[Open posterior-inferior capsule shift for the treatment of atraumatic posterior shoulder instability].

OBJECTIVE: Restoration of functional stability and full range of shoulder mobility.

INDICATIONS: Atraumatic, recurrent posterior dislocation or subluxation in cases of excessive posterior joint capsular volume without clinically relevant destruction of the glenoid or dysplasia. Additional procedure for traumatic posterior instability after reattachment of the labrum or screw fixation of the posterior glenoid fragment.

CONTRAINDICATIONS: Capsular shift should not be an isolated procedure in glenoid hypoplasia and/or glenoid retroversion > 15 degrees (relative). Multidirectional instability (relative). Deliberate (psychogenic) posterior instability (relative).

SURGICAL TECHNIQUE: Lateral decubitus position, Rockwood approach. Dissection of the posterior joint capsule after split of the external rotator muscles between the infraspinatus and teres minor. T-shaped incision of the posterior capsule with a medial base of about 0.5-1 cm lateral to the posterior glenoid rim. Retraction of the caudal and cranial capsular flaps. Inspection of the posterior labrum. If the labrum is detached, anatomic refixation of the labrum with suture anchors. The caudal flap is shifted cranially and medially in adduction and about 20 degrees external rotation. The cranial flap is then shifted caudally and medially. Suture with close-meshed Vicryl sutures. This creates double-contouring centrally and plication of the posterior capsule with reduction of the pathologically increased capsule volume. After wound closure and sterile dressing, the preoperatively prepared antirotation cast is applied and should be worn for 6 weeks.

RESULTS: From 10/2002 to 09/2004, eight patients with atraumatic, isolated posterior shoulder instability were treated using the technique described above. All patients were available to follow-up 2 years after the operation. There were no perioperative complications and no neurologic deficits related to surgery. All patients achieved freedom of movement at the shoulder joint. In two patients, recurrent posterior dislocation occurred after the 7th and 23rd postoperative month.