Open repair of multidirectional shoulder instability

Introduction

One of the earliest descriptions of multidirectional instability (MDI) was offered by Neer and Foster in 1980, who described this pathologic entity as the ability to dislocate or subluxate the glenohumeral joint anteriorly, posteriorly, and inferiorly. In that series, patients were most symptomatic during mid-range of motion while performing activities of daily living. MDI is described as global shoulder laxity that can be congenital, acquired or both. It is primarily caused by the combination of a redundant inferior capsular pouch, laxity of ligaments about the shoulder, and weakened musculotendinous structures. Congenital conditions that have poly-ligamentous laxity include Marfan and Ehlers-Danlos syndrome. Acquired laxity is often found in competitive athletes who require extremes of shoulder ranges of motion: specifically, gymnasts and swimmers. Patients who develop symptomatic laxity after mild to moderate trauma are likely a combination of congenital and acquired conditions.

Diagnosis is largely by history and clinical examination; however, magnetic resonance imaging (MRI) can be helpful in evaluating the presence and extent of a traumatic component. A simple and useful classification of shoulder instability relies on Frequency, Etiology, Direction, and Severity (FEDS).

By far, the mainstay of treatment is nonoperative management focusing on physical therapy and rehabilitation, including (a) strengthening of peri-scapular dynamic stabilizers and (b) neuromuscular coordination of the rotator cuff, deltoid, and scapula. ^, Operative management is reserved for those refractory to conservative measures. The open inferior capsular shift, as originally described by Neer and Foster, stabilizes the shoulder by decreasing capsular volume and has been the operative treatment of choice. With advances in arthroscopic techniques, the amount of capsular volume reduction is comparable to that with the open technique. The results of arthroscopic techniques have been promising and as a result, the open procedure is used less frequently but remains an option, especially in those in whom arthroscopic treatment has failed. ^,

Preoperative considerations

Physical examination

The mainstay of diagnosis is physical examination. Basic shoulder examination includes inspection for muscle atrophy, palpation for any point tenderness, and active and passive range of motion to evaluate shoulder biomechanics. As with any complete examination of the shoulder, the physician should also evaluate for cervical spine pathology. Signs of global ligamentous laxity including elbow hyperextension, ability to touch the thumb to the forearm ( Fig. 13.1 ), and patellar subluxation are frequently observed. A Beighton score may be calculated as a quantification of laxity, but this has shown to correlate poorly with MDI. A positive sulcus and/or apprehension sign is common ( Fig. 13.2 ). We also use the load and shift test to quantify both anterior and posterior laxity ( Fig. 13.3 ). This is done by placing the shoulder off the edge of the table in 90 degrees of abduction and applying an anterior and posterior translational force. The result is graded as minimal translation (trace), humeral head translation to the rim (1+), translation over the rim with spontaneous reduction (2+), and dislocation (3+). Findings on the load and shift test may underestimate the true laxity about the glenohumeral joint with the patient awake, as the patient may display guarding. The contralateral shoulder should be evaluated for laxity as well. Additional maneuvers to demonstrate increased translation include the Fukuda test and the jerk test.