Anterior Approach to the Humeral Shaft ‌

The anterior approach exposes the anterior surface of the shaft of the humerus.1–3 Normally, only a portion of the approach is needed for any one procedure. As in all approaches to the humerus, the radial nerve is the structure at greatest risk during surgery.

The uses of the anterior approach include the following:

1. Internal fixation of fractures of the humerus

2. Treatment of delayed or nonunion of humeral shaft fractures

3. Osteotomy of the humerus

4. Biopsy and resection of bone tumors

5. Treatment of osteomyelitis

Position of the Patient

Place the patient supine on the operating table, with the arm on an arm board, abducted about 60°. Tilt the patient away from the affected arm to reduce bleeding. Most surgeons prefer to sit facing the patient’s axilla, with the surgical assistant on the opposite side of the arm. Do not use a tourniquet; it will only get in the way (Fig. 2-1).

Figure 2-1 Place the patient supine on the operating table. Place his or her arm on an arm board and abduct the arm about 60 degrees.

Figure 2-2 For an anterior approach, make a longitudinal incision from the tip of the coracoid process distally in line with the deltopectoral groove and continue along the lateral aspect of the shaft of the humerus. Extend the incision as far distally as necessary, stopping about 5 cm above the flexion crease of the elbow. Palpate the coracoid process in a lateral to medial direction (inset).

Landmarks and Incision

Landmarks

Palpate the coracoid process of the scapula immediately below the junction of the middle- and outer-thirds of the clavicle (Fig. 2-2, inset).

Palpate the long head of the biceps brachii as it crosses the shoulder and runs down the arm. The lateral border of its freely moving muscular belly lies on the anterior surface of the arm.

Incision

Begin a longitudinal incision over the tip of the coracoid process of the scapula. Run it distally and laterally in the line of the deltopectoral groove to the insertion of the deltoid muscle on the lateral aspect of the humerus, about halfway down its shaft. From there, continue the incision distally as far as necessary, following the lateral border of the biceps muscle. The incision should be stopped about 5 cm above the flexion crease of the elbow (see Fig. 2-2).

Internervous Plane

The anterior approach makes use of two different internervous planes (Fig. 2-3A). Proximally, the 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). Distally, the plane lies between the medial fibers of the brachialis muscle (which are supplied by the musculocutaneous nerve) medially and the lateral fibers of the brachialis muscle (which are supplied by the radial nerve) laterally (Fig. 2-3B).

Superficial Surgical Dissection

Proximal Humeral Shaft

Identify the deltopectoral groove using the cephalic vein as a guide (Fig. 2-4, inset), and separate the two muscles, retracting the cephalic vein either medially with the pectoralis major or laterally with the deltoid, whichever is easier. Develop the muscular interval distally down to the insertion of the deltoid into the deltoid tuberosity and the insertion of the pectoralis major into the lateral lip of the bicipital groove (Fig. 2-4). Take care when retracting the deltoid; overzealous use of the retractor may paralyze the anterior half of the muscle by causing a compression injury to the axillary nerve.

Distal Humeral Shaft

Incise the deep fascia of the arm in line with the skin incision. Identify the muscular interval between the biceps brachii and the brachialis. Develop the interval by retracting the biceps medially. Beneath it lies the anterior aspect of the brachialis, which cloaks the humeral shaft (Fig. 2-5; see Fig. 2-4). At the very distal end of the incision the lateral cutaneous nerve of the forearm which is the terminal branch of the musculocutaneous nerve pierces the deep fascia on the lateral border of the biceps. If the incision is carried to its distal extent, identify and preserve this nerve.

Figure 2-3 Internervous plane. A: Proximally, the plane lies between the deltoid (axillary nerve) and the pectoralis major (medial and lateral pectoral nerves). B: Distally, the plane lies between the medial fibers of the brachialis (musculocutaneous nerve) medially and the lateral fibers of the brachialis (radial nerve) laterally.

Figure 2-4 Identify the deltopectoral groove, using the cephalic vein as a guide (inset). Develop the muscular interval down to the insertion of the deltoid into the deltoid tuberosity and the insertion of the pectoralis major into the lateral bicipital groove. Distally, incise the deep fascia in line with the skin incision to identify the interval between the biceps brachii and the brachialis.

Deep Surgical Dissection

Proximal Humeral Shaft

To expose the upper part of the shaft of the humerus, incise the periosteum longitudinally just lateral to the insertion of the tendon of the pectoralis major. Continue the incision proximally, staying lateral to the tendon of the long head of the biceps. The anterior circumflex humeral artery crosses the field of dissection in a medial to lateral direction and must be ligated (see Fig. 2-5). To expose the bone fully, you may need to detach part or all of the insertion of the pectoralis major muscle from the lateral lip of the bicipital groove of the humerus (Fig. 2-6). This must be done subperiosteally. Only detach the minimum amount of soft tissue to allow accurate visualization and reduction of the fracture. Try to preserve as much soft-tissue attachment as possible. If you need to dissect further around the bone, this dissection should remain in a strictly subperiosteal plane to avoid damage to the radial nerve, which lies in the spiral groove

of the humerus and crosses the back of the middle third of the bone in a medial to lateral direction (Fig. 2-7). Avoid the use of lever type retractors inserted around the bone as they may compress the nerve in its groove.

