Position of immobilization after dislocation of the shoulder. A cadaveric study.

BACKGROUND: After reduction of a shoulder dislocation, the torn edges of a Bankart lesion need to be approximated for healing during immobilization. The position of immobilization has traditionally been adduction and internal rotation, but there is little direct evidence to support or discredit the use of this position. The purpose of the present study was to determine the relationship between the position of the arm and the coaptation of the edges of a simulated Bankart lesion created in cadaveric shoulders. METHODS: Ten thawed fresh-frozen cadaveric shoulders were used for experimentation. All of the muscles were removed to expose the joint capsule. A simulated Bankart lesion was created by sectioning the anteroinferior aspect of the capsule from the labrum. With linear transducers attached to the anteroinferior and inferior portions of the Bankart lesion, the opening and closing of the lesion were recorded with the arm in 0, 30, 45, and 60 degrees of elevation in the coronal and sagittal planes as well as with the arm in rotation from full internal to full external rotation in 10-degree increments. RESULTS: With the arm in adduction, the edges of the simulated Bankart lesion were coapted in the range from full internal rotation to 30 degrees of external rotation. With the arm in 30 degrees of flexion or abduction, the edges of the lesion were coapted in neutral and internal rotation but were separated in external rotation. At 45 and 60 degrees of flexion or abduction, the edges were separated regardless of rotation. CONCLUSIONS: The present study demonstrated that, in the cadaveric shoulder, there was a so-called coaptation zone in which the edges of a simulated Bankart lesion were kept approximated without the surrounding muscles.