Association of Shoulder Dysfunction with Mobility Limitation in Older Adults of the BLSA

Mobility limitation affects one-third of older adults; yet, the impact of shoulder dysfunction which effects roughly 20%, is inadequately documented. As arm swing is a fundamental component of ambulation, we investigated the cross-sectional association between shoulder range of motion (ROM) and walking endurance using time to walk 400m as quickly as possible and lower extremity performance using the expanded Short Physical Performance Battery (e-SPPB). Data are from 614 men (50.5%) and women aged ≥ 60 years (mean 71.8 ±8 years) in the Baltimore Longitudinal Study of Aging (BLSA) who performed bilateral shoulder elevation and/or bilateral shoulder external rotation (ER) during nurse-administered physical examination. We examined odds of poor 400m-walk and e-SPPB performance defined as the worst quartile associated with abnormal shoulder elevation (≤9%) relative to bilateral normal shoulder elevation and abnormal shoulder external rotation (≤5%) relative to bilateral normal shoulder external rotation (ER) in separate analyses. Analyses were adjusted for age, sex, weight and height. Adjusted odds (95% confidence interval) of poor 400m-walk performance associated with abnormal shoulder elevation (N=254) were 4.7 (1.1-19.5;p=0.035) and with abnormal shoulder ER (n=401) were 4.8 (1.4-16.7;p=0.010). Adjusted odds of poor e-SPPB performance associated with abnormal shoulder elevation (N=462) were 3.5 (1.6-7.7;p=0.002) and with abnormal shoulder ER (n=457) were 2.9 (1.1-7.4;p=0.030). Results suggest abnormal shoulder ROM is associated with poorer walking endurance capacity and lower-extremity functional performance in the relatively healthy older adults. Future research is warranted to develop novel screening paradigms that mitigate mobility limitation and functional decline in older adults with shoulder dysfunction.

Assessment of Isokinetic Knee and Shoulder Strength in Elite Youth Boxers: Correlation with Punch Impact Force

This study aimed to assess the isokinetic strength performance of the knee and shoulder in amateur boxer, and further to explore the contribution of knee and shoulder peak torque to different punches. Boxers (6 females and 8 males) were measured the dynamic concentric torque of knee flexion(F) and extension(E), shoulder external rotation (ER) and internal rotation (IR) at 60°/S, 180°/S. We tested the punching force of three techniques by Kistler Instruments. At 60°/S, F/E ratios of the dominant (D) knee of female boxers were lower than those of non-dominant (ND) side (p=0.03). At two angular velocities, all boxers demonstrated higher ER/IR ratios in ND (p=0.011 for males, p=0.025 for females). Bilateral difference of knee flexor in females was greater (p=0.038) than that in males. The maximum correlation was found at 180°/S between punching forces and the joints strength. ANOVA analyses revealed that athletes with greater punching force tend to have higher knee strength. Although correlations between shoulders strength and punching forces were strong, they did not discriminate between athletes who punched with higher punching force. In order to effectively transfer muscle strength to punching force, rapid completion of action should be highlighted in strength training, especially lower-limb strength.

Increased Shoulder Distraction Force and Shoulder Horizontal Abduction in Professional Baseball Pitchers With Discordant Torso Rotation Order

Background: Inefficient energy transfer from the pelvis and trunk has been shown to increase compensation at the level of the shoulder. Kinetic chain sequencing of the core segments is underexamined in professional baseball pitchers, especially as it relates to changes in upper extremity kinetics. Purpose: To evaluate elbow and shoulder kinetics in a cohort of professional pitchers differentiated by instances of discordant pelvic to upper torso sequencing during the pitch. Study Design: Descriptive laboratory study. Methods: 285 professional baseball pitchers were evaluated using 3D motion capture (480 Hz). Pitchers were divided into “chronological” and “discordant” groups based on whether maximum pelvic rotation velocity occurred before (chronological) or after (discordant) maximum upper torso rotation velocity during the pitch motion. Pelvic, upper torso, and shoulder kinematic parameters, shoulder distraction force, shoulder internal rotation torque, and pitch efficiency (PE) were compared between groups. Results: Pitchers with discordant torso sequencing (n = 30; 110 pitches) had greater shoulder horizontal adduction at maximum external rotation (mean difference, 3.6°; 95% CI, −5.2° to −2.0°; t = −4.5; P < .001) and greater maximum shoulder external rotation (mean difference, 3.7°; 95% CI, 5.7° to 1.5°; t = −3.5; P < .001) than chronological pitchers (n = 255; 2974 pitches). PE did not differ between groups ( P = .856), whereas ball velocity was significantly faster in the discordant group (mean difference, 0.6 m/s; 95% CI, −1.1 to −0.3 m/s; t = −3.3; P = .0012). Chronological pitchers had significantly reduced shoulder distraction force (mean difference, −4.7% body weight (BW); 95% CI, −7.9% to −1.5% BW; t = −2.9; P = .004) with no difference in shoulder internal rotation torque ( P = .160). These kinematic and kinetic differences were not observed when accounting for interpitcher variability. Conclusion: Between pitchers, those who had a discordant pelvic to upper torso sequence experienced significantly greater shoulder distraction forces, potentially compensating by increasing maximum shoulder external rotation and horizontal abduction. Achieving maximal pelvic rotation velocity before maximal rotation velocity may be advantageous in preventing compensation at the upper extremity and excessive throwing arm loading. Clinical Relevance: Identifying risk factors for increased upper extremity forces has potential implications in injury prevention. Specifically, mitigating shoulder distraction forces may be beneficial in reducing risk of injury.

