulatory T cells infiltrate the joint in response to inflammation. This study aimed to characterize the dynamics of regulatory T and T helper 17 cell populations in synovial fluid from equine clinical patients with posttraumatic osteoarthritis to determine whether phenotype and function are associated with potential immunotherapeutic targets. Hypothesis: An imbalance of the ratio of regulatory T cells and T helper 17 cells would be associated with disease progression in posttraumatic osteoarthritis, suggesting opportunities for immunomodulatory therapy. Study Design: Descriptive laboratory study. Methods: Synovial fluid was aspirated from the joints of equine clinical patients undergoing arthroscopic surgery for posttraumatic osteoarthritis resulting from intra-articular fragmentation. Joints were classified as having mild or moderate posttraumatic osteoarthritis. Synovial fluid was also obtained from nonoperated horses with normal cartilage. Peripheral blood was obtained from horses with normal cartilage and those with mild and moderate posttraumatic osteoarthritis. Synovial fluid and peripheral blood cells were analyzed by flow cytometry, and native synovial fluid was analyzed by enzyme-linked immunosorbent assay. Results: CD3+ T cells represented 81% of lymphocytes in synovial fluid, which increased in animals with moderate posttraumatic osteoarthritis to 88.3% (P =.02). CD14+ macrophages were doubled in those with moderate posttraumatic osteoarthritis compared with mild posttraumatic osteoarthritis and controls (P <.001). Less than 5% of CD3+ T cells found within the joint were forkhead box P3 protein+ (Foxp3+) regulatory T cells, but a 4- to 8-times higher percentage of nonoperated and mild posttraumatic osteoarthritis joint regulatory T cells secreted interleukin (IL)–10 than peripheral blood Tregs (P <.005). T regulatory-1 cells that secreted IL-10 but did not express Foxp3 accounted for approximately 5% of CD3+ T cells in all joints. T helper 17 cells and Th17-like regulatory T cells were increased in those with moderate posttraumatic osteoarthritis (P <.0001) compared with mild and nonoperated patients. IL-10, IL-17A, IL-6, chemokine (C-C motif) ligand (CCL) 2 (CCL2), and CCL5 concentrations detected by enzyme-linked immunosorbent assay in synovial fluid were not different between groups. Conclusions: An imbalance of the ratio of regulatory T cells and T helper 17 cells and an increase in T helper 17 cell–like regulatory T cells in synovial fluid from joints with more severe disease provide novel insights into immunological mechanisms that are associated with posttraumatic osteoarthritis progression and pathogenesis. Clinical Relevance: Early and targeted use of immunotherapeutics in the mitigation of posttraumatic osteoarthritis may improve patient clinical outcomes. [ABSTRACT FROM AUTHOR]

Background: PARP-1 (poly[ADP-ribose]) was shown to influence the inflammatory response after rotator cuff tear, leading to fibrosis, muscular atrophy, and fatty infiltration in mouse rotator cuff degeneration. So far, it is not known how PARP-1 influences enthesis healing after rotator cuff tear repair. Hypothesis/Purpose: This study aimed to examine the feasibility of oral PARP-1 inhibition and investigate its influence on rat supraspinatus enthesis and muscle healing after rotator cuff repair. The hypothesis was that oral PARP-1 inhibition would improve enthesis healing after acute rotator cuff repair in a rat model. Study Design: Controlled laboratory study. Methods: In 24 Sprague-Dawley rats, the supraspinatus tendon was sharply detached and immediately repaired with a single transosseous suture. The rats were randomly allocated into 2 groups, with the rats in the inhibitor group receiving veliparib with a target dose of 12.5 mg/kg/d via drinking water during the postoperative recovery period. The animals were sacrificed 8 weeks after surgery. For the analysis, macroscopic, biomechanical, and histologic methods were used. Results: Oral veliparib was safe for the rats, with no adverse effects observed. In total, the inhibitor group had a significantly better histologic grading of the enthesis with less scar tissue formation. The macroscopic cross-sectional area of the supraspinatus muscles was 10.5% higher (P =.034) in the inhibitor group, which was in agreement with an 8.7% higher microscopic muscle fiber diameter on histologic sections (P <.0001). There were no statistically significant differences in the biomechanical properties between the groups. Conclusion: This study is the first to investigate the influence of PARP-1 inhibition on healing enthesis. On the basis of these findings, we conclude that oral veliparib, which was previously shown to inhibit PARP-1 effectively, is safe to apply and has beneficial effects on morphologic enthesis healing and muscle fiber size. Clinical Relevance: Modulating the inflammatory response through PARP-1 inhibition during the postoperative healing period is a promising approach to improve enthesis healing and reduce rotator cuff retearing. With substances already approved by the Food and Drug Administration, PARP-1 inhibition bears high potential for future translation into clinical application. [ABSTRACT FROM AUTHOR]

Background: The importance of maintaining lateral patellar stabilizing structures has been demonstrated by the presence of iatrogenic medial patellar instability after lateral retinacular release (LRR) procedures. In patients with medial patellar instability, lateral patellofemoral ligament (LPFL) reconstruction has been clinically shown to restore patellar stability while improving patient-reported outcomes. However, the biomechanics associated with different LPFL reconstruction techniques remain largely unknown. Purpose: To (1) investigate whether LPFL reconstruction restores medial patellar translation compared with the intact state after LRR and (2) evaluate for any biomechanical differences between soft tissue and osseous LPFL reconstruction techniques. Study Design: Controlled laboratory study. Methods: A total of 7 knees were included in the final analysis. The knees were dissected, and the tibia and femur were potted. An eye screw was then placed at the midpoint of the patella perpendicular to the medial surface. A custom jig was constructed to allow for a 1-kg load to be applied to the quadriceps muscle. Medial patellar displacement was investigated at 0°, 10°, 20°, 30°, 45°, 60°, and 90° of knee flexion using a tensile testing machine with a 20-N medial force applied to the patella. Medial patellar displacement was assessed in 4 states: intact, LRR, soft tissue LPFL reconstruction (inserted through incisions in the iliotibial band, quadriceps tendon, and patellar tendon), and osseous LPFL reconstruction. Results: The LRR group had significantly greater medial patellar translation compared with the intact group throughout flexion (P <.01 to P =.029). The soft tissue LPFL reconstruction group demonstrated significantly greater medial patellar translation at 30° (P =.020) and 45° (P =.025) compared with the intact group, with less translation compared with the LRR group at all degrees of knee flexion except for 45° (P =.065). The osseous LPFL reconstruction group demonstrated significantly greater medial patellar translation compared with the intact group at 30° of flexion (P =.036), with significantly less translation compared with the LRR group from 0° to 30° (P <.01 to P =.013). The soft tissue LPFL reconstruction group (15.94 ± 2.55 mm) demonstrated significantly greater medial patellar translation at 10° of flexion compared with the osseous LPFL reconstruction group (14.16 ± 2.34 mm) (P =.033). Conclusion: Soft tissue LPFL reconstruction led to significantly greater medial patellar translation at 30° and 45° compared with the intact state, while osseous LPFL reconstruction produced significantly greater translation only at 30°. Both the soft tissue and the osseous reconstruction techniques resulted in comparable medial patellar translation at all degrees of knee flexion except for 10°, in which osseous reconstruction was more similar to the intact state. Clinical Relevance: Compared with LRR, soft tissue LPFL reconstruction was able to restore stability against medial patellar translation at most degrees of knee flexion, while osseous LPFL reconstruction did not provide adequate stabilization beyond 30° of flexion. While the LPFL does appear to have osseous insertions, soft tissue reconstruction functioned more similarly to the intact state after LRR. [ABSTRACT FROM AUTHOR]

