Anterior Approach to the Shoulder Joint
The anterior surgical approach offers good wide exposure of the shoulder joint, allowing repairs to be made of its anterior, inferior, and superior coverings. Among its many uses, the anterior approach permits the following:
Figure 1-4 Position of the patient for the anterior approach to the shoulder. Elevate the table to 45 degrees. A sandbag placed under the spine at the medial end of the scapula will allow the shoulder to rotate externally and open the anterior part of the joint.
1. Reconstruction of recurrent dislocations4–9
2. Drainage of sepsis
3. Biopsy and excision of tumors
4. Repair or stabilization of the tendon of the long head of the biceps10
5. Shoulder arthroplasties or hemiarthroplasties which usually are insertedthrough modified anterior incisions11–13
6. Fixation of fractures of the proximal humerus14,15
The anterior approach is notorious for the amount of bleeding that occurs from skin and subcutaneous tissues during superficial dissection. The bleeding must be controlled before the deeper layers are dissected. Failure to do so may obscure important anatomic structures and endanger their integrity.
Position of the Patient
Place the patient in a supine position on the operating table. Wedge a sandbag under the spine and medial border of the scapula to push the affected side forward while allowing the arm to fall backward, opening up the front of the joint (Fig. 1-4). Elevate the head of the table 30 to 45 degrees to reduce venous pressure, and thereby decrease bleeding, and to allow the blood to drain away from the operative field during surgery. If a headrest is used, make sure that it is padded properly to prevent the development of a pressure sore on the occiput. Drape the arm free, because it will have to be moved during the approach. If image intensification is to be used during surgery, ensure that adequate images can be obtained prior to prepping and draping the patient.
Landmarks and Incision
Landmarks
Coracoid Process. Palpate the coracoid process by dropping your finger distally about 2.5 cm from the anterior edge of the clavicle at the deepest point in the clavicular concavity. Press laterally and posteriorly in an oblique line until the coracoid process is felt. The process faces anterolaterally; because it lies deep under the cover of the pectoralis major, it can be felt only by firm palpation.
Deltopectoral Groove. The deltopectoral groove is easier to see than to feel, especially in thin patients. The cephalic vein, which runs in the groove, sometimes is visible.
Incisions
The anterior aspect of the shoulder can be approached through either of two skin incisions.
Anterior Incision. Make a 10- to 15-cm straight incision, following the line of the deltopectoral groove. The incision should begin just above the coracoid process (Fig. 1-5).
Axillary Incision. With the patient supine, abduct the shoulder 90 degrees and rotate it externally. Mark the anterior axillary skin fold with a sterile pen. Make a vertical incision 8 to 10 cm long, starting at the midpoint of the anterior axillary fold and extending posteriorly into the axilla.16 The skin flaps should be undermined extensively with a finger, especially superiorly in the area of the deltopectoral groove, using the cephalic vein as a guide to ensure correct position in the vertical plane. Retract the skin flaps upward and laterally so that the incision comes to lie over the deltopectoral groove (Figs. 1-6 and 1-7).
Figure 1-5 Make a straight incision in the deltopectoral groove, starting at the level of the coracoid process.
Figure 1-6 Make an incision in the axilla. Dissect subcutaneously to mobilize skin.
The axillary incision has a significant cosmetic advantage over the anterior incision, both because it is hidden in the axilla and because the resulting scar is covered by hair. In addition, the suture line remains free from tension while it heals; thus, the scar has little opportunity to spread. The incision may be contraindicated when, in extremely muscular patients, the skin flaps cannot be moved enough to allow adequate exposure of the muscular structures that lie in front of the shoulder. If adequate exposure cannot be obtained through the axillary incision, it should be extended superiorly into the deltopectoral groove. This skin incision is not recommended for fracture fixation surgery.
Internervous Plane
The internervous plane lies between the deltoid muscle, which is supplied by the axillary nerve, and the pectoralis major muscle, which is supplied by the medial and lateral pectoral nerves (Fig. 1-8).
Figure 1-7 Retract the axillary incision cephalad to expose the cephalic vein and the deltopectoral groove.
