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Background: A few studies have documented the long-term results of chondrocyte-based procedures for the treatment of patellofemoral cartilage lesions, but specific results are lacking after matrix-assisted autologous chondrocyte transplantation (MACT) for patellar and trochlear lesions. Purpose: To document the clinical results of MACT for the treatment of patellar and trochlear chondral defects at long-term follow-up. Study Design: Cohort study; Level of evidence, 3. Methods: A total of 44 patients were prospectively evaluated after MACT for patellofemoral lesions. There were 24 patients affected by patellar lesions, 16 by trochlear lesions, and 4 with both patellar and trochlear defects. Clinical outcomes were analyzed using the International Knee Documentation Committee (IKDC) subjective form, EuroQol visual analog scale, and Tegner score for sport activity level before surgery and at follow-up time points of 5, 10, and a minimum of 15 years (mean final follow-up, 17.6 ± 1.6 years). A Kaplan-Meier survival analysis was performed to examine the survival to failure. Failure was defined as the need for a second surgery because of the persistence of symptoms related to the primary defect. Results: An overall significant improvement was documented from baseline to the last follow-up. The IKDC subjective score improved in the trochlear group from 41.0 ± 13.3 at baseline to 83.9 ± 21.6 at 5 years (P <.005), remaining stable up to the final follow-up (81.3 ± 20.5). In the patellar group, the IKDC subjective score improved from 36.1 ± 14.4 at baseline to 72.3 ± 17.5 at 5 years (P <.005), remaining stable up to the final follow-up (62.0 ± 20.3). Patients with trochlear lesions presented higher IKDC subjective scores compared with those with patellar lesions at 5 (P =.029), 10 (P =.023), and ≥15 years (P =.006) of follow-up. Similar trends were documented for the Tegner score, while no differences were documented for the EuroQol visual analog scale score between patellar and trochlear lesions. There were 4 failures (9.1%) during the follow-up period. The Kaplan-Meier survival analysis did not show statistically significant differences between trochlear and patellar lesions. Conclusion: This hyaluronic acid–based MACT technique offered positive and durable clinical outcomes with a low failure rate at long-term follow-up in patients affected by patellofemoral cartilage lesions. However, trochlear and patellar lesions demonstrated a notable difference in terms of clinical findings and sport activity level, with significantly higher results for patients with trochlear lesions but less satisfactory outcomes for patients with patellar lesions. [ABSTRACT FROM AUTHOR]

Background: It is necessary to better understand the structural characteristics of the supraspinatus tendon and associated muscle after rotator cuff repair and in the event of retear. Purpose: To study structural differences between the repaired and contralateral shoulders 1 year after rotator cuff repair in patients who received either progressive exercise therapy (PR) or usual care (UC) in a randomized controlled trial and to investigate whether there was interaction with tendon retear and limb dominance. Study Design: Cohort study; Level of evidence, 2. Methods: Patients with surgically repaired traumatic full-thickness rotator cuff tears involving the supraspinatus tendon were included. After surgery, they were randomized to PR or UC (active from postoperative week 2 or 6, respectively). The subacromial structures (acromiohumeral distance, supraspinatus tendon thickness, and vascularity) and the supraspinatus muscle thickness were examined with ultrasound at the 1-year follow-up. Results: A total of 79 patients were included. The characteristics of the 2 intervention groups (PR and UC) were comparable, including the Western Ontario Rotator Cuff Index score and number of retears. The authors found significantly thinner supraspinatus tendon (PR, P <.001; UC, P =.003) and reduced acromiohumeral distance (PR, P =.023; UC, P =.025) in the repaired versus the contralateral shoulders in both intervention groups. For neovascularization, there was no interlimb difference in either of the groups or between groups (PR vs UC). In patients with intact tendons, there was no interlimb difference in the muscle thickness, but in patients with tendon retear the muscle was significantly thinner on the repaired side (P =.024 and P <.001, respectively). When the dominant supraspinatus tendon was repaired (both groups), it was significantly thinner than the nondominant healthy tendon, but this difference was not seen when the nondominant supraspinatus tendon was repaired (P =.006). Conclusion: One year after rotator cuff surgery, the repaired supraspinatus tendon was significantly thinner and the corresponding acromiohumeral distance was reduced. In patients with retear, the supraspinatus muscle was significantly thinner on the repaired side and early initiation of tendon-loading exercises did not affect these findings. Registration: NCT02969135 (ClinicalTrials.gov identifier). [ABSTRACT FROM AUTHOR]

Background: Although pediatric medial epicondylar fractures and apophysitis are well studied, patterns of subapophyseal avulsion and ligamentous injuries of the medial elbow in this population merit investigation to inform optimal treatment strategies. Purpose: To describe the occurrence and demographic correlates of ulnar collateral ligament (UCL) avulsion and soft tissue injuries of the pediatric and adolescent elbow. Study Design: Cross-sectional study; Level of evidence, 3. Methods: An institutional review board–approved review was conducted to identify consecutive patients with medial elbow injuries treated in a tertiary pediatric sports medicine practice between 2016 and 2021. Radiographs were obtained during injury evaluation, and patients with nondisplaced medial epicondylar apophysitis and complete epicondylar fracture were excluded, resulting in 150 patients with soft tissue injuries occurring distal to the medial epicondyle apophysis (subapophyseal) for study. Radiographs were evaluated for bony avulsion of the UCL from either the medial epicondyle proximally or the ulnar sublime tubercle distally. Injuries without radiographic evidence of bony avulsion, but with clinical examination findings consistent with ligamentous injury, were classified as radiographically negative UCL injuries, and magnetic resonance imaging (MRI) was performed to further evaluate these injuries if moderate to severe medial swelling of the elbow or significant concern for medial structural injury was present on examination. These MRI scans were evaluated to classify the UCL injury and assess for periosteal or cartilaginous avulsions. Results: A total of 150 patients (mean age, 12.5 ± 3.4 years; 70 female), 55% (150/274) of the entire medial elbow injury population, had a subapophyseal injury. Of these patients, 62 had a bony avulsion detected on radiograph, and 88 had a radiographically negative injury. In addition to the 62 radiographic avulsions, the 61 MRI scans obtained on those radiographically negative injuries revealed 33 complete UCL disruptions, resulting in 63.3% (95/150) of patients sustaining a complete ligamentous disruption. With the MRI scans, 37 (61%) cases of cartilaginous or periosteal avulsion of the UCL were diagnosed. Overall, 66% of all 150 subapophyseal injuries had a bony, cartilaginous, or periosteal UCL avulsion. Patients with cartilaginous (mean age, 10.3 years) and bony (mean age, 10.6 years) avulsions were younger than those with central ligament injury (mean age, 14.2 years) or periosteal (mean age, 14.2 years) avulsions (P =.005). There was a significant association between the mechanism of injury and the location of UCL tear identified on MRI scans: traumatic falls were associated with distal tears, and throwing injuries were associated with proximal tears (P <.001). Conclusion: UCL central ligament and avulsion lesions may be frequently diagnosed after injury to the pediatric medial elbow, the majority of which are complete injuries, and may require MRI for diagnosis. The mechanism of injury may predict the location of ligamentous injury, and osteocartilaginous avulsions are more likely to present at younger ages than injuries to the soft tissue of the UCL or periosteum. The prevalence of these injuries merits further investigation into best protocols of nonoperative treatment or surgical repair techniques and outcomes. [ABSTRACT FROM AUTHOR]

Background: A major limitation of osteochondral allografts (OCA) is the deterioration of cartilage health associated with cell death during prolonged storage. However, little is known about the mechanisms that contribute to chondrocyte death during storage. Purpose/Hypothesis: This study aimed to determine whether bioactive lipid metabolites accumulate in the storage media of OCA and whether they are associated with a loss of chondrocyte viability during prolonged storage. It was hypothesized that free fatty acids (FFAs) would accumulate over time in the storage media of OCA and adversely affect cartilage health during storage. Study Design: Controlled laboratory study. Methods: A group of 21 (n = 6-8 OCA/treatment group) fresh human hemicondylar OCA tissues and media were analyzed after 7, 28, and 68 days of prolonged cold (4°C) storage. Targeted mass spectrometry analysis was used to quantify bioactive FFAs, as well as primary (lipid hydroperoxide [ROOH]) and secondary (malondialdehyde) lipid oxidation products. Chondrocyte viability was measured using a fluorescence-based live/dead assay and confocal microscopy. Results: The concentration of all targeted fatty acid metabolites in storage media was significantly increased with increased cold storage time (P <.05). ROOH was significantly higher on day 28 of cold storage. No difference in secondary ROOH products in storage media was observed. Chondrocyte viability significantly declined in both the en face and the vertical cross-sectional analysis with increased cold storage time and inversely correlated with fatty acid metabolites (P <.05). Conclusion: It is well established that elevated levels of certain FFAs and lipid oxidation products can alter cell function and cause cell death via lipotoxicity and other mechanisms. This work is the first to identify elevated levels of FFA metabolites and primary oxidation lipid products in the storage media from clinical OCA. The concentrations of FFA metabolites were measured at levels (>100 µM) known to induce cell death and were directly correlated with chondrocyte viability. Clinical Relevance: These findings provide important targets for understanding why cartilage health declines during cold storage, which can be used to optimize media formulations and improve graft health. [ABSTRACT FROM AUTHOR]

Background: Injuries to the deep medial collateral ligament (dMCL) and partial superficial MCL (psMCL) can cause anteromedial rotatory instability; however, the contribution of each these injuries in restraining anteromedial rotatory instability and the effect on the anterior cruciate ligament (ACL) load remain unknown. Purpose: To investigate the contributions of the different MCL structures in restraining tibiofemoral motion and to evaluate the load through the ACL after MCL injury, especially after combined dMCL/psMCL injury. Study Design: Controlled laboratory study. Methods: Sixteen fresh-frozen human cadaveric knees were tested using a 6 degrees of freedom robotic simulator. Tibiofemoral kinematic parameters were recorded at 0°, 30°, 60°, and 90° of knee flexion for the following measurements: 8-N·m valgus rotation, 4-N·m external tibial rotation (ER), 4-N·m internal tibial rotation, and a combined 89-N anterior tibial translation and 4-N·m ER for both anteromedial rotation (AMR) and anteromedial translation (AMT). The kinematic parameters of the 3 different MCL injuries (dMCL; dMCL/psMCL; dMCL/superficial MCL (sMCL)) were recorded and reapplied either in an ACL-deficient joint (load sharing) or before and after cutting the ACL (ACL load). The loads were calculated by applying the principle of superposition. Results: The dMCL had the largest effect on reducing the force/torque during ER, AMR, and AMT in extension and the psMCL injury at 30° to 90° of knee flexion (P <.05). In a comparison of the load through the ACL when the MCL was intact, the ACL load increased by 46% and 127% after dMCL injury and combined dMCL/psMCL injury, respectively, at 30° of knee flexion during ER. In valgus rotation, a significant increase in ACL load was seen only at 90° of knee flexion. Conclusion: The psMCL injury made the largest contribution to the reduction of net force/torque during AMR/AMT at 30° to 90° of flexion. Concomitant dMCL/psMCL injury increased the ACL load, mainly during ER. Clinical Relevance: If a surgical procedure is being considered to treat anteromedial rotatory instability, then the procedure should focus on restoring sMCL function, as injury to this structure causes a major loss of the knee joint's capacity to restrain AMR/AMT. [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: Restoration of osteochondral defects is critical, because osteoarthritis (OA) can arise. Hypothesis: Overexpression of insulin-like growth factor 1 (IGF-1) via recombinant adeno-associated viral (rAAV) vectors (rAAV-IGF-1) would improve osteochondral repair and reduce parameters of early perifocal OA in sheep after 6 months in vivo. Study Design: Controlled laboratory study. Methods: Osteochondral defects were created in the femoral trochlea of adult sheep and treated with rAAV-IGF-1 or rAAV- lacZ (control) (24 defects in 6 knees per group). After 6 months in vivo, osteochondral repair and perifocal OA were assessed by well-established macroscopic, histological, and immunohistochemical scoring systems as well as biochemical and micro–computed tomography evaluations. Results: Application of rAAV-IGF-1 led to prolonged (6 months) IGF-1 overexpression without adverse effects, maintaining a significantly superior overall cartilage repair, together with significantly improved defect filling, extracellular matrix staining, cellular morphology, and surface architecture compared with rAAV- lacZ. Expression of type II collagen significantly increased and that of type I collagen significantly decreased. Subchondral bone repair and tidemark formation were significantly improved, and subchondral bone plate thickness and subarticular spongiosa mineral density returned to normal. The OA parameters of perifocal structure, cell cloning, and matrix staining were significantly better preserved upon rAAV-IGF-1 compared with rAAV- lacZ. Novel mechanistic associations between parameters of osteochondral repair and OA were identified. Conclusion: Local rAAV-mediated IGF-1 overexpression enhanced osteochondral repair and ameliorated parameters of perifocal early OA. Clinical Relevance: IGF-1 gene therapy may be beneficial in repair of focal osteochondral defects and prevention of perifocal OA. [ABSTRACT FROM AUTHOR]

