Once the subscapularis is identified, then it needs to be separated from the shoulder capsule. Typically, only the upper three-quarters of the muscle is removed, with the lower one-quarter being left intact to act as protection for the axillary nerve. Also, usually the muscle is cut in an oblique fashion, running from superficial lateral toward medial deep, which gives you better tissue to sew into at the time of closure. The subscapularis muscle is usually adherent to the capsule. You will usually need to separate the muscle off of the capsule, either by sharp dissection or with an elevator.
Once that is done, then the capsule can be opened either transversely, if the goal is simply to shift it superiorly, or in a T-fashion, for an imbrication if the goal is to tighten and imbricate the capsule.
TRICKS
The major trick is to find the deltopectoral groove and take whichever vein seems easiest (typically laterally). The coracoid is the best landmark for the short head of the biceps; split the fascia in that direction, which will get you into the interval between the two heads. Another useful trick is to put a stay-suture in the subscapularis prior to cutting it free from the humeral head so that it does not retract out of the way. Finally, feel the shoulder joint and the glenoid edge prior to doing the capsulotomy, so you can place it correctly for whatever procedure you are attempting to do. This is especially important when attempting to do instability procedures.
HOW TO TELL IF YOU ARE LOST
It is relatively easy to be off a little medially or laterally when looking for the deltopectoral groove. The cephalic vein is the best landmark, so simply spread until you see it. There is no good way to tell if you are lost medially or laterally.
The coracoid is an excellent landmark to prevent your drifting too far medially when splitting the biceps fascia. It is difficult to get lost too far laterally because you can feel the humerus, and because the deltoid muscle gets in the way. It is possible to open the capsule too far laterally, making it difficult to get medial enough to actually see the glenoid. You need to be at least 1 cm medial to the subscapularis insertion into the humeral head to be in the correct place. Superiorly, it is easy to avoid getting lost because of the clavicle and acromioclavicular joint, which limits your upward mobility.
Inferiorly, the blood vessels of the humeral circumflex artery and vein are visible on the inferior border of the subscapularis. You should not be cutting in that area. If you see those fairly obvious blood vessels, stay superior to them.
FIGURE 1–1 The skin incision running from the axilla in the skin crease.
FIGURE 1–2 The subcutaneous tissue with the underlying deltoid or pectoralis major muscle. If you look on the edge of the fat, you will see a hint of the cephalic vein.
FIGURE 1–3 The cephalic vein.
FIGURE 1–4 The cephalic vein retracted, the pectoralis major is medial and the deltoid lateral, exposing the fascia overlying the short head of the biceps.
FIGURE 1–5 The fascia split, exposing the short head of the biceps.
FIGURE 1–6 The biceps retracted with the latissimus dorsi coming up from the bottom and the subscapularis coming across from the top.
FIGURE 1–7 The capsule open revealing the humeral head and the shoulder joint itself.
FIGURE 1–8 The subscapularis tendon released in its entirety, with the axillary nerve running on its inferior edge somewhat more posteriorly.
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POSTERIOR APPROACH
USES
This approach is used primarily for posterior capsular shift procedures. It would also be useful for scapular neck osteotomies and posterior dislocations, as well as for open reductions and internal fixations of the glenoid.
ADVANTAGES
For posterior dislocators, this is the only suitable approach.