Chapter 3 Instability

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CHAPTER 3 | Instability

FIGURE 3-6  Coracoid osteotomy may be performed with (A) an osteotome or (B) an angled sawblade. C, coracoid.

The capsular incision is begun 1 cmmedial to the rimof the glenoid by subperiosteal sharp dissection to preserve enough capsular length for later reattachment (Fig. 3-8). The anterior glenoid neck is prepared as the recipient bed for the coracoid bone graft by means of a curette or a burr, being careful to preserve as much native glenoid bone as possible. “Dusting” of the anterior glenoid neck to a bleeding surface is performed with a high-speed burr without actually removing the bone. Alternatively, in our preferred technique for bone bed preparation, a 70° angled sawblade can be used to create a completely flat surface on the anterior glenoid neck that will match the flat surface of the coracoid cut, maximizing the con- tact area and thereby enhancing the chances of bone union. Coracoid Preparation While stabilizing the coracoid with a Kocher grasper, use an oscillating saw to remove a thin sliver of the bone from the medial coracoid surface where the pectoralis minor had been inserted. This is the surface that will be in contact with the anterior glenoid neck (Fig. 3-9).

muscles may prevent a proper angle of approach anterior to the glenoid, resulting in the possibility of intra-articular glenoid fracture. Option 2, for muscular patients, involves the use of an angled sawblade to create the osteotomy (Fig. 3-6B). Neurovascular structures are protected by retractors medial and inferior to the sawblade. With either technique, the osteotomy is made just anterior to the cora- coclavicular ligaments in order to obtain as much length to the coracoid graft as possible. A graft measuring 2.5 to 3.0 cm in length is ideal, though in small patients a graft of 2.0 cm is adequate for fixation with two screws. The conjoined tendon is left attached to the coracoid graft to maintain vascularity of the graft and to augment stability of the glenohumeral joint by providing a sling effect upon completion of the procedure. After mobiliza- tion of the coracoid and conjoined tendon, the muscu- locutaneous nerve is protected by retracting the coracoid medially, thereby preventing any stretch injury to the nerve. Glenohumeral Joint Exposure Once the coracoid has been osteotomized, there is a clear view of the anterior shoulder. The upper half of the subscapularis tendon is detached distally and reflected medially (Fig. 3-7). The insertion of the lower half of the subscapularis is preserved. After detachment of the upper subscapularis tendon, the plane between lower subscapu- laris tendon and anterior joint capsule is developed. Alternatively, the glenoid may be exposed by using a subscapularis split approach. A deep Gelpi retractor is used to spread the split in the muscle. The subscapularis split is made through the muscular fibers at the junction of the superior and middle thirds of the muscle. The capsule is bluntly dissected from the subscapularis, and then, the capsular incision is made. We prefer not to use the sub- scapularis-splitting approach because visualization can be quite limited, and the position of the split severely limits the surgeon’s ability to change the position of the graft on the glenoid if needed. Instead, we detach the upper half of the subscapularis and then develop the plane between the lower subscapularis and capsule.

FIGURE 3-7  Management of the subscapularis tendon. Detach the superior half of the tendon and then develop a plane between the inferior half of the subscapularis and the capsule.