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Background: Superior capsular reconstruction (SCR) has been demonstrated to be a valuable treatment for patients with irreparable massive rotator cuff tears (IMRCTs). However, the torn medial supraspinatus (SSP) tendons, which acted as dynamic stabilizers, were left untreated in conventional SCR, and the dynamic force from the SSP tendon was not restored. Purpose: To evaluate the effect of dynamic SCR (dSCR) on fascia-to-bone healing in a rat model, and to compare the short-term clinical effectiveness of dSCR and SCR using autologous fascia lata (FL) in patients with IMRCTs. Study Design: Controlled laboratory study and cohort study; Level of evidence, 3. Methods: A total of 50 rats were divided randomly into 2 groups: the dSCR group and the SCR group (25 rats per group). First, chronic IMRCTs were created, and then the torn tendons in both groups were subjected to SCR using autologous thoracolumbar fascial (TLF) grafts. The remnant of the SSP tendon was sutured to the medial part of the TLF graft in the dSCR group but not in the SCR group. Histologic sections were assessed at 1, 2, 4, 8, and 16 weeks postoperatively. In the clinical study, 22 patients (9 SCR, 13 dSCR) were analyzed. The recovery of shoulder function, including the active range of motion (ROM), visual analog scale (VAS), American Shoulder and Elbow Surgeons score, Constant score, and University of California Los Angeles score, acromiohumeral distance (AHD), and fatty infiltration, was evaluated before surgery and at the last follow-up. Results: Histologic analysis of the fascia-to-bone junction in the rat model showed that the TLF gradually migrated into tendon-like tissue over the rotator cuff defects in both groups, and the modified tendon maturation score of the fascia-to-bone interface in the dSCR group was higher than that in the SCR group at 4 weeks (12.20 ± 1.30 vs 14.60 ± 1.52; P =.004), 8 weeks (19.60 ± 1.14 vs 22.20 ± 1.10; P =.019), and 16 weeks (23.80 ± 0.84 vs 26.20 ± 0.84 P =.024). The dSCR group showed earlier fibrocartilage cell formation and angiogenesis. In the clinical study, all 22 patients completed a minimum of 12 months of follow-up after surgery, and the mean follow-up duration was 22.89 ± 7.59 months in the SCR group and 25.62 ± 7.32 months in the dSCR group. The patients in both groups showed significant improvements in terms of ROM, shoulder function scores, and AHD. At the last follow-up, abduction (56.67°± 27.39° vs 86.54°± 30.37°; P =.029), external rotation (25.00°± 9.35° vs 33.08°± 8.55°; P =.049), internal rotation cone rank (–2.78 ± 2.44 vs –4.38 ± 1.12; P =.049), VAS (–3.00 ± 0.87 vs –3.92 ± 0.95; P =.031) and Constant (47.89 ± 15.39 vs 59.15 ± 9.74; P =.048) scores, and the AHD improvement degree (3.06 ± 1.41 mm vs 4.38 ± 1.35 mm; P =.039) in the dSCR group were significantly improved compared with those in the SCR group. The results of fatty infiltration at the last follow-up showed that there was significant improvement compared with the preoperative results in both the conventional SCR (P =.036) and the dSCR (P =.001) groups. However, there were no significant differences between the 2 groups (P =.511). Conclusion: dSCR can promote faster fascia-to-bone healing in a rat model, and the dSCR technique could provide a preferable treatment option for patients with IMRCTs. Clinical Relevance: dSCR might restore the dynamic of SSP in some sense and then improve the fatty infiltration in the SSP. [ABSTRACT FROM AUTHOR]

Background: The ligaments and soft tissue capsular structures of the knee joint that provide a resisting force to prevent abnormal knee hyperextension have not been determined. This knowledge is required for the diagnosis and treatment of knee hyperextension abnormalities. Purpose: To determine the resisting moment of knee ligament and capsular structures that resist knee hyperextension. Hypothesis: The combined posteromedial and posterolateral capsular structures function to provide a major restraint to prevent abnormal knee hyperextension. The anterior and posterior cruciate ligaments resist knee hyperextension but function as secondary restraints. Study Design: Descriptive laboratory study. Methods: A 6 degrees of freedom robotic system determined intact laxity limits in 24 cadaveric knees from 0° to 100° of knee flexion for anteroposterior limits at ±135 N, abduction-adduction limits at ±7 N·m, and external-internal limits at ±5 N·m. One loading method (n = 14 knees) used a static loading sequence with knee hyperextension to 27-N·m torque while maintaining all other degrees of freedom at zero load during sequential soft tissue cutting. The second method (n = 10 knees) used a cyclic loading sequence to decrease viscoelastic effects with soft tissue cutting at 0° of extension, followed by knee hyperextension to 27-N·m torque and cycled back to 0°. Selective soft tissue cuttings were performed of the following: oblique popliteal ligament, fabellofibular ligament, posterolateral capsule, posteromedial capsule with posterior oblique ligament, cruciate ligaments, lateral collateral ligament, popliteus, anterolateral ligament and iliotibial band, and superficial plus deep medial collateral ligaments. The sequential loss in the restraining moment with sectioning provides the function of that structure in resisting knee hyperextension. Results: The median resisting force to knee hyperextension, in descending order, was the posteromedial capsule and posterior oblique ligament (21.7%), posterorolateral ligament and fabellofibular ligament (17.1%), anterior and posterior cruciate ligaments (13% and 12.9%, respectively), superior and deep medial collateral ligament (9.6%), oblique popliteal ligament (7.7%), and lateral collateral ligament (5.4%). The combined posterior capsular structures provided 54.7% and the anterior and posterior cruciate ligaments 25.3% of the total resisting moment to prevent knee hyperextension. Conclusion: Diagnosis of abnormal knee hyperextension involves a combination of multiple ligament and soft tissue structures without 1 primary restraint. The posteromedial and posterolateral capsular structures provided the major resisting moment to prevent knee hyperextension. The cruciate ligaments produced a lesser resisting moment to knee hyperextension. Clinical Relevance: This is the first study to comprehensively measure all of the knee ligaments and capsular structures providing a resisting moment to abnormal knee hyperextension. These data are required for diagnostic and treatment strategies on the pathomechanics of abnormal knee hyperextension in patients after injury or developmental cases. [ABSTRACT FROM AUTHOR]

Background: High tibial osteotomy (HTO) reduces the load distribution of the medial compartment by modifying leg alignment. Knee adduction moment (KAM), a surrogate measure of dynamic loading in the knee joint, decreases after HTO. However, leg alignment does not fully account for KAM. Purpose: To assess the association between the pelvis-knee-ankle angle (PKA), a novel radiographic parameter reflecting leg alignment and pelvic width, and KAM and patient-reported outcomes after HTO. Study Design: Cross sectional study; Level of evidence, 3. Methods: PKA is the angle between the line from the midpoint of the anterior superior iliac spine to the center of the knee joint and the mechanical axis of the tibia. In this study, 54 patients with medial compartment knee osteoarthritis and varus alignment who underwent 3-dimensional gait analysis preoperatively and 2 years after medial open-wedge HTO were evaluated. The primary outcomes were hip-knee-ankle angle (HKA), PKA, KAM peaks, and Knee Society Score (KSS). Single and multivariate regression analysis including PKA and KAM peaks as well as other demographic and radiologic factors was performed. Results: HKA was weakly correlated with the first peak KAM (r = −0.33; P <.01) and second peak KAM (r = −0.27; P =.01) before HTO, but not significantly correlated after HTO. PKA was moderately correlated with the first peak KAM (r = 0.45; P <.01) and second peak KAM (r = 0.45; P <.01) before HTO and with the first peak KAM (r = 0.51; P <.01) and second peak KAM (r = 0.56; P <.01) after HTO. Multivariate linear regression revealed that postoperative PKA was still associated with the KAM peaks after HTO. Only postoperative PKA was correlated with the KSS satisfaction subscale (r = −0.30; P =.03). Conclusion: Although HKA was not correlated with KAM peaks after HTO, PKA was significantly correlated with KAM peaks in patients with varus knee osteoarthritis after HTO. [ABSTRACT FROM AUTHOR]

Background: Previous cadaveric kinematic studies on acromioclavicular injuries described mainly rotational differences during humerothoracic movements. Although isolated scapulothoracic movements are also often performed during activities of daily life and can be painful after acromioclavicular injuries, they have not been extensively studied. Further, the analysis of joint translations in kinematic studies has received little attention compared with biomechanical studies. Hypothesis: A kinematic analysis of joint motions in the intact shoulder versus a shoulder with Rockwood V injury would demonstrate a different pattern of kinematic alterations during humerothoracic and scapulothoracic movements. Study design: Descriptive laboratory study. Methods: A kinematic analysis was performed in 14 cadaveric shoulders during 3 humerothoracic passive movements (coronal and sagittal plane elevation and horizontal adduction) and 3 scapulothoracic passive movements (protraction, retraction, and shrug). An optical navigation system registered rotational motions in the sternoclavicular, scapulothoracic, and acromioclavicular joints in the intact and Rockwood V conditions. In the acromioclavicular joint, mediolateral, anteroposterior, and superoinferior translations were also analyzed. Results: In the Rockwood V condition, a significant increase in clavicular elevation in the sternoclavicular joint during both humerothoracic and scapulothoracic movements was demonstrated, whereas a significant decrease in posterior rotation of the clavicle occurred only during humerothoracic movements. In the scapulothoracic joint, the scapular position changed most significantly during protraction. In the acromioclavicular joint, the scapular tilting position was altered significantly during both humerothoracic and scapulothoracic movements, whereas the scapular rotational position changed only during coronal and sagittal plane elevation. The largest significant changes in the scapular protraction position were seen during protraction movement. Further, in the acromioclavicular joint there was a significant inferior translation of the scapula during all motions, a significant anterior translation during protraction and horizontal adduction, and a significant posterior translation during coronal plane elevation. Mediolaterally, the acromial end of the scapula slid further under the distal clavicle during protraction than during horizontal adduction. Conclusion: Large kinematic differences were seen between the intact state and a Rockwood V lesion not only during humerothoracic movements but also during scapulothoracic movements in the cadaveric model. During humerothoracic movements, rotational differences were mainly caused by alterations in the clavicular position. In contrast, during protraction, the alterations in the scapular position were the dominant factor. Clinical Relevance: This study demonstrates that protraction induces larger kinematic alterations than horizontal adduction in acromioclavicular injuries and can therefore be included in both clinical examination and kinematic analyses to identify lesions more clearly. [ABSTRACT FROM AUTHOR]