Background: Recent studies have investigated the effect of psychological factors on return to sport (RTS), but none has tested the existence of psychological profiles linked to reinjury anxiety and its links with RTS and reinjury. Purpose: To assess the effect of different psychological profiles on RTS and reinjury. Study Design: Cohort study; Level of evidence, 2. Methods: The study screened patients who were involved in all types of sports for anterior cruciate ligament (ACL) reconstruction (hamstring and patellar tendon autografts). All participants were included during the RTS phase (90-180 days after ACL reconstruction). Reinjury anxiety, fear of reinjury, kinesiophobia, perceived stress, anxiety, depression, knee confidence, self-esteem, optimism, coping, and pain were measured. Hierarchical cluster analysis (Ward method) and analysis of variance were performed. In the second year after surgery, patients were recontacted by telephone to follow-up. RTS and reinjury were compared by profile type. Results: A total of 162 athletes were initially included, of whom 123 responded regarding RTS and reinjury. Cluster analysis showed a 4-cluster solution (χ2[21] = 428.59; λ =.064; P <.001). Profile 1 (27.8%) was characterized by moderate reinjury anxiety and no depression. Profile 2 (22.8%) was characterized by moderate reinjury anxiety and minor anxious-depressive reaction. Profile 3 (30.9%) was characterized by no reinjury anxiety, no depression, and high confidence. Profile 4 (18.5%) was characterized by high anxiety, high depression, and low confidence. Profile 4 had the lowest self-esteem and optimism scores compared with profile 3 (P <.001). In addition, a higher percentage of men was found in profile 3 as opposed to profile 4 (χ2[3] = 11.35; P <.01). Profile 4 had the highest rate of non-RTS with 54.2% (profile 1: 14.3%, P =.001; profile 2: 25.0%, P =.031; profile 3: 22.2%, P =.011). Finally, patients with profile 3 had a higher risk of reinjury (13.9%) than those with profile 4 (0%) (P =.047), who had an extremely conservative RTS. Conclusion: The different profiles will affect RTS, but also the risk of reinjury exclusively for profiles 3 and 4. Rehabilitation management will probably require all stakeholders to understand psychological profiles of athletes to develop an on-demand rehabilitation plan. [ABSTRACT FROM AUTHOR]

Background: It has been shown that chronic ankle instability (CAI) leads to abnormalities in neuromuscular control of more proximal joints than the ankle. Although strength of the hip and the ankle muscles has been largely investigated providing concordant results, limited evidence with contrasting results has been reported regarding knee extensor and flexor muscles. Purpose: To investigate maximal and submaximal isometric muscle strength in individuals with CAI. Study Design: Controlled laboratory study. Methods: Fifteen participants with unilateral CAI and 15 healthy matched controls were recruited. To quantify maximal strength, peak forces were recorded during a maximal isometric voluntary contraction of knee extensor and flexor muscles at 30° and 90° of knee flexion and normalized by the body weight of each participant. At both angles, submaximal isometric contractions at 20%, 50%, and 80% of the maximal voluntary isometric contraction were performed to analyze strength steadiness, in terms of coefficient of variation, and strength accuracy, in terms of absolute error. During all the assessments, knee extensor and flexor muscle activation was recorded by means of surface electromyography. Results: Knee flexor maximal isometric strength was significantly lower in the injured limb of individuals with CAI in comparison with healthy controls at both 30° (0.15 ± 0.05 vs 0.20 ± 0.05; P <.05) and 90° (0.14 ± 0.04 vs 0.18 ± 0.05; P <.05). Knee extensor and flexor steadiness was significantly lower (higher coefficient of variation) in both the injured and the noninjured limbs of individuals with CAI in comparison with healthy individuals at 90° and at 30° for knee flexor steadiness of the injured limb. Knee extensor and flexor accuracy was lower (higher absolute error) in both the injured and noninjured limbs of individuals with CAI in comparison with healthy individuals, mainly at 30°, while at 90° it was lower only in the injured limb. No differences between the 2 groups were found for maximal isometric strength of knee extensor muscles, as well as for muscle activations. Conclusion: Individuals with CAI show abnormalities in maximal and submaximal isometric strength of knee flexor muscles, and submaximal strength of the knee extensor muscles. Further studies should deeply investigate mechanisms leading to these abnormalities. Clinical Relevance: Rehabilitation interventions should consider abnormalities of neuromuscular control affecting joints more proximal than the ankle in individuals with CAI. Registration: NCT05273177 (ClinicalTrials.gov identifier). [ABSTRACT FROM AUTHOR]

Background: Time-dependent postoperative changes in knee joint line obliquity (KJLO) and subsequent adaptational changes in the hip and ankle joints have not been fully proven after medial open wedge high tibial osteotomy (MOWHTO). Purpose: To investigate the serial postoperative changes in KJLO and subsequent adaptational changes in the hip and ankle joints over time after MOWHTO. Study design: Case series, Level of evidence, 4. Methods: A total of 92 patients who underwent MOWHTO between April 2015 and December 2020 were evaluated. Radiographic parameters, including KJLO, ankle joint line obliquity (ALO), hip abduction angle (HAA), joint line convergence angle, weightbearing line ratio, and hip-knee-ankle angle, were analyzed in time sequence (preoperatively and 3, 6, 12, and 24 months postoperatively). Repeated-measures analysis of variance and post hoc analysis were used to demonstrate alterations and the statistical significance of KJLO and other related radiographic parameters over time. Results: The mean KJLO values were –1.9°, –2.1°, –2.7°, and –3.2° at 3, 6, 12, and 24 months postoperatively, respectively, indicating that there was consistent increase in valgus tilting of KJLO from 6 to 24 months (P <.001 for both 6-12 months and 12-24 months). ALO and HAA showed significant changes from 6 to 12 months (ALO, P <.001; HAA, P =.002), but not between 12 and 24 months (ALO: –3.0°, –2.7°, –1.9°, and −1.6°; HAA: –0.8°, –0.9°, –1.5°, and −1.8° at 3, 6, 12, and 24 months, respectively). The mean joint line convergence angle, weightbearing line ratio, and hip-knee-ankle angle did not change significantly from 3 months to 24 months postoperatively. Conclusion: There was a consistent increase in valgus tilting of the postoperative KJLO from 6 to 24 months after MOWHTO. The adaptive ALO and HAA significantly changed between 6 and 12 months and were maintained until 24 months after MOWHTO. It is necessary to consider the adaptive change when hip or ankle surgery is planned within this period. [ABSTRACT FROM AUTHOR]

Background: Quantitative analysis of the glenoid face knotless-type anchor placement for arthroscopic Bankart repair has not been reported. Purpose: To evaluate the clinical and radiologic outcomes after arthroscopic Bankart repair using knotless bioabsorbable anchors depending on the anchor location. Study design: Case series, Level of evidence, 4. Methods: A total of 124 patients (113 men and 11 women; age, 25.6 ± 7.5 years; follow-up time, 46.5 ± 18.2 months [range, 6.2-75.5 months]) who underwent arthroscopic Bankart repair with the bioabsorbable knotless anchor between 2017 and 2021 were included in this study. Among them, 118 patients were observed for >2 years (mean, 48.2 ± 16.8 months [range, 24-75.5 months]) and were analyzed for final clinical and radiologic outcomes. Using postoperative 6-month magnetic resonance imaging, remnant glenoid (%) and labral height were measured. Shoulder range of motion (ROM), radiographic osteoarthritic change, dislocation, apprehension test, and return to sports were recorded. Three groups were established based on the remnant glenoid, which represented the percentage of the exposed glenoid anteroposterior diameter to the original diameter using the best-fit circle method—group A: lower quartile; group B: interquartile; and group C: upper quartile—and variables were analyzed. Results: Overall, the remnant glenoid was 57% ± 6.4% (range, 41.5%-75%) after the surgery. Osteoarthritic change, dislocations, and positive apprehension tests were observed in 5 (4.2%), 4 (3.4%), and 12 (10.2%) patients, respectively. A total of 34 (28.8%) and 64 (54.2%) patients could return to sports without and with restrictions, respectively. Comparing groups A, B, and C, postoperative labral height (7 ± 1, 7 ± 2, and 7 ± 1 mm; P =.623), final osteoarthritic change (1, 4, and 0; P =.440), positive apprehension tests (5, 5, and 2; P =.387), and return to sports (complete/restricted/unable, 6/18/5, 19/29/11, 9/17/4; P =.769) were not different. All ROM were similar across the groups (all P >.054), except for external rotation (ER) at postoperative 6 months (41.3°± 12.8°; 50.2°± 18.5°; and 49.8°± 15.2°; P =.050). However, ER after 1 year was similar across the groups (all P >.544). In further analysis, patients with positive apprehension tests had lower labral height compared with others (5 [4-6] mm and 7 [6-8] mm; P <.001). Conclusion: In arthroscopic Bankart repair, the placement of knotless bioabsorbable anchors on the glenoid face, combined with the remplissage procedure or rotator interval closure, resulted in a low recurrence rate and moderate return to sports. However, most patients had some restrictions in returning to sports. Moreover, this technique was not associated with postoperative arthritis and shoulder stiffness, including ER deficit, which was not affected by the position of the anchor on the glenoid face for a minimum 2-year follow-up. [ABSTRACT FROM AUTHOR]

