Open Posterior Stabilization

The posterior approach to the shoulder begins with a vertical incision extending from approximately 1 cm medial to the pos-terolateral corner of the acromion and extends down toward the posterior axillary fold. Dissection is carried down to the deltoid muscle, which is split in line with its fibers from the scapular spine extending inferiorly. Classically, the approach is then continued in the internervous plane between the infraspinatus and teres minor, dividing this interval transversely to expose the underlying posterior capsule (Fig. 19-3). Care must be taken not to stray inferiorly because the axillary nerve and posterior humeral circumflex artery exit the quadrilateral space below the teres minor.

An alternative approach involves splitting the infraspinatus in line with its fibers.13 This allows for a more direct approach to the posterior capsule, but the split must not be carried more than 1.5 cm medial to the glenoid in order to avoid injury to the suprascapular nerve.

The capsule is opened and retractors placed to expose the posterior glenoid. If a reverse Bankart lesion is present, it is repaired. Suture anchors are placed at the glenoid margin. The sutures are passed around the labrum and knots tied sequentially. A posterior capsular shift is then performed to address capsular laxity. Because the posterior capsule is quite thin, this repair can appear to be somewhat tenuous. To combat this, some surgeons prefer to divide the infraspinatus tendon vertically, incorporating this tendon into the repair by repairing the lateral flap to the glenoid, then taking the medial flap and suturing it over the top of the lateral flap.12

Arthroscopic Posterior Stabilization

Arthroscopic posterior stabilization may be performed in the beach chair or lateral decubitus position. Use of the beach chair position prevents potential distortion of normal anatomy, allows the arm to be free to dynamically evaluate the glenohumeral ligaments throughout a range of motion, and provides easier conversion to an open procedure. The primary advantage of the lateral position is that distraction of the joint is obtained, allowing easier access to the inferior aspect of the posterior labrum, glenoid, glenohumeral ligaments, and capsule, the most important part of the repair.

A standard diagnostic arthroscopy, starting with visualization from the posterior portal, is performed first. An anterosuperior portal is placed within the rotator interval. A second anterior portal, placed just above the subscapularis tendon, is helpful in allowing the shuttling of sutures. After inspection of the entire joint, the arthroscope is then placed in the anterosuperior portal, allowing a view to the posterior aspect of the shoulder. The posterior glenoid, labrum, and capsule are carefully inspected. If a posterior labral detachment is present, surgical stabilization involves repair of the labrum back to the glenoid, with incorporation of the capsule into the repair in order to perform a cap-sulorraphy. The posterior glenoid rim is abraded with a shaver

Figure 19-3 A, The capsule is approached between the infraspinatus and teres minor. B, Alternative approach, splitting the infraspinatus transversely. C, The infraspinatus and capsule are divided vertically as one layer. The lateral flap is then sutured to the glenoid to bolster the posterior capsular repair.

Figure 19-3 A, The capsule is approached between the infraspinatus and teres minor. B, Alternative approach, splitting the infraspinatus transversely. C, The infraspinatus and capsule are divided vertically as one layer. The lateral flap is then sutured to the glenoid to bolster the posterior capsular repair.

or rasp to expose bleeding bone. In order to place suture anchors posteriorly, an accessory posterior portal is made more laterally than the portal made for the diagnostic arthroscopy. It is remarkable how steep the angle must be with regard to the arm in order to place the anchors. A drill guide is placed, a hole drilled, and suture anchor positioned near the inferior aspect of the detachment, often as low as the 7 o'clock position (right shoulder). The suture from the anchor is passed through the labrum and a portion of the capsule (Fig. 19-4). Several variations of suture passers are available. Often a suture is passed, then used to "shuttle" the suture from the anchor through the tissue. An arthroscopic knot is then tied. This process is repeated, moving superiorly, with three anchors commonly placed.

In cases in which no posterior labral detachment is present, capsulorraphy is performed without labral repair. Many surgeons still place anchors at the glenoid margin and perform the repair as described previously. Alternatively, the posterior capsule may be plicated, with sutures passed through the capsule and labrum and knots tied (Fig. 19-5). The capsule is simply folded over to reduce the size of the posterior recess. Suture capsulorraphy in the rotator interval, the area between the subscapularis and supraspinatus tendons, has also been advocated in addressing posterior instability. Rotator interval plication has been shown to decrease posterior translation of the glenohumeral joint.14

Some authors have advocated thermal treatment of the capsule to perform capsulorraphy. This technique is controversial, and its efficacy is undetermined, particularly relating to the posterior capsule. A cadaveric study found that posterior translation was not decreased with thermal treatment.15 These authors postulated that the lack of substantial collagenous material in the thin posterior capsule may account for the ineffectiveness of thermal treatment posteriorly. Given these findings, along with concerns about the long-term effectiveness of thermal capsulorraphy in general, as well as the potential for complications, this technique is not recommended.

Open Reduction of Chronic Dislocation

When a posterior dislocation cannot be reduced through closed means, open reduction is generally performed through an anterior approach. A standard deltopectoral approached is used. If the lesser tuberosity is fractured, this fragment is identified and dissected free working on its lateral side to allow repair with the subscapularis tendon remaining attached. Releases are performed to regain length of the subscapularis. The glenohumeral joint is entered lateral to the fragment, and the humeral head is carefully levered laterally and externally rotated to allow it to be reduced to the glenoid. The lesser tuberosity is then sutured back to the defect from the fracture. When dislocation occurs without fracture of the lesser tuberosity, the subscapularis tendon may be divided off of the lesser tuberosity. After reduction of the humeral head back into the glenoid fossa, the sub-scapularis is mobilized, then transferred into the reverse Hill-Sachs lesion, which is lateral to the lesser tuberosity. Alternatively, the lesser tuberosity may be osteotomized and transferred into the defect, with the subscapularis remaining attached (Fig. 19-6).

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