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

Background: The treatment strategies for meniscal injuries during anterior cruciate ligament (ACL) reconstruction remain a topic of debate. Hypothesis: After ACL reconstruction, knee kinematics would be affected by different medial meniscal treatment (partial medial meniscectomy [PMM] and medial meniscal repair [MMR]). Study Design: Controlled laboratory study. Methods: A total of 161 patients underwent primary single-bundle ACL reconstruction and simultaneous medial meniscal treatment. Of these, 32 patients were eligible to participate in the kinematic assessment at 24.8 ± 1.7 months after surgery. Patients were divided into 2 groups: (1) those who underwent MMR (Group MMR; n = 18) and (2) those who underwent PMM (Group PMM; n = 14). Twenty healthy participants (Group Intact) were recruited who were comparable in age, body mass index, and sex. The kinematic parameters were collected using an optical tracking system during treadmill gait. Range of motion and kinematic parameters at key events during the gait cycle were compared between the 3 groups. The primary outcomes were the differences in adduction/abduction and internal/external rotation. Results: Patients in Group PMM walked with increased adduction as compared with those in Group Intact during the early stance phase (P =.003; η2 = 0.172) and midstance phase (P =.003; η2 = 0.167). In terms of internal/external rotation, patients in Group PMM walked with significantly larger tibial external rotation when compared with Group MMR by approximately 3.4° to 3.7° (loading response: P =.026, η2 = 0.090; midstance: P =.035, η2 = 0.093) and Group Intact (P =.028; η2 = 0.095) in the early stance phase. In addition, there was significantly increased anterior tibial translation in Groups MMR and PMM compared with Group Intact. Conclusion: ACL reconstruction (via transtibial technique) with concurrent PMM demonstrated larger adduction and external tibial rotation at 24 months of follow-up during level walking. Clinical Relevance: Patients undergoing different medial meniscal treatment strategies in the presence of ACL reconstruction showed distinct knee kinematics. These results suggest that MMR is strongly recommended during ACL reconstructive surgery to reduce the abnormal kinematics close to that of the ACL-intact condition. [ABSTRACT FROM AUTHOR]

Background: Core stability is influential in the incidence of lower extremity injuries, including anterior cruciate ligament (ACL) injuries, but the effects of core strength training on the risk for ACL injury remain unclear. Hypothesis: Core muscle strength training increases the knee flexion angle, hamstring to quadriceps (H:Q) coactivation ratio, and vastus medialis to vastus lateralis (VM:VL) muscle activation ratio, as well as decreases the hip adduction, knee valgus, and tibial internal rotation angles. Study Design: Controlled laboratory study. Methods: A total of 48 male participants were recruited and randomly assigned to either the intervention group (n = 32) or the control group (n = 16). Three-dimensional trunk, hip, knee, and ankle kinematic data and muscle activations of selected trunk and lower extremity muscles were obtained while the participants performed side-step cutting. The core endurance scores were measured before and after training. Two-way analyses of variance were conducted for each dependent variable to determine the effects of 10 weeks of core strength training. Results: The trunk endurance scores in the intervention group significantly increased after training (P <.05 for all comparisons). The intervention group showed decreased knee valgus (P =.038) and hip adduction angles (P =.032) but increased trunk flexion angle (P =.018), rectus abdominis to erector spinae coactivation ratio (P =.047), H:Q coactivation ratio (P =.021), and VM:VL activation ratio (P =.016). In addition, the knee valgus angle at initial contact was negatively correlated with the VM:VL activation ratio in the precontact phase (R 2 = 0.188; P <.001) but was positively correlated with the hip adduction angle (R 2 = 0.120; P <.005). No statistically significant differences were observed in the trunk endurance scores, kinematics, and muscle activations for the control group. Conclusion: Core strength training altered the motor control strategies and joint kinematics for the trunk and the lower extremity by increasing the trunk flexion angle, VM:VL activation ratio, and H:Q activation ratio and reducing the knee valgus and hip adduction angles. Clinical Relevance: Training core muscles can modify the biomechanics associated with ACL injuries in a side-step cutting task; thus, core strength training might be considered in ACL injury prevention programs to alter the lower extremity alignment in the frontal plane and muscle activations during sports-related tasks. [ABSTRACT FROM AUTHOR]

Background: Loss of upper and lower extremity range of motion (ROM) is a significant risk factor for injuries in professional baseball players. Purpose/Hypothesis: The purpose was to determine changes in ROM in professional baseball players over the course of a single season and their careers. We hypothesized that pitchers and position players would lose ROM, specifically total shoulder motion (total ROM [TROM]) and hip internal rotation (IR), over the course of a season and their careers. Study Design: Case series; Level of evidence, 4. Methods: Upper and lower extremity ROM measurements were recorded during pre-, mid-, and postseason on all professional baseball players for a single organization between 2011 and 2018. ROM measurements were compared for pitchers and position players over the course of the season and their careers. Also, ROM measurements over the pre-, mid-, and postseason were compared between pitchers and position players. Results: A total of 166 professional baseball players (98 pitchers, 68 position players) were included. Pitcher hip external rotation (ER; P <.001), IR (P =.010), and TROM (P <.001) for lead and trail legs decreased over the course of the season. Pitcher shoulder ER (P =.005), TROM (P =.042), and horizontal adduction (P <.001) significantly increased over the course of the season. Position player shoulder flexion (P =.046), hip ER (P <.001, lead leg; P <.001, trail leg), and hip TROM (P =.001; P =.002) decreased over the course of the season. Position player shoulder ER (P =.031) and humeral adduction (P <.001) significantly increased over the course of the season. Over the course of pitchers' careers, there was decreased shoulder IR (P =.014), increased shoulder horizontal adduction (P <.001), and hip IR (P =.042) and hip TROM (P =.027) for the lead leg. Position players experienced loss of hip TROM (P =.010, lead leg; P =.018, trail leg) over the course of their careers. Pitchers started with and maintained more shoulder ER and gained more shoulder TROM over a season as compared with position players. Conclusion: Pitchers and position players saw overall decreases in hip ROM but increases in shoulder ROM over the course of the season and career. [ABSTRACT FROM AUTHOR]

Background: Patients with symptomatic femoroacetabular impingement (FAI) typically have anterior groin pain. However, a subset of these patients may have pain located laterally, posteriorly, or in a combination of locations around the hip. Purpose: To report and compare outcomes of hip arthroscopy for patients with FAI and atypical hip pain versus classic anterior groin pain. Study Design: Cohort study; Level of evidence, 2. Methods: Consecutive patients undergoing hip arthroscopy for FAI between August 2011 and March 2013 were identified. A total of 258 patients were identified as having symptomatic FAI based on clinical, radiographic, and advanced imaging diagnosis of FAI. Exclusion criteria included isolated thigh, knee, or low back pain. We also excluded patients with hip abductor pathology and trochanteric bursitis. Of the 226 patients ultimately included, 159 (70.4%) reported anterior groin pain, while 67 (29.6%) reported isolated lateral or posterior hip pain or a combination of locations. Patients were categorized into 4 groups: isolated anterior groin pain, lateral hip pain, posterior hip pain, and multiple primary hip pain locations (combined). These patients were followed prospectively with a minimum follow-up of 2 years. Patient characteristics, surgical characteristics, modified Harris Hip Score (mHHS), Non-arthritic Hip Score (NAHS), revision hip arthroscopy, and conversions to total hip arthroplasty (THA) were recorded. Results: All 226 patients were included at final follow-up. Hip arthroscopy was performed by a single sports medicine fellowship-trained orthopaedic surgeon. Preoperative patient characteristics and baseline functional outcome scores did not significantly differ among groups. All 4 groups showed statistically significant improvements in mHHS and NAHS from baseline to final follow-up of a mean 2.63 years (range, 2.01-3.23 years). Functional outcome scores and rates of revision hip arthroscopy or conversion to THA did not significantly differ between groups. Conclusion: Hip arthroscopy can effectively improve patient outcomes in atypical hip pain. A careful history and physical examination should identify this clinically meaningful subset of patients with FAI who can benefit from surgical intervention while identifying patients with concomitant posterior extra-articular hip or spine pathology that should be addressed appropriately. [ABSTRACT FROM AUTHOR]

Background: Aberrant frontal-plane hip and pelvis kinematics have been frequently observed in runners with patellofemoral pain (PFP). Gait retaining interventions have been shown to improve running kinematics and may therefore be beneficial in runners with PFP. Purpose: To investigate whether a 10% increase in the running step rate influences frontal-plane kinematics of the hip and pelvis as well as clinical outcomes in runners with PFP. Study Design: Case series; Level of evidence, 4. Methods: Runners with PFP underwent a 3-dimensional gait analysis to confirm the presence of aberrant frontal-plane hip and/or pelvis kinematics at baseline. A total of 12 participants with frontal-plane hip and/or pelvis kinematics 1 standard deviation above a reference database were invited to undergo the gait retraining intervention. Running kinematics along with clinical outcomes of pain and functional outcomes were recorded at baseline, 4 weeks after retraining, and 3 months. Gait retraining consisted of a single session where step rate was increased by 10% using an audible metronome. Participants were asked to continue their normal running while self-monitoring their step rate using a global positioning system smartwatch and audible metronome. Results: After gait retraining, significant improvements in running kinematics and clinical outcomes were observed at 4-week and 3-month follow-up. Repeated-measures analysis of variance with post hoc Bonferroni correction (P <.016) showed significant reductions in peak contralateral pelvic drop (mean difference [MD], 3.12° [95% CI, 1.88°-4.37°]), hip adduction (MD, 3.99° [95% CI, 2.01°-5.96°]), and knee flexion (MD, 4.09° [95% CI, 0.04°-8.15°]) as well as significant increases in self-reported weekly running volume (MD, 13.78 km [95% CI, 4.62-22.93 km]) and longest run pain-free (MD, 6.84 km [95% CI, 3.05-10.62 km]). Friedman test with a post hoc Wilcoxon signed-rank test showed significant improvements on a numerical rating scale for worst pain in the past week and the Lower Extremity Functional Scale. Conclusion: A single session of gait retraining using a 10% increase in step rate resulted in significant improvements in running kinematics, pain, and function in runners with PFP. These improvements were maintained at 3-month follow-up. It is important to assess for aberrant running kinematics at baseline to ensure that gait interventions are targeted appropriately. Registration: NCT03067545 (ClinicalTrials.gov identifier) [ABSTRACT FROM AUTHOR]