Figure 1-8 The internervous plane lies between the deltoid muscle (axillary nerve) and the pectoralis major muscle (medial and lateral pectoral nerves).
Figure 1-9 Develop the groove between the fascia overlying the pectoralis major and the fascia overlying the deltoid. The cephalic vein will be of help in locating the groove.
Superficial Surgical Dissection
Find the deltopectoral groove, with its cephalic vein (Fig. 1-9). The vein may be difficult to visualize. It is often surrounded by some fatty tissue which can act as a guide to identifying it. Retract the pectoralis major medially and the deltoid laterally, splitting the two muscles apart. The vein may be retracted either medially or laterally. Taking a small cuff of deltoid with the vein may reduce the number of bleeding tributaries that require ligation, but it leaves a small amount of denervated muscle. For that reason, it is not recommended as a routine practice. Try to preserve the cephalic vein in order to reduce postoperative upper limb edema.
Deep Surgical Dissection
The short head of the biceps (which is supplied by the musculocutaneous nerve) and the coracobrachialis (which is supplied by the musculocutaneous nerve) must be displaced medially before access can be gained to the anterior aspect of the shoulder joint. Simple medial retraction after division of the overlying fascia may be enough for procedures such as the Magnuson–Stack subscapularis tendon advancement,6 the Putti–Platt subscapularis5 and capsule imbrication, and open reduction and internal fixation of a proximal humeral fracture but if more exposure is necessary, or if the coracoid process is to be transposed,8 the two muscles can be detached with the tip of the coracoid process. To release them, detach the tip of the coracoid process with an osteotome. The bone can be reattached later either with a screw or with sutures. If a screw is used, the coracoid process must be drilled and tapped before the osteotomy is carried out. Otherwise, the small piece of coracoid may split during drilling, and anatomic reduction can be obtained only with extreme difficulty (Figs. 110 and 1-11).
The axillary artery is surrounded by the cords of the brachial plexus, which lie behind the pectoralis minor muscle. Abduction of the arm causes these neurovascular structures to become tight and brings them close to the tip of the coracoid and the operative site. Therefore, the arm should be kept adducted while work is being done around the coracoid process (Fig.
1-12).4
Figure 1-10 Retract the pectoralis major medially and the deltoid laterally to expose the conjoined tendon of the short head of the biceps and coracobrachialis muscle. Drill the tip of the coracoid process before cutting it. Incise the fascia on the lateral aspect of the conjoint tendon. Note the leash of vessels at the inferior end of the subscapularis muscle.
Figure 1-11 Cut through the predrilled coracoid process. Retract the conjoint tendon medially to give greater exposure to the subscapularis tendon.
Figure 1-12 Protect the axillary sheath during coracoid osteotomy by having the arm in the dependent position; abduction of the arm will draw the sheath against the coracoid process.
Retract the coracoid (with its attached muscles) medially. Divide the fascia that fans out from the conjoined tendons of the coracobrachialis and the short head of the biceps on the lateral side of the coracobrachialis—the safe side of the muscle, because the musculocutaneous nerve enters the coracobrachialis on its medial side. If a coracoid osteotomy has been used, take care in retracting the coracoid with its attached muscles; overzealous downward retraction can cause a neurapraxia of the musculocutaneous nerve. If the coracoid process is left intact, the attached coracoid muscles protect the nerve from traction injury (Fig. 1-13) but nevertheless do not apply vigorous medial retraction as this can also damage the nerve.
Beneath the conjoined tendons of the coracobrachialis and the short head of the biceps lie the transversely running fibers of the subscapularis muscle, which forms the only remaining anterior covering of the shoulder joint capsule (Fig. 1-14).4 As the muscle crosses the glenoid cavity, a bursa separates it from the joint capsule; that bursa may communicate with the shoulder joint. In cases of multiple anterior dislocations, adhesions often exist between the muscle and the joint capsule, making it difficult, if not impossible, to find the layer between the two. If you need to divide or detach the insertion of subscapularis to gain access to the shoulder joint apply external rotation to the arm to stretch the subscapularis, bringing the muscle belly into the wound and making its superior and inferior borders easier to define. External rotation of the humerus also increases the distance between the subscapularis and the axillary nerve as it disappears below the lower border of the muscle (see Fig. 1-14).
