Anterolateral approach to the humerus

Introduction

The anterolateral approach to the humerus provides exposure to the distal quarter of the humerus. Its main advantage over the anterior brachialis-splitting approach is that it can be extended both distally and proximally.

This approach is indicated for:

1. Open reduction and internal fixation of humeral shaft fractures.
2. Exploration of the radial nerve in the distal arm.

Patient Positioning

The patient is placed in the supine position on the operating table with the arm resting on an arm board, abducted 45 to 60 degrees.

Landmarks and Incision

Landmarks

• The biceps brachii muscle.
• The elbow flexion crease.

Incision

Make a curved incision over the lateral border of the biceps muscle. Begin the incision approximately 10 cm proximal to the elbow flexion crease and end it directly over the crease.

Internervous Plane

There is no true internervous plane for the anterolateral approach to the humerus. This is because both the brachioradialis muscle and the lateral half of the brachialis muscle are innervated by the radial nerve proximal to the incision area.

The interval lies between:

• The brachialis muscle (innervated by the musculocutaneous and radial nerves).
• The brachioradialis muscle (innervated by the radial nerve).

Superficial Dissection

Incise the deep fascia of the arm. Identify the lateral border of the biceps muscle and retract it medially to expose the brachialis and brachioradialis muscles. Ensure the lateral antebrachial cutaneous nerve is retracted along with the biceps muscle.

Deep Dissection

Incise the fascia overlying these muscles and develop the intermuscular plane. The radial nerve lies between the brachialis and brachioradialis muscles. The nerve is typically easiest to locate in the distal arm, just proximal to the elbow. It must be traced proximally until it pierces the lateral intermuscular septum and must be carefully protected.

Retract the brachialis and biceps muscles medially and the brachioradialis muscle laterally. Subperiosteal elevation of the brachialis muscle exposes the underlying humeral shaft.

Approach Extension

Proximal Extension of the Anterolateral Approach to the Humerus

The incision can be extended proximally by developing the plane between the brachialis muscle medially and the lateral head of the triceps muscle posterolaterally. Removing the brachialis from the anterior aspect of the humerus will expose the bone.

Distal Extension of the Anterolateral Approach to the Humerus

The anterolateral approach can be extended into an anterior approach to the elbow. This is done by continuing the skin incision distally and developing a plane between the brachioradialis muscle (innervated by the radial nerve) and the pronator teres muscle (innervated by the median nerve). Care should be taken to avoid the lateral antebrachial cutaneous nerve (the continuation of the musculocutaneous nerve), which emerges along the lateral side of the biceps tendon.

Dangers

Structures at risk during the anterolateral approach to the humerus include:

1. Lateral antebrachial cutaneous nerve: This terminal branch of the musculocutaneous nerve can be injured at the distal end of the incision as it emerges laterally from the biceps.
2. Radial nerve: Must be identified before any incision is made into the brachialis muscle or before subperiosteal elevation of the brachialis from the humerus is performed.

References

• Book: "Surgical Exposures in Orthopaedics" – 4th Edition
• Campbell's "Operative Orthopaedics," 12th Edition
• Liskutin T, Summers H, Lack W, Bernstein M. Surgical Technique: Anterolateral Approach to the Humerus. J Orthop Trauma. 2018 Aug;32 Suppl 1:S6-S7. doi: 10.1097/BOT.0000000000001206. PMID: 29985891.
• Chang AC, Ha NB, Sagar C, Bain GI, Leonello DT. The modified anterolateral approach to the humerus. J Orthop Surg (Hong Kong). 2019 Sep-Dec;27(3):2309499019865954. doi: 10.1177/2309499019865954. PMID: 31423937.