Background: Previous studies have shown that changing acutely from shod to barefoot running induces several changes to running biomechanics, such as altered ankle kinematics, reduced ground-reaction forces, and reduced loading rates. However, uncertainty exists whether these effects still exist after a short period of barefoot running habituation. Purpose/Hypothesis: The purpose was to investigate the effects of a habituation to barefoot versus shod running on running biomechanics. It was hypothesized that a habituation to barefoot running would induce different adaptations of running kinetics and kinematics as compared with a habituation to cushioned footwear running or no habituation. Study Design: Controlled laboratory study. Methods: Young, physically active adults without experience in barefoot running were randomly allocated to a barefoot habituation group, a cushioned footwear group, or a passive control group. The 8-week intervention in the barefoot and footwear groups consisted of 15 minutes of treadmill running at 70% of VO2 max (maximal oxygen consumption) velocity per weekly session in the allocated footwear. Before and after the intervention period, a 3-dimensional biomechanical analysis for barefoot and shod running was conducted on an instrumented treadmill. The passive control group did not receive any intervention but was also tested prior to and after 8 weeks. Pre- to posttest changes in kinematics, kinetics, and spatiotemporal parameters were then analyzed with a mixed effects model. Results: Of the 60 included participants (51.7% female; mean ± SD age, 25.4 ± 3.3 years; body mass index, 22.6 ± 2.1 kg·m-2), 53 completed the study (19 in the barefoot habituation group, 18 in the shod habituation group, and 16 in the passive control group). Acutely, running barefoot versus shod influenced foot strike index and ankle, foot, and knee angles at ground contact (P < .001), as well as vertical average loading rate (P = .003), peak force (P < .001), contact time (P < .001), flight time (P < .001), step length (P < .001), and cadence (P < .001). No differences were found for average force (P = .391). After the barefoot habituation period, participants exhibited more anterior foot placement (P = .006) when running barefoot, while no changes were observed in the footwear condition. Furthermore, barefoot habituation increased the vertical average loading rates in both conditions (barefoot, P = .01; shod, P = .003) and average vertical ground-reaction forces for shod running (P = .039). All other outcomes (ankle, foot, and knee angles at ground contact and flight time, contact time, cadence, and peak forces) did not change significantly after the 8-week habituation. Conclusion: Changing acutely from shod to barefoot running in a habitually shod population increased the foot strike index and reduced ground-reaction force and loading rates. After the habituation to barefoot running, the foot strike index was further increased, while the force and average loading rates also increased as compared with the acute barefoot running situation. The increased average loading rate is contradictory to other studies on acute adaptations of barefoot running. Clinical Relevance: A habituation to barefoot running led to increased vertical average loading rates. This finding was unexpected and questions the generalizability of acute adaptations to long-term barefoot running. Sports medicine professionals should consider these adaptations in their recommendations regarding barefoot running as a possible measure for running injury prevention. [ABSTRACT FROM AUTHOR]

Background: Surgical management of cam femoroacetabular impingement (FAI) aims to preserve the native hip and restore joint function, although it is unclear how the capsulotomy, cam deformity, and capsular repair influence joint mechanics to balance functional mobility. Purpose: To examine the contributions of the capsule and cam deformity to hip joint mechanics. Using in vitro, cadaveric methods, we examined the individual effects of the surgical capsulotomy, cam resection, and capsular repair on passive range of motion and resistance of applied torque. Study Design: Descriptive laboratory study. Methods: Twelve cadaveric hips with cam deformities were skeletonized to the capsule and mounted onto a robotic testing platform. The robot positioned each intact hip in multiple testing positions: (1) extension, (2) neutral 0°, (3) flexion 30°, (4) flexion 90°, (5) flexion-adduction and internal rotation (FADIR), and (6) flexion-abduction and external rotation. Then the robot performed applicable internal and external rotations, recording the neutral path of motion until a 5-N·m of torque was reached in each rotational direction. Each hip then underwent a series of surgical stages (T-capsulotomy, cam resection, capsular repair) and was retested to reach 5 N·m of internal and external torque again after each stage. During the capsulotomy and cam resection stages, the initial intact hip's recorded path of motion was replayed to measure changes in resisted torque. Results: Regarding changes in motion, external rotation increased substantially after capsulotomies, but internal rotation only further increased at flexion 90° (change +32%, P = .001, d = 0.58) and FADIR (change +33%, P < .001, d = 0.51) after cam resections. Capsular repair provided marginal restraint for internal rotation but restrained the external rotation compared with the capsulotomy stage. Regarding changes in torque, both internal and external torque resistance decreased after capsulotomy. Compared with the capsulotomy stage, cam resection further reduced internal torque resistance during flexion 90° (change −45%, P < .001, d = 0.98) and FADIR (change −37%, P = .003, d = 1.0), where the cam deformity accounted for 21% of the intact hip's torsional resistance in flexion 90° and 27% in FADIR. Conclusion: Although the capsule played a predominant role in joint constraint, the cam deformity provided 21% to 27% of the intact hip's resistance to torsional load in flexion and internal rotation. Resecting the cam deformity would remove this loading on the chondrolabral junction. Clinical Relevance: These findings are the first to quantify the contribution of the cam deformity to resisting hip joint torsional loads and thus quantify the reduced loading on the chondrolabral complex that can be achieved after cam resection. [ABSTRACT FROM AUTHOR]

Background: During pitching, an overloaded joint reaction force exerted on the shoulder and excessive shoulder horizontal abduction at ball release are considered risk factors causing anterior shoulder pain for young baseball pitchers. Hypothesis/Purpose: The first aim was to examine the relationship between shoulder horizontal abduction position and force on the shoulder at ball release. The second was to identify the relative rotational position of the shoulder and the range of shoulder motion at ball release that minimize force on the shoulder. It was hypothesized that the amount of force on the shoulder would be exacerbated by excessive shoulder horizontal abduction. Study Design: Descriptive laboratory study. Methods: Participants were 183 adolescent baseball pitchers (mean ± SD age, 15.5 ± 1.2 years) without shoulder/elbow problems. Each pitcher threw 5 fastballs to a catcher behind a home plate. The kinematics and kinetics of the throwing shoulder during fastball pitching were calculated with 3-dimensional measurements from 36 reflective markers. In data analysis, the correlations were calculated between the relative rotational positions of the shoulder (abduction, horizontal adduction-abduction) and the forces on the shoulder (anterior-posterior, proximal, and superior-inferior) at ball release. Subsequently, the specific rotational position and range of motion of the shoulder at ball release that minimized forces on the shoulder were determined. Results: Statistically significant correlations were identified between the magnitude of superior-inferior force on the shoulder and shoulder abduction position (R2 = 0.44, P < .001) as well as between the magnitude of anterior-posterior force on the shoulder and shoulder horizontal adduction-abduction position (R2 = 0.72, P < .001). Minimal anterior-posterior and superior-inferior forces were obtained with a combination of 80.6° of shoulder abduction and 10.7° of shoulder horizontal adduction. Any deviation >5° from this position significantly increased the anterior-posterior and superior-inferior forces on the shoulder. Conclusion: Increasing shoulder horizontal abduction position significantly increased the magnitude of anterior force on the shoulder at ball release. The combination of 80.6° of shoulder abduction and 10.7° of horizontal shoulder adduction minimized the shear forces on the shoulder at this point. Clinical Relevance: The present data can be useful for screening pitching technique to prevent shoulder pain and injury with motion capture assessment. [ABSTRACT FROM AUTHOR]

Background: In professional baseball pitchers, pitching biomechanics have not been examined for the slider, and the only known study for the curveball and changeup examined limited kinetics. Moreover, no known studies have investigated pitching biomechanics between strikes and balls. Purpose/Hypothesis: The purpose was to compare pitching biomechanics in professional baseball pitchers among the fastball, slider, curveball, and changeup and between balls and strikes. It was hypothesized that pitching kinematics and kinetics would be similar among the slider, fastball, and curveball; shoulder and elbow forces and torques would be significantly lower in the changeup; and pitching biomechanics would be similar between balls and strikes. Study Design: Controlled laboratory study. Methods: Among 18 professional baseball pitchers, 38 reflective markers were positioned on the body and each player threw 32 to 40 maximum effort pitches—consisting of the fastball, curveball, slider, and changeup pitch types—from a regulation mound to a catcher. The markers were tracked by 18 high-speed 180-Hz cameras, and data were processed and run through a computer program to calculate 25 kinematic parameters, 7 kinetic parameters, and 4 temporal parameters for each pitch type and for both strikes and balls. A 2-way repeated-measures analysis of variance (P < .01) was used to assess pitching biomechanical differences among pitch type and pitch result (balls vs strikes). Results: During arm cocking, elbow varus torque was 8% to 9% greater in the fastball and slider compared with the changeup, shoulder horizontal adduction torque was 17% to 20% greater in the slider and curveball compared with the changeup, and shoulder anterior force was 13% greater in the curveball compared with the changeup. During arm deceleration, elbow flexor torque was 9% to 14% greater in the fastball compared with the curveball and changeup, and elbow and shoulder proximal forces were 10% to 14% greater in the fastball, slider, and curveball compared with the changeup. At ball release, forward trunk tilt was 16% to 19% greater in the fastball and curveball compared with the changeup, contralateral trunk tilt was 26% to 41% greater in the curveball compared with the slider and changeup, knee flexion was 18% greater in the changeup compared with the fastball, and the knee extended 7° more from lead foot contact to ball release in the fastball compared with the changeup. During arm cocking, pelvis angular velocity was 7% to 8% greater in the fastball compared with the curveball and changeup, and upper trunk angular velocity was 5% greater in the fastball compared with the changeup. During arm acceleration, shoulder internal rotation angular velocity was 6% to 7% greater in the fastball, slider, and curveball compared with the changeup, and ball velocity at ball release was 11% to 18% greater in the fastball compared with the slider, changeup, and curveball and 6% greater in the slider compared with the curveball. For all the kinematic, kinetic, and temporal parameters, analysis showed no significant differences between balls and strikes and no significant interactions between pitch type and pitch result. Conclusion: Nearly all kinetic differences among pitch types occurred between the changeup and the remaining 3 pitch types. Shoulder and elbow forces and torques and injury risk were greater among the fastball, slider, and curveball compared with the changeup but were similar among the fastball, slider, and curveball. Body segment and joint positions were similar among all pitch types at lead foot contact and at maximum shoulder external rotation; however, at ball release, throwing a fastball and curveball resulted in greater knee extension and more forward and contralateral trunk tilt compared with throwing a changeup and slider. Movement speeds for the pelvis, upper trunk, and shoulder were greatest in the fastball and least in the changeup and were generally similar among the fastball, slider, and curveball. The timing of when pelvis, upper trunk, elbow, and shoulder velocities occurred among the fastball, slider, curveball, and changeup was similar, and no kinematic or kinetic differences were noted between throwing balls and strikes. Clinical Relevance: The results from the current study will help clinicians understand differences in pitching biomechanics in professional baseball pitchers among the fastball, slider, curveball, and changeup; the study provides limited insight into shoulder and elbow injury risk associated with different types of pitches. [ABSTRACT FROM AUTHOR]

