J Sports Med 2002 Jan-Feb;30(1):66-73
Magnetic resonance imaging of the shoulder in asymptomatic professional baseball pitchers.
Miniaci A, Mascia AT, Salonen DC, Becker EJ.
Medicine Program, Toronto Western Hospital, University Health Network,
University of Toronto, Toronto, Canada.
The purpose of this study was
to evaluate the magnetic resonance imaging findings in both shoulders of
asymptomatic professional baseball pitchers. Fourteen pitchers who were
without significant prior injury underwent a blinded clinical assessment and
magnetic resonance imaging of both shoulders. All images were interpreted by
two experienced musculoskeletal radiologists. The appearance of the rotator
cuff tendons was graded, with additional evaluation of the biceps, labrum, and
osseous structures. Ten athletes were found to have stable shoulders and
painless full range of motion. Clinically, four athletes had at least a 40
degrees loss in internal rotation as compared with the nonthrowing arm. There
were no significant differences in magnetic resonance imaging findings of the
supraspinatus and infraspinatus tendons between the throwing and nonthrowing
shoulders. The labrum was abnormal in 79% of the 28 shoulders. Enthesopathic
changes of the posterior glenoid labrum were identified in the four pitchers
who had loss of internal rotation. We conclude that unenhanced magnetic
resonance imaging of the shoulder in asymptomatic high performance throwing
athletes reveals abnormalities that may encompass a spectrum of
"nonclinical" findings. These data can be useful in separating
symptomatic pathologic findings from these variants. Enthesopathic changes of
the posterior glenoid labrum in the throwing arm may represent an early
Bennett-type lesion. The cause may be excessive traction on the posterior
capsule during the pitching motion, with subclinical injury to this area.