Minimally Invasive Anterior Approach to the Humeral Shaft‌

The minimally invasive anterior approach to the humerus utilizes two soft-tissue windows, proximal and distal that are the proximal and distal portions of the anterolateral approach to the humerus described earlier in this chapter. An alternative proximal approach using a deltoid split will not be described in this section. The use of this approach is almost exclusively for internal fixation of fractures of the humerus. The advantage of this

approach is the preservation of the blood supply to the fracture zone. The disadvantage is that the fracture is not exposed, which makes reduction more difficult to achieve and assess as well as exposing both patient and surgeon to radiation.5–9

Position of the Patient

Place the patient supine on the operating table in the same position as for the anterior approach to the humerus (see Fig. 2-1). Ensure that you can obtain adequate x-ray images of the pathology to be treated before prepping and draping. Use the best possible radiation protection for the patient and surgical team. Do not use a tourniquet.

Landmarks and Incision

Landmarks

Palpate the coracoid process of the scapula immediately below the junction of the middle and outer thirds of the clavicle (see Fig. 2-2, inset) and the lateral border of the biceps brachii (Fig. 2-9).

Incision

Make a 5- to 7-cm longitudinal incision beginning just below the coracoid process running down the arm in the line of the deltopectoral groove. Make a second 5- to 7-cm longitudinal incision overlying the lateral border of the biceps brachii in the distal third of the arm. The exact positioning of the incisions are determined by the site of the fracture.

Internervous Plane

Proximally, the anterior minimally invasive approach utilizes the plane between the deltoid muscle (axillary nerve) and the pectoralis major muscle (lateral and medial pectoral nerves). Distally, the plane lies between the medial half of the brachialis muscle supplied by the musculocutaneous nerve and the lateral half of the brachialis muscle supplied by the radial nerve (see Figs. 2-3 and 2-4).

Figure 2-9 Proximally make a 6- to 8-cm longitudinal incision overlying the deltopectoral groove. Distally make a 6- to 8-cm incision overlying the lateral border of the biceps brachii. The precise length and positioning of the incisions depends on the site of the pathology and the implant used to treat it.

Superficial Surgical Dissection

Proximal Window

Identify the deltopectoral groove, using the cephalic vein as a guide. Separate the two muscles. This can usually be done with blunt dissection (see Fig. 2-4). Retract the vein either laterally or medially and try to preserve it if possible.

Distal Window

Incise the deep fascia of the arm in the line of the skin incision and identify the muscular interval between the biceps brachii and the brachialis. Develop this interval by retracting the biceps medially and identify the brachialis muscle covering the anterior humeral shaft (Figs. 2-10 and 2-11).

Deep Surgical Dissection

Proximal Window

Develop the plane between the deltoid and the pectoralis major down to the bone. Stay lateral to the tendon of the long head of the biceps. For

access to the bone for plate application, detach part or all of the insertion of pectoralis major and part of the insertion of the deltoid.

Distal Window

Split the fibers of the brachialis longitudinally and develop an epiperiosteal plane between the deep surface of the brachialis and the periosteum covering the anterior surface of the humerus. Try to preserve as much of the soft tissue as possible. To make your task easier, flex the elbow to decrease the tension on the brachialis muscle.

Figure 2-10 Deepen the incision in the line of the skin incision. Proximally expose the deltopectoral interval. Distally expose the lateral border of the biceps brachii.

Figure 2-11 Proximally develop the interval between the pectoralis major muscle and the deltoid to expose the underlying bone. Part of the tendon of pectoralis major may need to be detached from the bone.

To connect the two windows, develop an epiperiosteal plane on the anterior surface of the humerus using your finger, a periosteal surfer, blunt elevator or the plate to be used. Begin distally and stick closely to the anterior surface of the bone. You may also need to develop this plane working distally through the proximal window (Figs. 2-12 and 2-13).

Dang

The radial nerve is lateral to the surgical approach in the distal window, lying between the lateral border of the brachialis and the brachioradialis. If the approach is used to treat a distal humeral fracture, identify the radial nerve as it lies between the brachialis and the brachioradialis muscles before starting the brachialis split to ensure that the nerve is well lateral to the deep dissection. In such fractures the nerve may be caught by the spike of bone on the distal fragment which will distort its position. If you wish to access the lateral column, develop a plane between the biceps and brachialis muscles medially and the brachioradialis, extensor carpi radialis longus, and brevis (the mobile wad of three) laterally.

Figure 2-12 Distally retract the belly of the biceps brachii muscle medially to expose the anterior surface of the brachialis muscle. Split the brachialis longitudinally in the line of its fibers to expose the anterior surface of the humerus. Next, develop an epiperiosteal plane on the anterior surface of the bone. Proximally develop an epiperiosteal plane on the anterior surface of the humerus using finger dissection.

Figure 2-13 Connect the proximal and distal windows by blunt dissection in an epiperiosteal plane on the anterior surface of the humerus.

The musculocutaneous nerve and its distal branch, the lateral cutaneous nerve of the forearm, lie medial to the brachialis and the distal window. To avoid damage to either nerve make sure that the brachialis is split in its midline.

Vessels

The anterior circumflex humeral vessels cross the operative field in the interval between the pectoralis major and the deltoid muscle in the upper third of the arm. These structures need to be identified while developing the plane and, if possible, avoided.

How to Enlarge the Approach

Local Measures

The minimally invasive anterior approach to the humerus can be converted into the anterior approach to the humerus by connecting the two skin incisions. Splitting brachialis completes the exposure.