Background: The FIFA 11+ was developed as a complete warm-up program to prevent injuries in soccer players. Although reduced hip adduction strength is associated with groin injuries, none of the exercises included in the FIFA 11+ seem to specifically target hip adduction strength. Purpose: To investigate the effect on eccentric hip adduction strength of the FIFA 11+ warm-up program with or without the Copenhagen adduction exercise. Study Design: Randomized controlled trial; Level of evidence, 1. Methods: We recruited 45 eligible players from 2 U19 elite male soccer teams. Players were randomized into 2 groups; 1 group carried out the standard FIFA 11+ program, while the other carried out the FIFA 11+ but replaced the Nordic hamstring exercise with the Copenhagen adduction exercise. Both groups performed the intervention 3 times weekly for 8 weeks. Players completed eccentric strength and sprint testing before and after the intervention. Per-protocol analyses were performed, and 12 players were excluded due to low compliance (<67% of sessions completed). The main outcome was eccentric hip adduction strength (N·m/kg). Results: Between-group analyses revealed a significantly greater increase in eccentric hip adduction strength of 0.29 Nm/kg (8.9%; P = .01) in favor of the group performing the Copenhagen adduction exercise, whereas no within-group change was noted in the group that used the standard FIFA 11+ program (–0.02 N·m/kg [–0.7%]; P = .69). Conclusion: Including the Copenhagen adduction exercise in the FIFA 11+ program increases eccentric hip adduction strength, while the standard FIFA 11+ program does not. Registration: Registration: ISRCTN13731446 (International Standard Randomised Controlled Trial Number registry). [ABSTRACT FROM AUTHOR]

Background: Although acetabular labral repair has been biomechanically validated to improve stability, capsular management of the hip remains a topic of growing interest and controversy. Purpose: To biomechanically evaluate the effects of several arthroscopically relevant conditions of the capsule through a robotic, sequential sectioning study. Study Design: Controlled laboratory study. Methods: Ten human cadaveric unilateral hip specimens (mean age, 51.3 years [range, 38-65 years]) from full pelvises were used to test range of motion (ROM) for the intact capsule and for multiple capsular conditions including portal incisions, interportal capsulotomy, interportal capsulotomy repair, T-capsulotomy, T-capsulotomy repair, a large capsular defect, and capsular reconstruction. Hips were biomechanically tested using a 6 degrees of freedom robotic system to assess ROM with applied 5-N·m internal, external, abduction, and adduction rotation torques throughout hip flexion and extension. Results: All capsulotomy procedures (portals, interportal capsulotomy, and T-capsulotomy) created increases in external, internal, adduction, and abduction rotations compared with the intact state throughout the full tested ROM (−10° to 90° of flexion). Reconstruction significantly reduced rotation compared with the large capsular defect state for external rotation at 15° (difference, 1.4°) and 90° (difference, 1.3°) of flexion; internal rotation at −10° (difference, 0.4°), 60° (difference, 0.9°), and 90° (difference, 1.4°) of flexion; abduction rotation at −10° (difference, 0.5°), 15° (difference, 1.1°), 30° (difference, 1.2°), 60° (difference, 0.9°), and 90° (difference, 1.0°) of flexion; and adduction rotation at 0° (difference, 0.7°), 15° (difference, 0.8°), 30° (difference, 0.3°), and 90° (difference, 0.6°) of flexion. Repair of T-capsulotomy resulted in significant reductions in rotation compared with the T-capsulotomy condition for abduction rotation at −10° (difference, 0.3°), 15° (difference, 0.9°), 30° (difference, 1.3°), 60° (difference, 1.7°), and 90° (difference, 1.5°) of flexion and for internal rotation at −10° (difference, 0.9°), 60° (difference, 1.5°), and 90° (difference, 2.6°) of flexion. Similarly, repair of interportal capsulotomy resulted in significant reductions in abduction (difference, 0.9°) and internal (difference, 1.4°) rotations compared with interportal capsulotomy at 90° of flexion. In most cases, however, after the repair procedures, ROM was still increased in comparison with the intact state. Conclusion: The results of this study suggest that common hip arthroscopic capsulotomy procedures can result in increases in external, internal, abduction, and adduction rotations throughout a full range (−10° to 90°) of hip flexion. However, capsular repair and reconstruction succeeded in partially reducing the increased rotational ROM caused by common capsulotomy procedures. Thus, consideration should be allotted toward capsular repair or reconstruction in cases with an increased risk of residual instability. Clinical Relevance: Although complete restoration of joint stability may not be fully achieved at time zero, capsular repair and reconstruction may lead to improved patient outcomes by bringing hip rotational movements nearer to normal values in the immediate postoperative period, especially in cases in which extensive capsulotomy is performed. [ABSTRACT FROM AUTHOR]

Background: Altered knee joint biomechanics is thought to play a role in the pathogenesis of knee osteoarthritis and has been reported in patients after arthroscopic partial meniscectomy (APM) while performing various activities. Longitudinally, understanding knee joint biomechanics during jogging may assist future studies to assess the implications of jogging on knee joint health in this population. Purpose: To investigate knee joint biomechanics during jogging in patients 3 months after APM and a healthy control group at baseline and 2 years later at follow-up. Study Design: Controlled laboratory study. Methods: Seventy-eight patients who underwent medial APM and 38 healthy controls underwent a 3-dimensional motion analysis during barefoot overground jogging at baseline. Sixty-four patients who underwent APM and 23 controls returned at follow-up. External peak moments (flexion and adduction) and the peak knee flexion angle during stance were evaluated for the APM leg, non-APM leg (nonoperated leg), and control leg. Results: At baseline, the peak knee flexion angle was 1.4° lower in the APM leg compared with the non-APM leg (P = .03). No differences were found between the moments in the APM leg compared with the control leg (all P > .05). However, the normalized peak knee adduction moment was 35% higher in the non-APM leg compared with the control leg (P = .008). In the non-APM leg, the normalized peak knee adduction and flexion moments were higher compared with the APM leg by 16% and 10%, respectively, at baseline (P ≤ .004). Despite the increase in the peak knee flexion moment in the APM leg compared with the non-APM leg (P < .001), there were no differences in the peak knee flexion moment or any other parameter assessed at 2-year follow-up between the legs (P > .05). Conclusion: Comparing the APM leg and control leg, no differences in knee joint biomechanics during jogging for the variables assessed were observed. Higher knee moments in the non-APM leg may have clinical implications for the noninvolved leg. Kinematic differences were small (~1.4°) and therefore of questionable clinical relevance. Clinical Relevance: These results may facilitate future clinical research regarding the implications of jogging on knee joint health in middle-aged, overweight patients after APM. [ABSTRACT FROM AUTHOR]

Background: Anterior cruciate ligament (ACL) injuries are common, and children as young as 10 years of age exhibit movement patterns associated with an ACL injury risk. Prevention programs have been shown to reduce injury rates, but the mechanisms behind these programs are largely unknown. Few studies have investigated biomechanical changes after injury prevention programs in children. Purpose/Hypothesis: To investigate the effects of the F-MARC 11+ injury prevention warm-up program on changes to biomechanical risk factors for an ACL injury in preadolescent female soccer players. We hypothesized that the primary ACL injury risk factor of peak knee valgus moment would improve after training. In addition, we explored other kinematic and kinetic variables associated with ACL injuries. Study Design: Controlled laboratory study. Methods: A total of 51 female athletes aged 10 to 12 years were recruited from soccer clubs and were placed into an intervention group (n = 28; mean [±SD] age, 11.8 ± 0.8 years) and a control group (n = 23; mean age, 11.2 ± 0.6 years). The intervention group participated in 15 in-season sessions of the F-MARC 11+ program (2 times/wk). Pre- and postseason motion capture data were collected during preplanned cutting, unanticipated cutting, double-leg jump, and single-leg jump tasks. Lower extremity joint angles and moments were estimated using OpenSim, a biomechanical modeling system. Results: Athletes in the intervention group reduced their peak knee valgus moment compared with the control group during the double-leg jump (mean [±standard error of the mean] pre- to posttest change, -0.57 ± 0.27 %BW×HT vs 0.25 ± 0.25 %BW×HT, respectively; P = .034). No significant differences in the change in peak knee valgus moment were found between the groups for any other activity; however, the intervention group displayed a significant pre- to posttest increase in peak knee valgus moment during unanticipated cutting (P = .044). Additional analyses revealed an improvement in peak ankle eversion moment after training during preplanned cutting (P = .015), unanticipated cutting (P = .004), and the double-leg jump (P = .016) compared with the control group. Other secondary risk factors did not significantly improve after training, although the peak knee valgus angle improved in the control group compared with the intervention group during unanticipated cutting (P = .018). Conclusion: The F-MARC 11+ program may be effective in improving some risk factors for an ACL injury during a double-leg jump in preadolescent athletes, most notably by reducing peak knee valgus moment. Clinical Relevance: This study provides motivation for enhancing injury prevention programs to produce improvement in other ACL risk factors, particularly during cutting and single-leg tasks. [ABSTRACT FROM AUTHOR]

Background:Monitoring pitch count is standard practice in minor league baseball but not in softball because of the perception that fast-pitch softball pitching is a less stressful motion.Purpose:To examine muscle fatigue after fast-pitch softball performances to provide an assessment of performance demand.Study Design:Descriptive laboratory study.Methods:Bilateral strength measurements (handheld dynamometer) were made on 19 female softball pitchers (mean age [±SD], 15.2 ± 1.2 years) before and after pitching a game (mean number of pitches, 99 ± 21; mean innings pitched, 5 ± 1). A total of 20 tests were performed on the dominant and nondominant sides: forearm (grip, wrist flexion/extension, pronation/supination, elbow flexion/extension), shoulder (flexion, abduction/adduction, external/internal rotation, empty can test), scapula (middle/lower trapezius, rhomboid), and hip (hip flexion/extension, abduction/adduction). Fatigue (percentage strength loss) was categorized based on bilateral versus unilateral presentation using paired t tests: bilateral symmetric (significant on dominant and nondominant and not different between sides), bilateral asymmetric (significant on dominant and nondominant but significantly greater on dominant), unilateral asymmetric (significant on dominant only and significantly greater than nondominant), or unilateral equivocal (significant on dominant only but not different from nondominant).Results:Bilateral symmetric fatigue was evident for all hip (dominant, 19.3%; nondominant, 15.2%) and scapular tests (dominant, 19.2%; nondominant, 19.3%). In general, shoulder tests exhibited bilateral asymmetric fatigue (dominant, 16.9%; nondominant, 11.6%). Forearm tests were more variable, with bilateral symmetric fatigue in the elbow flexors (dominant, 22.5%; nondominant, 19.2%), and wrist flexors (dominant, 21.6%; nondominant, 19.0%), bilateral asymmetric fatigue in the supinators (dominant, 21.8%; nondominant, 15.5%), unilateral asymmetric fatigue in the elbow extensors (dominant, 22.1%; nondominant, 11.3%), and unilateral equivocal fatigue in the pronators (dominant, 18.8%; nondominant, 15.2%) and grip (dominant, 11.4%; nondominant, 6.6%). The mean (±SD) pitch velocity was 49 ± 4 mph, with a small loss of velocity from the first to last inning pitched (3.4% ± 5.0%, P < .01).Conclusion:Fast-pitch softball pitching resulted in profound bilateral fatigue in the hip and scapular muscles, with more selective fatigue in the shoulder and arm muscles.Clinical Relevance:These findings emphasize the importance of strength in the proximal musculature to provide a stable platform for the arm to propel the ball. [ABSTRACT FROM AUTHOR]