Shoulder External Rotational Properties During Physical Examination Are Associated With Injury That Requires Surgery and Shoulder Joint Loading During Baseball Pitching

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.

Nerve Transfer Is Superior to Nerve Grafting for Suprascapular Nerve Reconstruction in Obstetrical Brachial Plexus Birth Injury: A Meta-Analysis

Background Restoration of shoulder function in obstetrical brachial plexus injury is paramount. There remains debate as to the optimal method of upper trunk reconstruction. The purpose of this study was to test the hypothesis that spinal accessory nerve to suprascapular nerve transfer leads to improved shoulder external rotation relative to sural nerve grafting. Methods A systematic review of Medline, EMBASE, EBSCO CINAHL, SCOPUS, Cochrane Library, and TRIP Pro from inception was conducted. Our primary outcome was shoulder external rotation. Results Four studies were included. Nerve transfer was associated with greater shoulder external rotation relative to nerve grafting (mean difference: 0.82 AMS 95% confidence interval [CI]: 0.27-1.36, P < .005). Patients undergoing nerve grafting were more likely to undergo a secondary shoulder stabilizing procedure (odds ratio [OR]: 1.27, 95% CI: 0.8376-1.9268). Conclusion In obstetrical brachial plexus injury, nerve transfer is associated with improved shoulder external rotation and a lower rate of secondary shoulder surgery. Level of Evidence Level III; Therapeutic

The influence of shoulder abduction and external rotation on throwing arm kinetics in professional baseball pitchers

Background The relationships between shoulder abduction and external rotation with peak kinetic values at the shoulder and elbow in professional baseball pitchers are not well established. Methods Professional pitchers ( n = 322) threw 8–12 fastballs under 3D motion analysis (480 Hz). Pitchers were stratified into quartiles by shoulder abduction and external rotation at distinct timepoints. Regression analyses were performed to quantify associations between shoulder position and kinetics. Results Shoulder abduction remained relatively consistent throughout the pitch (foot contact–ball release: 85.5 ± 11.1–90.7 ± 8.4°); shoulder external rotation increased dramatically (foot contact–ball release: 30.8 ± 24.6–165.2 ± 9.7°). For every 10° increase in maximum shoulder rotation, shoulder superior force increased by 2.3% body weight ( p < 0.01), shoulder distraction force increased by 5.9% body weight ( p < 0.01), and ball velocity increased by 0.60 m/s ( p < 0.01). Shoulder abduction was significantly associated with shoulder superior force at all timepoints but not with ball velocity ( p > 0.05). For every 10° increase in shoulder abduction at ball release, shoulder superior force increased by 3.7% body weight ( p < 0.01) and shoulder distraction force increased by 11.7% body weight ( p < 0.01). Conclusion Increased shoulder abduction at ball release and increased maximum shoulder external rotation were associated with greater superior and distraction forces in the shoulder. Pitchers can consider decreasing shoulder abduction at later stages of the pitch to around 80° in order to minimize shoulder superior force, with no impact on ball velocity.

ANALYSIS OF TRUNK POWER AND JOINT STRESSES BETWEEN PROFESSIONAL AND COLLEGIATE PITCHERS

The dynamic motion of a baseball pitch generates high elbow and shoulder torques that can result in injury. Previous research has noted the importance of properly transferring energy from the lower extremities through the throwing arm to decrease joint stress. The goal of this study was to compare segmental powers between two levels of pitchers at various moments throughout the pitching cycle and observe their influence on upper extremity torques. Thirteen professional and thirteen collegiate pitchers participated in this study. Forty-seven reflective markers were attached to the subjects at specific landmarks. An 8-camera motion analysis system was set up surrounding an artificial pitching mound, where participants threw 10 fastballs. Data were exported and processed using Visual 3D software. Welch’s T-tests compared the means between groups with a significance set at p < 0.05. Professional pitchers were found to have significantly greater torso power at foot contact, maximum shoulder external rotation, ball release, and overall peak torso power. They also demonstrated significantly greater pitch velocity. Professional pitchers generated similar elbow varus torque and shoulder internal rotation torque compared to collegiate pitchers. These findings suggest professional pitchers more effectively use torso power to help increase pitch speed without increasing overall joint torques.