Movement Patterns During a Jump-Landing Task in Athletes After Sport-Related Concussion and Healthy Control Individuals.

CONTEXT: A relationship between a history of sport-related concussion (SRC) and lower extremity injury has been well established in the literature. OBJECTIVE: To determine if biomechanical differences existed during a double-limb jump landing between athletes who had been released to return to play after SRC and healthy matched control individuals. DESIGN: Cross-sectional study. SETTING: Health system-based outpatient sports medicine center. PATIENTS OR OTHER PARTICIPANTS: A total of 21 participants with SRC (age = 15.38 ± 1.77 years, height = 169.23 ± 8.59 cm, mass = 63.43 ± 7.39 kg, time since release to return to sport after SRC = 16.33 ± 12.7 days) were compared with 21 age-, sex-, and activity-matched healthy participants serving as controls (age = 15.36 ± 1.73 years, height = 169.92 ± 11.1 cm, mass = 65.62 ± 12.08 kg). MAIN OUTCOME MEASURE(S): Biomechanical performance during the double-limb jump landing was assessed using a motion-capture system and force plates. The average of 3 consecutive trials was used to calculate lower extremity joint kinetics and kinematics. The variables of interest were internal knee-extension moment, internal varus moment, and total sagittal-plane knee displacement for the dominant and nondominant limbs. Independent t tests were performed to examine the differences between SRC and control groups for the variables of interest. RESULTS: No differences existed between groups for the descriptive data. The SRC group demonstrated greater internal knee-extension moments in the dominant (-0.028 ± 0.009 Nm/kg, P = .003) and nondominant (-0.018 ± 0.007, P = .02) limbs. The SRC group also exhibited greater internal varus moments in the dominant (0.012 ± 0.004 Nm/kg, P = .005) and nondominant (0.010 ± 0.003, P = .005) limbs. For sagittal-plane knee displacement, the SRC group displayed less knee-flexion displacement in the dominant (-12.56 ± 4.67°, P = .01) but not the nondominant (-8.30 ± 4.91°, P = .10) limb. CONCLUSIONS: Athletes who had been released for return to sport after SRC landed with greater knee valgus than healthy matched control participants.

The Relationship Between Humeral Retrotorsion and Shoulder Range of Motion in Baseball Players With an Ulnar Collateral Ligament Tear.

BACKGROUND: Humeral retrotorsion has been investigated in relation to shoulder range of motion (ROM) in healthy baseball players. Currently, there is limited information on the osseous anatomy and development of ulnar collateral ligament (UCL) tears. PURPOSE: To determine the relationship between humeral retrotorsion and shoulder ROM in baseball players with a UCL tear. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: Fifty-four baseball players (mean age, 18.5 ± 2.0 years) with a UCL tear volunteered for this study. Participants were measured bilaterally for shoulder internal (IR) and external rotation (ER) ROM and humeral retrotorsion. Differences between sides (involved to uninvolved) were used to calculate the glenohumeral internal rotation deficit (GIRD), external rotation ROM difference (ERDiff), total rotational motion difference (TRM), and humeral retrotorsion difference (HTDiff). A multivariate regression analysis was performed with GIRD, ERDiff, and TRM regressing on HTDiff. Univariate analysis was performed to further evaluate the effect of the predictors on each outcome separately. To control for the effect of age, weight, duration of symptoms, and years of experience, the variables were included as covariates. An a priori level was set at P < .05. RESULTS: There was a statistically significant relationship between the GIRD, ERDiff, and TRM results compared with HTDiff (P = .003). Independent analysis revealed a statistically significant relationship between GIRD and HTDiff (P = .004) and between ERDiff and HTDiff (P = .003) but no significant relationship between TRM and HTDiff (P = .999). After adjusting for age, weight, duration of symptoms, years of experience, dominant arm, and position, a significant relationship was found between GIRD and HTDiff (P = .05) and between ERDiff and HTDiff (P = .01). No significant relationship was found between TRM and HTDiff (P = .54). Adjusted univariate regression analysis determined that HTDiff explains approximately 16% of the variance in GIRD (r2 = 0.158) and approximately 24% of the variance in ERDiff (r2 = 0.237). CONCLUSION: In baseball players with a UCL tear, approximately 16% of the variance in GIRD and 24% of the variance in ERDiff can be attributed to differences found in humeral retrotorsion between sides. This indicates that humeral retroversion contributes significantly to GIRD and increased ER ROM in baseball players. Recognition of differences in humeral retrotorsion between the dominant and nondominant upper extremities may help explain some but not all of the changes in shoulder ROM commonly seen in baseball players.