Background: A relatively high number of active professional baseball pitchers have a history of ulnar collateral ligament reconstruction (UCLr) on their throwing elbow. Controversy exists in the literature about whether professional baseball pitchers regain optimal performance after return from UCLr. It has been suggested that pitchers may have different biomechanics after UCLr, but this has not been previously tested. Hypothesis: It was hypothesized that, compared with a control group without a history of UCLr, professional pitchers with a history of UCLr would have (1) significantly different throwing elbow and shoulder biomechanics; (2) a shortened stride, insufficient trunk forward tilt, and excessive shoulder horizontal adduction, characteristics associated with ‘‘holding back’’ or being tentative; (3) late shoulder rotation; and (4) improper shoulder abduction and trunk lateral tilt. Study Design: Controlled laboratory study. Methods: A total of 80 active minor league baseball pitchers (and their 8 Major League Baseball organizations) agreed to participate in this study. Participants included 40 pitchers with a history of UCLr and a matched control group of 40 pitchers with no history of elbow or shoulder surgery. Passive ranges of motion were measured for each pitcher’s elbows and shoulders, and then 23 reflective markers were attached to his body. The pitcher took as many warm-up pitches as desired and then threw 10 full-effort fastballs for data collection. Ball speed was recorded with a radar gun. The reflective markers were tracked with a 10-camera, 240-Hz automated motion analysis system. Eleven biomechanical parameters were computed for each pitch and then averaged for each participant. Demographic, range of motion, and biomechanical parameters were compared between the UCLr group and the control group by use of Student t tests (significance set at P \ .05). Results: All hypotheses were rejected, as there were no differences in pitching biomechanics between the UCLr group and the control group. There were also no differences in passive range of motion between the 2 groups. Conclusion: Compared with a control group, active professional pitchers with a history of UCLr displayed no significant differences in shoulder and elbow passive range of motion and no significant differences in elbow and shoulder biomechanics. Clinical Relevance: Clinical studies have previously shown that 10% to 33% of professional pitchers do not return to their preinjury level; however, the current study showed that those pitchers who successfully return to professional baseball after UCLr pitch with biomechanics similar to that of noninjured professionals. [ABSTRACT FROM AUTHOR]

Background: The clinical effect of sustained hyperglycemia on tendon-to-bone healing after rotator cuff repair has not been wellcharacterized.Purpose: To compare the clinical and structural outcomes between diabetic and nondiabetic patients after arthroscopic rotatorcuff repair and to determine the effect of a diabetic phenotype on tendon-to-bone healing.Study Design: Cohort study; Level of evidence, 3.Methods: This study retrospectively evaluated a total of 335 shoulders that were available for magnetic resonance imaging (MRI)evaluation at least 6 months after arthroscopic rotator cuff repair using the suture-bridge technique with a minimum follow-up of 1year. Only patients who had medium- to large-sized tears with supraspinatus of fatty infiltration <2 and no or mild atrophy wereenrolled in this study. There were 271 nondiabetic patients (group A) and 64 diabetic patients (group B). The mean age at the timeof operation for groups A and B was 57.7 and 58.2 years, respectively, and the mean duration of follow-up after surgery was 27.8and 24.8 months, respectively.Results: At the last follow-up, there were no statistically significant differences between the 2 groups with regard to pain at restand during motion (P = .212 and .336, respectively). Both groups reported statistically significant improvement in Constant andShoulder Rating Scale of the University of California at Los Angeles scores (P = .323 and .241, respectively), but there was nostatistically significant difference between the 2 groups. In assessing the repair integrity with postoperative MRI scans, 39 of271 cases in group A (14.4%) and 23 of 64 cases in group B (35.9%) had retears, and the difference between the 2 groupswas statistically significant (P < .001). In analyzing the retear rates according to the severity of sustained hyperglycemia in groupB, retear was found in 16 of 37 (43.2%) uncontrolled diabetic patients with poor glycemic control (>=7.0% of preoperative serumglycosylated hemoglobin [HbA1c] levels) and in 7 of 27 (25.9%) controlled diabetic patients (<7.0%) (P < .001).Conclusion: Pain, range of motion, and function all significantly improved after arthroscopic rotator cuff repair using the suture-bridgetechnique, regardless of the presence of diabetes. However, sustained hyperglycemia increased the possibility of anatomic failure atthe repaired cuff. In diabetic patients, an effective glycemic control was associated with better rate of healing after rotator cuff repair. [ABSTRACT FROM AUTHOR]

Background: Symptomatic rotator cuff tears are often treated surgically. However, there is a paucity of information regarding the outcomes of revision arthroscopic rotator cuff repairs. Purpose: To evaluate the outcome of revision arthroscopic rotator cuff surgery when compared with primary arthroscopic rotator cuff surgery in a large cohort of patients. Study Design: Cohort study; Level of evidence, 3. Method: A consecutive series of 50 revision arthroscopic rotator cuff repairs performed by a single surgeon, with minimum 2-year follow-up, were retrospectively reviewed using prospectively collected data. As a comparison, 3 primary arthroscopic rotator cuff repair cases (primary group; n = 310) were chosen immediately before each revision case, and 3 were chosen after. Standardized patient-ranked outcomes, examiner-determined assessments, and ultrasound-determined rotator cuff integrity were assessed preoperatively at 6 months and at a minimum of 2 years after surgery. Results: The revision group was older (mean age, 63 years; range, 43-80 years) compared with the primary group (mean age, 60 years; range, 18-88 years) (P <.05) and had larger tear size (mean ± SEM) (4.1 ± 0.5 cm2) compared with the primary group (3.0 ± 0.2 cm2) (P < .05). Two years after surgery, the primary group reported less pain at rest (P < .02), during sleep (P < .05), and with overhead activity (P<.01) compared with the revision group. The primary group had better passive forward flexion (+13°; P<.05), abduction (+18°; P<.01), internal rotation (12 vertebral levels; P<.001) and also significantly greater supraspinatus strength (115 N; P<.001), lift-off strength (19.3 N; P<.05), and adduction strength (120 N; P<.01) compared with the revision group at 2 years. When compared with the primary group, the revision group was more satisfied with the overall shoulder function before surgery but was less satisfied with their shoulder function than the primary group at 2 years (P<.005). The retear rate for primary rotator cuff repair was 16% at 6 months and 21% at 2 years, while the retear rate for revision rotator cuff repair was 28% at 6 months and deteriorated to 40% at 2 years (P<.05). Conclusion: The short-term clinical outcomes of patients undergoing revision rotator cuff repair were similar to those after primary rotator cuff repair. However, these results did not persist, and by 2 years patients who had revision rotator cuff repair were twice as likely to have retorn compared with those undergoing primary repair. The increase in retear rate in the revision group at 2 years was associated with increased pain, impaired overhead function, less passive motion, weaker strength, and less overall satisfaction with shoulder function. [ABSTRACT FROM AUTHOR]

Background: Anterior cruciate ligament (ACL) reconstruction (ACLR) is common after an ACL tear and is thought to restore func-tional stability to the knee. A recent investigation demonstrated that individuals who have undergone ACLR exhibited increased lower extremity coupling variability during gait, suggestive of altered dynamic stability. However, little is known about whether they exhibit alterations in lower extremity variability during dynamic sport-specific tasks.Purpose: To determine if female soccer players who have had an ACLR demonstrate differences in lower extremity coupling var-iability as compared with athletes with no history of knee injury during a side-step cutting maneuver.Study Design: Controlled laboratory study.Methods: Ten female soccer players who had undergone ACLR served as the experimental group, and 10 female soccer players with no history of knee ligament injury composed the control group (CON). Three-dimensional kinematics and ground-reaction forces were collected while each participant performed a side-step cutting maneuver. Based on known ACL loading patterns, 7 lower extremity intralimb couplings were created. With use of a vector-coding technique, the coordination variability was cal-culated for each coupling. Independent t tests were used to determine group differences in variability for each coupling (P .05).Results: Individuals who had undergone ACLR exhibited increased lower extremity variability during side-step cutting as com-pared with control subjects in the following couplings: hip rotation/knee abduction-adduction (27.2L 6 11.5L [ACLR] vs 19.7L 6 6.8L [CON]; P = .04), hip flexion-extension/knee abduction-adduction (26.0L 6 13.3L [ACLR] vs 18.6L 6 5.3L [CON]; P = .05), knee abduction-adduction/knee flexion-extension (13.5L 6 5.7L [ACLR] vs 7.3L 6 2.7L [CON]; P \.01), and knee abduction-adduction/ knee rotation (26.4L 6 10.8L [ACLR] vs 19.3L 6 4.5L [CON]; P = .03). In addition, there was a trend toward increased variability in the hip rotation/ankle inversion-eversion coupling (22.9L 6 9.3L [ACLR] vs 18.0L 6 6.7L [CON]; P = .09) and knee abduction-adduction/ankle inversion-eversion coupling (25.9L 6 10.0L [ACLR] vs 20.2L 6 9.7L [CON]; P = .10).Conclusion: Female soccer players who have undergone ACLR and returned to sports participation exhibit altered lower extrem-ity coupling variability during side-step cutting.Clinical Relevance: While individuals who have had an ACLR exhibit mechanical knee stability before returning to sports, the observed increased movement variability during side-step cutting is likely reflective of altered neuromuscular control and may contribute to the known increased risk for ACL reinjury and knee osteoarthritis after return to sports participation. Improving the understanding of altered lower extremity coupling variability after ACLR will aid in the development of more effective rehabilitation programs. [ABSTRACT FROM AUTHOR]

The article explores the graft differences in biomechanics of the knee, hip and trunk during squats among patients who underwent anterior cruciate ligament (ACL) reconstruction. Topics discussed include the benefits of using single-legged squat in testing biomechanics after rehabilitation of musculoskeletal injuries, the results of the study conducted by the authors including differences in joint angles and moments during peak knee flexion and correlations with kinematics with knee extension.

The article focuses on factors behind the limited shoulder range of motion among baseball pitchers who underwent superior labrum anterior-posterior (SLAP) repair. Topics discussed include the concept behind the surgical technique used to treat SLAP tears, as well as its unwanted side-effects, the role played by refractory postoperative stiffness in forward flexion and external rotation in limited range of motion and challenges faced by players who were able to return after a SLAP repair.

