TRICKS
The major trick is to identify the humerus by palpating the lateral epicondyle and following the bone proximally, exposing the anterior and posterior sides of the humerus as needed. The radial nerve wraps around the lateral edge of the humerus approximately 6 cm proximal to the lateral epicondyle. It is protected by the brachioradialis muscle so that as soon as the more posterior fibers of the brachioradialis are identified, there should be no further stripping along the humerus. If, for some reason, you need to expose the humerus more proximally along its lateral border, then the radial nerve should be identified underneath the brachioradialis muscle prior to exposing the humerus.
HOW TO TELL IF YOU ARE LOST
There is no difficulty in identifying that you are lost too far posteriorly. You will simply run into the triceps with its fibers parallel to the humerus if you are lost in the proximal part of the incision. If you see the longitudinal fibers of the triceps, but are not seeing its anterior edge, you are too far posterior. You will run into the subcutaneous portion of the ulna in the distal part of the incision if you are too posterior.
The landmark anteriorly is the brachioradialis muscle. This is an important landmark because the radial nerve enters the forearm just underneath this muscle. With the elbow flexed, which is usually the way the procedure is done, the brachioradialis runs from a position 4 cm proximal to the lateral epicondyle down toward the distal radius in a straight line. If you see fibers running in that direction, you are too far anterior.
FIGURE 11–1 The skin incision.
FIGURE 11–2 The triceps running along the humerus posteriorly. The fibers of the brachioradialis are perpendicular to the triceps.
FIGURE 11–3 The brachioradialis coming into the humerus. This is a large muscle with a broad insertion into the humerus spanning 4 cm or more.
FIGURE 11–4 The brachioradialis lifted anteriorly exposing the radial nerve just underneath it. The nerve has not yet divided at this point.
FIGURE 11–5 The nerve and brachioradialis retracted anteriorly. The triceps is posterior. The capitellum is easily visualized, as is the radial head.
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POSTEROLATERAL/ANCONEUS APPROACH
USES
This approach to the radial head is easy and safe. It is generally used for radial head resections or open reduction internal fixation of radial head fractures.
ADVANTAGES
This approach is easy.
DISADVANTAGES
This approach is limited to the radial head or capitellum. It is not suitable for proximal or distal extension.
STRUCTURES AT RISK
It is difficult to get lost with this exposure. The radial nerve is at risk anteriorly, but you would need to be far anterior to reach it. The posterior interosseous branch in the supinator muscle is at risk if the dissection is carried distal to the annular ligament. Pronation of the forearm moves this nerve farther away from the approach.
TECHNIQUE
The incision starts at the lateral epicondyle and then proceeds at a 45-degree angle in relation to the axis of the humerus toward the ulna. After splitting the subcutaneous tissue, the oblique fibers of the anconeus are identified. The capsule is opened along the anterior aspect of those fibers, exposing the radial head and the capitellum.
TRICKS
The only significant trick to this approach is finding the interval between the anconeus and the extensor musculature by looking at the fiber orientation. As you come to the superficial fascia, the anconeus fibers run obliquely toward the ulna, whereas the extensor muscles run parallel to the ulna down the forearm.
HOW TO TELL IF YOU ARE LOST
If you are too far posterior, you will split the fibers of the anconeus. If you run into the longitudinal fibers of the triceps, you are far posterior. Anteriorly, you will see longitudinal fibers of the extensor origin running parallel to the ulna. As long as you see the anterior edge of the oblique fibers and stay out of the longitudinal fibers, this is an easy approach.
FIGURE 12–1 Skin incision and lateral epicondyle is at the top.
FIGURE 12–2 The subcutaneous tissue retracted out of the way and the fibers of the anconeus