Background: Bone morphogenetic protein 2 (BMP2) is an appealing osteogenic and chondrogenic growth factor for promoting tendon-bone healing. Recently, it has been reported that soluble vascular endothelial growth factor (VEGF) receptor 1 (sVEGFR1) (a VEGF receptor antagonist) could enhance BMP2-induced bone repair and cartilage regeneration; thus, their combined application may represent a promising treatment to improve tendon-bone healing. Moreover, BMP2 could stimulate skeletal stem cell (SSC) expansion and formation, which is responsible for wounded tendon-bone interface repair. However, whether the codelivery of BMP2 and sVEGFR1 increases tendon enthesis injury–activated SSCs better than does BMP2 alone needs further research. Purpose: To study the effect of BMP2 combined with sVEGFR1 on tendon-bone healing and injury-activated SSC lineage. Study Design: Controlled laboratory study. Methods: A total of 128 C57BL/6 mice that underwent unilateral supraspinatus tendon detachment and repair were randomly assigned to 4 groups: (1) untreated control group; (2) hydrogel group, which received a local injection of the blank hydrogel at the injured site; (3) BMP2 group, which received an injection of hydrogel with BMP2; and (4) BMP2 with sVEGFR1 group, which received an injection of hydrogel with BMP2 and sVEGFR1. Histology, micro–computed tomography, and biomechanical tests were conducted to evaluate tendon-bone healing at 4 and 8 weeks after surgery. In addition, flow cytometry was performed to detect the proportion of SSCs and their downstream differentiated subtypes, including bone, cartilage, and stromal progenitors; osteoprogenitors; and pro-chondrogenic progenitors within supraspinatus tendon enthesis at 1 week postoperatively. Results: The repaired interface in BMP2 with sVEGFR1 group showed a significantly improved collagen fiber continuity, increased fibrocartilage, greater newly formed bone, and elevated mechanical properties compared with the other 3 groups. There were more SSCs; bone, cartilage, and stromal progenitors; osteoprogenitors; and pro-chondrogenic progenitors in the BMP2 with sVEGFR1 group than that in the other groups. Conclusion: Our study suggests that the combined delivery of BMP2 and sVEGFR1 could promote tendon-bone healing and stimulate the expansion of SSCs and their downstream progeny within the injured tendon-bone interface. Clinical Relevance: Combining BMP2 with sVEGFR1 may be a good clinical treatment for wounded tendon enthesis healing. [ABSTRACT FROM AUTHOR]

Background: Chronic ankle instability (CAI) is a clinical sequela that causes the recurrence of ankle sprain by inducing ankle sensorimotor dysfunction. Animal models of CAI have recently shown that ankle ligament injuries mimicking an ankle sprain result in chronic loss of ankle sensorimotor function. However, the underlying mechanisms determining the pathogenesis of CAI remain unclear. Hypothesis: Ankle instability after an ankle sprain leads to the degeneration of the mechanoreceptors, resulting in ankle sensorimotor dysfunction and the development of CAI. Study Design: Controlled laboratory study. Methods: Four-week-old male Wistar rats (N = 30) were divided into 2 groups: (1) the ankle joint instability (AJI) group with ankle instability induced by transecting the calcaneofibular ligament (n = 15) and (2) the sham group (n = 15). Ankle instability was assessed using the anterior drawer test and the talar tilt test at 4, 6, and 8 weeks after the operation (n = 5, for each group at each time point), and ankle sensorimotor function was assessed using behavioral tests, including ladder walking and balance beam tests, every 2 weeks during the postoperative period. Morphology and number of mechanoreceptors in the intact anterior talofibular ligament (ATFL) were histologically analyzed by immunofluorescence staining targeting the neurofilament medium chain and S100 proteins at 4, 6, and 8 weeks postoperatively (n = 5 per group). Sensory neurons that form mechanoreceptors were histologically analyzed using immunofluorescence staining targeting the mechanosensitive ion channel PIEZO2 at 8 weeks postoperatively (n = 5). Results: Ankle sensorimotor function decreased over time in the AJI group, exhibiting decreased ankle instability compared with the sham group (P =.045). The number of mechanoreceptors in the ATFL was reduced (P <.001) and PIEZO2 expression in the sensory neurons decreased (P =.008) at 8 weeks postoperatively. The number of mechanoreceptors was negatively correlated with ankle sensorimotor dysfunction (P <.001). Conclusion: The AJI model demonstrated degeneration of the mechanoreceptors in the ATFL and decreased mechanosensitivity of the sensory neurons, which may contribute to CAI. Clinical Relevance: Ankle instability causes degeneration of mechanoreceptors and decreases the mechanosensitivity of sensory neurons involved in the development of CAI. This finding emphasizes the importance of controlling ankle instability after ankle sprains to prevent recurrence and the onset of CAI. [ABSTRACT FROM AUTHOR]

Background: Surgical treatments for chronic posterosuperior massive rotator cuff tear (MRCT) are still controversial. Superior capsular reconstruction (SCR), which provides a static stabilizer to decrease superior humeral head translation, and lower trapezius tendon transfer (LTTT) with centralization of the humeral head, which prevents superior humeral head migration, are potential surgical options. To date, SCR combined with LTTT has not been fully investigated. Hypothesis: Restoration of static stabilizer and dynamic stabilizer together would effectively improve shoulder kinematics in posterosuperior MRCT. Study Design: Controlled laboratory study. Methods: A custom-made shoulder mechanics testing system was used to test 8 fresh-frozen cadaveric shoulders. The testing conditions were as follows: (1) intact; (2) posterosuperior MRCT (supraspinatus and infraspinatus removed); (3) SCR using the fascia lata; (4) LTTT; and (5) SCR combined with LTTT. The total rotational range of motion (ROM), superior translation, anteroposterior translation, and peak subacromial contact pressure were evaluated at 0°, 30°, and 60° of shoulder abduction. Repeated-measures analysis of variance and Tukey post hoc tests were performed. Results: The total rotational ROM, superior translation, anteroposterior translation, and peak subacromial contact pressure increased in posterosuperior MRCTs (all, P <.05). The rotational ROM, superior translation, anteroposterior translation, and peak subacromial contact pressure at 0° and 30° of shoulder abduction decreased in SCR (all, P <.05). However, there was no significant improvement in rotational ROM, superior translation, and peak subacromial contact pressure at 60° of shoulder abduction (P >.05). LTTT resulted in a significant decrease in the superior translation, anteroposterior translation, and peak subacromial contact pressure at 0°, 30°, and 60° of shoulder abduction (P <.05). SCR combined with LTTT restored the total rotational ROM, superior translation, anteroposterior translation, and peak subacromial contact pressure at 0°, 30°, and 60° of shoulder abduction (all, P <.05). Conclusion: In the cadaveric model, SCR combined with LTTT showed improved shoulder kinematics and contact pressures in the posterosuperior MRCT model compared with SCR or LTTT alone. Clinical Relevance: SCR combined with LTTT may be regarded as an alternative surgical procedure for posterosuperior MRCTs. [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: The prevalence of wrist pain among gymnasts ranges from 46% to 79%. To alleviate wrist pain, gymnasts wear wrist guards/supports (WG/S). Purpose: To investigate the effect of WG/S on the wrist joint through joint moment, angles, total joint range of motion (ROM) arc, and ground-reaction force (GRF). Study Design: Controlled laboratory study. Methods: A cross-sectional study design was used to investigate 23 female gymnasts (mean ± SD: age, 12.3 ± 1.5 years; height, 143.4 ± 7.6 cm; mass, 37.7 ± 6.6 kg; body mass index, 18.6 ± 2.9) who performed back handsprings (analyzed by first half [phase 1] and second half [phase 2]) with the following 3 conditions: no WG/S, Skids/Ultimate Wrist Supports (S/UWS), and Tiger Paws (TP). Wrist joint moments, angles, total ROM arc, and GRF were examined by the 3 conditions using analysis of variance with Bonferroni correction and effect size (Cohen d). Results: For mean wrist flexion moment, both S/UWS and TP showed significantly higher values than the no-WG/S condition in landing phase 1 (S/UWS: P =.001, d = 1.30; TP: P =.019, d = 0.87). In angle comparisons in landing phase 1, no WG/S showed greater mean wrist extension angles compared with S/UWS (P =.046; d = 0.80), but no significant differences with TP (P =.096; d = 0.65). Also, in landing phase 1, total ROM arc of the right wrist was greater in the no-WG/S condition compared with S/UWS (P =.018; d = 0.88), but there were no differences with TP (P =.400; d = 0.52). Conclusion: These data show an increased wrist flexion moment using S/UWS and TP compared with the no-WG/S condition in landing phase 1 of back handsprings. Also, increased wrist extension angles and total arc ROM of the right wrist were found in the no-WG/S condition compared with S/UWS, but not with TP in landing phase 1. S/UWS may be helpful to reduce wrist joint angles, specifically wrist extension in landing phase 1, but both S/UWS and TP caused higher wrist flexion joint moment in landing phase 1. There were no differences found in GFG among the three variables. Clinical Relevance: In the first half of the back handspring, wrist guards can limit wrist extension joint angles and total arc ROM; however, an increased wrist flexion moment was found when wrist guards were worn, which may potentially lead to an increased risk of injury. Injury history, especially overuse signs/symptoms, and previous surgery on the wrist joint need to be well considered before the application or use of wrist guards. Also, the amount of time/exposure wearing wrist guards should be carefully controlled in young female gymnasts. [ABSTRACT FROM AUTHOR]

Background: The influence of bony morphology on the development of posterior shoulder instability is not well known. Purpose: To determine if acromial morphology, as measured on magnetic resonance imaging (MRI), is associated with posterior or anterior shoulder instability. Design: Cross-sectional study; Level of evidence, 3. Methods: MRI measurements of posterior acromial coverage (PAC), posterior acromial height (PAH), posterior acromial tilt (PAT), and anterior acromial coverage (AAC) were completed for 3 separate matched groups who underwent surgical intervention: posterior instability, anterior instability, and a comparison group of patients who underwent arthroscopic surgery for snapping scapula. Inclusion criteria were patients with recurrent instability <40 years of age without multidirectional instability, glenoid bone loss >13.5%, or glenoid retroversion >10%. Results: Overall, 37 patients were included in each group. PAC was significantly less in the posterior instability group than in the anterior instability and comparison groups (68.3° vs 88.7° vs 81.7°; P <.001). PAH was significantly greater in the posterior group than in the anterior instability group (11.0 mm vs −0.1 mm; P <.001) and comparison group (0.7 mm; P <.001). There was no difference between the posterior and anterior groups in terms of PAT or AAC (P =.45 and P =.05, respectively). PAT was significantly smaller in the posterior instability group than the comparison group (55.2° vs 62.2°; P =.026). The anterior and comparison groups were not significantly different in PAH or PAT (P =.874 and P =.067, respectively) but were significantly different in AAC (P =.026). Conclusion: A higher and flatter posterior acromion, as measured on preoperative MRI, appears to be associated with patients who require arthroscopic capsulolabral repair due to posterior shoulder instability. This information may help clinicians to both diagnose and predict the need for operative intervention for patients with posterior labral tears. [ABSTRACT FROM AUTHOR]