The most easily identified landmarks on the inferior border of the subscapularis are a series of small vessels that run transversely and often require ligation or cauterization. The vessels run as a triad: A small artery with its two surrounding venae comitantes, one above and one below the artery (Fig. 1-15). The superior border of the subscapularis muscle is indistinct and blends in with the fibers of the supraspinatus muscle.
Pass a blunt instrument between the capsule and the subscapularis, moving upward (see Fig. 1-15). Tag the muscle belly with stay sutures to prevent it from disappearing medially when it is cut and to allow easy reattachment of the muscle to its new insertion onto the humerus. Then divide the subscapularis 2 to 3 cm from its insertion onto the lesser tuberosity of the humerus (Fig. 1-16). Note that some of its muscle fibers insert onto the joint capsule itself; the capsule frequently may be opened inadvertently when the muscle is divided, because the two layers cannot always be defined.
Alternatively, rotate the shoulder internally and identify the insertion of the tendon of the subscapularis onto the humerus. Detach this insertion with a small flake of bone using a fine osteotome. This will allow more lateral reattachment of the muscle in a prepared channel in the bone, using staples.
Incise the capsule longitudinally to enter the joint wherever the selected repair must be performed. Each type of repair has its own specific location for incision (Fig. 1-17).
If the approach is used for treatment of fractures, the deep surgical dissection has often been performed by the trauma. Fractures of the greater and lesser tuberosities usually have their musculotendinous insertions preserved and the unopposed pull of the muscles causes displacement and rotation of the bony fragments. Attachment of sutures to the tendons allows manipulation and reduction of the tuberosities. Try to preserve any remaining blood supply to the head fragment if possible to reduce the risk of avascular necrosis. The biceps tendon, which runs in the groove between the greater and lesser tuberosities, is usually preserved and can act as a key surgical landmark for bony reconstruction.
Figure 1-13 Vigorous retraction of the conjoint tendon distally can injure the musculocutaneous nerve, causing neurapraxia or avulsion.
Figure 1-14 A: The subscapularis muscle lies in the deep part of the wound. It is to be incised perpendicular to its fibers, close to its tendon. The axillary nerve passes anteroposteriorly through the quadrangular space. B: External rotation of the arm during incision into the subscapularis tendon will draw the point of incision away from the axillary nerve.
Figure 1-15 Insert a curved artery clamp under the subscapularis muscle. A leash of vessels at the caudal end of the wound marks the lower border of the subscapularis.
Figure 1-16 Incise the end of the subscapularis. Tag and place stay sutures into the muscle to prevent it from retracting medially. Some of the subscapularis fibers insert directly into the joint capsule.
Figure 1-17 Incise the joint capsule longitudinally to expose the humeral head and the glenoid cavity.
Dangers
Nerves
The musculocutaneous nerve enters the body of the coracobrachialis about 5 to 8 cm distal to the muscle’s origin at the coracoid process. Because the nerve enters the muscle from its medial side, all dissection must remain on the lateral side of the muscle. Great care should be taken not to retract the muscle inferiorly, to avoid stretching the nerve and causing paralysis of the elbow flexors (see Fig. 1-13). Also take care to avoid overzealous medial retraction if a coracoid osteotomy is not performed.
The axillary nerve runs on the deep surface of the deltoid muscle running from posterior to anterior. Retraction of the deltoid muscle posteriorly cannot therefore damage the nerve but instruments placed around the lateral side of the proximal humerus to facilitate retraction of the deltoid may press directly on the nerve causing a neurapraxia. The nerve is also in danger when dividing the subscapularis muscle tendon. The nerve lies just inferior to the inferior border of the muscle. The danger can be reduced by externally rotating the arm before dividing the tendon (see Fig. 1-14A,B). If the dissection is not carried out inferior to the triad of vessels marking the lower border of the muscle the nerve will be safe.
Vessels
The cephalic vein should be preserved, if possible to reduce the risk of postoperative upper limb edema. However a traumatized cephalic vein should be ligated to prevent the slight danger of thromboembolism. There are no valves between the cephalic vein and the superior vena cava.