The article discusses a study which assessed the relationship between femoral tunnel angle and kinetic parameters of the knee joint during walking following single-bundle anterior cruciate ligament reconstruction (ACLR). Results show correlations of femoral tunnel angle with peak external knee flexion moment and posterior shear force during early stance. It concluded that the anteromedial portal (AMP) technique provides better restoration compared with the transtibial (TT) technique.

The article discusses a study that determined the effects of team sport membership and sex of dancer on the biomechanics of a single-legged droplanding as to anterior cruciate ligament (ACL) injury risk factors. Recorded were kinetics and kinematics of 40 ballet and modern dancers and 40 team sport dancers, the multivariate analysis of variance (MANOVA) and the pairwise t tests. Results showed greater trunk stability among dancers than athletes and greater peak knee valgus in female athletes.

Background:While posterior glenohumeral instability is becoming increasingly common among young athletes, little is known of the risk factors for injury.Purpose:To determine the modifiable and nonmodifiable risk factors for posterior shoulder instability in a high-risk cohort.Study Design:Case-control study (prognosis); Level of evidence, 2.Methods:A prospective cohort study in which 714 young athletes were followed from June 2006 through May 2010 was conducted. Baseline testing included a subjective history of instability, instability testing by a sports medicine fellowship–trained orthopaedic surgeon, range of motion, strength measurement with a handheld dynamometer, and bilateral noncontrast magnetic resonance imaging of the shoulder. A musculoskeletal radiologist measured glenoid version, height, depth, rotator interval (RI) height, RI width, RI area, and RI index. Participants were followed to document all acute posterior shoulder instability events during the 4-year follow-up period. The time to the posterior shoulder instability event during the follow-up period was the primary outcome of interest. Univariate and multivariable Cox proportional hazards regression models were used to analyze the data.Results:Complete data on 714 participants were obtained. During the 4-year surveillance period, 46 shoulders sustained documented glenohumeral instability events, of which only 7 were posterior in direction. The baseline factors that were associated with subsequent posterior instability during follow-up were increased glenoid retroversion (P < .0001), increased external rotation strength in adduction (P = .029) and at 45° of abduction (P = .015), and increased internal rotation strength in adduction (P = .038).Conclusion:This is the largest known prospective study to follow healthy participants in the development of posterior shoulder instability. Posterior instability represents 10% of all instability events. The most significant risk factor was increased glenoid retroversion. While increased internal/external strength was also associated with subsequent instability, it is unclear whether these strength differences are causative or reactive to the difference in glenoid anatomy. This work confirms that increased glenoid retroversion is a significant prospective risk factor for posterior instability. [ABSTRACT FROM AUTHOR]

Background:Excessive trunk motion and deficits in neuromuscular control (NMC) of the lumbopelvic hip complex are risk factors for anterior cruciate ligament (ACL) injury. However, the relationship between trunk motion, NMC of the lumbopelvic hip complex, and triplanar knee loads during a sidestep cutting task has not been examined.Purpose:To determine if there is an association between multiplanar trunk motion, NMC of the lumbopelvic hip complex, and triplanar knee loads with ACL injury during a sidestep cutting task.Study Design:Descriptive laboratory study.Methods:The hip and knee biomechanics and trunk motion of 30 participants (15 male, 15 female) were analyzed during a sidestep cutting task using an optoelectric camera system interfaced to a force plate. Trunk and lower extremity biomechanics were calculated from the kinematic and ground-reaction force data during the first 50% of the stance time during the cutting task. Pearson product moment correlation coefficients were calculated between trunk and lower extremity biomechanics. Multiple linear regression analyses were carried out to determine the amount of variance in triplanar knee loading explained by trunk motion and hip moments.Results:A greater internal knee varus moment (mean, 0.11 ± 0.12 N·m/kg*m) was associated with less transverse-plane trunk rotation away from the stance limb (mean, 20.25° ± 4.42°; r = -0.46, P = .011) and a greater internal hip adduction moment (mean, 0.33 ± 0.25 N·m/kg*m; r = 0.83, P < .05). A greater internal knee external rotation moment (mean, 0.11 ± 0.08 N·m/kg*m) was associated with a greater forward trunk flexion (mean, 7.62° ± 5.28°; r = 0.42, P = .020) and a greater hip internal rotation moment (mean, 0.15 ± 0.16 N·m/kg*m; r = 0.59, P = .001). Trunk rotation and hip adduction moment explained 81% (P < .05) of the variance in knee varus moment. Trunk flexion and hip internal rotation moment explained 48% (P < .05) of the variance in knee external rotation moment.Conclusion:Limited trunk rotation displacement toward the new direction of travel and hip adduction moment are associated with an increased internal knee varus moment, while a combined increase in trunk flexion displacement and hip internal rotation moment is associated with a higher internal knee external rotation moment.Clinical Relevance:Prevention interventions for ACL injury should encourage trunk rotation toward the new direction of travel and limit excessive trunk flexion while adjusting frontal- and transverse-plane hip NMC. [ABSTRACT FROM AUTHOR]

The article reports a study which investigated frontal plane knee joint angles and moments during a sidestep cutting maneuver in soccer athletes after anterior cruciate ligament reconstruction (ACLR) compared with soccer athletes with no history of knee injury. The results revealed that female soccer players after ACLR demonstrated increased knee abduction angles and knee adductor moments. Both have been associated with an increased risk for primary ACL injury.

The article discusses the study conducted to measure effectiveness of chronic adductor enthesopathy. Study includes collection of radiographs and magnetic resonance imaging groin study protocol. Also included is the note of visual analog scale (VAS) pain score. It was concluded that selective partial adductor longus release provides excellent pain relief for chronic adductor enthesopathy in professional athletes.

The article discusses a study carried out in Forth Worth, Texas to compare the shoulder range of motion (ROM) deficits of baseball players diagnosed with ulnar collateral ligament (UCL) tear to players without UCL tear. It describes that the study was made on 60 male competitive high school and collegiate baseball players, subsequently tested and analyzed for data. Subjects diagnosed with UCL tear showed greater deficits in total rota- tional motion (TRM) compared to those without UCL tears.

The article reports a study which investigated the acromiohumeral distance (AHD) between the dominant side and nondominant side of overhead athletes and the effect of a sleeper stretch program on range of motion (ROM) and AHD. The results demonstrated a smaller AHD at the dominant side of overhead athletes with glenohumeral internal rotation deficit (GIRD) of more than 15 degree. The sleeper stretch for 6 weeks resulted in an increase of the AHD on the dominant side of the stretch group.

The article reports a study which was conducted to determine the extent to which tibial plateau geometry is associated with frontal and transverse plane hip and knee joint biomechanics during the initial landing phase of a double-legged drop landing. The results indicate that substantial intersubject differences in tibial condylar geometry influence biomechanics of hip and knee motion during the initial landing phase.

Background: A link between femoroacetabular impingement and athletic pubalgia has been reported clinically. One proposed origin of athletic pubalgia is secondary to repetitive loading of the pubic symphysis, leading to instability and parasymphyseal tendon and ligament injury.Hypothesis/Purpose: The purpose of this study was to investigate the effect of simulated femoral-based femoroacetabular impingement on rotational motion at the pubic symphysis. The authors hypothesize that the presence of a cam lesion leads to increased relative symphyseal motion.Study Design: Controlled laboratory study.Methods: Twelve hips from 6 fresh-frozen human cadaveric pelvises were used to simulate cam-type femoroacetabular impingement. The hips were held in a custom jig and maximally internally rotated at 90° of flexion and neutral adduction. Three-dimensional motion of the pubic symphysis was measured by a motion-tracking system for 2 states: native and simulated cam. Load-displacement plots were generated between the internal rotational torque applied to the hip and the responding motion in 3 anatomic planes of the pubic symphysis.Results: As the hip was internally rotated, the motion at the pubic symphysis increased proportionally with the degrees of the rotation as well as the applied torque measured at the distal femur for both states. The primary rotation of the symphysis was in the transverse plane and on average accounted for more than 60% of the total rotation. This primary motion caused the anterior aspect of the symphyseal joint to open or widen, whereas the posterior aspect narrowed. At the torque level of 18.0 N·m, the mean transverse rotation in degrees was 0.89° ± 0.35° for the native state and 1.20° ± 0.41° for cam state. The difference between cam and the native groups was statistically significant (P < .03).Conclusion: Dynamic femoroacetabular impingement as caused by the presence of a cam lesion causes increased rotational motion at the pubic symphysis.Clinical Relevance: Repetitive loading of the symphysis by cam impingement is thought to lead to increased symphyseal motion, which is one possible precursor to athletic pubalgia. [ABSTRACT FROM PUBLISHER]

Background: Baseball pitchers often have increased anterior glenohumeral (GH) laxity and posterior shoulder tightness due to large forces produced during the throwing motion. As such, many clinicians have hypothesized that a relationship exists between these common characteristics.Hypothesis: A negative relationship will exist between anterior GH laxity and the summation of GH adduction range of motion (ROM) and GH internal rotation ROM asymmetry.Study Design: Cross-sectional study; Level of evidence, 3.Methods: Anterior GH laxity, GH rotation ROM, and GH horizontal adduction ROM were measured in 58 asymptomatic professional baseball pitchers. Differences in GH internal rotation at 90° of abduction were calculated between both shoulders. A multiple regression analysis was used to determine the strength of the relationships between anterior GH laxity (dependent variable) and GH adduction ROM and GH internal rotation ROM asymmetry (independent variables) (P < .05).Results: A large portion of anterior GH laxity was predicted by the summation of GH adduction ROM and GH internal rotation ROM asymmetry (r2 = .45, P = .001). Furthermore, increased anterior GH laxity had a significant relationship with both decreased GH horizontal adduction ROM (r = .53, P = .001) and differences in GH internal rotation ROM (r = .43, P = .001).Conclusion: The results of this study suggest that decreased GH horizontal adduction and internal rotation ROM may be considered partial predictors for increased anterior GH laxity in the throwing arm of baseball players. Because of the association between these variables, clinicians may find it advantageous to address posterior shoulder tightness during the prevention, diagnosis, and treatment of shoulder injuries associated with anterior GH laxity. [ABSTRACT FROM PUBLISHER]