Background: Femoral torsion measurements and outcomes are variable throughout the literature and have focused on short-term follow-up. However, there is a paucity of literature investigating clinically meaningful outcomes at midterm follow-up after hip arthroscopy for femoroacetabular impingement syndrome (FAIS). Purpose: To quantify femoral version using computed tomography imaging in patients with FAIS and to explore the relationship between version abnormalities and 5-year outcomes after hip arthroscopy. Study Design: Cohort study; Level of evidence, 3. Methods: Patients who underwent primary hip arthroscopy for FAIS between January 2012 and November 2017 were identified. Patients were included if they had 5-year follow-up with completion of ≥1 patient-reported outcome (PRO) scores and excluded if they had Tönnis grade >1, revision hip surgery, a concomitant hip procedure, a developmental disorder, or a lateral center-edge angle <20°. Torsion groups were defined as severe retrotorsion (<0°), moderate retrotorsion (0.1°-5°), normal torsion (5.1°-20°), moderate antetorsion (20.1°-25°), and severe antetorsion (>25.1°) based on computed tomography measurements. Patient characteristics were analyzed among the torsion cohorts, as were preoperative and 5-year PROs: Hip Outcome Score–Activities of Daily Living, Hip Outcome Score–Sports Subscale, modified Harris Hip Score, international Hip Outcome Tool, visual analog scale for pain, and visual analog scale for satisfaction. Achievement rates of cohort-specific thresholds for the minimal clinically important difference and Patient Acceptable Symptom State were calculated and compared among cohorts. Results: A total of 362 patients (244 female, 118 male; mean ± SD age, 33.1 ± 11.5 years; body mass index, 26.9 ± 17.8) met inclusion/exclusion criteria and were analyzed at a final mean follow-up of 64.3 ± 9.4 months (range, 53.5-115.5 months). Mean femoral torsion was 12.8°± 9.2°. The number of patients within each group was 20 for severe retrotorsion (torsion, −6.3°± 4.9°), 45 for moderate retrotorsion (2.7°± 1.3°), 219 for normal torsion (12.2°± 4.1°), 39 for moderate antetorsion (21.9°± 1.3°), and 39 for severe antetorsion (29.0°± 4.2°). No significant differences in age, body mass index, sex, smoking status, workers' compensation, psychiatric history, back pain, or physical activity were found among the torsional groups. All groups demonstrated significant improvements at 5 years postoperatively (P <.01 for all). All torsion subgroups demonstrated similar pre- to postoperative changes in PROs (P ≥.515) and PRO values at 5-year follow-up (P ≥.098). There were no significant differences in the achievement of the minimal clinically important difference (P ≥.422) or Patient Acceptable Symptom State (P ≥.161) for any of the PROs among the torsion groups. Conclusion: The orientation and severity of femoral torsion at the time of hip arthroscopy for FAIS in this study's cohort did not affect the propensity for clinically meaningful outcome improvement at midterm follow-up. [ABSTRACT FROM AUTHOR]

Background: Several tibiofemoral anatomic features have been repeatedly associated with increased anterior cruciate ligament (ACL) injury risk. Previous studies have highlighted age and sex differences among these anatomic risk factors, but little is known about the normal and pathologic development of these differences during skeletal maturation. Purpose: To investigate differences in anatomic risk factors at various stages of skeletal maturation between ACL-injured knees and matched controls. Study Design: Cross-sectional study; Level of evidence, 3. Methods: After institutional review board approval, magnetic resonance imaging scans from 213 unique ACL-injured knees (age, 7-18 years, 48% female) and 239 unique asymptomatic ACL-intact knees (age, 7-18 years, 50% female) were used to measure femoral notch width, posterior slope of the lateral and medial tibial plateau, medial and lateral tibial spinal height (MTSH, LTSH), medial tibial depth, and posterior lateral meniscus-bone angle. Linear regression was performed to assess change in quantified anatomic indices with age for male and female patients in the ACL-injured cohort. Two-way analysis of variance with Holm-Sidak post hoc testing was performed to compare anatomic indices between ACL-injured knees and ACL-intact controls in each age group. Results: In the ACL-injured cohort, notch width, notch width index and medial tibial depth increased with age (R 2 > 0.1; P <.001) in both sexes. MTSH and LTSH increased with age only in boys (R 2≥ 0.09; P ≤.001), whereas meniscus-bone angle decreased with age only in girls (R 2 = 0.13; P <.001). There were no other age differences in quantified anatomic indices. Patients with ACL injury consistently had a significantly higher lateral tibial slope (P <.01) and smaller LTSH (P <.001) as compared with ACL-intact controls across all age groups and sexes. When compared with age- and sex-matched ACL-intact controls, ACL-injured knees had a smaller notch width (boys, 7-18 years; girls, 7-14 years; P <.05), larger medial tibial slope (boys and girls, 15-18 years; P <.01), smaller MTSH (boys, 7-14 years; girls, 11-14 years; P <.05), and larger meniscus-bone angle (girls, 7-10 years; P =.050). Conclusion: The consistent morphologic differences throughout skeletal growth and maturation suggest a developmental role in high-risk knee morphology. The observed high-risk knee morphology at an earlier age preliminarily suggests the potential of knee anatomy measurements in identifying those with a predisposition toward ACL injury. [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: Platelet-rich plasma (PRP) has been used extensively in clinical practice to treat patients with symptomatic knee osteoarthritis (OA). Leukocyte-poor PRP (LP-PRP) has been clinically preferred over leukocyte-rich PRP (LR-PRP); however, it is unclear which cytokine mediators of pain and inflammation are present in LR-PRP and LP-PRP from patients with mild to moderate knee OA in order to rationalize a specific formulation. Hypothesis: LP-PRP would be predominantly anti-inflammatory and have reduced nociceptive pain mediators compared with LR-PRP from the same individual with mild to moderate knee OA. Study Design: Controlled laboratory study. Methods: A total of 24 unique samples of PRP were prepared in order to assess 48 samples of LR-PRP and LP-PRP taken from 12 patients (6 male and 6 female) with symptomatic knee OA of Kellgren-Lawrence grade 2 to 3. Patients underwent blood collection for LR-PRP and LP-PRP preparation through a double-spin protocol to obtain baseline whole blood, platelet concentration, and white blood cell subtypes. LR-PRP and LP-PRP from the same patient were produced at the same time and underwent a comprehensive panel through Luminex (multicytokine profiling) to assess key mediators of inflammation: interleukin 1 receptor antagonist (IL-1Ra), interleukin 4, 6, 8, and 10 (IL-4, IL-6, IL-8, and IL-10), IL-1β, tissue necrosis factor α (TNF-α), and matrix metalloproteinase 9 (MMP-9). To assess mediators of nociceptive pain, nerve growth factor (NGF) and tartrate resistant acid phosphatase 5 (TRAP5) were also assessed. Results: LR-PRP from patients with mild to moderate knee OA expressed significantly more IL-1Ra, IL-4, IL-8, and MMP-9 compared with LP-PRP formulations from the same patients. No significant differences were found between LR-PRP and LP-PRP in mediators of nociceptive pain—namely, NGF and TRAP5. Other mediators including TNF-α, IL-1β, IL-6, and IL-10 were also found to have no significant expression differences between LR-PRP and LP-PRP. Conclusion: LR-PRP expressed significantly more IL-1Ra, IL-4, and IL-8, suggesting that LR-PRP may be more anti-inflammatory than LP-PRP. MMP-9 was expressed in higher concentrations in LR-PRP, suggesting that LR-PRP may be more chondrotoxic than LP-PRP. Clinical Relevance: LR-PRP was found to have a robust expression of anti-inflammatory mediators compared with LP-PRP and may be beneficial to patients with long-term knee OA where chronic low-grade inflammation is present. Mechanistic clinical trials are needed to elucidate the key mediators in both LR-PRP and LP-PRP to assess their effect on long-term progression of knee OA. [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: 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: The Knee injury and Osteoarthritis Outcome Score–Anterior Cruciate Ligament (KOOS-ACL) is a short form version of the KOOS, developed to target populations of young active patients with ACL tears. The KOOS-ACL consists of 2 subscales: Function (8 items) and Sport (4 items). The KOOS-ACL was developed and validated using data from the Stability 1 study from baseline to postoperative 2 years. Purpose: To validate the KOOS-ACL in an external sample of patients matching the outcome's target population. Study Design: Cohort study (diagnosis); Level of evidence, 1. Methods: The Multicenter Orthopaedic Outcomes Network group cohort of 839 patients aged 14 to 22 years who tore their ACLs while playing sports was used to assess internal consistency reliability, structural validity, convergent validity, responsiveness to change, and floor/ceiling effects of the KOOS-ACL at 4 time points: baseline and postoperative 2, 6, and 10 years. Detection of treatment effects between graft type (hamstring tendon vs bone–patellar tendon–bone) were also compared between the full-length KOOS and KOOS-ACL. Results: The KOOS-ACL demonstrated acceptable internal consistency reliability (α =.82-.89), structural validity (Tucker-Lewis index and comparative fit index = 0.98-0.99; standardized root mean square residual and root mean square error of approximation = 0.04-0.07), convergent validity (Spearman correlation with International Knee Documentation Committee subjective knee form = 0.66-0.85; Western Ontario and McMaster Universities Osteoarthritis Index function = 0.84-0.95), and responsiveness to change across time (large effect sizes from baseline to postoperative 2 years; d = 0.94 [Function] and d = 1.54 [Sport]). Stable scores and significant ceiling effects were seen from 2 to 10 years. No significant differences in KOOS or KOOS-ACL scores were detected between patients with different graft types. Conclusion: The KOOS-ACL shows improved structural validity when compared with the full-length KOOS and adequate psychometric properties in a large external sample of high school and college athletes. This strengthens the argument to use the KOOS-ACL to assess young active patients with ACL tears in clinical research and practice. [ABSTRACT FROM AUTHOR]

Background: Injuries to the anterior cruciate ligament (ACL), Kaplan fibers (KFs), anterolateral capsule/ligament (C/ALL), and lateral meniscus posterior root (LMPR) have been separately linked to anterolateral instability. Purpose: To investigate the contributions of the ACL, KFs, C/ALL, and LMPR to knee stability and to measure instabilities resulting from their injury. Study Design: Controlled laboratory study. Methods: Ten fresh-frozen human knees were tested robotically to determine restraints of knee laxity at 0° to 90° of flexion. An 88-N anterior-posterior force (anterior and posterior tibial translation), 5-N·m internal-external rotation, and 8-N·m valgus-varus torque were imposed and intact kinematics recorded. The kinematics were replayed after sequentially cutting the structures (order varied) to calculate their contributions to stability. Another 10 knees were tested in a kinematics rig with optical tracking to measure instabilities after sequentially cutting the structures across 0° to 100° of flexion. One- and 2-way repeated-measures analyses of variance with Bonferroni correction were used to find significance (P <.05) for the robotic and kinematics tests. Results: The ACL was the primary restraint for anterior tibial translation; other structures were insignificant (<10% contribution). The KFs and C/ALL resisted internal rotation, reaching 44% ± 23% (mean ± SD; P <.01) and 14% ± 13% (P <.05) at 90°. The LMPR resisted valgus but not internal rotation. Anterior tibial translation increased after ACL transection (P <.001) and after cutting the lateral structures from 70° to 100° (P <.05). Pivot-shift loading increased anterolateral rotational instability after ACL transection from 0° to 40° (P <.05) and further after cutting the lateral structures from 0° to 100° (P <.01). Conclusion: The anterolateral complex acts as a functional unit to provide rotatory stability. The ACL is the primary stabilizer for anterior tibial translation. The KFs are the most important internal rotation restraint >30° of flexion. Combined KFs + C/ALL injury substantially increased anterolateral rotational instability while isolated injury of either did not. LMPR deficiency did not cause significant instability with the ACL intact. Clinical Relevance: This study is a comprehensive biomechanical sectioning investigation of the knee stability contributions of the ACL, anterolateral complex, and LMPR and the instability after their transection. The ACL is significant in controlling internal rotation only in extension. In flexion, the KFs are dominant, synergistic with the C/ALL. LMPR tear has an insignificant effect with the ACL intact. [ABSTRACT FROM AUTHOR]