In extreme proximal humeral fractures, especially comminuted fractures, the head and anatomic neck of the humerus may need to be exposed. To accomplish this, the subscapularis muscle must be divided, with care taken to coagulate the triad of vessels that runs along the lower border of that muscle (Fig. 2-8; see Fig. 1-20). Frequently, however, the lesser tuberosity with the attached subscapularis tendon forms a separate fracture fragment, rendering division of the subscapularis tendon unnecessary.

Distal Humeral Shaft

Spiral fractures of the distal third of the humerus may be associated with radial nerve palsies and the spike of the distal fracture fragment may have the nerve wrapped around it.4 For this reason, in such cases it is safest to identify the radial nerve just above the elbow joint by gently opening up the intermuscular plane between the brachialis and the brachioradialis muscles before developing the intermuscuscular plane between bracialis and biceps brachii. This plane between brachialis and brachioradialis is oblique with brachioradialis overlying the brachialis muscle. Carefully follow the nerve proximally until it penetrates the lateral intermuscular septum. Then split the fibers of the brachialis longitudinally along its midline a safe distance from the nerve to expose the periosteum on the anterior surface of the humeral shaft. Strip the brachialis off the anterior surface of the bone. Try to preserve as much soft-tissue attachment as possible. To make the task easier, flex the elbow to take tension off the brachialis. The bone is now exposed (see Fig. 2-6).

Figure 2-5 Retract the biceps medially, being careful to identify the musculocutaneous nerve. Proximally, identify the anterior circumflex humeral artery as it crosses the field of dissection in a medial to lateral direction.

Figure 2-6 Proximally, detach the insertion of the pectoralis major from the lateral bicipital groove and then continue dissection subperiosteally to expose the upper portion of the humerus. Distally, split the fibers of the brachialis to expose the periosteum of the anterior humerus. Incise the periosteum, and strip the brachialis off the bone. Flexion of the elbow will take tension off the brachialis, making the exposure easier.

Figure 2-7 The radial nerve is vulnerable at two points as it courses along the humerus: one, in the spiral groove, and two, as it pierces the lateral intermuscular septum to run between the brachioradialis and the brachialis.

Figure 2-8 Proximal extension of the exposure. Using the deltopectoral interval, cut the tip of the coracoid and incise the subscapularis to provide an anterior approach to the shoulder.

Dang

Nerves

The radial nerve is vulnerable at the following two points:

1. In the spiral groove on the back of the middle third of the humerus. Do not stray onto the posterior surface of the bone (see Figs. 2-7 and 2-43). Remember that the radial nerve may be damaged by drills, taps, or screws that are inserted anteroposteriorly when anterior plates are being applied in the middle third of the bone. Take great care not to overpenetrate the posterior cortex when applying an anterior plate. Do not use lever type retractors placed around the bone.

2. In the anterior compartment of the distal third of the arm. At this point, the nerve has pierced the lateral intermuscular septum and lies between the brachioradialis and brachialis muscles. Note that this plane is oblique and not vertical (see Fig. 2-43). To avoid damaging the nerve, identify it before splitting the brachialis along its midline; the lateral portion of the muscle then serves as a cushion between the retractors that are being used in the exposure and the nerve itself (see Figs. 2-7 and 2-43).

The axillary nerve, which runs on the underside of the deltoid muscle, may be damaged as a result of a compression injury caused by overly vigorous retraction of the muscle. Care should be taken when the retractors are being positioned on the deltoid to avoid injuring the nerve (see Fig. 2-4).

The lateral cutaneous nerve of the forearm pierces the deep fascia just above the level of the elbow crease. It may be at risk if the dissection between biceps and brachialis is carried out to the distal extent of the approach.

Vessels

The anterior circumflex humeral vessels cross the operative field in the interval between the pectoralis major and deltoid muscles in the upper third of the arm. Because cutting these vessels cannot be avoided, they should be ligated or subjected to diathermy (see Figs. 2-5 and 2-6).

How to Enlarge the Approach

Local Measures

Flexion of the elbow relaxes both the brachialis and the biceps brachii, facilitating retraction of these muscles.

Extensile Measures

Proximal Extension. Because the anterior approach uses the deltopectoral interval, its upper end can be modified easily into an anterior approach to the shoulder (see Fig. 2-8).

Distal Extension. The anterior approach cannot be extended distally.