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Objective: To establish reference values of rotator cuff (RC) cross sectional area (CSA) in males., Materials and Methods: We retrospectively analyzed shoulder MRIs from 500 patients aged 13-78 years, grouped as follows (N=100 in each): <20, 20-30, 30-40, 40-50, >50 years. All examinations were reviewed to exclude prior surgery, tears, or significant RC pathology. We segmented a standardized T1 sagittal MR image in each case to obtain CSA of supraspinatus (SUP), infraspinatus/teres minor (INF), and subscapularis (SUB) muscles. Across age groups, we recorded individual and total muscle CSA. We also performed ratios between individual muscle CSA and total CSA to examine total muscle mass contribution over age groups. We tested for differences between age groups controlled for BMI., Results: CSAs for SUP, INF, SUB, and total RC CSA were lower in subjects >50 years compared to all other groups (P<0.003 for all comparisons), persisting after controlling for BMI (P<0.03). Relative contribution of SUP CSA to total RC CSA was stable across age groups (P>0.32). INF CSA relative to total RC CSA increased with age, whereas SUB decreased (P<0.005). Subjects >50 years showed lower SUP (-15%), INF (-6%), and SUB (-21%) CSA, when compared to mean CSAs of all subjects <50 years. Total RC CSA significantly correlated with age (r=-0.34, P<0.001), persisting after controlling for BMI (r=-0.42, P<0.001)., Conclusion: RC muscles in male subjects with no tears on MRI show decreasing CSA with age, independent of BMI., (© 2023. The Author(s), under exclusive licence to International Skeletal Society (ISS).)

Although there is a commonly held belief within the baseball community that delivery from the stretch confers more stress at the elbow and shoulder joints than delivery from the windup, there remains little evidence in the literature investigating this hypothesis. This study aimed to help address this gap in the literature by studying both intra-pitcher kinematic sequence variability, and intra-pitcher joint torque variability when throwing from the windup vs. the stretch. We hypothesized that 1) each pitchers' kinematic sequence would remain similar whether throwing from the windup or stretch, and 2) Kinematic sequence would influence peak arm torque more than delivery method. This cross-sectional 3D biomechanical study included 88 pitches thrown by ten (6 collegiate, 4 high school) pitchers with a mean age of 17.60 ± 2.63 years. Pitch velocity, throwing shoulder/elbow torques and the kinematic sequence of each pitch utilizing segmental peak angular velocities were captured. No statistically significant differences in ball velocity (p = 0.17), peak shoulder external rotation torque (p = 0.80), shoulder extension torque (p = 0.97), or elbow valgus torque (p = 0.83) were found between delivery approaches. Three primary kinematic sequences were identified. Shoulder external rotation torque [ F (53,2) = 10.992, ɳ 2 = .293, p < 0.00], shoulder extension torque [ F (53,2) = 15.517, ɳ 2 = .369, p < 0.00] and elbow valgus torque [ F (53,2) = 9.994, ɳ 2 = .274, p < 0.00] did vary significantly across these three kinematic sequence patterns. Our data suggest that the kinematic sequence influences shoulder and elbow torque more than the delivery approach. Instructing ideal kinematic sequence may be more influential for injury avoidance than delivery method., (© Journal of Sports Science and Medicine.)