Background: Doxycycline (Doxy) has been shown to facilitate tendon healing by reducing on-site matrix metalloproteinase (MMP) activity, but its effect on graft healing after anterior cruciate ligament reconstruction (ACLR) has not been investigated, and the therapeutic effect of Doxy in preventing ACLR-induced posttraumatic osteoarthritis (PTOA) is unclear. Hypothesis: Doxy promotes graft healing and alleviates the progression of PTOA after ACLR. Study Design: Controlled laboratory study. Methods: Sprague Dawley rats (n = 74; age, 12-13 weeks; male) that underwent ACLR were divided into untreated control and Doxy treatment (50 mg/kg/d orally until sacrifice) groups. At 2 and 6 weeks after surgery, graft healing was assessed by biomechanical testing, histology, immunohistochemical staining, and micro–computed tomography (μCT). The progression of PTOA was evaluated at 6 weeks by histology, the Mankin score, and immunofluorescence staining of the tibial plateau, and osteophyte formation was evaluated by μCT. Hindlimb weight distribution was evaluated at 6 weeks, and gait patterns were evaluated at 2 and 6 weeks. Intra-articular MMP activity was evaluated at 6 weeks in vivo using an MMP-activatable near-infrared fluorescent probe. Results: Graft healing was enhanced by Doxy treatment, and the ultimate failure load (P =.002) and stiffness of the graft (P =.007) were significantly higher in the Doxy group at week 2. Bone mineral density and bone volume/total volume for both the tibial and the femoral tunnels at week 6 in the Doxy group were significantly higher compared with in the control group (P <.05). The overall graft healing scores were significantly higher in the Doxy group. Doxy treatment enhanced graft integration, intratunnel graft integrity, and collagen birefringence; more collagen types 1 and 10 and less MMP-13 were found at the graft-bone interface. At week 6, the Doxy group had a lower modified Mankin score (P =.033) and showed fewer MMP 13–positive chondrocytes at the articular cartilage surface (P =.002), indicating moderate joint cartilage damage. μCT revealed less osteophyte formation, and gait analysis revealed more symmetric weightbearing and gait patterns, after Doxy treatment at week 6 (P <.05). In vivo imaging with the near-infrared fluorescent probe identified significantly lower intra-articular MMP activity in the Doxy group at week 6 (P =.016). Conclusion: The oral administration of Doxy was able to synchronously promote graft healing and attenuate PTOA in an ACLR rat model. Clinical Relevance: Our results indicated that Doxy, a widely used drug, is potentially beneficial to patients after ACLR. [ABSTRACT FROM AUTHOR]

Background: Noncontact anterior cruciate ligament (ACL) injuries typically occur during deceleration movements such as landing or cutting. However, conflicting data have left the kinematic mechanisms leading to these injuries unclear. Quantifying the influence of sagittal and coronal plane knee kinematics on in vivo ACL strain may help to elucidate noncontact ACL injury mechanisms. Purpose/Hypothesis: The purpose of this study was to measure in vivo sagittal and coronal plane knee kinematics and ACL strain during a single-leg jump. We hypothesized that ACL strain would be modulated primarily by motion in the sagittal plane and that limited coronal plane motion would be measured during this activity. Study Design: Descriptive laboratory study. Methods: Seventeen healthy participants (8 male/9 female) underwent magnetic resonance imaging (MRI) followed by high-speed biplanar radiography, obtained as participants performed a single-leg jump. Three-dimensional models of the femur, tibia, and associated ACL attachment site footprints were created from the MRIs and registered to the radiographs to reproduce the position of the knee during the jump. ACL strain, knee flexion/extension angles, and varus/valgus angles were measured throughout the jump. Spearman rank correlations were used to assess relationships between mean ACL strain and kinematic variables. Results: Mean ACL strain increased with decreasing knee flexion angle (ρ = −0.3; P =.002), and local maxima in ACL strain occurred with the knee in a straight position in both the sagittal and the coronal planes. In addition, limited coronal plane motion (varus/valgus angle) was measured during this activity (mean ± SD, −0.5°± 0.3°). Furthermore, we did not detect a statistically significant relationship between ACL strain and varus/valgus angle (ρ = −0.01; P =.9). Conclusion: ACL strain was maximized when the knee was in a straight position in both the sagittal and coronal planes. Participants remained in <1° of varus/valgus position on average throughout the jump. As a ligament under elevated strain is more vulnerable to injury, landing on a straight knee may be an important risk factor for ACL rupture. Clinical Relevance: These data may improve understanding of risk factors for noncontact ACL injury, which may be useful in designing ACL injury prevention programs. [ABSTRACT FROM AUTHOR]

Background: Although randomized controlled trials comparing hip arthroscopy with physical therapy for the treatment of femoroacetabular impingement (FAI) syndrome have emerged, no studies have investigated potential moderators or mediators of change in hip-related quality of life. Purpose: To explore potential moderators, mediators, and prognostic indicators of the effect of hip arthroscopy and physical therapy on change in 33-item international Hip Outcome Tool (iHOT-33) score for FAI syndrome. Study Design: Cohort study; Level of evidence, 2. Methods: Overall, 99 participants were recruited from the clinics of orthopaedic surgeons and randomly allocated to treatment with hip arthroscopy or physical therapy. Change in iHOT-33 score from baseline to 12 months was the dependent outcome for analyses of moderators, mediators, and prognostic indicators. Variables investigated as potential moderators/prognostic indicators were demographic variables, symptom duration, alpha angle, lateral center-edge angle (LCEA), Hip Osteoarthritis MRI Scoring System (HOAMS) for selected magnetic resonance imaging (MRI) features, and delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) score. Potential mediators investigated were change in chosen bony morphology measures, HOAMS, and dGEMRIC score from baseline to 12 months. For hip arthroscopy, intraoperative procedures performed (femoral ostectomy ± acetabular ostectomy ± labral repair ± ligamentum teres debridement) and quality of surgery graded by a blinded surgical review panel were investigated for potential association with iHOT-33 change. For physical therapy, fidelity to the physical therapy program was investigated for potential association with iHOT-33 change. Results: A total of 81 participants were included in the final moderator/prognostic indicator analysis and 85 participants in the final mediator analysis after exclusion of those with missing data. No significant moderators or mediators of change in iHOT-33 score from baseline to 12 months were identified. Patients with smaller baseline LCEA (β = −0.82; P =.034), access to private health care (β = 12.91; P =.013), and worse baseline iHOT-33 score (β = −0.48; P <.001) had greater iHOT-33 improvement from baseline to 12 months, irrespective of treatment allocation, and thus were prognostic indicators of treatment response. Unsatisfactory treatment fidelity was associated with worse treatment response (β = −24.27; P =.013) for physical therapy. The quality of surgery and procedures performed were not associated with iHOT-33 change for hip arthroscopy (P =.460-.665 and P =.096-.824, respectively). Conclusion: No moderators or mediators of change in hip-related quality of life were identified for treatment of FAI syndrome with hip arthroscopy or physical therapy in these exploratory analyses. Patients who accessed the Australian private health care system, had smaller LCEAs, and had worse baseline iHOT-33 scores, experienced greater iHOT-33 improvement, irrespective of treatment allocation. [ABSTRACT FROM AUTHOR]

Background: Approximately half of concussions go undisclosed and therefore undiagnosed. Among diagnosed concussions, 51% to 64% receive delayed medical care. Understanding the influence of undiagnosed concussions and delayed medical care would inform medical and education practices. Purpose: To compare postconcussion longitudinal clinical outcomes among (1) individuals with no concussion history, all previous concussions diagnosed, and ≥1 previous concussion undiagnosed, as well as (2) those who have delayed versus immediate symptom onset, symptom reporting, and removal from activity after concussion. Study Design: Cohort study; Level of evidence, 2. Methods: Participants included 2758 military academy cadets and intercollegiate athletes diagnosed with concussion in the CARE Consortium. We determined (1) each participant's previous concussion diagnosis status self-reported at baseline (no history, all diagnosed, ≥1 undiagnosed) and (2) whether the participant had delayed or immediate symptom onset, symptom reporting, and removal from activity. We compared symptom severities, cognition, balance, and recovery duration at baseline, 24 to 48 hours, date of asymptomatic status, and date of unrestricted return to activity using tests of parallel profiles. Results: The ≥1 undiagnosed concussion group had higher baseline symptom burdens (P <.001) than the other 2 groups and poorer baseline verbal memory performance (P =.001) than the all diagnosed group; however, they became asymptomatic and returned to activity sooner than those with no history. Cadets/athletes who delayed symptom reporting had higher symptom burdens 24 to 48 hours after injury (mean ± SE; delayed, 28.8 ± 0.8; immediate, 20.6 ± 0.7), took a median difference of 2 days longer to become asymptomatic, and took 3 days longer to return to activity than those who had immediate symptom reporting. For every 30 minutes of continued participation after injury, days to asymptomatic status increased 8.1% (95% CI, 0.3%-16.4%). Conclusion: Clinicians should expect that cadets/athletes who delay reporting concussion symptoms will have acutely higher symptom burdens and take 2 days longer to become asymptomatic. Educational messaging should emphasize the clinical benefits of seeking immediate care for concussion-like symptoms. [ABSTRACT FROM AUTHOR]

