Shoulder MR arthrography of the posterior labrocapsular complex in overhead throwers with pathologic internal impingement and internal rotation deficit.
OBJECTIVE
To determine if overhead-throwing athletes with internal impingement pain and internal rotation deficit have thickening of the posterior inferior labrocapsular complex on MR arthrogram images.


METHODS
This study was approved and a waiver of consent granted by our institutional review board. Twenty-six overhead-throwing athletes with internal impingement pain and internal rotation deficit, and 26 controls who had undergone MR arthrograms, were retrospectively examined. The MR studies were combined and read in a blind fashion. On an axial image through the posteroinferior glenoid rim, the readers measured the labral length, capsule-labrum length, and the posterior recess angle. A t-test was used to determine statistical significance.


RESULTS
The mean labral length was 4.9 mm [standard deviation (SD) 1.4 mm] for the controls, and 6.4 mm (SD 1.6 mm) for the athletes (P = 0.001). The mean capsule-labrum length was 5.4 mm (SD 2.1 mm) for the controls, and 8.8 mm (SD 2.9 mm) for the athletes (P < 0.001). The mean posterior recess angle measured 65 degrees (SD 27 degrees) for the controls and 94 degrees (SD 38 degrees) for the athletes (P = 0.002).


CONCLUSIONS
Overhead-throwing athletes with internal impingement pain and internal rotation deficit tend to have a thicker labrum and a shallower capsular recess in the posterior inferior shoulder joint than do non-overhead-throwing athletes. In many, the posteroinferior capsule is also thickened. These MR findings should alert the radiologist to closely inspect the posterior cuff and posterosuperior labrum for the tears associated with internal impingement.
Tuite
Michael J
MJ
Department of Radiology, University of Wisconsin Hospital and Clinics, 600 Highland Avenue, Madison, WI 53792, USA. mjtuite@wisc.edu
Petersen
Brian D
BD
Wise
Steven M
SM
Fine
Jason P
JP
Kaplan
Lee D
LD
Orwin
John F
JF
D000293:Adolescent; D000328:Adult; D001484:Baseball / Q000293:injuries; D001696:Biomechanical Phenomena; D003287:Contrast Media; D005260:Female; D019786:Gadolinium DTPA; D006801:Humans; D007091:Image Processing, Computer-Assisted; D017746:Joint Capsule / Q000503:physiopathology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D016059:Range of Motion, Articular / Q000502:physiology*; D012189:Retrospective Studies; D012399:Rotation; D019534:Shoulder Impingement Syndrome / Q000503:physiopathology*; D000070599:Shoulder Injuries; D012785:Shoulder Joint / Q000503:physiopathology*; D020069:Shoulder Pain
D003287:Contrast Media; C064925:gadodiamide; D019786:Gadolinium DTPA