Introduction: Despite high injury incidence rates in gymnastics, there is a paucity of data characterizing upper extremity injury causation and biomechanical risk factors. This study investigated contact forces across multiple joints in both upper extremities during a round-off back handspring (ROBHS), a fundamental gymnastics tumbling maneuver., Objective: (1) To characterize the three-dimensional (3-D) biomechanics of the sequential, asynchronous contact of each upper extremity with the ground during a ROBHS using 3-D motion capture, and (2) to evaluate potential correlations to upper extremity injury risk., Design: Observational cross-sectional study., Setting: Controlled laboratory environment., Participants: Fourteen competitive female gymnasts aged 10-21 years (mean age: 16.6 ± 3.1 years) (1) participating on a competitive gymnastics team; (2) capable of successfully completing a ROBHS; and (3) free of reported injury at enrollment., Interventions: Not applicable., Main Outcome Measures: Variables evaluated include joint angle, torque, compression force, ground reaction force (GRF), time to peak GRF, and limb loading rates. Variables were analyzed at the wrist, elbow, and shoulder of both limbs at ground contact. The hypothesis that these dependent variables would differ by ROBHS upper extremity contact order was formulated retrospectively after data collection., Results: The first contact limb experienced significantly greater extension torque at the elbow (first: 48.89 ± 18.01 Nm, second: 22.49 ± 9.19 Nm; P = .014; CI 95% [14.83, 37.97]) and faster time to peak GRF (P < .001, CI 95% [-1.79, -0.99]). The second limb of contact experienced significantly greater abduction torque at the shoulder (P = .007; CI 95% [-21.58,-8.08]) and anterior-posterior GRF at contact (P = .007; CI 95% [-1.06,-0.26])., Conclusions: The biomechanical differences between contact limbs during the ROBHS may lead to different injury risk. Recognition of the stresses at the elbow and shoulder for both limbs also provides new insight for rehabilitation clinicians to consider when guiding patients to return to gymnastics activity after injury., (© 2020 American Academy of Physical Medicine and Rehabilitation.)

Background: Softball pitching is a ballistic, complex movement that requires an underhand windmill motion to create force and ball velocity. In addition to proper pitch biomechanics, upper and lower extremity strength and joint motion likely contribute to ball location accuracy and velocity. Yet, the number of studies reporting muscle strength and joint range of motion among softball pitchers is scarce., Objective: To assess differences between throwing and nonthrowing shoulder, elbow, and hip (lead and trail leg) strength and range of motion (ROM) in high school and collegiate level softball windmill pitchers., Design: Cross-sectional study., Participants: Thirty-three female softball pitchers (24 high school, 9 collegiate) were recruited from local teams., Methods: Goniometric joint ROM and handheld dynamometer strength measurements of the bilateral shoulders, elbows, and hips were measured., Main Outcome Measurements: Goniometric joint ROM of the bilateral elbows (flexion, extension), shoulders, and hips (flexion, extension, internal rotation [IR], external rotation [ER]). Handheld dynamometer strength measurements of the bilateral shoulders (flexion, extension, abduction, IR, ER), elbows (flexion, extension), and hips (flexion, extension, IR, ER, abduction)., Results: Across all pitchers, there was greater shoulder flexion ROM in the nonthrowing limb than in the throwing limb (P = .004). There was greater hip extension in the lead leg than trail leg. Among high school pitchers, there was greater shoulder ER (x = 105.792 ± 7.11) than collegiate pitchers (x = 100.1 ± 6.92), P = .05. There was no difference in total arc of shoulder rotational motion (ER+ IR) between throwing and nonthrowing limbs across all pitchers, nor between high school and collegiate pitchers. Strength measures demonstrated greater throwing limb shoulder abduction (P = .006) and IR strength (P = .001) than the nonthrowing shoulder across all pitchers. Elbow flexion strength was significantly greater than the nonthrowing side (P = .001). No difference was noted in hip strength between lead and trail lower extremities., Conclusions: Developing normative data for softball pitchers upper and lower extremity strength and range of motion may allow providers to assess players more comprehensively and identify athletes out of the expected value range. This information may help in guiding strength and conditioning programs for softball pitchers., Level of Evidence: III., (© 2019 American Academy of Physical Medicine and Rehabilitation.)