Background: Despite considerable medical advances, arthroscopy remains the only definitive means of superior labrum anterior-posterior (SLAP) lesion diagnosis. Natural shoulder anatomic variants limit the reliability of radiographic findings and clinical evaluations are not consistent. Accurate clinical diagnostic techniques would be advantageous because of the invasiveness, patient risk, and financial cost associated with arthroscopy.Purpose: The purpose of this study was to examine the behavior of the joint-stabilizing muscles in provocative tests for SLAP lesions. Electromyography was used to characterize the muscle behavior, with particular interest in the long head of the biceps brachii (LHBB), as activation of the long head and subsequent tension in the biceps tendon should, based on related research, elicit labral symptoms in SLAP lesion patients.Study Design: Controlled laboratory study.Methods: Volunteers (N = 21) without a history of shoulder injury were recruited. The tests analyzed were active compression, Speed’s, pronated load, biceps load I, biceps load II, resisted supination external rotation, and Yergason’s. Tests were performed with a dynamometer to improve reproducibility. Muscle activity was recorded for the long and short heads of the biceps brachii, anterior deltoid, pectoralis major, latissimus dorsi, infraspinatus, and supraspinatus. Muscle behavior for each test was characterized by peak activation and proportion of muscle activity.Results: Speed’s, active compression palm-up, bicep I, and bicep II produced higher long head activations. Resisted supination external rotation, bicep I, bicep II, and Yergason’s produced a higher LHBB proportion.Conclusion: Biceps load I and biceps load II elicited promising long head behavior (high activation and selectivity). Speed’s and active compression palm up elicited higher activation of the LHBB, and resisted supination and Yergason’s elicited selective LHBB activity. These top performing tests utilize a unique range of test variables that may prove valuable for optimal SLAP test design and performance.Clinical Relevance: This study examines several provocative tests that are frequently used in the clinical setting as a means of evaluating a potential SLAP lesion. [ABSTRACT FROM AUTHOR]

Background: The treatment of exercise-related injuries is often a problem, and recurrent injuries are common. Two recent systematic reviews found only one high-quality paper on the treatment of long-standing groin pain. In this randomized clinical trial, a training program including strength training resulted in a return of 79% of the athletes to the previous level of sport without any groin pain. The long-term effect of this exercise program was evaluated.Hypothesis: The effect of the exercise program for adductor-related groin pain is long lasting.Study Design: Randomized controlled trial; Level of evidence, 1.Methods: Forty-seven (80%) of the 59 original participants of the study agreed to participate in this 8- to 12-year follow-up. They were all interviewed and examined using a standardized and reproducible protocol, identical to the one used in the original trial. The investigating physician (P.N.) was not involved in the original study and was unaware of the original treatment allocation.Results: A significant effect of the active training treatment still existed for the whole group (P = .047) and even more for the subgroup of 39 (83%) soccer players (P = .012). No significant differences were found regarding age, present sports activity, reasons for activity reduction, or time to follow-up.Conclusion: The beneficial short-term effect of the exercise program used in the primary randomized clinical trial for treating long-standing adductor-related groin pain in athletes was found to be lasting, both for the whole group and even more for the large subgroup of soccer players. This is the first time an exercise treatment for overuse injuries to the musculoskeletal system has been shown to have a long-lasting effect (8-12 years). [ABSTRACT FROM PUBLISHER]

Background: Hip muscle weakness has been proposed to contribute to patellofemoral malalignment and the development of the patellofemoral dysfunction syndrome (PFDS). However, from the retrospective studies that have addressed this issue, it is still unclear if hip muscle weakness is a cause or a consequence of PFDS.Purpose: This study was undertaken to investigate if hip muscle weakness is a predisposing factor for the development of PFDS.Study Design: Cohort study (prognosis); Level of evidence, 2.Methods: Before the start of a 10-week “start to run” program, the isometric strength of the hip flexor, extensor, abductor, adductor, and external and internal rotator muscles was measured in 77 healthy female novice runners. During the 10-week training period, patellofemoral pain was diagnosed and registered by an orthopaedic surgeon.Results: Statistical analysis revealed that there was no significant difference in strength of any of the assessed hip muscle groups between the runners who did and did not develop PFDS. Logistic regression analysis did not identify a deviation in strength of any of the assessed hip muscle groups as a risk factor for PFDS.Conclusion: The findings of this study suggest that isometric hip muscle strength might not be a predisposing factor for the development of PFDS. [ABSTRACT FROM AUTHOR]

Background: Female athletes are at a greater risk for noncontact anterior cruciate ligament injuries than male athletes. Gender differences in frontal plane kinematics (hip adduction, knee valgus, and ankle eversion) and temporal relationships that make up the components of dynamic knee valgus may explain this discrepancy.Hypothesis: The authors hypothesized that women would reach peak frontal plane kinematic values earlier during landing compared with their male counterparts.Study Design: Controlled laboratory study.Methods: Hip, knee, and ankle 3-dimensional kinematics were measured using high-speed motion capture in 10 National Collegiate Athletic Association Division I female athletes and 10 male practice squad athletes during a drop-jump landing. Independent t tests were used to analyze each dependent variable to identify differences between genders.Results: Maximum hip adduction, knee valgus, and ankle eversion occurred earlier in women than in men (mean differences 33.7% of stance [95% CI, 20.2%-47.2%], 41.7% [95% CI, 31.5%-51.6%], 16.5% of stance [95% CI, 7.3%-25.6%], respectively). Maximum hip adduction and knee valgus occurred before maximum knee flexion in women and after in men (mean differences 0.11 seconds [95% CI, 0.05-0.18 seconds], 0.19 seconds [95% CI, 0.13-0.25 seconds], respectively). Maximum ankle eversion occurred earlier in women than in men (mean difference 0.06 seconds [95% CI, 0.01-0.11 seconds]). There was a significant difference between genders for angular velocity of knee valgus (mean difference = 25.53 deg/sec [95% CI, 8.30-42.77 deg/sec]).Conclusion: Frontal plane kinematic temporal relationships at the hip, knee, and ankle differ between genders. The components of dynamic knee valgus peak during the deceleration phase in women and during the acceleration phase in men during a drop-jump landing. These data suggest that men and women employ a completely different kinematic landing/jumping strategy and that women land and collapse very rapidly into valgus compared with their male counterparts.Clinical Relevance: The differences in timing of the components of dynamic knee valgus between women and men may contribute to the increased risk of noncontact anterior cruciate ligament injuries in female athletes. There may be implications for neuromuscular reeducation training in those at risk for anterior cruciate ligament injury so the components of dynamic valgus occur later in the landing phase of jumping. [ABSTRACT FROM AUTHOR]

Background: Medial elbow distraction during pitching as the primary mechanism contributing to adaptations in ulnar collateral ligament (UCL) appearance during magnetic resonance imaging (MRI) evaluation has not been established.Hypothesis: Uninjured high school–aged pitchers with unilateral adaptations of the UCL exhibit a higher peak internal elbow adduction moment than those without UCL adaptations.Study Design: Cohort study (Prevalence); Level of evidence, 2.Methods: Twenty uninjured, asymptomatic high school–aged pitchers underwent bilateral elbow MRI examinations. Three-dimensional motion analysis testing was performed to collect throwing arm biomechanics as participants pitched from an indoor mound. Nonparametric tests were performed to compare peak internal elbow adduction moment in uninjured participants with and without adaptations in UCL appearance and to determine the nature of the relationship between the peak internal adduction moment and UCL appearance.Results: Uninjured participants with UCL thickening exhibited a higher peak internal elbow adduction moment of 53.3 ± 6.8 N·m compared with uninjured participants without adaptations in UCL appearance, 38.8 ± 10.9 N·m (P = .05), as higher moments were correlated with ligament thickening (correlation coefficient, 0.45) (P = .02).Conclusion: This study establishes the association between medial elbow distraction captured by the internal adduction moment during pitching and UCL adaptations visible during MRI evaluation. [ABSTRACT FROM AUTHOR]

Background: Although posterior thigh muscle strains are common in athletes, there are no reports regarding isolated gracilis muscle injuries. The authors present a case series of 7 elite athletes with isolated gracilis muscle ruptures.Purpose: To present the injury pattern, clinical presentation, diagnosis, and outcome of gracilis muscle ruptures.Study Design: Case series; Level of evidence, 4.Methods: This is a retrospective review of 7 elite athletes with posterior thigh pain (3 dancers, 2 soccer players, 1 tae kwon do player, 1 tennis player). In all athletes, the injury occurred during thigh adduction with the hip internally rotated, as clearly evident at ultrasound scans performed 1 to 20 days after the injury. Management included an initial rest period, followed by physiotherapy and gradual return to sports activities.Results: According to the ultrasound scans, the lesions were in the proximal-middle third junction of the thigh, at the muscle-tendon junction. The lesions were classified as grade 2 (partial discontinuity). The muscle injury area was, on average, 17.1 × 23.7 mm (range, 10-31 × 9-46 mm). The average length of the lesions was 40.14 mm (range, 20-52 mm). All athletes recovered and returned to full performance within 6 weeks of the injury (average, 35.6 days).Conclusion: Medial thigh pain after eccentric contraction during hip adduction should raise suspicion of a gracilis muscle tear. Ultrasound is useful, and full recovery occurs within 6 weeks from the injury. [ABSTRACT FROM AUTHOR]

Background: An ipsilateral hip adduction/abduction strength ratio of more than 90%, and hip adduction strength equal to that of the contralateral side have been suggested to clinically represent adequate strength recovery of hip adduction strength in athletes after groin injury. However, to what extent side-to-side symmetry in isometric hip adduction and abduction strength can be assumed in soccer players remains uncertain.Purpose: To compare isometric hip adduction and abduction strength on the dominant and nondominant side in injury-free soccer players.Study Design: Cross-sectional study; Level of evidence, 3.Methods: One hundred elite soccer players were included. Maximal unilateral isometric hip adduction and abduction strength on the dominant and nondominant side were measured with a handheld dynamometer, using a reliable test procedure.Results: The dominant side was stronger than the nondominant side for both isometric hip adduction (2.45 ± 0.54 vs 2.37 ± 0.48 Nm/kg, P = .02) and hip abduction (2.35 ± 0.33 vs 2.25 ± 0.31 Nm/kg, P < .001), corresponding to a 3% and 4% difference, respectively. Isometric hip adduction was greater than isometric hip abduction for both the dominant (2.44 ± 0.53 vs 2.35 ± 0.33 Nm/kg, P = .04) and nondominant (2.37 ± 0.48 vs 2.26 ± 0.33 Nm/kg, P = .03) side. Isometric hip adduction/abduction ratio was not different between the dominant (1.04 ± 0.18) and nondominant (1.06 ± 0.17, P = .40) side. A post hoc analysis showed that isometric hip adduction/abduction ratio was significantly lower in players with groin pain during hip adduction testing compared with players with a pain-free test (0.80 ± 0.14, P < .001)Conclusion: The marginal difference between the dominant and the nondominant side is within the measurement variation of the test procedure, and contralateral isometric hip adduction strength can therefore be used as a simple clinical reference point of full recovery of hip adduction muscle strength in soccer players. Furthermore, it is suggested that the ipsilateral hip adduction/ abduction strength ratio is used as a guideline for evaluating hip adduction strength recovery in soccer players with bilateral groin problems. [ABSTRACT FROM AUTHOR]

