ANTERIOR SHOULDER INSTABILITY: OPEN RECONSTRUCTION FOR RECURRENT TRAUMATIC INSTABILITY

Anterior Shoulder Instability: Open Reconstruction for Recurrent Traumatic Instability

Edward V. Fehringer and Frederick A. Matsen III

Bankart’s 1939 assertion that “the only rational treatment is to reattach the glenoid ligament (or the capsule) to the bone from which it has been torn” has held true for patients with traumatic anterior shoulder instability. Although variations of this theme exist, the primary objective remains restoration of normal anatomy. This restores ligamentous and capsular attachments but also effectively restores the concavity-compression mechanism and the glenohumeral “suction cup,” both important contributors to stability. With an appropriate history of traumatic anterior dislocation, the Bankart lesion is a predictable intraoperative finding. Excellent results have been achieved with its repair.

Indications

1. Recurrent anterior shoulder instability

2. Bankart lesion (Fig. 24–1)

Contraindications

1. Unclear history of dislocation

2. Ill-defined shoulder pain

3. Atraumatic instability

Mechanism of Injury

With shoulder instability, it is imperative to obtain a sound history and perform a thorough, concise physical examination. One must clearly define the position of the arm at the index dislocation, the surrounding events, and the direction of dislocation. In traumatic anterior instability, the anteroinferior labrum and capsule are avulsed from the glenoid. This injury usually occurs with the arm in an abducted and externally rotated position or with the arm in an extended position. The long lever arm of the upper extremity applies a force to the glenohumeral ligaments 20 to 40 times greater than that applied to the arm. Patients with recurrent anterior instability experience recurrent dislocation, subluxation, or apprehension with the arm in extension and abduction with external rotation. These shoulders are usually comfortable in midrange positions. Patients with traumatic instability who are over 40 years of age may have injuries to their rotator cuff or greater tuberosity avulsions. Such patients may have pain and weakness on shoulder flexion and external rotation.

Physical Examination

The impression of anterior instability may be confirmed by the following:

1. Apprehension with the arm in extension and external rotation.

2. Pain, laxity, and relocation tests for traumatic instability are not specific.

3. An anterior load-and-shift maneuver examines the effectiveness of the anterior glenoid concavity (Figs. 24–2A,B).

Diagnostic Tests

Radiographs may help confirm the diagnosis of recurrent anterior instability.

1. An anterior-posterior view in the plane of the scapula, an axillary, and an apical oblique allow an excellent view of the posterolateral humeral head and the anterior-inferior glenoid. In shoulders with recurrent glenohumeral joint instability, these radiographs may reveal Hill-Sachs lesions, loss of the inferior glenoid lip, glenohumeral subluxation, loose bodies, and fractures of the glenoid or proximal humerus (Fig. 24–3).

2. Dynamic sonography, magnetic resonance imaging, or arthrography may be utilized to evaluate the rotator cuff.

Special Considerations

After the initial traumatic anterior dislocation, reported rates of recurrent dislocation vary. Some authors have reported a redislocation rate of 90% for individuals less than 20 years of age, although others report a much lower incidence for a similar age group. Patients with symptomatic recurrent traumatic instability may wish to consider surgical repair. The goals of surgical repair for recurrent traumatic instability are: (1) reestablishment of the depth of the glenoid concavity; (2) anatomic and secure reattachment of the glenohumeral capsule and ligaments; and (3) preservation of normal joint motion.

If there is substantial loss of the anterior glenoid lip, as is often seen in chronic anterior instability, soft tissue repair alone may be insufficient to restore the glenoid concavity. In such situations, an anterior extracapsular iliac crest graft may help restore glenoid shape. The graft is fixed to the anterior glenoid neck using cortical screws after contouring the neck and the graft to well-opposed, flattened, bleeding surfaces (Figs. 24–4A,B). Once in position, the graft may be contoured with a high-speed burr. Some patients with recurrent anterior instability have subscapularis ruptures. If possible, such ruptures are repaired primarily. If a substantial tendon defect exists, it may be bridged with a hamstring autograft. Depending on the status of the subscapularis and its retraction, the tendon autograft may act as a checkrein rather than as a dynamic muscle-tendon unit.

Anesthetic Options

1. General anesthesia

2. Scalene block (infiltrate the inferior aspect of the incision with local anesthetic to adequately anesthetize the low axillary region)

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