title: The Relationship Between Humeral Retrotorsion and Shoulder Range of Motion in Baseball Players With an Ulnar Collateral Ligament Tear.
abstract: 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.
  
  
  OBJECTIVE
  To determine the relationship between humeral retrotorsion and shoulder ROM in baseball players with a UCL tear.
  
  
  METHODS
  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 atP< .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).
  
  
  CONCLUSIONS
  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.
authors.affiliation: Texas Health Ben Hogan Sports Medicine, Fort Worth, Texas, USA.
authors.forename: Bobby Jean S
authors.initials: BJ
authors.lastname: Lee
authors.affiliation: Texas Health Ben Hogan Sports Medicine, Fort Worth, Texas, USA.
authors.forename: J Craig
authors.initials: JC
authors.lastname: Garrison
authors.affiliation: Orthopedic Specialty Associates, Fort Worth, Texas, USA.
authors.forename: John E
authors.initials: JE
authors.lastname: Conway
authors.affiliation: Texas Health Ben Hogan Sports Medicine, Fort Worth, Texas, USA.
authors.forename: Kalyssa
authors.initials: K
authors.lastname: Pollard
authors.affiliation: Department of Biostatistics and Epidemiology, University of North Texas Health Science Center, Fort Worth, Texas, USA.
authors.forename: Subhash
authors.initials: S
authors.lastname: Aryal
keywords: UCL; humeral retrotorsion; overhead athlete; shoulder ROM