Background: Glenohumeral dislocations often
recur, probably because a Bankart lesion does not heal sufficiently during
the period of immobilization. Using magnetic resonance imaging,
we assessed the position of the Bankart lesion, with the arm in
internal and external rotation, in shoulders that had had a dislocation.
Methods: Coaptation of a Bankart lesion was examined
with use of magnetic resonance imaging, with the arm held at the
side of the trunk and positioned first in internal rotation (mean,
29°) and then in external rotation (mean, 35°), in nineteen shoulders.
Six shoulders (six patients) had had an initial anterior dislocation,
and thirteen shoulders (twelve patients) had had recurrent anterior
dislocation. Fast-spin-echo T2-weighted axial images were made when the
dislocation had occurred less than two weeks earlier, and spin-echo
T1-weighted axial images after intra-articular injection of gadolinium-diethylenetriamine
pentaacetic acid were made when the dislocation had occurred more
than two weeks earlier. Separation and displacement of the anteroinferior
portion of the labrum from the glenoid rim were measured on the
axial images, and coaptation of the anterior part of the capsule
to the glenoid neck was assessed by measurement of the detached area,
opening angle, and detached length.
Results: Separation and displacement of the labrum
were both significantly less (p = 0.0047 and p = 0.0017, respectively)
when the arm was in external rotation than when it was in internal
rotation. The detached area and the opening angle of the anteroinferior portion
of the capsule were both significantly smaller (p = 0.0003
and p < 0.0001, respectively), and the detached length
was significantly shorter (p < 0.0001) with the arm in
Conclusion: Immobilization of the arm in external
rotation better approximates the Bankart lesion to the glenoid neck
than does the conventional position of internal rotation.