Background: Augmented (internal braced) lateral ulnar collateral ligament (LUCL) repair has been biomechanically compared with reconstruction techniques in the elbow. However, LUCL repair alone has not yet been compared with augmented repair and reconstruction techniques. Hypothesis: Internal bracing of LUCL repair would improve time-zero stabilization regarding gap formation, stiffness, and residual torque as compared with repair alone and reconstruction techniques to restore native elbow stability. Study Design: Controlled laboratory study. Methods: Overall, 24 cadaveric elbows were used for either internal braced LUCL repair (Repair-IB) or single- and double-strand ligament reconstruction with triceps (Recon-TR) and palmaris longus tendon graft (Recon-PL), respectively. Laxity testing in external rotation was consecutively performed at 90° of elbow flexion on the intact, dissected, and repaired conditions and with the previously assigned techniques. First, intact elbows were loaded to 7.0-N·m external torque to evaluate time-zero ligament rotations at 2.5, 4.0, 5.5, and 7.0 N·m. Rotation-controlled cycling was performed (total of 1000 cycles) for each surgical condition. Gapping, stiffness, and residual torque were analyzed. Finally, these and 8 additional intact elbows underwent torque-to-failure testing (30 deg/min). Results: The dissected state showed the highest gap formation and lowest peak torques (P <.001). While gap formation of Repair-IB (P <.021) was significantly lower than that of repair without internal bracing at all rotation levels, gaps of Recon-PL were similar to and Recon-TR were significantly higher than those of Repair-IB except for the highest torsion level. Residual peak torques at specific rotation angles between native state and Recon-TR (α2.5), Recon-PL (α4.0), and Repair-IB (α5.5) were similar; all other comparisons were significantly different (P <.027). Torsional stiffness of Repair-IB was significantly higher at all rotation angles measured. Analysis of covariance showed significantly less gap formation over residual peak torques for Repair-IB (P <.001) as compared with all other groups. The native state failure load was significantly higher than Recon-PL and Recon-TR failure loads, with similar stiffness to all other groups. Conclusion: Repair-IB and Recon-PL of the LUCL showed increased rotational stiffness relative to the intact elbow for restoring posterolateral stability to the native state in a cadaveric model. Recon-TR demonstrated lower residual peak torques but provided near-native rotational stiffness. Clinical Relevance: Internal bracing of LUCL repair may reduce suture-tearing effects through tissue and provide sufficient stabilization for healing throughout accelerated and reliable recovery without the need for a tendon graft. [ABSTRACT FROM AUTHOR]

Background: Anterior cruciate ligament reconstruction (ACLR) using the quadriceps tendon is an increasingly popular technique. Both partial-thickness quadriceps tendon (PT-Q) and full-thickness quadriceps tendon (FT-Q) graft depths are employed. Hypothesis/Purpose: This study was designed to assess isokinetic peak torque, average power, and total work during knee extension in patients with FT-Q or PT-Q grafts for ACLR. We hypothesized that both groups would show lower isokinetic values for the operated side, with greater deficits in the FT-Q group than in the PT-Q group. Study Design: Cohort study; Level of evidence, 3. Methods: A total of 26 patients who underwent ACLR with either an FT-Q or PT-Q graft were recruited between June 2021 and November 2021. Patients underwent isokinetic knee extension testing at > 1 year after surgery. Mixed repeated-measures analysis of covariance with least square difference post hoc testing was used to determine significant differences or interactions for all variables. Results: Peak torque was significantly lower for the operated limb than the nonoperated limb in the FT-Q group (mean difference [MD] ± standard error [SE], −38.6 ± 8.3 Nċm [95% CI, −55.7 to −21.5 Nċm]; P <.001; d = 0.90) but not in the PT-Q group (MD ± SE, −7.3 ± 7.7 Nċm [95% CI, −23.2 to 8.5 Nċm]; P =.348; d = 0.20). Similarly, average power for the operated limb was lower than that for the nonoperated limb in the FT-Q group (MD ± SE, −53.6 ± 13.4 W [95% CI, −81.3 to −26.9 W]; P <.001; d = 0.88) but not in the PT-Q group (MD ± SE, –4.1 ± 12.4 W [95% CI, −29.8 to 21.5 W]; P =.742; d = 0.07), and total work was lower for the operated limb compared with the nonoperated limb in the FT-Q group (MD ± SE, −118.2 ± 27.1 J [95% CI, −174.3 to −62.2 J]; P <.001; d = 0.96) but not in the PT-Q group (MD ± SE, −18.3 ± 25.1 J [95% CI, −70.2 to 33.6 J]; P =.472; d = 0.15). Conclusion: The FT-Q group showed significant deficits in the operated limb compared with the nonoperated limb for all isokinetic variables. In contrast, no significant differences were found between the nonoperated and operated limbs for the PT-Q group. [ABSTRACT FROM AUTHOR]

Background: No study has evaluated whether best-fit circles based on glenoids with defects accurately represent normal inferior glenoids before injury. Purpose: To investigate whether the best-fit circles on the affected side with a glenoid defect can accurately represent native glenoids before injury. Study Design: Cohort study (diagnosis); Level of evidence, 3. Methods: This retrospective study included 58 patients with unilateral recurrent anterior shoulder instability. First, we compared the diameter of best-fit circles based on affected and unaffected glenoids. Glenoid defect sizes based on each best-fit circle were then calculated and compared. Second, we created serial virtual glenoid defects (10%, 15%, 20%, 25%) on unaffected glenoids and compared diameters of best-fit circles on the glenoids before and after virtual defects. We also analyzed and compared the size of virtual and calculated glenoid defects. Bland-Altman plots and intraclass coefficients (ICCs) were used to compare and analyze agreement of measurements. After categorization of glenoid defects based on clinical cutoff values, Cohen κ and percentage agreement were calculated. Results: The diameter of 55.2% (32/58) of best-fit circles from affected glenoids over- or underestimated the diameter on the unaffected side by >5%. In 28 of the 32 patients, the diameter of the affected side circle was overestimated. Consequently, 41.4% (24/58) of glenoid defects were over- or underestimated by >5%. In 19 of the 24 patients, the glenoid defect from the affected side was >5% larger. ICCs between sides for best-fit circle diameters and defect sizes were 0.632 and 0.800, respectively. Agreement of glenoid defect size between sides was 58.6% (34/58) overall, but when the defect was ≥10%, agreement decreased to 32.3% (10/31). Among 232 glenoids with virtual defects created from 58 normal glenoids, the diameter of 31.0% (72/232) of best-fit circles and the size of 11.6% (27/232) of defects were over- or underestimated by >5%. Conclusion: When assessing glenoid defects in anterior shoulder instability, best-fit circles based on affected glenoids do not always represent the native glenoid and may thus lead to inaccurate circle sizes and defect estimates. [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: Loss of initial reduction of the acromioclavicular joint after coracoclavicular (CC) ligament reconstruction remains a challenge for various repair techniques. Previous studies using polydioxanone suture cerclage augments for CC ligament reconstruction demonstrated poor clinical and biomechanical outcomes. Tape-style sutures have recently gained popularity because of their added stiffness and strength relative to traditional sutures. These tape cerclage systems have yet to be biomechanically studied in CC ligament reconstruction. Purpose: To determine the efficacy of a tape cerclage system as an augment to CC ligament reconstruction. Study Design: Controlled laboratory study. Methods: A total of 24 human cadaveric shoulders were utilized. These were divided into 4 repair groups: anatomic CC ligament reconstruction (ACCR), ACCR with a tape cerclage augment (ACCR + C), tendon graft sling with a cerclage augment (TGS + C), or tape cerclage sling alone (CS). The repairs underwent superior/inferior cyclic loading to evaluate for displacement. Specimens were visually inspected for cortical erosion by the tape cerclage after cyclic loading. Finally, the constructs underwent superior plane load-to-failure testing. Results: Less displacement after cyclic loading was observed in the ACCR + C (mean ± SD, 0.42 ± 0.32 mm), TGS + C (0.92 ± 0.42 mm), and CS (0.93 ± 0.39 mm) groups as compared with the ACCR group (4.42 ± 3.40 mm; P =.002). ACCR + C (813.3 ± 257.5 N), TGS + C (558.0 ± 120.7 N), and CS (759.5 ± 173.7 N) demonstrated significantly greater load at failure relative to ACCR (329.2 ± 118.2 N) (P <.001). ACCR + C (60.88 ± 17.3 N/mm), TGS + C (44.97 ± 9.15 N/mm), and CS (54.52 ± 14.24 N/mm) conferred greater stiffness than ACCR (27.43 ± 6.94 N/mm) (P =.001). No cortical erosion was demonstrated in any specimen after cyclic loading. Conclusion: In a cadaveric model at time zero, repairs utilizing a tape cerclage system confer significantly greater load to failure and stiffness, as well as decreased displacement with cyclic loading, when compared with traditional ACCR repair. Clinical Relevance: Tape cerclage augmentation may provide a useful augment for CC ligament reconstruction. [ABSTRACT FROM AUTHOR]

Background: Identification of morphological risk factors associated with the knee that threaten ligaments is important for understanding injury mechanisms and prevention. However, the morphological risk factors for posterior cruciate ligament (PCL) lesions are not clearly understood. Purpose: To investigate whether the medial tibial depth (MTD), medial and lateral posterior tibial slope, asymmetry of the medial and lateral slopes, radius of the sagittal plane medial femoral condyle, coronal tibial slope, and notch width index (NWI) were risk factors for PCL intrasubstance tearing (PCLIT) and tibial avulsion fractures (PCLAF). Study Design: Cross-sectional study; Level of evidence, 3. Methods: Between January 2015 and March 2022, 82 patients with isolated PCLIT, 68 patients with isolated PCLAF, and 82 controls without any ligamentous or meniscal pathologic findings as determined via physical examination and magnetic resonance imaging were included. Values were compared among the 3 groups. Logistic regression analysis was performed to confirm the risk factors. Receiver operating characteristic curves were defined for the morphological indicators and combination of risk factors. Results: Logistic regression analysis revealed (1) MTD, lateral minus medial posterior tibial slope, radius of the posterior circle of the medial femoral condyle, and NWI as significant independent predictors for PCLIT and (2) MTD and NWI for PCLAF. The areas under the curve combining the 4 indicators for PCLIT and noncontact PCLIT were 0.79 (95% CI, 0.72-0.86) and 0.90 (95% CI, 0.85-0.96), respectively. The area under the curve for the combination of MTD and NWI for PCLAF was 0.78 (95% CI, 0.70-0.86). Conclusion: Decreased MTD and NWI were associated with an increased incidence of PCLIT and PCLAF. Increased asymmetry of the medial and lateral slopes and the radius of the posterior circle of the medial femoral condyle were associated with the presence of PCLIT. In addition, the model of a combination of risk factors showed good predictive ability for noncontact PCLIT. These findings may aid clinicians in identifying patients at risk for PCL lesions. Further studies are warranted for identifying the effect of these factors on biomechanical mechanisms. [ABSTRACT FROM AUTHOR]

