approach can be used for any anterior shoulder surgery, including capsular shift and dislocation procedures, proximal humeral fracture work, shoulder prosthetic replacement, and long head of the biceps tendon repair.
ADVANTAGES
The approach is through an internervous plane between the deltoid and pectoralis major. The incision can be expanded proximally or distally as needed.
DISADVANTAGES
For anterior shoulder surgery, this approach is clearly the best, and it has no significant disadvantages.
STRUCTURES AT RISK
Superiorly, the major structure at risk is the acromial branch of the thoracoacromial artery, which is in the medial aspect of the coracoacromial ligament. Inferiorly, the musculocutaneous nerve comes out and enters the biceps approximately 5 cm distal to the coracoid. This structure is usually not cut, but it can be retracted and damaged with the retraction. The axillary nerve is also at risk. This crosses the inferior aspect of the capsule of the shoulder. A retractor placed below the subscapularis and the capsule puts this nerve in grave danger. The cephalic vein can also be damaged if it is not identified and protected as the deltopectoral groove is being developed.
TECHNIQUE
The incision is in the deltopectoral groove and is usually placed directly over one of the axillary skin folds to provide a more cosmetic incision. If the procedure is a capsular shift procedure, then typically most of the incision will be toward the axilla and hardly noticeable. If a more extensive exposure is needed, the incision can be carried all the way from the clavicle to the deltoid insertion.
When working deep to the subcutaneous tissue, it is important to identify the cephalic vein and the deltopectoral groove. The fascia of these two muscles is conjoined, and so frequently there is a small amount of exploration necessary to find that interval. The clue to finding it is usually an indentation, which is occasionally present, or some fat between the muscles. Another clue is the difference in fiber orientation, with the deltoid being more vertical and the pectoralis major being more horizontal. That difference is usually more apparent distally than proximally.
Once the groove is identified and the cephalic vein is identified, usually it is retracted laterally along with the deltoid. However, it can be retracted medially if it looks like that retraction would require the ligation of fewer tributaries or put less stretch on the vein.
Once the vein is identified and protected, you can use your finger to develop a plane between the two muscles and develop the plane underneath the deltoid for a short distance. When these two muscles are separated, you will see the fascia overlying the biceps and the coracobrachialis. This fascia is split in between the two heads of the biceps, retracting the short head medially and the long head laterally. At that point, the subscapularis will be in view and is identified by its muscular layer and the transverse direction of the fibers. You must also be aware that the musculocutaneous nerve enters the coracobrachialis muscle from its medial side and will exit through it and the short head of the biceps on its way down the arm. Aggressive retraction on the short head of the biceps in a medial direction can damage the nerve, and it is important to remember to look for the nerve and protect it. The musculocutaneous nerve has been known to pierce through the short head of the biceps within 5 cm of the coracoid process. Typically, it is much further distal than that, but you must be on the lookout for a more proximal position of the nerve.
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.