Background: Superior capsule reconstruction (SCR) was developed as an alternative treatment for irreparable rotator cuff tears to restore superior stability of the glenohumeral joint. Although fatty infiltration (FI) of the rotator cuff muscles, especially the infraspinatus, has been implicated as a predictor of outcomes and graft integrity after rotator cuff repair, it has not been fully investigated in cases of SCR. Purpose: To evaluate the effect of FI of the infraspinatus muscle on clinical and radiological outcomes after SCR. Study Design: Cohort study; Level of evidence, 3. Methods: A total of 55 consecutive patients with irreparable posterosuperior rotator cuff tears who underwent SCR between January 2013 and August 2020 were included retrospectively. Preoperative and postoperative clinical and radiological findings (median follow-up of >2 years), including magnetic resonance imaging results, were thoroughly reviewed. The patients were divided into 2 groups: group 1 with mild FI of the infraspinatus (Goutallier grades 0-2) and group 2 with severe FI of the infraspinatus (Goutallier grades 3-4). The American Shoulder and Elbow Surgeons score, Constant score, visual analog scale score for pain, and range of motion were evaluated. Acromiohumeral distance and rotator cuff tear arthropathy using the Hamada classification were assessed on plain radiography. Postoperative graft integrity was evaluated by magnetic resonance imaging. Graft failure was defined as complete discontinuity. Univariate and multivariable logistic regression analyses were performed to evaluate clinical and radiological findings that might be associated with successful SCR. Results: Clinical and radiological outcomes significantly improved after SCR. Graft failure was noted in 15 (27.3%) patients and was more frequent in group 2 than in group 1 (50.0% vs 14.3%, respectively; P =.004). Univariate analysis indicated a significant association between severe FI in the infraspinatus (group 2) and graft failure after SCR (odds ratio, 6.00 [95% CI, 1.65-21.80]; P =.006). Multivariable analysis indicated that FI of the infraspinatus was the only factor associated with graft failure (odds ratio, 6.37 [95% CI, 1.63-24.90]; P =.008). Conclusion: Severe FI of the infraspinatus muscle was a factor indicating a poor prognosis for graft integrity after SCR. Preoperative evaluation of FI in the rotator cuff muscles can help predict postoperative outcomes and may help guide therapeutic options. [ABSTRACT FROM AUTHOR]

Background: Previous studies have examined the transcriptomes and mechanical properties of whole tendons in different regions of the body. However, less is known about these characteristics within a single tendon. Purpose: To develop a regional transcriptomic atlas and evaluate the region-specific mechanical properties of Achilles tendons. Study Design: Descriptive laboratory study. Methods: Achilles tendons from 2-month-old male Sprague Dawley rats were used. Tendons were isolated and divided into proximal, middle, and distal thirds for RNA sequencing (n = 5). For mechanical testing, the Achilles muscle-tendon-calcaneus unit was mounted in a custom-designed materials testing system with the unit clamped over the musculotendinous junction (MTJ) and the calcaneus secured at 90° of dorsiflexion (n = 9). Tendons were stretched to 20 N at a constant speed of 0.0167 mm/s. Cross-sectional area, strain, stress, and Young modulus were determined in each tendon region. Results: An open-access, interactive transcriptional atlas was generated that revealed distinct gene expression signatures in each tendon region. The proximal and distal regions had the largest differences in gene expression, with 2596 genes significantly differentially regulated at least 1.5-fold (q <.01). The proximal tendon displayed increased expression of genes resembling a tendon phenotype and increased expression of nerve cell markers. The distal region displayed increases in genes involved in extracellular matrix synthesis and remodeling, immune cell regulation, and a phenotype similar to cartilage and bone. There was a 3.72-fold increase in Young modulus from the proximal to middle region (P <.01) and an additional 1.34-fold increase from the middle to distal region (P =.027). Conclusion: Within a single tendon, there are region-specific transcriptomic signatures and mechanical properties, and there is likely a gradient in the biological and functional phenotype from the proximal origin at the MTJ to the distal insertion at the enthesis. Clinical Relevance: These findings improve our understanding of the underlying biological heterogeneity of tendon tissue and will help inform the future targeted use of regenerative medicine and tissue engineering strategies for patients with tendon disorders. [ABSTRACT FROM AUTHOR]

Background: Clinical trials are currently underway to investigate the efficacy of intra-articular administration of mesenchymal stromal cells (MSCs) to mitigate osteoarthritis (OA) progression in the knee. Although multiple MSC sources exist, studies have yet to determine whether differences in therapeutic efficacy exist between them. Purpose: To compare the ability of intra-articularly injected adipose-derived MSCs (AD-MSCs) and amnion-derived MSCs (AM-MSCs) to mitigate the progression of knee OA in a small animal model of spontaneous OA, as well as to compare the therapeutic potential of MSCs in hyaluronic acid (HA) and in HA only with saline (OA) controls. Study Design: Controlled laboratory study. Methods: Injections of AD-MSCs or AM-MSCs suspended in HA or HA only were performed in the rear stifle joints of 3-month-old Dunkin Hartley guinea pigs (DHGPs). Repeat injections occurred at 2 and 4 months after the initial injection in each animal. Contralateral limbs received saline injections and served as untreated controls. Subsequently, joints were analyzed for osteoarthritic changes of the cartilage and subchondral bone via histologic and biochemical analyses. To evaluate MSC retention time in the joint space, DHGPs received a single intra-articular injection of fluorescently labeled AD-MSCs or AM-MSCs, and the fluorescence intensity was longitudinally tracked via an in vivo imaging system. Results: No statistically significant differences in outcomes were found when comparing the ability of AD-MSCs and AM-MSCs to mitigate OA. However, the injection of AD-MSCs, AM-MSCs, and HA-only treatments more effectively mitigated cartilage damage compared with that of saline controls by demonstrating higher amounts of cartilage glycosaminoglycan content and improved histological proteoglycan scoring while reducing the percentage of osteophytes present. Conclusion: Intra-articular injection of AD-MSCs, AM-MSCs, or HA only was able to similarly mitigate the progression of cartilage damage and reduce the percentage of osteophytes compared with that of saline controls in the DHGP. However, this study was unable to establish the superiority of AD-MSCs versus AM-MSCs as a treatment to mitigate spontaneous OA. Clinical Relevance: MSCs demonstrate the ability to mitigate the progression of knee OA and thus may be used in a prophylactic approach to delay the need for end-stage treatment strategies. [ABSTRACT FROM AUTHOR]