Background: Posterior open-wedge osteotomy and glenoid reconstruction using a J-shaped iliac crest bone graft showed promising clinical results for the treatment of posterior instability with excessive glenoid retroversion and posteroinferior glenoid deficiency. Purpose: To evaluate the biomechanical performance of the posterior J-shaped graft to restore glenoid retroversion and posteroinferior deficiency in a cadaveric shoulder instability model. Study Design: Controlled laboratory study. Methods: A posterior glenoid open-wedge osteotomy was performed in 6 fresh-frozen shoulders, allowing the glenoid retroversion to be set at 0°, 10°, and 20°. At each of these 3 preset angles of glenoid retroversion, the following conditions were simulated: (1) intact joint, (2) posterior Bankart lesion, (3) 20% posteroinferior glenoid deficiency, and (4) posterior J-shaped graft (at 0° of retroversion). With the humerus in the Jerk position (60° of glenohumeral anteflexion, 60° of internal rotation), stability was evaluated by measuring posterior humeral head (HH) translation (in mm) and peak translational force (in N) to translate the HH over 25% of the glenoid width. Glenohumeral contact patterns were measured using pressure-sensitive sensors. Fixation of the posterior J-graft was analyzed by recording graft micromovements during 3000 cycles of 5-mm anteroposterior HH translations. Results: Reconstructing the glenoid with a posterior J-graft to 0° of retroversion significantly increased stability compared with a posterior Bankart lesion and posteroinferior glenoid deficiency in all 3 preset degrees of retroversion (P <.05). There was no significant difference in joint stability comparing the posterior J-graft with an intact joint at 0° of retroversion. The posterior J-graft restored mean contact area and contact pressure comparable with that of the intact condition with 0° of retroversion (222 vs 223 mm2, P =.980; and 0.450 vs 0.550 MPa, P =.203). The mean total graft displacement after 3000 cycles of loading was 43 ± 84 µm, and the mean maximal mediolateral graft bending was 508 ± 488 µm. Conclusion: Biomechanical analysis of the posterior J-graft demonstrated reliable restoration of initial glenohumeral joint stability, normalization of contact patterns comparable with that of an intact shoulder joint with neutral retroversion, and secure initial graft fixation in the cadaveric model. Clinical Relevance: This study confirms that the posterior J-graft can restore stability and glenohumeral loading conditions comparable with those of an intact shoulder. [ABSTRACT FROM AUTHOR]

Background: Anterior cruciate ligament (ACL) injuries and bone tunnel enlargement (BTE) after ACL reconstruction (ACLR) remain frequent issues. Bone dust (BD) produced by tunnel preparation with osteogenic ability and reverse drilling (RD), an easy compaction technique, make it accessible to enhance tendon-bone healing in the clinic. Hypothesis: RD and BD synergistically promote tendon-bone healing by improving peritunnel bone and preventing BTE in femurs. Study Design: Controlled laboratory study. Methods: In total, 96 New Zealand White rabbits underwent ACLR. The semitendinosus tendon was freed before medial parapatellar arthrotomy. After the native ACL was transected, bone tunnels were prepared through the footprint of the native ACL. All animals were randomly assigned to 1 of 4 groups according to different tunnel preparation methods: group 1 (irrigation after extraction drilling [ED]; control group), group 2 (irrigation after RD), group 3 (no irrigation after ED), and group 4 (no irrigation after RD). BD was harvested by irrigating tunnels and was characterized by morphology and size. The specimens underwent microarchitectural, histological, and biomechanical evaluations at 4, 8, and 12 weeks postoperatively. Results: Micro–computed tomography demonstrated more peritunnel bone and less BTE in the femurs of group 4 compared with the other groups. Histologically, BD possessed osteogenic activity in bone tunnels postoperatively. Meanwhile, group 4 regenerated a higher amount of the tendon-bone interface and more peritunnel bone than group 1. Biomechanically, group 4 showed higher failure loads and stiffness than group 1. However, peritunnel bone loss, active osteoclasts, and significant BTE were found in the femurs of group 1 and group 3 at 12 weeks postoperatively, while no strong correlation was found between BTE and inflammatory cytokines. Scanning electron microscopy and particle size analysis suggested that BD produced by ED and RD had no difference in size. Conclusion: Tendon-bone healing was facilitated by the synergistic effect of RD and BD in femurs. Clinical Relevance: This study provides a more accessible and effective surgical strategy to promote tendon-bone healing after ACLR by increasing peritunnel bone and preventing BTE in femurs. [ABSTRACT FROM AUTHOR]

Background: The increase in anterior cruciate ligament (ACL) injuries in pediatric patients and the high failure rate reported in the literature in this population are driving surgeons to search for specific techniques to better restore knee stability. Recent literature has reported that the combination of lateral extra-articular tenodesis (LET) and ACL reconstruction improves outcomes in high-risk patients. However, such advantages in pediatric patients have been infrequently evaluated. Purpose: To assess whether adding LET to ACL reconstruction can significantly improve knee stability, clinical outcomes, and failure rates in pediatric patients. Study Design: Cohort study; Level of evidence, 3. Methods: A multicentric study involving 3 orthopaedic teaching centers was conducted to evaluate pediatric patients aged between 12 and 16 years who had undergone primary ACL reconstruction using a physeal-sparing femoral tunnel drilling technique. A minimum 2-year follow-up evaluation was required. Based on the surgical technique performed, the patients were divided into 2 group. The patients in group 1 underwent an isolated arthroscopic ACL reconstruction, while the patients in group 2 had an arthroscopic ACL reconstruction in combination with a modified Lemaire LET procedure. Group 1 was a historical control cohort of patients, whereas group 2 was prospectively enrolled. All the patients included in the present study were clinically evaluated using the Pediatric International Knee Documentation Committee (Pedi-IKDC) subjective score and the Pediatric Functional Activity Brief Scale (Pedi-FABS) score. Anteroposterior knee stability was measured using the KT-1000 knee ligament arthrometer, and the objective pivot-shift evaluation was documented using a triaxial accelerometer (Kinematic Rapid Assessment [KiRA]). The included patients also underwent a standardized radiological protocol to evaluate leg-length discrepancies, axial deviation, and degenerative signs preoperatively and at last follow-up. Results: This study included 66 pediatric patients with an anatomic hybrid ACL reconstruction using an autologous 4-strand hamstring graft. In group 1, there were 34 patients (mean age, 13.5 ± 1.2 years), while 32 patients (mean age, 13.8 ± 1.4 years) were included in group 2. The clinical outcome scores showed no difference between the 2 groups (Pedi-IKDC, P =.072; Pedi-FABS, P =.180). Nevertheless, the patients in group 2 had better anteroposterior stability measured using a KT-1000 arthrometer (1.9 ± 1.1 mm in group 1 vs 0.8 ± 0.8 mm in group 2; P =.031), as well as better rotational stability measured using the KiRA (–0.59 ± 1.05 m/s2 in group 2 vs 0.98 ± 1.12 m/s2 in group 1; P =.012). The patients in group 1 returned to sports at the same competitive level at a rate of 82.4%, while patients included in group 2 returned at the same competitive level in 90.6% of the cases without a significant difference between the 2 groups (P =.059). No leg-length discrepancies were found between the 2 groups at last follow-up (P =.881). Two patients displayed an increased valgus deformity of 3° on the operated limb at last follow-up (1 patient in group 1 and 1 patient in group 2). Group 1 had a significatively higher cumulative failure rate (14.7% vs 6.3%; P =.021). No intra- or postoperative complications was observed between the 2 groups. Conclusion: Performing a modified Lemaire LET along with an ACL reconstruction with hamstring graft in pediatric patients reduced the cumulative failure rate and improved objective stability with no increase in intra- or postoperative complications. No significant difference was found between the 2 groups in terms of patient-reported outcomes or in the return-to-sports activity. [ABSTRACT FROM AUTHOR]

Background: Owing to the disappointing regenerative ability of osteochondral tissue, without treatment an osteochondral defect would progress to osteoarthritis. This situation motivates the need for new strategies to enhance the regeneration of osteochondral defects. Purpose: To develop a tissue-engineering scaffold by tethering bone morphogenetic protein 2 (BMP2) and transforming growth factor beta 3 (TGFβ3) in a layer-specific manner on a slotted decellularized osteochondral matrix (SDOM) and to evaluate the efficacy of this scaffold for osteochondral regeneration. Study Design: Controlled laboratory study. Methods: Normal osteochondral tissue from the rabbit patellofemoral groove was sectioned into a slot shape and decellularized for fabricating an SDOM. The collagen-binding domain (CBD) was fused into the N-terminus of BMP2 or TGFβ3 to synthesize 2 recombinant growth factors (GFs) (CBD-BMP2 or CBD-TGFβ3), which were tethered to the bone layer and cartilage layer, respectively, of the SDOM to prepare a tissue-engineering scaffold (namely, CBD-GFs/SDOM). After examining the influence of the CBD-GFs/SDOM on the viability and layer-specific differentiation of bone marrow mesenchymal stem cells in vitro, we determined the regeneration potential of the CBD-GFs/SDOM on osteochondral regeneration in a rabbit model. A total of 72 New Zealand White rabbits with a cylindrical osteochondral defect in the patellofemoral groove were randomly assigned to 3 groups: defect only (control [CTL] group), defect patched with an SDOM (SDOM group), and defect patched with the CBD-GFs/SDOM (CBD-GFs/SDOM group). At 6 or 12 weeks postoperatively, the rabbits were euthanized to harvest the knee joint, which was then evaluated via gross observation, micro–computed tomography, histological staining, and mechanical testing. Results: In vitro, the CBD-GFs/SDOM was noncytotoxic, showed high biomimetics with normal osteochondral tissue, was suitable for cell adhesion and growth, and had good layer-specific ability in inducing stem cell differentiation. Macroscopic images showed that the CBD-GFs/SDOM group had significantly better osteochondral regeneration than the CTL and SDOM groups had. Micro–computed tomography demonstrated that much more bony tissue was formed at the defect sites in the CBD-GFs/SDOM group compared with the defect sites in the CTL or SDOM group. Histological analysis showed that the CBD-GFs/SDOM group had a significant enhancement in osteochondral regeneration at 6 and 12 weeks postoperatively in comparison with the CTL or SDOM group. At 12 weeks postoperatively, the mechanical properties of reparative tissue were significantly better in the CBD-GFs/SDOM group than in the other groups. Conclusion: The CBD-GFs/SDOM is a promising scaffold for osteochondral regeneration. Clinical Relevance: The findings of this study indicated that the CBD-GFs/SDOM is an excellent candidate for reconstructing osteochondral defects, which may be translated for clinical use in the future. [ABSTRACT FROM AUTHOR]

Background: It is unknown how different pitch count limits and rest day requirements affect cumulative pitch counts during a baseball season. Purpose: To determine (1) the variability of pitch count rules in high school baseball and (2) the theoretical effect of different pitch count limits and rest day combinations on game, weekly, and seasonal pitch totals in high school baseball pitchers. Study Design: Cross-sectional study. Methods: Pitch count rules for the 2019-2020 academic year for 48 sanctioned states were recorded from each state's athletic association website. Maximum pitch count limits were recorded along with the number of pitches allowed before requiring 0 to 5 rest days before the next pitching outing. Rules were also analyzed for several distinctions, including the athlete's level of competition, age, and grade. To determine the effect of pitch count rules and rest days, a theoretical 3-month season was calculated in the following scenarios: (1) variable maximum pitch count limits with a universal 3-day rest requirement, (2) universal 110 pitch count limit with variable rest day requirements (3, 4, or 5 days), and (3) actual pitch count limits and required rest days for every state assuming pitchers throw as many pitches as allowed. Analysis of variance and Student t tests were used to compare between-group and intragroup seasonal pitch totals based on variations in required rest days. Results: The most common maximum pitch count limit for a varsity high school athlete was 110 pitches (range, 100-125 pitches) with 4 rest days (range, 0-5 days). We found that 23 states (48%) did not make distinctions for pitch count rules based on the athlete's level of competition, age, or grade. We noted a 25% increase in total seasonal pitch counts between the smallest and largest pitch count limit when assuming constant 3-day rest. We found a 53% difference in total seasonal pitch count when rest days varied between 3 and 5 days with a constant 110-pitch limit. Allowing 140 pitches in a 4-day span without a specific rest day requirement resulted in the highest seasonal pitch count (Nevada). There was a 49% difference in maximum seasonal pitch counts between the most and least restrictive states (P <.001). Submaximum pitch limits resulted in higher seasonal pitch counts than maximum pitch limits in 56% of states. Conclusion: Pitch count rules vary widely by state. Required rest days influenced total seasonal pitch counts more than maximum or submaximum pitch count limits. [ABSTRACT FROM AUTHOR]

