Asymptomatic Shoulder Injuries in Throwing Athletes
Asymptomatic Shoulder Injuries in Throwing Athletes
Abstract & Commentary
Synopsis: Internal glenoid impingement causes pathologic changes in the rotator cuff, labrum, and bone in the shoulders of baseball players even in the absence of symptoms.
Source: Halbrecht J, et al. Internal impingement of the shoulder: Comparison of findings between the throwing and nonthrowing shoulders of college baseball players. Arthroscopy 1999;15:253-258.
Halbrecht and colleagues performed an evaluation of symptomatic shoulder injuries in 10 college baseball players. First, the athletes were all examined for instability, range of motion, and impingement. MR imaging of both shoulders was then performed on all athletes, both in the standard position and in abduction/external rotation (ABER). By physical examination, Halbrecht et al found evidence of impingement in only three patients and found only one patient with significant instability. However, the MRIs showed four throwing shoulders with tendinosis or interstitial tear of the rotator cuff and three throwing shoulders with superior labral tears (SLAP) and associated paralabral cysts. There were also two throwing shoulders with posterior-superior humeral head cystic changes. There were no lesions consistent with internal glenoid impingement in the nonthrowing shoulders, even though there was evidence of contact between the rotator cuff and posterior-superior labrum in each shoulder when placed in the ABER position. Halbrecht et al conclude that internal glenoid impingement between the articular surface of the rotator cuff and the posterior glenoid and labrum does exist in asymptomatic throwing athletes. They also suggest that the repetitive contact of the throwing motion may be the cause of these changes.
Comment by Stephen B. Gunther, MD
Rotator cuff impingement is a painful syndrome caused by abrasion of the rotator cuff. Impingement can be caused extrinsically by such factors as acromial overhang, spurring, AC joint arthritis, bursitis, or ossification of the coracoacromial ligament. Intrinsic impingement can be caused by degeneration and tearing of the rotator cuff.1 Internal glenoid impingement is a condition caused by abrasion of the articular surface of the rotator cuff on the posterior-superior rim of the glenoid and glenoid labrum. This syndrome has been documented in overhead athletes.2 However, this study examined the role of throwing as a mechanism of injury by comparing the throwing and nonthrowing shoulders of these young baseball players. Halbrecht et al documented seven pathologic lesions in the 10 throwing shoulders and only one pathologic lesion in a nonthrowing shoulder. Thus, Halbrecht et al have provided indirect evidence that repetitive throwing can cause pathologic lesions consistent with internal glenoid impingement even in the absence of symptoms.
References
1. Neer CS II. Anterior acromioplasty for the chronic impingement syndrome in the shoulder. J Bone Joint Surg Am 1972;54:41-50.
2. Kvitne RS, Jobe FW. The diagnosis and treatment of anterior instability in the throwing athlete. Clin Orthop 1993;291:107-123.
All of the following are pathologic structures associated with internal glenoid impingement in overhead athletes except:
a. posterior-superior glenoid labrum.
b. humeral head.
c. rotator cuff.
d. biceps tendon.
e. glenoid.
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