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 (r 2 = .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.
Background: Glenohumeral internal rotation deficit (GIRD) indicates a 20° or greater loss of internal rotation of the throwing shoulder compared with the nondominant shoulder.
Purpose: To determine whether GIRD and a deficit in total rotational motion (external rotation + internal rotation) compared with the nonthrowing shoulder correlate with shoulder injuries in professional baseball pitchers.
Study Design: Case series; Level of evidence, 4.
Methods: Over 3 competitive seasons (2005 to 2007), passive range of motion measurements were evaluated on the dominant and nondominant shoulders for 170 pitcher-seasons. This included 122 professional pitchers during the 3 seasons of data collection, in which some pitchers were measured during multiple seasons. Ranges of motion were measured with a bubble goniometer during the preseason, by the same examiner each year. External and internal rotation of the glenohumeral joint was assessed with the participant supine and the arm abducted 90° in the plane of the scapula, with the scapula stabilized anteriorly at the coracoid process. The reproducibility of the test methods had an intraclass correlation coefficient of .81. Days in which the player was unable to participate because of injury or surgery were recorded during the season by the medical staff of the team and defined as an injury.
Results: Pitchers with GIRD (n = 40) were nearly twice as likely to be injured as those without but without statistical significance (P = .17). Pitchers with total rotational motion deficit greater than 5° had a higher rate of injury. Minor league pitchers were more likely than major league pitchers to be injured. However, when players were injured, major league pitchers missed a significantly greater number of games than minor league pitchers.
Conclusion: Compared with pitchers without GIRD, pitchers with GIRD appear to be at a higher risk for injury and shoulder surgery.
Internal impingement of the shoulder is a pathologic condition characterized by excessive or repetitive contact of the greater tuberosity of the humeral head with the posterosuperior aspect of the glenoid when the arm is abducted and externally rotated. This arm positioning leads to rotator cuff and glenoid labrum impingement by the bony structures of the glenohumeral joint. Although some degree of contact between these structures occurs under normal conditions, to date most of the orthopaedic literature has focused on internal impingement as a disease state that affects overhead athletes and is characterized by the development of articular-sided rotator cuff tears and posterosuperior labral lesions. The precise cause of these impingement lesions remains unclear. However, it is believed that varying degrees of glenohumeral instability, posterior capsular contracture, and scapular dyskinesis may play a role in the development of symptomatic internal impingement. The purpose of this article is to review the pathomechanics, clinical complaints, physical examination findings, and imaging findings that are associated with internal impingement. The results of treatment will be reviewed, and a diagnostic and therapeutic algorithm for the management of internal impingement is presented.
Background: The ability to identify pitchers at risk for injury could be valuable to a professional baseball organization. To our knowledge, there have been no prior studies examining the predictive value of preseason strength measurements.
Hypothesis: Preseason weakness of shoulder external rotators is associated with increased risk of in-season throwing-related injury in professional baseball pitchers.
Study Design: Cohort study (prognosis); Level of evidence, 2.
Methods: Preseason shoulder strength was measured for all pitchers in a professional baseball organization over a 5-year period (2001-2005). Prone internal rotation (IR), prone external rotation (PER), seated external rotation (SER), and supraspinatus (SS) strength were tested during spring training before each season. The players were then prospectively followed throughout the season for incidence of throwing-related injury. Injuries were categorized on an ordinal scale, with no injury, injury treated conservatively, and injury resulting in surgery delineated 0, 1, and 2, respectively. Subset analyses of shoulder injuries and of players with prior surgery were also performed. The association between strength measurements and injury was analyzed using Spearman rank correlation.
Results: A statistically significant association was observed for PER strength (P = .003), SER strength (P = .048), and SS strength (P = .006) with throwing-related injury requiring surgical intervention. Supraspinatus strength was also significantly associated with incidence of any shoulder injury (P = .031). There was an association between the ratio of PER/IR strength and incidence of shoulder injury (P = .037) and some evidence for an association with overall incidence of throwing-related injury (P = .051). No associations were noted in the subgroup of players with prior surgery.
Conclusion: Preseason weakness of external rotation and SS strength is associated with in-season throwing-related injury resulting in surgical intervention in professional baseball pitchers. Thus, preseason strength data may help identify players at risk for injury and formulate strengthening plans for prevention.
Background: Excessive and untimely scapular dyskinesis during the throwing motion has been associated with several shoulder injuries. The scapula provides attachment for many soft tissue structures. Therefore, many have hypothesized that posterior shoulder tightness may alter proper scapular kinematics.
Hypothesis: As posterior shoulder tightness increases, so will forward scapular posture. Baseball players will have a significantly more forward scapular position of their dominant arm compared with their nondominant arm. The bilateral difference in forward scapular posture will be greater in pitchers than in position players, indicating pitchers have more forward scapular posture.
Study Design: Cross-sectional study; Level of evidence, 3.
Methods: Bilateral forward scapular posture, glenohumeral horizontal adduction, and rotational range of motion were measured among 20 professional baseball pitchers and 20 position players.
Results: A regression analysis showed a moderate to good negative relationship between glenohumeral horizontal adduction range of motion and forward scapular posture (r2 = .50, P = .001). T tests demonstrated that the dominant shoulders of both groups had significantly more forward scapular posture compared with nondominant shoulders (P < .004). There were no other significant relationships or differences found (r2 < .04, P > .15).
Conclusion: There was a moderate to good relationship between posterior shoulder tightness and forward scapular posture. Furthermore, baseball players had more forward scapular posture of the dominant arm than the nondominant arm. These results suggest that posterior shoulder tightness as evidenced by decreased glenohumeral adduction range of motion may be considered a partial predictor for excessive forward scapular posture and vice versa. Because of the association between this scapular dyskinesis and shoulder dysfunction, clinicians may find it advantageous to address these characteristics when examining and treating such athletes.