Background: Lytic or malpositioned tunnels may require bone grafting during revision anterior cruciate ligament reconstruction (rACLR) surgery. Patient characteristics and effects of grafting on outcomes after rACLR are not well described. Purpose: To describe preoperative characteristics, intraoperative findings, and 2-year outcomes for patients with rACLR undergoing bone grafting procedures compared with patients with rACLR without grafting. Study Design: Cohort study; Level of evidence, 3. Methods: A total of 1234 patients who underwent rACLR were prospectively enrolled between 2006 and 2011. Baseline revision and 2-year characteristics, surgical technique, pathology, treatment, and patient-reported outcome instruments (International Knee Documentation Committee [IKDC], Knee injury and Osteoarthritis Outcome Score [KOOS], Western Ontario and McMaster Universities Osteoarthritis Index, and Marx Activity Rating Scale [Marx]) were collected, as well as subsequent surgery information, if applicable. The chi-square and analysis of variance tests were used to compare group characteristics. Results: A total of 159 patients (13%) underwent tunnel grafting—64 (5%) patients underwent 1-stage and 95 (8%) underwent 2-stage grafting. Grafting was isolated to the femur in 31 (2.5%) patients, the tibia in 40 (3%) patients, and combined in 88 patients (7%). Baseline KOOS Quality of Life (QoL) and Marx activity scores were significantly lower in the 2-stage group compared with the no bone grafting group (P ≤.001). Patients who required 2-stage grafting had more previous ACLRs (P <.001) and were less likely to have received a bone–patellar tendon–bone or a soft tissue autograft at primary ACLR procedure (P ≤.021) compared with the no bone grafting group. For current rACLR, patients undergoing either 1-stage or 2-stage bone grafting were more likely to receive a bone–patellar tendon–bone allograft (P ≤.008) and less likely to receive a soft tissue autograft (P ≤.003) compared with the no bone grafting group. At 2-year follow-up of 1052 (85%) patients, we found inferior outcomes in the 2-stage bone grafting group (IKDC score = 68; KOOS QoL score = 44; KOOS Sport/Recreation score = 65; and Marx activity score = 3) compared with the no bone grafting group (IKDC score = 77; KOOS QoL score = 63; KOOS Sport/Recreation score = 75; and Marx activity score = 7) (P ≤.01). The 1-stage bone graft group did not significantly differ compared with the no bone grafting group. Conclusion: Tunnel bone grafting was performed in 13% of our rACLR cohort, with 8% undergoing 2-stage surgery. Patients treated with 2-stage grafting had inferior baseline and 2-year patient-reported outcomes and activity levels compared with patients not undergoing bone grafting. Patients treated with 1-stage grafting had similar baseline and 2-year patient-reported outcomes and activity levels compared with patients not undergoing bone grafting. [ABSTRACT FROM AUTHOR]

Background: Point-of-care treatment options for medium to large symptomatic articular cartilage defects are limited. Minced cartilage implantation is an encouraging single-stage option, providing fresh viable autologous tissue with minimal morbidity and cost. Purpose: To determine the histological properties of mechanically minced versus minimally manipulated articular cartilage. Study Design: Controlled laboratory study. Methods: Remnant articular cartilage was collected from fresh femoral condylar allografts. Cartilage samples were divided into 4 groups: cartilage explants with or without fibrin glue and mechanically minced cartilage with or without fibrin glue. Samples were cultured for 42 days. Chondrocyte viability was assessed using live/dead assay. Cellular migration and outgrowth were monitored using bright-field microscopy. Extracellular matrix deposition was assessed via histological staining. Proteoglycan content and synthesis were assessed using dimethylmethylene blue assay and radiolabeled 35S-sulfate, respectively. Type II collagen (COL2A1) gene expression was analyzed via polymerase chain reaction. Results: The mean viability of minced cartilage particles (34% ± 14%) was not significantly reduced compared with baseline (46% ± 13%) on day 0 (P =.90). After culture, no significant difference in the percentage of live cells was appreciated between mechanically minced (58% ± 23%) and explant (73% ± 14%) cartilage in the presence of fibrin glue (P =.52). The addition of fibrin glue did not significantly affect the viability of cartilage samples. The qualitative assessment revealed comparable cellular migration and outgrowth between groups. Proteoglycan synthesis was not significantly different between groups. Histological analysis findings were positive for COL2A1 in all groups, and matrix formation was appreciated in all groups. COL2A1 expression in minced cartilage (1.72 ± 1.88) was significantly higher than in explant cartilage (0.15 ± 0.07) in the presence of fibrin glue (P =.01). Conclusion: Mechanically minced articular cartilage remained viable after 42 days of culture in vitro and was comparable with cartilage explants with regard to cellular migration, outgrowth, and extracellular matrix synthesis. Clinical Relevance: Mechanically minced articular cartilage is an encouraging intervention for the treatment of symptomatic cartilage defects. Further translational work is warranted to determine the viability of minced cartilage implantation as a single-stage therapeutic intervention in vivo. [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: Individual contributions of the rotator cuff (RC) and superior capsule (SC) to prevent superior translation of the humerus are not well understood. Purpose: To evaluate the relative contributions of the SC and RC to normal and pathologic shoulder biomechanics by determining their independent effects on superior humeral translation. Study Design: Controlled laboratory study. Methods: Twelve cadaveric shoulders were tested at 0º, 45º, and 90º of abduction under 5 conditions: intact RC/SC, RC sectioned first, SC sectioned first, both structures sectioned, and RC repair. Matched pairs were randomly assigned to the second or third testing condition (RC or SC sectioned first). Specimens were tested under 2 static conditions (40-N deltoid load [balanced load], 80-N deltoid load [superiorly directed load]) and 1 dynamic condition during active abduction. A mixed-design 2-way repeated-measures analysis of variance with Bonferroni adjustments was performed to compare testing conditions. Paired t tests were used to compare specimens in the intact state versus the repaired state. Significance was set at P <.05. Results: During balanced deltoid loading at 0° and 45º, there was significantly greater humeral translation when both structures were sectioned as compared with the intact state and with both isolated sectioned states (P <.05 for all). No significant differences were observed between or within groups at 90º of abduction. These effects remained consistent with superiorly directed loading. Dynamic testing of both groups showed a significant increase in superior translation for specimens in which the RC was deficient versus the intact state (P =.027), with no difference when the SC was sectioned. The RC repair state returned translation to values similar to the intact state at all abduction angles and loading conditions (P >.05). Conclusion: In this cadaveric study, the SC and RC played an important role in preventing superior humeral translation; however, dynamic testing suggested preferential contribution of the RC. RC repair was effective in preventing superior humeral translation, even with a sectioned SC at the level of the glenohumeral joint. Clinical Relevance: RC repair was effective in preventing superior humeral translation, even in the presence of a sectioned SC at the level of the glenohumeral joint in this cadaveric model. Our data lay the groundwork for future studies investigating the clinical effect of RC repair in an SC sectioned state. [ABSTRACT FROM AUTHOR]

Background: Cartilage defects result in joint inflammation. The presence of proinflammatory factors has been described to negatively affect cartilage formation. Purpose: To evaluate the effect and timing of administration of triamcinolone acetonide (TAA), an anti-inflammatory drug, on cartilage repair using a mouse model. Study Design: Controlled laboratory study. Methods: A full-thickness cartilage defect was created in the trochlear groove of 10-week-old male DBA/1 mice (N = 80). Mice received an intra-articular injection of TAA or saline on day 1 or 7 after induction of the defect. Mice were euthanized on days 10 and 28 for histological evaluation of cartilage defect repair, synovial inflammation, and synovial membrane thickness. Results: Mice injected with TAA had significantly less synovial inflammation at day 10 than saline-injected mice independent of the time of administration. At day 28, the levels of synovitis dropped toward healthy levels; nevertheless, the synovial membrane was thinner in TAA- than in saline-injected mice, reaching statistical significance in animals injected on day 1 (70.1 ± 31.9 µm vs 111.9 ± 30.9 µm, respectively; P =.01) but not in animals injected on day 7 (68.2 ± 21.86 µm vs 90.2 ± 21.29 µm, respectively; P =.26). A thinner synovial membrane was moderately associated with less filling of the defect after 10 and 28 days (r = 0.42, P =.02; r = 0.47, P =.01, respectively). Whereas 10 days after surgery there was no difference in the area of the defect filled and the cell density in the defect area between saline- and TAA-injected knees, filling of the defect at day 28 was lower in TAA- than in saline-injected knees for both injection time points (day 1 injection, P =.04; day 7 injection, P =.01). Moreover, there was less collagen type 2 staining in the filled defect area in TAA- than in saline-injected knees after 28 days, reaching statistical significance in day 1–injected knees (2.6% vs 18.5%, respectively; P =.01) but not in day 7–injected knees (7.4% vs 15.8%, respectively; P =.27). Conclusion: Intra-articular injection of TAA reduced synovial inflammation but negatively affected cartilage repair. This implies that inhibition of inflammation may inhibit cartilage repair or that TAA has a direct negative effect on cartilage formation. Clinical Relevance: Our findings show that TAA can inhibit cartilage defect repair. Therefore, we suggest not using TAA to reduce inflammation in a cartilage repair setting. [ABSTRACT FROM AUTHOR]

Background: Acute adaptations in clinical measures of range of motion and strength have been found after baseball pitching; however, there is a lack of research concerning the physiological mechanism responsible for these changes. Adaptations in muscle architecture of the infraspinatus and teres minor may serve as the structural changes responsible for these clinical measure changes. Purpose: To longitudinally assess the acute changes in range of motion, strength, and muscle architecture of the infraspinatus and teres minor muscles in baseball pitchers after a simulated baseball game. Additionally, we examined the relationship between muscle architecture and changes in clinical measures of range of motion and strength. Study Design: Controlled laboratory study. Methods: Ten healthy nonvarsity collegiate club baseball pitchers (mean ± SD; age, 20.1 ± 1.10 years) were examined pre-pitching, immediately after pitching, and each subsequent day for 5 days after pitching in a simulated baseball game. A digital inclinometer and handheld dynamometer were used to assess range of motion and strength, respectively. Diagnostic ultrasound was used to assess pennation angle and muscle thickness of the infraspinatus and teres minor at rest and at maximal contraction. Results: Internal rotation range of motion significantly decreased immediately and did not return to baseline until 4 days after pitching (P ≤.05). External rotation strength also immediately decreased and returned on the third day after pitching (P ≤.05). Moreover, the resting pennation angle of the superficial and deep portions of the infraspinatus increased immediately after pitching, with the superficial portion returning to baseline on day 4 and the deep portion returning on day 5 (P ≤.05). Furthermore, the pennation angle changes of the infraspinatus and thickness of the teres minor were predictive of the loss of internal rotation range of motion after pitching (R 2 = 0.419; P ≤.05). Conclusion: This study found diminished internal rotation range of motion and external rotation strength after pitching, with alterations in muscle architecture of the infraspinatus. The pennation angle increase in the infraspinatus at rest is indicative of increased tension in the muscle, which was found to be the underlying mechanism for the clinical loss of internal rotation range of motion. This was demonstrated by the inverse relationship between internal rotation range of motion and the pennation angle of the superficial and deep fibers of the infraspinatus. Clinical Relevance: Clinicians should consider recovery time after pitching to prevent chronic losses of shoulder range of motion and strength. Identification of the underlying mechanisms of range of motion loss after pitching allows clinicians to optimize recovery strategies in baseball pitchers. [ABSTRACT FROM AUTHOR]