Background: It is hypothesized that patients with patellofemoral pain syndrome (PFPS) have hip and core muscle weakness leading to dynamic malalignment of the lower extremity. Thus, hip strengthening is a common PFPS treatment approach.Purpose: To determine changes in hip strength, core endurance, lower extremity biomechanics, and patient outcomes after proximally focused rehabilitation for PFPS patients.Study Design: Case series; Level of evidence, 4.Methods: Nineteen women (age, 22.68 ± 7.19 years; height, 1.64 ± 0.07 m; mass, 60.2 ± 7.35 kg) with PFPS participated in an 8-week program to strengthen the hip and core muscles and improve dynamic malalignment. Paired t tests were used to compare the dependent variables between prerehabilitation and postrehabilitation. The dependent variables were pain; functional ability; isometric hip abduction and external rotation strength; anterior, lateral, and posterior core endurance; joint range of motion (ROM; rearfoot eversion, knee abduction and internal rotation, and hip adduction and internal rotation); and peak internal joint moments (rearfoot inversion, knee abduction, and hip abduction and external rotation) during the stance phase of running.Results: Significant improvements in pain, functional ability, lateral core endurance, hip abduction, and hip external rotation strength were observed. There was also a significant reduction in the knee abduction moment during running, although there were no significant changes in joint ROM.Conclusion: An 8-week rehabilitation program focusing on strengthening and improving neuromuscular control of the hip and core musculature produces positive patient outcomes, improves hip and core muscle strength, and reduces the knee abduction moment, which is associated with developing PFPS. [ABSTRACT FROM AUTHOR]

Background: Pelvis and trunk motions during baseball pitching are associated with ball velocity. Thus, limits in hip flexibility may adversely affect pitching biomechanics and the ability to generate ball velocity.Hypotheses: Professional baseball pitchers will have less passive range of motion in the nondominant hip and the measured ranges of motion of both the nondominant and dominant hips will correlate with biomechanical parameters of the lower extremity among professional pitchers.Study Design: Cross-sectional study; Level of evidence, 3.Methods: Nineteen healthy professional baseball pitchers volunteered for testing. Fluid goniometry was used to measure passive range of motion of adduction (ADD), abduction (ABD), internal rotation, external rotation, total arc of rotation, and total arc of ADD + ABD. Pitching biomechanical data were collected using an automated 3-dimensional motion analysis system while participants threw fastballs.Results: Pitchers possessed significantly less passive range of motion in the nondominant hip when compared with the dominant hip for all ranges. Total arc of rotation of the nondominant hip correlated with ball velocity (r = .50). Total arc of ADD + ABD in the nondominant hip and ABD in the nondominant hip were correlated with stride length (r = —.72 and .70, respectively). Dominant hip ABD (r = .63), total arc of rotation in the nondominant hip (r = —.45), and total arc of ADD + ABD of the dominant hip (r = .44) were correlated with trunk separation. Total arc of ADD + ABD of the nondominant hip (r = —.52) and total arc of rotation of the dominant hip (r = —.44) were correlated with pelvic orientation.Conclusion: Passive range of motion is smaller in the nondominant hip than the dominant hip among professional pitchers. The measured disparity between the hips is significantly correlated with various pitching biomechanical parameters of the trunk and pelvis. Future research is required to investigate a causal relationship between less hip passive range of motion and both ball velocity and pitching biomechanics. [ABSTRACT FROM AUTHOR]

Background: Glenohumeral internal rotation deficit (GIRD) and posterior shoulder tightness have been linked to internal impingement. Purpose: To determine if improvements in GIRD and/or decreased posterior shoulder tightness are associated with a resolution of symptoms. Study Design: Cohort study; Level of evidence, 3. Methods: Passive internal rotation and external rotation (ER) range of motion (ROM) at 90° of shoulder abduction and posterior shoulder tightness (cross-chest adduction in side lying) were assessed in 22 patients with internal impingement (11 men, 11 women; age 41 ± 13 years). Treatment involved stretching and mobilization of the posterior shoulder. The Simple Shoulder Test (SST) was administered on initial evaluation and discharge. Changes in GIRD, ER ROM, and posterior shoulder tightness were compared between patients with complete resolution of symptoms versus patients with residual symptoms using independent t tests. Results: Patients had significant GIRD (35°), loss of ER ROM (23°), and posterior shoulder tightness (35°) on initial evaluation (all P < .01). Physical therapy (7 ± 2 weeks; range, 3-12 weeks) improved GIRD (26° ± 14°; P < .01), ER ROM loss (14° ± 20°), and posterior shoulder tightness (27° ±19°). The SST improved from 5 ± 3 to 11 ± 1 (P < .01). A greater improvement in posterior shoulder tightness was seen in patients with complete resolution of symptoms (n = 12) compared with patients with residual symptoms (35° vs 18°; P < .05). Improvements in GIRD and ER ROM loss were not different between groups (GIRD, 25° vs 28°, P = .57; ER ROM, 14° vs 15°, P = .84). Conclusion: Resolution of symptoms after physical therapy treatment for internal impingement was related to correction of posterior shoulder tightness but not correction of GIRD. [ABSTRACT FROM AUTHOR]

Background: It has been speculated that the hormonal cycle may be correlated with higher incidence of ACL injury in female athletes, but results have been very contradictory. Hypothesis: Knee joint loads are influenced by knee joint laxity (KJL) during the menstrual cycle. Study Design: Controlled laboratory study. Methods: Serum samples and KJL were assessed at the follicular, ovulation, and luteal phases in 26 women. Knee joint mechanics (angle, moment, and impulse) were measured and compared at the same intervals. Each of the 26 subjects had a value for knee laxity at each of the 3 phases of their cycle, and these were ordered and designated low, medium, and high for that subject. Knee joint mechanics were then compared between low, medium, and high laxity. Results: No significant differences in knee joint mechanics were found across the menstrual cycle (no phase effect). However, an increase in KJL was associated with higher knee joint loads during movement (laxity effect). A 1.3-mm increase in KJL resulted in an increase of approximately 30% in adduction impulse in a cutting maneuver, an increase of approximately 20% in knee adduction moment, and a 20% to 45% increase in external rotation loads during a jumping and stopping task (P < .05). Conclusion: Changes in KJL during the menstrual cycle do change knee joint loading during movements. Clinical Relevance: Our findings will be beneficial for researchers in the development of more effective ACL injury prevention programs. [ABSTRACT FROM AUTHOR]

Background: Muscle weakness, particularly of shoulder external rotation, is common after rotator cuff repair surgery. Neuromuscular electrical stimulation has been shown to be an effective adjunct in the enhancement of muscle recruitment. Hypothesis: Shoulder external rotation peak force can be enhanced by neuromuscular electrical stimulation after rotator cuff repair surgery. Study Design: Controlled laboratory study. Methods: Thirty-nine patients (20 men, 19 women) who had undergone rotator cuff repair surgery were tested a mean of 10.5 days after surgery. Testing consisted of placing patients supine with the shoulder in 45° of abduction, neutral rotation, and 150 of horizontal adduction. Neuromuscular electrical stimulation was applied to the infraspinatus muscle belly and inferior to the spine of the scapula. Placement was confirmed by palpating the muscle during a resisted isometric contraction of the external rotators. Patients performed 3 isometric shoulder external rotation contractions with and without neuromuscular electrical stimulation, each with a 5-second hold against a handheld dynamometer. Neuromuscular electrical stimulation was applied at maximal intensity within comfort at 50 pulses per second, symmetrical waveform, and a 1-second ramp time. The 3 trials under each condition were recorded, and an average was taken. The order of testing was randomized for each patient tested. A paired samples t test was used to determine significant differences between conditions (P < .05). Each group was also divided based on age, rotator cuff tear size, number of days postoperative, and neuromuscular electrical stimulation intensity. Analysis of variance models were used to determine the influence of these variables on external rotation force production (P < .05). Results: Peak force production was significantly greater (P < .001) when tested with neuromuscular electrical stimulation (3.75 kg) as opposed to without neuromuscular electrical stimulation (3.08 kg) for all groups tested. There was no significant difference based on the size of the tear, age of the patient, number of days after surgery, or level of neuromuscular electrical stimulation intensity. Conclusion: Peak shoulder external rotation force was significantly increased by 22% when tested with neuromuscular electrical stimulation after rotator cuff repair surgery. Neuromuscular electrical stimulation significantly increased force production regardless of the age of the patient, size of the tear, intensity of the current, or the number of days postoperative. Clinical Relevance: Neuromuscular electrical stimulation may be used concomitantly with exercises to enhance the amount of force production and potentially minimize the inhibition of the rotator cuff after repair surgery. [ABSTRACT FROM AUTHOR]

Background: Labral tears commonly cause disabling intra-articular hip pain and are commonly treated with hip arthroscopy. However, the function and role of the labrum are still unclear.Hypotheses: (1) Flexion, adduction, and internal rotation (a position clinically defined as the position for physical examination known as the impingement test) places greatest circumferential strain on the anterolateral labrum and posterior labrum; (2) extension with external rotation (a position clinically utilized during physical examination to assess for posterior impingement and for anterior instability) places significant circumferential strains on the anterior labrum; (3) abduction with external rotation during neutral flexion-extension (the position the extremity rests in when a patient lies supine) places the greatest load on the lateral labrum.Study Design: Descriptive laboratory study.Methods: Twelve cadaveric hips (age, 79 years) without labral tears or arthritis were studied. Hips were dissected free of soft tissues, except the capsuloligamentous structures. Differential variable reluctance transducers were placed in the labrum anteriorly, anterolaterally, laterally, and posteriorly to record circumferential strains in all 4 regions as the hip was placed in 36 different positions.Results: The posterior labrum had the greatest circumferential strains identified; the peak was in the flexed position, in adduction or neutral abduction-adduction. The greatest strains anteriorly were in flexion with adduction. The greatest strains anterolaterally were in full extension. External rotation had greater strains than neutral rotation and internal rotation. The greatest strains laterally were at 90° of flexion with abduction, and external or neutral rotation. In the impingement position, the anterolateral strain increased the most, while the posterior labrum showed decreased strain (greatest magnitude of strain change). When the hip is externally rotated and in neutral flexion-extension or fully extended, the posterior labrum has significantly increased strain, while the anterolateral labrum strain is decreased.Conclusion: These are the first comprehensive strain data (of circumferential strain) analyzing the whole hip labrum. For the intact labrum, the greatest strain change was at the posterior acetabulum, whereas clinically, acetabular labral tears occur most frequently anterolaterally or anteriorly. The results are consistent with the impingement test as an assessment of anterolateral acetabular labral stress. The hyperextension-rotation test, often used clinically to assess anterior hip instability and posterior impingement, did not show a change in strain anteriorly, but did reveal an increase in strain posteriorly.Clinical Relevance: Although this study does not include muscular forces across the hip joint, it does provide a clue as to the stresses about the labrum through the complete range of motions of the hip, which may help in providing a better understanding of the cause of labral tears and in the protection of labral repairs. [ABSTRACT FROM AUTHOR]