Anterolateral Approach to the Distal Humerus
Anterolateral Approach to the Distal Humerus
This anterolateral approach exposes the distal fourth of the humerus. Its major advantage over the brachialis-splitting anterior approach is that it can be extended both distally and proximally, whereas the brachialis-splitting approach cannot be extended distally. Its uses include the following:
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Open reduction and internal fixation of fractures of the distal half of the humerus, especially the Holstein Lewis fracture
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Exploration of the radial nerve in the distal part of the arm
Position of the Patient
Place the patient supine on the operating table, with the arm lying on an arm board and abducted about 60 degrees. Exsanguinate the limb either by elevating it for 3 minutes or by applying a soft rubber bandage; then apply a tourniquet in as high a position as possible (see Fig. 2-1).
Landmarks and Incision
Landmarks
The landmarks in this approach are the biceps brachii muscle (see Applied Surgical Anatomy of the Anterior Approach in Chapter 1) and the flexion crease of the elbow.
Incision
Make a curved longitudinal incision over the lateral border of the biceps, starting about 10 cm proximal to the flexion crease of the elbow. Follow the contour of the muscle, ending the incision just above the flexion crease
of the elbow (Fig. 2-22).
Internervous Plane
There is no true internervous plane, because both the brachioradialis muscle and the lateral half of the brachialis muscle are supplied by the radial nerve proximal to the area of the incision. Proximal extension of the incision may denervate part of the brachialis, but this is of no clinical significance, because the radial nerve supply to the brachialis is minor and, probably, only proprioceptive. For this reason, the plane is both safe and extensile. Care should be taken during dissection down to the deep fascia; the lateral cutaneous nerve of the forearm runs roughly in the line of approach and should be retracted clear of the incision, in conjunction with the biceps (Figs. 2-23 and 2-24).
Superficial Surgical Dissection
Incise the deep fascia of the arm in line with the skin incision and identify the lateral border of the biceps (see Fig. 2-23). Retract the biceps medially to reveal the brachialis and brachioradialis (see Fig. 2-24). Next, identify the interval between these muscles just above the elbow, incise the deep fascia over them in line with the intermuscular interval, and develop the intermuscular plane (Fig. 2-25). Find the radial nerve between the two muscles at the level of the elbow joint by exploring this oblique intermuscular plane gently with a finger. This is the easiest point at which to find the nerve. (The elbow is the point at which the radial nerve should be identified in all surgery performed in this general area.) Take care not to stretch the radial nerve while manipulating fractures in this area to obtain a reduction. Retract the brachioradialis laterally and the brachialis and biceps medially. Trace the radial nerve proximally until it pierces the lateral intermuscular septum.
Deep Surgical Dissection
Carefully avoiding the radial nerve and staying on its medial side, incise the lateral border of the brachialis muscle longitudinally, cutting down to bone (Fig. 2-26). Incise the periosteum of the anterolateral aspect of the humerus longitudinally and retract the brachialis medially, lifting it off the anterior aspect of the bone by subperiosteal dissection. The anterior aspect of the distal humeral shaft now is exposed.
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Figure 2-22 The incision for the anterior lateral approach. Make a curved longitudinal incision over the lateral border of the biceps, starting about 10 cm proximal to the flexion crease of the elbow. End the incision just above the flexion crease.
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Figure 2-23 There is no true internervous plane, but both the brachioradialis and the lateral half of the brachialis are supplied well proximal to the incision by the radial nerve. The sensory branch of the musculocutaneous nerve, the lateral cutaneous nerve of the forearm (lateral antebrachial cutaneous nerve), is seen emerging between the biceps and brachialis muscles.
Dang
Nerves
The radial nerve must be identified and preserved before any incision is made through the substance of the brachialis muscle.
How to Enlarge the Approach
Extensile Measures
Proximal Extension. The incision can be extended proximally (although this rarely is required) by developing the plane between the brachialis medially and the lateral head of the triceps posterolaterally. Stripping brachialis from the front of the anterior aspect of the humerus exposes the bone. However, care must be taken if the dissection is taken further posteriorly, as posterior dissection may endanger the radial nerve as it
passes in the spiral groove. If the approach is therefore extended posteriorly, a subperiosteal plane must be used. The disadvantage of soft-tissue stripping of the bone is in this case outweighed by the need to reduce the risk of damage to the radial nerve (Fig. 2-27).
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Figure 2-24 Retract the biceps medially. Identify the lateral cutaneous nerve of the forearm (the sensory continuation of the musculocutaneous nerve) and retract it with the biceps. Identify the interval between the brachialis and the brachioradialis.
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Figure 2-25 Develop the intermuscular plane between the brachialis and the brachioradialis. Identify the radial nerve between the two muscles. Retract the brachioradialis laterally and the brachialis and biceps medially.Then trace the radial nerve proximally until it pierces the lateral intermuscular septum.
Alternatively develop a plane between the lateral intermuscular septum and the triceps muscle entering the posterior compartment of the arm. Internally rotate the shoulder. Follow the radial nerve through the lateral intermuscular septum dividing some of the septum to allow gentle mobilization of the nerve. Identify and preserve the posterior antebrachial cutaneous nerve which arises from the radial nerve. Gently retract the triceps posteriorly to expose the posterior surface of the humerus with the radial nerve lying in its spiral groove (follow the radial nerve proximally, posterior to the humerus and anterior to the triceps; Fig. 2-28). This allows safe exposure of the distal two-thirds of the humerus.
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Figure 2-26 Incise the periosteum of the anterolateral aspect of the humerus, and retract the brachialis and the periosteum medially to expose the anterior aspect of the distal shaft of the humerus.
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Figure 2-27 The incision can be extended proximally by developing the plane between the brachialis and the lateral head of the triceps. The radial nerve is seen piercing the intermuscular septum. Posterior dissection may endanger the nerve as it passes through the spiral groove unless the dissection is kept below the periosteum.
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Figure 2-28 Develop a plane between the lateral intermuscular septum and the triceps muscle entering the posterior compartment of the arm. Follow the radial nerve through the lateral intermuscular septum dividing some of the septum to allow gentle mobilization of the nerve. Follow the radial nerve proximally, posterior to the humerus and anterior to the triceps.
Distal Extension. The anterolateral approach may be extended into an anterior approach to the elbow by continuing the skin incision distally and developing a plane between the brachioradialis muscle (which is supplied by the radial nerve) and the pronator teres muscle (which is supplied by the median nerve). Care should be taken to avoid the lateral cutaneous nerve of the forearm (the continuation of the musculocutaneous nerve), which emerges along the lateral side of the biceps tendon (