Background: Bony Bankart lesions can perpetuate chronic anterior glenohumeral instability. When surgical treatment is pursued, several factors need to be considered to obtain optimal outcomes. Purpose: To (1) quantitatively describe patterns of bone fragment resorption and associated risk factors for developing glenoid bone loss (GBL) and (2) to compare clinical and radiological results of attritional bone loss treated with either the arthroscopic Bankart or the open Latarjet procedure. Study Design: Cohort study; Level of evidence, 3. Methods: A retrospective analysis of prospectively collected data was conducted for patients who underwent arthroscopic stabilization (group A1, 10%-20% GBL; group A2, >20% GBL) or open Latarjet (group B, >10% GBL) for recurrent shoulder instability with bony Bankart lesion. Patient characteristics, number of dislocations, and Western Ontario Shoulder Instability Index (WOSI) scores were obtained. Pre- and postoperative computed tomography imaging was used to quantitatively describe patterns of bone fragment resorption. Results: A total of 120 consecutive patients (group A1, 40; group A2, 23; group B, 57) were included in the study, with a mean age of 25.6 years (range, 19-35 years). The average follow-up was 5.0 years for all groups (range, 4.83-5.16 years in group A1, 4.58-5.41 years in group A2, and 4.33-5.67 years in group B). The mean times between dislocation event and surgery were 12.8 months (range, 6-32 months) and 13.6 months (range, 6-38 months) for groups A and B, respectively. Redislocation rates were 7.5% in group A1 versus 13.0% in group A2, and only occurred in patients with ≥13.5% GBL. There were no redislocations for group B (0%). Patients had better WOSI scores in group B (234.1 ± 126.9) than in group A (576.1 ± 224.6) (P <.0001). In group A, smaller preoperative bone fragment size displayed a higher percentage of resorption after surgery (r = −0.64; P <.05). Conclusion: A significant inverse relationship exists between preoperative bone fragment size and percentage of postoperative resorption. Patients treated with arthroscopic bony Bankart repair who had final GBL ≥13.5% had worse outcomes. When planned GBL approaches 13.5% in high-demand patients, a smaller fragment size can result in worse clinical outcomes because of resorption. In these cases, choosing the open Latarjet procedure leads to better clinical results. [ABSTRACT FROM AUTHOR]

Background: Various cell-free scaffolds are already in use for the treatment of osteochondral defects (OCDs); however, a gold standard material has not yet been defined. Purpose: This study compared the macroscopic, histological, and scanning electron microscopy (SEM) characteristics of Chondro-Gide (CG), MaioRegen (MA), and poly- d, l -lactide-co-caprolactone (PLCL) cell-free scaffolds enhanced with small-diameter microfractures (SDMs) for OCDs in a rabbit model. Study Design: Controlled laboratory study. Methods: In total, 54 knees from 27 rabbits were used in this study. Three rabbits were sacrificed at the beginning of the study to form an intact cartilage control group (group IC). An OCD model was created at the center of the trochlea, and SDMs were generated in 24 rabbits. Rabbits with OCDs were divided into 4 groups (n = 12 knees per group) according to the cell-free scaffold applied: CG (group CG), MA (group MA), PLCL (group PLCL), and a control group (group SDM). Half of the rabbits were sacrificed at 1 month after treatment, while the other half were sacrificed at 3 months after treatment. Healed cartilage was evaluated macroscopically (using International Cartilage Regeneration & Joint Preservation Society [ICRS] classification criteria) and histopathologically (using modified O'Driscoll scores and collagen staining). Additionally, cell-free scaffold morphologies were compared using SEM analysis. Results: ICRS and modified O'Driscoll classification and staining with collagen type 1 and type 2 demonstrated significant differences among groups at both 1 and 3 months after treatment (P <.05). The histological characteristics of the group IC samples were superior to those of all other groups, except group PLCL, at 3 months after treatment (P <.05). In addition, the histological properties of group PLCL samples were superior to those of group SDM samples at both 1 and 3 months after treatment in terms of the modified O'Driscoll scores and type 1 collagen staining (P <.05). Concerning type 2 collagen staining intensity, the groups were ranked from highest to lowest at 3 months after treatment as follows: group PLCL (30.3 ± 2.6) > group MA (26.6 ± 1.2) > group CG (23.3 ± 2.3) > group SDM (18.9 ± 0.9). Conclusion: OCDs treated with enhanced SDM using cell-free PLCL scaffolds had superior histopathological and microenvironmental properties, more hyaline cartilage, and more type 2 collagen compared with those treated using CG or MA scaffolds. Clinical Relevance: OCDs treated with PLCL cell-free scaffolds may have superior histopathological properties and contain more type 2 collagen than do OCDs treated with CG or MA cell-free scaffolds. [ABSTRACT FROM AUTHOR]

Background: Platelet-rich plasma (PRP) is gaining large interest in clinical practice as a minimally invasive injective treatment for knee osteoarthritis (OA). Different preparation methods are available, and the presence of leukocytes, deemed detrimental in some preclinical studies, is one of the most debated aspects regarding PRP efficacy. Purpose: To compare the safety and effectiveness of leukocyte-rich PRP (LR-PRP) and leukocyte-poor PRP (LP-PRP) for the treatment of knee OA. Study Design: Randomized controlled trial; Level of evidence, 1. Methods: A total of 192 patients with symptomatic knee OA (Kellgren-Lawrence grade 1-3) were randomly allocated to 3 weekly injections of LR-PRP or LP-PRP. LP-PRP was obtained with a filter for leukodepletion. LR-PRP and LP-PRP were divided into aliquots of 5 mL, with a mean platelet concentration of 1146.8 × 109/L and 1074.9 × 109/L and a mean leukocyte concentration of 7991.4 × 106/L and 0.1 × 106/L, respectively. Patients were evaluated at baseline and thereafter at 2, 6, and 12 months for the primary outcome, the International Knee Documentation Committee (IKDC) subjective score; and for secondary outcomes, the Knee injury and Osteoarthritis Outcome Score (KOOS) subscales, EuroQol–visual analog scale (EQ-VAS), and Tegner score. Results: No differences between groups were observed in terms of absolute values or improvement of the clinical scores across all follow-up intervals. The mean IKDC subjective score at baseline and 12 months improved from 45.6 to 60.7 in the LR-PRP group as compared with 46.8 to 62.9 in the LP-PRP group (P =.626). No severe adverse events were described in either group, although 15 mild adverse events (knee pain or swelling) were reported: 12.2% for LR-PRP and 4.7% for LP-PRP (P =.101). No statistically significant difference was also found between LR-PRP and LP-PRP in terms of failures (7.8% vs 3.5%, P =.331). Conclusion: This double-blind randomized trial showed that 3 intra-articular LR-PRP or LP-PRP injections produced similar clinical improvement in the 12 months of follow-up in patients with symptomatic knee OA. Both treatment groups reported a low number of adverse events, without intergroup differences. The presence of leukocytes did not significantly affect the clinical results of PRP injections. Registration: NCT02923700 (ClinicalTrials.gov identifier). [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: The injection of mesenchymal stem cells (MSCs) mitigates fat accumulation in released rotator cuff muscle after tendon repair in rodents. Purpose: To investigate whether the injection of autologous MSCs halts muscle-to-fat conversion after tendon repair in a large animal model for rotator cuff tendon release via regional effects on extracellular fat tissue and muscle fiber regeneration. Study Design: Controlled laboratory study. Methods: Infraspinatus (ISP) muscles of the right shoulder of Swiss Alpine sheep (n = 14) were released by osteotomy and reattached 16 weeks later without (group T; n = 6) or with (group T-MSC; n = 8) electropulse-assisted injection of 0.9 Mio fluorescently labeled MSCs as microtissues with media in demarcated regions; animals were allowed 6 weeks of recovery. ISP volume and composition were documented with computed tomography and magnetic resonance imaging. Area percentages of muscle fiber types, fat, extracellular ground substance, and fluorescence-positive tissue; mean cross-sectional area (MCSA) of muscle fibers; and expression of myogenic (myogenin), regeneration (tenascin-C), and adipogenic markers (peroxisome proliferator-activated receptor gamma [PPARG2]) were quantified in injected and noninjected regions after recovery. Results: At 16 weeks after tendon release, the ISP volume was reduced and the fat fraction of ISP muscle was increased in group T (137 vs 185 mL; 49% vs 7%) and group T-MSC (130 vs 166 mL; 53% vs 10%). In group T-MSC versus group T, changes during recovery after tendon reattachment were abrogated for fat-free mass (–5% vs –29%, respectively; P =.018) and fat fraction (+1% vs +24%, respectively; P =.009%). The area percentage of fat was lower (9% vs 20%; P =.018) and the percentage of the extracellular ground substance was higher (26% vs 20%; P =.007) in the noninjected ISP region for group T-MSC versus group T, respectively. Regionally, MCS injection increased tenascin-C levels (+59%) and the water fraction, maintaining the reduced PPARG2 levels but not the 29% increased fiber MCSA, with media injection. Conclusion: In a sheep model, injection of autologous MSCs in degenerated rotator cuff muscle halted muscle-to-fat conversion during recovery from tendon repair by preserving fat-free mass in association with extracellular reactions and stopping adjuvant-induced muscle fiber hypertrophy. Clinical Relevance: A relatively small dose of MSCs is therapeutically effective to halt fatty atrophy in a large animal model. [ABSTRACT FROM AUTHOR]

Background: Loss to follow-up in registry studies might affect generalizability and interpretation of results. Purpose: To evaluate the effect of nonresponder bias in our anterior cruciate ligament (ACL) registry. Study Design: Case-control study; Level of evidence, 3. Methods: A total of 2042 patients with ACL reconstruction in the Hospital for Special Surgery ACL Registry between 2009 and 2013 were included in the study. Patients who completed the patient-reported outcome measures at 2 or 5 years were considered responders (n = 808). Baseline data and patient characteristics were compared between responders and nonresponders (n = 1234). Both responders and nonresponders were contacted and invited to complete the International Knee Documentation Committee (IKDC) and Marx scores electronically and respond to questions regarding return to sports and subsequent surgeries. Nonresponders who completed the questionnaires after reminders were considered late responders. The remaining nonresponders were considered never-responders. The late responders (n = 367) completed the questionnaires after a mean follow-up of 7.8 years (range, 6.7-9.6 years), while follow-up for the responders was 6.8 years (range, 5.0-9.7 years). Responders and late responders were then compared in terms of differences in IKDC and Marx scores from baseline to final follow-up. Results: Nonresponders were younger (28.5 vs 31.5 years; P <.001) and more often male (60% vs 53%; P =.003) compared with responders. Responders had a higher level of education and were more likely to be White (79% vs 74%; P =.04). There were no substantial differences in patient characteristics or baseline IKDC and Marx scores between the late responders and never-responders. There were no statistically significant differences in patient-reported outcomes, return to sports, or subsequent surgeries between responders and late responders at a mean follow-up time of 8.8 years (range, 6.7-9.7 years). Repeat email reminders and telephone calls increased response rate by 18% (from 40% to 58%). Conclusion: There was no difference in clinical outcome as evaluated using IKDC and Marx scores between responders and late responders. [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]