Background: Articular step-off between the donor and recipient in osteochondral allograft transplant has been shown to alter contact pressures. Currently, commercial allograft donor selection is primarily based on simple anatomic parameters such as trochlear length, trochlear width, and tibial width. Purpose: To identify anatomic factors associated with optimal graft matching by using a 3-dimensional simulation model. Study Design: Descriptive laboratory study. Methods: Computed tomography images of 10 cadaveric trochlear specimens were obtained to generate 3-dimensional models. Circular defects were created virtually in the recipient trochleae at both superolateral (18.0 mm and 22.5 mm) and central (18.0 mm, 22.5 mm, 30.0 mm) locations. The donor models were virtually projected onto the defect models, and the most optimal graft from any location of the donor specimen was selected. Cartilage incongruity, subchondral bone incongruity, and peripheral articular step-off were calculated for each graft-defect combination. Linear regression models were generated to identify predictors of incongruity, step-off, and the effect of sulcus and sagittal angle mismatch. Akaike information criterion–driven stepwise regression models were generated to identify multivariate predictors. Results: Ideal matches were found for 100% of superolateral defects but for only 15% to 53% of central defects, depending on the defect size. Multivariate stepwise regression identified laterality (odds ratio [OR], 0.54; P =.081), sulcus angle (OR, 0.79; P <.001), sagittal angle (OR, 0.83; P =.001), lateral radius of curvature (OR, 0.81; P <.001), and medial facet width (OR, 0.86; P =.155) as predictors of ideal graft matching. In central defects with proud grafts, increasing sagittal angle and sulcus angle resulted in significantly (P <.001) increased articular step-off, which became sequentially larger with defect size. Conclusion: Sagittal angle, sulcus angle, and lateral radius of curvature mismatch should be used to determine optimal donor allografts, especially in the setting of large (30-mm) central defects. Increasing sulcus angle and sagittal angle mismatch correlated with increasing step-off in proud grafts, whereas sulcus angle and sagittal angle inconsistently correlated with step-off in recessed grafts. Clinical Relevance: Additional descriptive trochlear measurements should be incorporated into the algorithm for donor selection. These findings can be used to identify acceptable mismatch parameters. [ABSTRACT FROM AUTHOR]

Background: Previous studies have demonstrated a clinically impactful change in patients between 1 and 2 years after hip arthroscopy. Assessment of differences in patient-specific factors between patients who remain the same and those who change (ie, either improve or decline) could provide valuable outcome information for orthopaedic surgeons treating those patients. Purpose: To identify patients who experienced change in functional status between 1 and 2 years after hip arthroscopy for femoroacetabular impingement syndrome and assess differences in patient-specific factors between those who improved, remained the same, or declined in functional status. Study Design: Cohort study; Level of evidence, 3. Methods: Prospectively collected data for patients who underwent hip arthroscopy at 1 of 7 centers were analyzed retrospectively at 1 year and 2 years postoperatively. Patients were categorized as "improved,""remained the same," or "declined" between 1- and 2-year follow-up based on the 12-item International Hip Outcome Tool (iHOT-12) minimal clinically important difference (MCID) value. A 1-way analysis of variance was used to assess differences in iHOT-12 scores, age, body mass index (BMI), alpha angle, and center-edge angle (CEA) between groups. Chi-square analyses were used to assess differences in the proportions of male and female patients in the outcome groups. Results: The study included 753 patients (515 women and 238 men), whose mean ± SD age was 34.7 ± 12 years. Average 1-year (±1 month) and 2-year (±2 months) iHOT-12 scores for all patients were 73.7 and 74.9, respectively. Based on the calculated MCID of ±11.5 points, 162 (21.5%) patients improved, 451 (59.9%) remained the same, and 140 (18.6%) declined in status between 1- and 2-year follow-up. Those who improved between 1 and 2 years had lower 1-year iHOT-12 scores (P <.0005). We found no difference in age, BMI, alpha angle, CEA, or sex between groups (P >.05). Conclusion: Between 1- and 2-year follow-up assessments, 21.5% of patients improved and 18.6% declined in self-reported functional status. Those with iHOT-12 scores indicating abnormal function at 1 year improved beyond the MCID at 2 years follow-up. Thus, any decisions about the failure or success of arthroscopic hip procedures should not be made until at least the 2-year follow-up. Failing to thrive at 1-year follow-up may not accurately predict outcomes at year 2 or beyond. This could potentially decrease the perceived need for revision surgery in patients who do not thrive before 2-year follow-up. [ABSTRACT FROM AUTHOR]

Background: Femoroacetabular impingement (FAI) is one of the most common causes of hip osteoarthritis, yet the factors controlling disease progression are poorly understood. Purpose: To investigate rates of initial and subsequent symptoms in the contralateral hip of patients with FAI, and identify predictors of disease progression (symptom development and surgical intervention) in the contralateral hip. Study Design: Cohort study; Level of evidence, 2. Methods: This prospective study included a minimum 5-year follow-up of the contralateral hip in 179 patients undergoing FAI surgery. Symptoms (moderate pain) and surgical progression were monitored. Univariate and multivariate analyses compared patient-specific and imaging characteristics of symptomatic patients with those who remained asymptomatic to identify factors associated with disease progression. Results: A total of 150 patients (84% follow-up) were followed for a mean of 7.1 years (range, 5-11 years). Thirty-nine of these patients (26% [39/150]) had contralateral hip symptoms at initial evaluation. Of those without contralateral hip symptoms at initial evaluation, 32% (36/111) had developed contralateral hip symptoms by latest follow-up. Those who developed symptoms during the study period had a lower anteroposterior head-neck offset ratio (0.153 vs 0.165; P =.005), decreased total arc of rotation in 90° of flexion (39.9° vs 51.1°; P =.005), and decreased external rotation in 90° of flexion (28.6° vs 37.1°; P =.003) compared with those who never developed symptoms. Age, sex, body mass index, alpha angle, lateral center-edge angle, internal rotation in flexion, and University of California, Los Angeles (UCLA), activity score were similar between these groups. Those with contralateral symptoms at initial evaluation progressed to contralateral surgery at a rate of 41% (16/39) and those who developed contralateral symptoms during the study period progressed to contralateral surgery at a rate of 28% (10/36). Among those with contalateral hip symptoms (either present initially or developed during study period)), younger age (24.6 vs 34.1 years; P <.001) and baseline UCLA activity score ≥9 (P =.003) were associated with progression to surgery. By Kaplan-Meier analysis, 64%, 54%, and 48% of patients remained free of contralateral hip symptoms at 2, 5, and 10 years. Conclusion: At a mean follow-up of 7.1 years, significant symptoms in the contralateral hip of patients with FAI were present in approximately 50% of patients. FAI disease progression (symptom development and surgical intervention) was associated with decreased hip rotation arc, decreased external rotation, and decreased head-neck offset ratio. In symptomatic patients, younger age and UCLA activity score ≥9 were associated with progression to surgery. These findings represent important factors for patient counseling and risk modeling in FAI. [ABSTRACT FROM AUTHOR]

Background: The preservation of the native labral vascularization is assumed to be the potential advantage of acetabular labral augmentation, the effect of which remains unknown. Purpose: To identify the vascular distribution within the labral autograft and its effect on the healing process between labral augmentation (AUG) and reconstruction (RECON) in a porcine model. Study Design: Controlled laboratory study. Methods: A total of 36 pigs randomly underwent unilateral labral augmentation or reconstruction (AUG group, n = 18; RECON group, n = 18). The pigs were randomly sacrificed at 6, 12, and 24 weeks postoperatively. The labral autografts were harvested for macroscopic evaluation and histologic assessment. The labral autograft was zoned into 2 halves to observe the vascular distribution: the capsular half (zone I) and the articular half (zone II). Each zone was divided into 2 parts: the peripheral part (IA and IIA) and the part attached to the acetabulum (IB and IIB). Results: At 6 weeks, there existed more vascular ingrowth in zone I, whereas zone IIB appeared nearly avascular in both groups. At 12 weeks, the area with the greatest vascularity was zone II in the RECON group and zone IA in the AUG group. The vascularity was concentrated at zones IA and IIA in both groups at 24 weeks. The labral autografts were hypertrophic with sufficient filling of the labral defect in both groups at 6 weeks. At 12 weeks, an insufficient volume of the articular half was observed in 3 of 6 labral autografts in the RECON group, while all autografts remained well integrated with the chondrolabral junction in the AUG group. At 24 weeks, unsatisfactory merging of the labral autograft with the cartilage at the articular side was found in 2 of 6 labral autografts in the RECON group, which was not observed in the AUG group despite the sufficient volume of autografts labrum in both groups. Conclusion: Slow vascular ingrowth within the articular half might account for the poor healing of the reconstructed labral autograft. Labral augmentation provides the possibility of better tissue healing because of the preservation of the original chondrolabral junction compared with labral reconstruction. Clinical Relevance: Labral augmentation might be a feasible alternative to labral reconstruction under the condition of viable labral remnants. [ABSTRACT FROM AUTHOR]