Background: Female softball pitchers commonly throw more pitches per game and season than their baseball counterparts. The greatest stress to the shoulder during a softball windmill pitch is at ball release (BR). This study investigated shoulder torques at BR among female softball pitchers and identified relationships to the kinematics of the elbow and forearm and alignment of the elbow (carrying angle and elbow extension)., Methods: High-speed 3-dimensional biomechanical analyses were performed in 33 pitchers (25 high school, 8 collegiate). Elbow and shoulder biomechanics at BR during fastball pitches and goniometric measures of carrying angle and elbow extension were collected and analyzed., Results: Carrying angle correlated positively with shoulder extension torque at BR (r s  = 0.371, P = .048) and forearm pronation at BR (r s  = 0.370, P = .048). During the windmill pitch, the greater the elbow flexion, the greater shoulder adduction torque at BR (r s  = -0.522, P = .007). Multiple regression analysis revealed that the carrying angle, passive elbow extension, and elbow flexion/extension angle at BR predicted shoulder flexion/extension torque at BR (F 3,24  = 3.463, R 2  = .302, P = .032.) CONCLUSIONS: Our findings demonstrate that shoulder torques during the softball fastpitch are influenced by the carrying angle and the kinematic elbow flexion angle at BR. Sports medicine clinicians and coaches should consider the role that the elbow carrying angle plays in creating shoulder stress when treating and training fastpitch softball players., (Copyright © 2018 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Hypothesis: The anteromedial approach to the shoulder with detachment of the anterior deltoid from its clavicular and anterior acromial origins is a method of enhancing exposure for difficult shoulder arthroplasty cases. The aim of this study is to describe the current frequency of use, indications, complications, and results of this approach., Materials and Methods: Between 2000 and 2003, 723 consecutive shoulder arthroplasties were performed. In 110 (15%) an anteromedial approach was used. Patient data; previous surgery; indications for surgery; pain, motion, and strength before and after surgery; complications; and the need for reoperation were assessed., Results: This approach was used in 9.5% of primary cases and 39% of revision cases. Seventy percent had had previous surgery. For primary arthroplasty, the most frequent diagnoses were osteoarthritis and the sequelae of fractures. In revision cases the most common diagnoses were instability and glenoid loosening. The structural indications for the anteromedial approach were severe scarring, protection of a frail deltoid, improvement in rotator cuff or glenoid exposure, protection of osteopenic bone, or enhancement of exposure in oncologic cases or resections. Ninety patients had more than 2 years of follow-up. Pain improved after primary and revision arthroplasty. Motion only improved in primary arthroplasty. There was little change in strength. No proximal deltoid detachments or other approach-related complications were identified., Conclusions: The anteromedial approach is a reliable technique to improve surgical exposure in difficult shoulder arthroplasty cases. When performed adequately, it can be applied safely without anterior deltoid detachment or clinically evident major complications., (2010 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Mosby, Inc. All rights reserved.)

Introduction: Despite high injury incidence rates in gymnastics, there is a paucity of data characterizing upper extremity injury causation and biomechanical risk factors. This study investigated contact forces across multiple joints in both upper extremities during a round-off back handspring (ROBHS), a fundamental gymnastics tumbling maneuver.Objective: (1) To characterize the three-dimensional (3-D) biomechanics of the sequential, asynchronous contact of each upper extremity with the ground during a ROBHS using 3-D motion capture, and (2) to evaluate potential correlations to upper extremity injury risk.Design: Observational cross-sectional study.Setting: Controlled laboratory environment.Participants: Fourteen competitive female gymnasts aged 10-21 years (mean age: 16.6 ± 3.1 years) (1) participating on a competitive gymnastics team; (2) capable of successfully completing a ROBHS; and (3) free of reported injury at enrollment.Interventions: Not applicable.Main Outcome Measures: Variables evaluated include joint angle, torque, compression force, ground reaction force (GRF), time to peak GRF, and limb loading rates. Variables were analyzed at the wrist, elbow, and shoulder of both limbs at ground contact. The hypothesis that these dependent variables would differ by ROBHS upper extremity contact order was formulated retrospectively after data collection.Results: The first contact limb experienced significantly greater extension torque at the elbow (first: 48.89 ± 18.01 Nm, second: 22.49 ± 9.19 Nm; P = .014; CI 95% [14.83, 37.97]) and faster time to peak GRF (P < .001, CI 95% [-1.79, -0.99]). The second limb of contact experienced significantly greater abduction torque at the shoulder (P = .007; CI 95% [-21.58,-8.08]) and anterior-posterior GRF at contact (P = .007; CI 95% [-1.06,-0.26]).Conclusions: The biomechanical differences between contact limbs during the ROBHS may lead to different injury risk. Recognition of the stresses at the elbow and shoulder for both limbs also provides new insight for rehabilitation clinicians to consider when guiding patients to return to gymnastics activity after injury. [ABSTRACT FROM AUTHOR]