Background: Posttraumatic osteoarthritis (PTOA) is a common sequela of anterior cruciate ligament (ACL) injury, even when surgical treatment is selected. The effect of patient sex on cartilage health after ACL injury and surgical treatment has been less studied. Purpose/Hypothesis: The study objective was to compare the macroscopic cartilage damage that develops after ACL surgery in male and female Yucatan minipigs. It was hypothesized that after ACL surgery, the macroscopic cartilage damage of the tibiofemoral joints from female animals would be greater than that from male animals. Additionally, it was hypothesized that the effect of sex on the macroscopic cartilage damage would depend on surgical treatment. Study Design: Controlled laboratory study Methods: Twelve-month follow-up data were obtained for 55 adolescent Yucatan minipigs (22 female/33 male) that were randomized to 1 of 3 experimental groups: no treatment (ACL transection [ACLT]), ACL reconstruction, and bridge-enhanced ACL restoration. The Osteoarthritis Research Society International guidelines were used to determine a standardized macroscopic cartilage damage score on 5 surfaces of the knee joint. Results: Females had significantly worse mean total macroscopic cartilage damage scores on the surgical side (adjusted P value [ P adj] =.04) and significantly better scores on the contralateral side (P adj =.01) when compared with males. The trochlear damage scores were also significantly worse in females for surgical limbs (P adj =.009) and significantly better for the contralateral limbs (P adj <.001) when compared with males. Although there were no significant differences in total macroscopic cartilage damage scores between sexes within treatment groups on the surgical limbs (ACLT, P adj = 0.45; ACL reconstruction, P adj =.56; bridge-enhanced ACL restoration, P adj =.23), the mean trochlear scores on the surgical limb of females were significantly worse than those of the males in the ACLT group (P adj =.003). Conclusion: Mean total macroscopic cartilage damage scores of Yucatan minipigs were significantly worse in females than males, regardless of treatment. These differences were predominantly found in the trochlear scores across all treatment groups. Clinical Relevance: These data suggest that patient sex could be more influential in the progression of PTOA than surgical treatment after ACL injury. Identifying factors responsible for this discrepancy may prove valuable to identify targets to slow PTOA progression in male and female ACL-injured populations. [ABSTRACT FROM AUTHOR]

Background: There are many descriptions of medial collateral ligament (MCL) reconstruction, but they may not reproduce the anatomic structures and there is little evidence of their biomechanical performance. Purpose: To investigate the ability of "anatomic" MCL reconstruction to restore native stability after grade III MCL plus posteromedial capsule/posterior oblique ligament injuries in vitro. Study Design: Controlled laboratory study. Methods: Twelve cadaveric knees were mounted in a kinematic testing rig to impose tibial displacing loads while the knee was flexed-extended: 88-N anteroposterior translation, 5-N·m internal-external rotation, 8-N·m valgus-varus, and combined anterior translation plus external rotation (anteromedial rotatory instability). Joint motion was measured via optical trackers with the knee intact; after superficial MCL (sMCL), deep MCL (dMCL), and posterior oblique ligament transection; and then after MCL double- and triple-strand reconstructions. Double strands reproduced the sMCL and posterior oblique ligament and triple-strands the sMCL, dMCL, and posterior oblique ligament. The sMCL was placed 5 mm posterior to the epicondyle in the double-strand technique and at the epicondyle in the triple-strand technique. Kinematic changes were examined by repeated measures 2-way analysis of variance with posttesting. Results: Transection of the sMCL, dMCL, and posterior oblique ligament increased valgus rotation (5° mean) and external rotation (9° mean). The double-strand reconstruction controlled valgus in extension but allowed 5° excess valgus in flexion and did not restore external rotation (7° excess). The triple-strand reconstruction restored both external rotation and valgus throughout flexion. Conclusion: In a cadaveric model, a triple-strand reconstruction including a dMCL graft restored native external rotation, while a double-strand reconstruction without a dMCL graft did not. A reconstruction with the sMCL graft placed isometrically on the medial epicondyle restored valgus rotation across the arc of knee flexion, whereas a reconstruction with a more posteriorly placed sMCL graft slackened with knee flexion. Clinical Relevance: An MCL injury may rupture the anteromedial capsule and dMCL, causing anteromedial rotatory instability. Persistent MCL instability increases the likelihood of ACL graft failure after combined injury. A reconstruction with an anteromedial dMCL graft restored native external rotation, which may help to unload/protect an ACL graft. It is important to locate the sMCL graft isometrically at the femoral epicondyle to restore valgus across flexion. [ABSTRACT FROM AUTHOR]

Background: Wnt/β-catenin signaling suppresses the differentiation of cultured tenocytes, but its roles in tendon repair remain mostly elusive. No chemical compounds are currently available to treat tendon injury. Hypothesis: We hypothesized that the inhibition of Wnt/β-catenin signaling would accelerate tendon healing. Study Design: Controlled laboratory study. Methods: Tendon-derived cells (TDCs) were isolated from rat Achilles tendons. The right Achilles tendon was injured via a dermal punch, while the left tendon was sham operated. A Wnt/β-catenin inhibitor, IWR-1, and an antihistamine agent, promethazine (PH), were locally and intramuscularly injected, respectively, for 2 weeks after surgery. The healing tendons were histologically and biomechanically evaluated. Results: The amount of β-catenin protein was increased in the injured tendons from postoperative weeks 0.5 to 2. Inhibition of Wnt/β-catenin signaling by IWR-1 in healing tendons improved the histological abnormalities and decreased β-catenin, but it compromised the biomechanical properties. As we previously reported that antihistamine agents suppressed Wnt/β-catenin signaling in human chondrosarcoma cells, we examined the effects of antihistamines on TDCs. We found that a first-generation antihistamine agent, PH, increased the expression of the tendon marker genes Mkx and Tnmd in TDCs. Intramuscular injection of PH did not improve histological abnormalities, but it decreased β-catenin in healing tendons and increased the peak force and stiffness of the healing tendons on postoperative week 2. On postoperative week 8, however, the biomechanical properties of vehicle-treated tendons became similar to those of PH-treated tendons. Conclusion: IWR-1 and PH suppressed Wnt/β-catenin signaling and improved the histological abnormalities of healing tendons. IWR-1, however, compromised the biomechanical properties of healing tendons, whereas PH improved them. Clinical Relevance: PH is a candidate repositioned drug that potentially accelerates tendon repair. [ABSTRACT FROM AUTHOR]

Background: As many researchers have focused on promoting the graft-bone healing of artificial ligaments, even with numerous chemical coatings, identifying a biosafe, effective, and immediately usable method is still important clinically. Purpose: (1) To determine whether a low-intensity pulsed ultrasound system (LIPUS) promotes in vitro cell viability and osteogenic differentiation and (2) to assess the applicability and effectiveness of LIPUS in promoting the graft-bone healing of artificial ligaments in vivo. Study Design: Controlled laboratory study. Methods: Polyethylene terephthalate (PET) sheets and grafts were randomly assigned to control and LIPUS groups. MC3T3-E1 preosteoblasts were cultured on PET sheets. Cell viability and morphology were evaluated using a live/dead viability assay and scanning electron microscopy. Alkaline phosphatase activity, calcium nodule formation, and Western blot were evaluated for osteogenic differentiation. For in vivo experiments, the effect of LIPUS was evaluated via an extra-articular graft-bone healing model in 48 rabbits: the osteointegration and new bone formation were tested by micro–computed tomography and histological staining, and the graft-bone bonding was tested by biomechanical testing. Results: Cell viability was significantly higher in the LIPUS group as compared with control (living and dead compared between control and LIPUS groups, P =.0489 vs P =.0489). Better adherence of cells and greater development of extracellular matrix were observed in the LIPUS group. Furthermore, LIPUS promoted alkaline phosphatase activity, calcium nodule formation, and the protein expression of collagen 1 (P =.0002) and osteocalcin (P =.0006) in vitro. Micro–computed tomography revealed higher surrounding bone mass at 4 weeks and newly formed bone mass at 8 weeks in the LIPUS group (P =.0014 and P =.0018). Histological analysis showed a narrower interface and direct graft-bone contact in the LIPUS group; the surrounding bone area at 4 weeks and the mass of newly formed bone at 4 and 8 weeks in the LIPUS group were also significantly higher as compared with control (surrounding bone, P <.0001; newly formed bone, P =.0016 at 4 weeks and P =.005 at 8 weeks). The ultimate failure load in the LIPUS group was significantly higher than in the control group (P <.0001 at 4 weeks; P =.0008 at 8 weeks). Conclusion: LIPUS promoted the viability and osteogenic differentiation of MC3T3-E1 preosteoblasts in vitro and enhanced the graft-bone healing of PET artificial ligament in vivo. Clinical Relevance: LIPUS is an effective physical stimulation to enhance graft-bone healing after artificial ligament implantation. [ABSTRACT FROM AUTHOR]

Background: Patient-reported outcome measures (PROMs) are essential clinical instruments used for assessing patient function, assisting in clinical decision making, and quantifying outcomes of surgical and nonsurgical management. However, PROMs are often designed using patients with preexisting pathology and typically assume that a patient without the pathology would have a perfect or near perfect score. This may result in unrealistic expectations or falsely underestimate how well a patient is doing after treatment. The influence of age on PROMs about the hip of healthy individuals has not been studied. Hypothesis: We hypothesize that in asymptomatic individuals hip-specific PROM scores will decrease in an age-dependent manor. Study Design: Cross-sectional study; Level of evidence, 3. Methods: In this multicenter survey study, volunteers who denied preexisting hip pathology and previous hip surgery completed 3 PROMs online or as traditional paper questionnaires. The International Hip Outcome Tool (iHOT), the modified Harris Hip Score (mHHS), and the Hip Outcome Score–Activities of Daily Living (HOS-ADL) and HOS—Sport were completed. Analysis of variance with a Tukey post hoc test was used to analyze differences in PROMs among subgroups. An independent-samples Student t test and a χ2 test were used to analyze differences in continuous and categorical data, respectively. Results: In total 496, 571, 534, and 532 responses were collected for the iHOT, mHHS, HOS-ADL, and HOS–Sport, respectively. Respondents' PROMs were scored and arranged into 3 groups by age: <40 years, 40 to 60 years, and >60 years. The iHOT, mHHS, HOS-ADL, and HOS–Sport of these asymptomatic respondents all decreased in an age-dependent manner: iHOT (<40, 94.1; 40-60, 92.4; >60, 87.0), mHHS (<40, 94.8; 40-60, 91.3; >60, 89.1), HOS-ADL (<40, 98.4; 40-60, 95.0; >60, 90.9), and HOS–Sport (<40, 95.7; 40-60, 82.9; >60, 72.9) (analysis of variance between-group differences, P <.05). Conclusion: This study demonstrated that the iHOT, mHHS, and HOS-ADL and HOS–Sport scores in asymptomatic people decrease in an age-dependent manner. It is important to compare a patient's outcome scores with the age-normalized scores to establish an accurate reference frame with which to interpret outcomes. [ABSTRACT FROM AUTHOR]

Background: Fatty infiltration of rotator cuff muscle is a limiting factor in the success of repairs. Fibroadipogenic progenitors (FAPs) are a population of stem cells within the rotator cuff that can differentiate into white adipocytes, fibroblasts, and beige adipocytes. The effects of patient age and rotator cuff tendon tear size on the number, differentiation patterns, and gene expression profiles of FAPs have not yet been analyzed. Purpose: To determine if patient age and rotator cuff tear size independently regulate FAP number, differentiation patterns, and gene expression profiles. Study Design: Controlled laboratory study. Methods: Supraspinatus muscle samples were collected from 26 patients between the ages of 42 and 76 years with partial- or full-thickness rotator cuff tears. FAPs were quantified using fluorescence-activated cell sorting. Gene expression analysis was performed across a custom 96-gene panel using NanoString. In vitro differentiation assays of FAPs were conducted using adipogenic, fibrogenic, and beige-inducing (amibegron-treated) media, and quantitative polymerase chain reaction was used to assess gene expression differences between adipogenic and amibegron media conditions. Multivariable linear regressions were performed using Stata to independently analyze the effects of age and rotator cuff tear size on FAP number, differentiation, and gene expression. Results: Increasing age and tear size were independently correlated with increased FAP number (βage = 0.21, P =.03; βtear size = 3.86, P =.05). There was no clear association between age and gene expression of freshly sorted FAPs. Under adipogenic and fibrogenic media conditions, increasing age and tear size were independently associated with increased adipogenic and fibrogenic differentiation of FAPs. Under amibegron treatment conditions, age positively correlated with increased beige differentiation (β = 1.03; P <.0001), while increasing tear size showed a trend toward decreased beige differentiation (β = −4.87; P =.1). When gene expression patterns between adipogenic and amibegron media conditions were compared, larger tear size strongly inhibited beige gene expression, while advanced age did not. Conclusion: Patient age and rotator cuff tear size independently regulated FAP number, differentiation, and gene expression. Age and tear size were positively correlated with increased FAP number and fibrogenic/adipogenic differentiation. Advancing patient age did not limit FAP beige differentiation and gene expression, while increasing rotator cuff tear size strongly inhibited these processes. [ABSTRACT FROM AUTHOR]

Background: The long-term chondroprotective effect of meniscal allograft transplant (MAT) and its superiority over meniscectomy have rarely been reported. Hypothesis: MAT would reduce osteoarthritis (OA) progression when compared with the meniscus-deficient knee. Graft extrusion distance would strongly affect the chondroprotective effect of the MAT. Study Design: Cohort study; Level of evidence, 3. Methods: A total of 17 knees receiving MAT were followed up as the MAT group. The MAT group was further divided into the nonextrusion subgroup (n = 9) and the extrusion subgroup (n = 8) according to 3-mm extrusion on the magnetic resonance imaging (MRI) coronal section. A further 26 consecutive patients receiving meniscectomy in the same period were followed up as the ME group. The healthy control group consisted of healthy contralateral legs chosen from the MAT and ME groups (n = 27). Joint space width (JSW) narrowing was measured on radiographs. Three-dimensional MRI with a T2 mapping sequence was used to quantitatively analyze cartilage degeneration and meniscal allograft extrusion in 5 directions (0°, 45°, 90°, 135°, and 180°). The cartilage degeneration index (CDI) was calculated according to the size and degree of the chondral lesions on MRI scans. The correlation between the CDI increase and the extrusion distance was analyzed. Results: The mean follow-up time was 11.3 years (range, 10-14 years). The MAT group had moderate superiority in chondral protection with less JSW narrowing (0.58 ± 0.66 mm) and CDI increase (1132 ± 1589) compared with the ME group (JSW narrowing: 1.26 ± 1.13 mm, P =.025; CDI increase: 2182 ± 1958, P =.079). The JSW narrowing (0.71 ± 0.80 mm; P =.186) and CDI increase (2004 ± 1965; P =.830) of the extrusion subgroup were close to those of the ME group, demonstrating that a 3-mm extrusion led to complete loss of the meniscal chondroprotective effect. The nonextrusion group had significantly less JSW narrowing (0.48 ± 0.48 mm; P =.042) and CDI increase (358 ± 249; P =.011) than the ME group. The JSW narrowing of the healthy control group was 0.22 ± 0.27 mm. The cartilage T2 values of the extrusion subgroup were similar to those of the ME group, with more OA features, whereas the T2 values of the nonextrusion subgroup were closer to those of the healthy control group. The extrusion distance in the 90° direction (P =.002) and the follow-up time (P =.019) significantly affected the CDI increase in the multivariate regression model. The average extrusion distance in the 45°, 90°, and 135° directions better predicted chondroprotection compared with the other individual directions. Conclusion: MAT had moderate advantages in chondroprotection compared with meniscectomy in the long term. Graft extrusion distance strongly affected the chondroprotective effect of MAT. The chondroprotective effect of the nonextruded meniscal allograft was close to that of the native meniscus, whereas the allografts with an extrusion >3 mm completely lost their function after meniscectomy. [ABSTRACT FROM AUTHOR]

Background: The ability to predict meniscus tear reparability based on preoperative magnetic resonance imaging (MRI) is desirable for postoperative planning; however, the accuracy of predictive methods varies widely within the orthopaedic and radiology literature. Purpose/Hypothesis: The purpose was to determine if the higher resolution offered by 3-T MRI improves the accuracy of predicting reparability compared with previous investigations using 1.5-T MRI. Our hypothesis was that a higher field strength of 3-T MRI would result in improved reliability assessments and predictions of meniscus tear reparability compared with previous studies utilizing a 1.5-T MRI platform. Study Design: Cohort study (diagnosis); Level of evidence, 2. Methods: A total of 44 patients who underwent meniscus repair were matched by age, sex, and body mass index to 43 patients who underwent partial meniscectomy. Overall, 2 orthopaedic surgeons and 2 musculoskeletal radiologists independently and blindly reviewed the preoperative MRI scans for all 87 patients. For each meniscus tear, reviewers evaluated the following criteria: tear pattern, tear length, tear distance from the meniscocapsular junction, tear thickness, and integrity of any inner meniscal fragment. The resultant data were then applied to 5 different approaches for predicting meniscal reparability. Results: The accuracy for all examined prediction methods was poor, ranging from 55% (3-point method) to 72% (classification tree method) among all reviewers. Interobserver reliability for examined criteria was also poor, with kappa values ranging from 0.07 (inner meniscal fragment status) to 0.40 (tear pattern). Conclusion: MRI continues to be a poor predictor of meniscus tear reparability as assessed by arthroscopic criteria, even when using higher resolution 3-T scanners. Interobserver reliability in this setting can be poor, even among experienced clinicians. [ABSTRACT FROM AUTHOR]

Background: Access to quality health care and treatment outcomes can be affected by patients' socioeconomic status (SES). Purpose: To evaluate the effect of patient SES on patient-reported outcome measures (PROMs) after arthroscopic hip surgery. Study Design: Cohort study; Level of evidence, 3. Methods: Demographic, radiographic, and intraoperative data were prospectively collected and retrospectively reviewed on all patients who underwent hip arthroscopy for femoroacetabular impingement syndrome (FAIS) and labral tear between February 2008 and September 2017 at one institution. Patients were divided into 4 cohorts based on the Social Deprivation Index (SDI) of their zip code. SDI is a composite measure that quantifies the level of disadvantage in certain geographical areas. Patients had a minimum 2-year follow-up for the modified Harris Hip Score (mHHS), Nonarthritic Hip Score (NAHS), International Hip Outcome Tool—12, and visual analog scale (VAS) for both pain and satisfaction. Rates of achieving the minimal clinically important difference (MCID) and patient acceptable symptom state (PASS) were calculated for the mHHS, NAHS, and VAS pain score. Rates of secondary surgery were also recorded. Results: A total of 680 hips (616 patients) were included. The mean follow-up time for the entire cohort was 30.25 months. Division of the cohort into quartiles based on the SDI national averages yielded 254 hips (37.4%) in group 1, 184 (27.1%) in group 2, 148 (21.8%) in group 3, and 94 (13.8%) in group 4. Group 1 contained the most affluent patients. There were significantly more men in group 4 than in group 2, and the mean body mass index was greater in group 4 than in groups 1 and 2. There were no differences in preoperative radiographic measurements, intraoperative findings, or rates of concomitant procedures performed. All preoperative and postoperative PROMs were similar between the groups, as well as in the rates of achieving the MCID or PASS. No differences in the rate of secondary surgeries were reported. Conclusion: Regardless of SES, patients were able to achieve significant improvements in several PROMs after hip arthroscopy for FAIS and labral tear at the minimum 2-year follow-up. Additionally, patients from all SES groups achieved clinically meaningful improvement at similar rates. [ABSTRACT FROM AUTHOR]

Background: Gene transfer of the transcription factor SOX9 with clinically adapted recombinant adeno-associated virus (rAAV) vectors offers a powerful tool to durably enhance the repair process at sites of osteochondral injuries and counteract the development of perifocal osteoarthritis (OA) in the adjacent articular cartilage. Purpose: To examine the ability of an rAAV sox9 construct to improve the repair of focal osteochondral defects and oppose perifocal OA development over time in a large translational model relative to control gene transfer. Study Design: Controlled laboratory study. Methods: Standardized osteochondral defects created in the knee joints of adult sheep were treated with rAAV-FLAG-h sox9 relative to control (reporter) rAAV- lacZ gene transfer. Osteochondral repair and degenerative changes in the adjacent cartilage were monitored using macroscopic, histological, immunohistological, and biochemical evaluations after 6 months. The microarchitecture of the subchondral bone was assessed by micro–computed tomography. Results: Effective, prolonged sox9 overexpression via rAAV was significantly achieved in the defects after 6 months versus rAAV- lacZ treatment. The application of rAAV-FLAG-h sox9 improved the individual parameters of defect filling, matrix staining, cellular morphology, defect architecture, surface architecture, subchondral bone, and tidemark as well as the overall score of cartilage repair in the defects compared with rAAV- lacZ. The overexpression of sox9 led to higher levels of proteoglycan production, stronger type II collagen deposition, and reduced type I collagen immunoreactivity in the sox9 - versus lacZ -treated defects, together with decreased cell densities and DNA content. rAAV-FLAG-h sox9 enhanced semiquantitative histological subchondral bone repair, while the microstructure of the incompletely restored subchondral bone in the sox9 defects was not different from that in the lacZ defects. The articular cartilage adjacent to the sox9 -treated defects showed reduced histological signs of perifocal OA changes versus rAAV- lacZ. Conclusion: rAAV-mediated sox9 gene transfer enhanced osteochondral repair in sheep after 6 months and reduced perifocal OA changes. These results underline the potential of rAAV-FLAG-h sox9 as a therapeutic tool to treat cartilage defects and afford protection against OA. Clinical Relevance: The delivery of therapeutic rAAV sox9 to sites of focal injuries may offer a novel, convenient tool to enhance the repair of osteochondral defects involving both the articular cartilage and the underlying subchondral bone and provide a protective role by reducing the extent of perifocal OA. [ABSTRACT FROM AUTHOR]

Background: Throwing arm injuries are common because of the demand on the shoulder. The shoulder is qualitatively checked regularly by team physicians. Excessive instability and joint loading in baseball pitching are risk factors for throwing arm injuries. Knowledge of shoulder flexibility, range of motion, and joint loading may provide new insights for treatments to reduce the likelihood of injury incidence. Purpose: To investigate the relationship among injuries, shoulder external rotational properties, and shoulder joint loading in baseball pitchers. Study Design: Descriptive laboratory study. Methods: Pitching kinetics, shoulder rotational tests, and self-reported injury questionnaires were used to study 177 collegiate baseball pitchers. Pitching motion data were collected at 240 Hz using a motion capture system. A custom program calculated the shoulder joint loading. The shoulder rotational test quantitatively records shoulder range of motion and flexibility using a custom-made wireless device. Self-reported injury questionnaires were filled out during tests and yearly follow-ups. The total length of the study was 5 years. Analysis of variance, chi-square, and regression tests were performed to compare differences among groups and detect correlations with surgery and shoulder joint loadings. Results: There were significant differences in shoulder flexibility among surgery groups. Shoulder external rotational properties during physical examination were significantly associated with shoulder joint loading in baseball pitching. High shoulder external rotation was associated with 14% to 36% lower shoulder posterior force and adduction, internal rotation, and horizontal adduction torque (P <.05). High shoulder flexibility was associated with 13% higher anterior force (P <.05). High shoulder external rotation before external rotation torque was applied was associated with 13% to 33% lower shoulder inferior force and adduction, internal rotation, and horizontal adduction torque (P <.05). There were no significant differences in shoulder joint loading among the surgery groups. Conclusion: Shoulder injuries that require surgery were associated with shoulder external rotation flexibility. High shoulder external rotation may be advantageous because it lowers the force and torque on the shoulder joint. Clinical Relevance: The ability to understand shoulder external rotational properties, joint loading, and injury during baseball pitching helps further our understanding of injury mechanisms. The shoulder rotational test should be used as a screening tool to identify players at risk. [ABSTRACT FROM AUTHOR]

Background: Although polyvinyl alcohol (PVA) implants have been developed and used for the treatment of femoral osteochondral defects, their effect on joint contact mechanics during gait has not been assessed. Purpose/Hypothesis: The purpose was to quantify the contact mechanics during simulated gait of focal osteochondral femoral defects and synthetic PVA implants (10% and 20% by volume of PVA), with and without porous titanium (pTi) bases. It was hypothesized that PVA implants with a higher polymer content (and thus a higher modulus) combined with a pTi base would significantly improve defect-related knee joint contact mechanics. Study Design: Controlled laboratory study. Methods: Four cylindrical implants were manufactured: 10% PVA, 20% PVA, and 10% and 20% PVA disks mounted on a pTi base. Devices were implanted into 8 mm–diameter osteochondral defects created on the medial femoral condyles of 7 human cadaveric knees. Knees underwent simulated gait and contact stresses across the tibial plateau were recorded. Contact area, peak contact stress, the sum of stress in 3 regions of interest across the tibial plateau, and the distribution of stresses, as quantified by tracking the weighted center of contact stress throughout gait, were computed for all conditions. Results: An osteochondral defect caused a redistribution of contact stress across the plateau during simulated gait. Solid PVA implants did not improve contact mechanics, while the addition of a porous metal base led to significantly improved joint contact mechanics. Implants consisting of a 20% PVA disk mounted on a pTi base significantly improved the majority of contact mechanics parameters relative to the empty defect condition. Conclusion: The information obtained using our cadaveric test system demonstrated the mechanical consequences of femoral focal osteochondral defects and provides biomechanical support to further pursue the efficacy of high-polymer-content PVA disks attached to a pTi base to improve contact mechanics. Clinical Relevance: As a range of solutions are explored for the treatment of osteochondral defects, our preclinical cadaveric testing model provides unique biomechanical evidence for the continued investigation of novel solutions for osteochondral defects. [ABSTRACT FROM AUTHOR]

Background: Preinjury running biomechanics are an ideal comparator for quantifying recovery after anterior cruciate ligament (ACL) reconstruction (ACLR), allowing for assessments within the surgical and nonsurgical limbs. However, availability of preinjury running biomechanics is rare and has been reported in case studies only. Purpose/Hypothesis: The purpose of this study was to determine if running biomechanics return to preinjury levels within the first year after ACLR among collegiate athletes. We hypothesized that (1) surgical knee biomechanics would be significantly reduced shortly after ACLR and would not return to preinjury levels by 12 months and (2) nonsurgical limb mechanics would change significantly from preinjury. Study Design: Cohort study; Level of evidence, 2. Methods: Thirteen Division I collegiate athletes were identified between 2015 and 2020 (6 female; mean ± SD age, 20.7 ± 1.3 years old) who had whole body kinematics and ground-reaction forces recorded during treadmill running (3.7 ± 0.6 m/s) before sustaining an ACL injury. Running analyses were repeated at 4, 6, 8, and 12 months (4M, 6M, 8M, 12M) after ACLR. Linear mixed effects models were used to assess differences in running biomechanics between post-ACLR time points and preinjury within each limb, reported as Tukey-adjusted P values. Results: When compared with preinjury, the surgical limb displayed significant deficits at all postoperative assessments (P values <.01; values reported as least squares mean difference [SE]): peak knee flexion angle (4M, 13.2° [1.4°]; 6M, 9.9° [1.4°]; 8M, 9.8° [1.4°]; 12M, 9.0° [1.5°]), peak knee extensor moment (N·m/kg; 4M, 1.32 [0.13]; 6M, 1.04 [0.13]; 8M, 1.04 [0.13]; 12M, 0.87 [0.15]; 38%-57% deficit), and rate of knee extensor moment (N·m/kg/s; 4M, 22.7 [2.4]; 6M, 17.9 [2.3]; 8M, 17.5 [2.4]; 12M, 16.1 [2.6]; 33%-46% deficit). No changes for these variables from preinjury (P values >.88) were identified in the nonsurgical limb. Conclusion: After ACLR, surgical limb knee running biomechanics were not restored to the preinjury state by 12M, while nonsurgical limb mechanics remained unchanged as compared with preinjury. Collegiate athletes after ACLR demonstrate substantial deficits in running mechanics as compared with preinjury that persist beyond the typical return-to-sport time frame. The nonsurgical knee appears to be a valid reference for recovery of the surgical knee mechanics during running, owing to the lack of change within the nonsurgical limb. [ABSTRACT FROM AUTHOR]

Background: Chronic rotator cuff (RC) tendinopathy is one of the most prevalent causes of shoulder pain. Growing evidence suggests that macrophages play a significant role in the proinflammatory response, resolution of inflammation, and tissue healing of tendinopathy. In particular, enhancement of M2 macrophage (M2φ) activity contributes to the accelerated healing of tendinopathy. Therefore, a treatment that enhances M2φ polarization would be useful for patients with this common musculoskeletal disorder. Purpose: To investigate whether adipose stem cell–derived exosomes (ASC-Exos) enhance M2φ polarization and ameliorate chronic RC tendinopathy. Study Design: Controlled laboratory study. Methods: First, we compared the effects of ASC-Exos on polarization of mouse bone marrow–derived macrophages between a classically activated phenotype (M1φ) and an alternatively activated phenotype (M2φ) in vitro. In total, 72 C57BL/6 mice were assigned to normal cage activity (n = 24) or 5 weeks of treadmill overuse (n = 48). The supraspinatus tendon of each treadmill overuse mouse was treated with ASC-Exos (n = 24) or saline (n = 24). Histological and biomechanical outcomes were assessed 4 weeks after treatment. Finally, tissue samples from human patients with RC tendinopathy were obtained to assay the effect of ASC-Exos on the M1φ/M2φ balance in tissue-resident macrophages. Results: ASC-Exos inhibited M1φ polarization and augmented M2φ polarization in vitro and in vivo. Mice in the ASC-Exos group showed less severe pathological changes than those in the saline group, including less cellular infiltration, disorganization of collagen, and ground substance deposition. The modified Bonar score of the ASC-Exos group (mean ± SD, 7.68 ± 1.03) was significantly lower than that of the saline group (9.81 ± 0.96; P <.05). Furthermore, the maximum failure load was significantly higher in the ASC-Exos group than in the saline group (4.23 ± 0.66 N vs 3.86 ± 0.65 N; P <.05), as was stiffness (3.38 ± 0.34 N/m vs 2.68 ± 0.49 N/m; P <.05). Conclusion: ASC-Exos–mediated polarization balance of M1φ/M2φ contributes to the amelioration of chronic RC tendinopathy. Regulation of the M1φ/M2φ balance could be a new target for the treatment of chronic RC tendinopathy. Clinical Relevance: Administration of ASC-Exos is a cell-free approach that may become a novel treatment option for chronic RC tendinopathy and should be explored further. [ABSTRACT FROM AUTHOR]