Anterior and Posterior Approaches for the Treatment of Forearm Compartment Syndrome

The forearm contains muscle compartments constrained by strong fascia.

Fractures and their associated soft tissue injury bleed and create edema which increases the pressure within these compartments. As the pressure increases, the venous return decreases; in certain cases, the pressure becomes so high that it reduces the arterial blood supply to the muscles and creates muscle ischemia. Muscle ischemia in turn creates more edema, further increasing compartment pressure. This is known as a compartment syndrome. It is important to note that compartment syndrome can occur without the presence of a fracture. Crushing injuries of the forearm especially those caused by rollers are a potent cause of this condition.

The resultant muscle ischemia produces pain disproportionate to the other injuries which is the cardinal presenting symptom. If the pressure within the compartment is not relieved within a short period of time, permanent muscle necrosis will occur with associated damage to the nerves traversing the affected compartment (Volkmann ischemic contracture). In extreme cases, arterial occlusion occurs, leading to gangrene. Note, however, that normal distal pulses occur in all but the very late stages of this condition and physicians should not wait until changes in pulse pressure occur before initiating treatment.

Treatment of compartment syndrome consists of dividing the fascia constraining the compartment thereby relieving the intercompartmental pressure. All affected compartments must be decompressed. In the forearm these are the anterior/flexor compartments (superficial and deep) and the posterior/extensor compartment.

Anterior Approaches for Flexor Compartment Decompression

The compartment most commonly affected in the forearm is the anterior forearm compartment. It can be decompressed by incising the deep fascia that covers it along its entire length. In cases of compartment syndrome, both the superficial and the deep compartments on the volar side should be released along with the posterior compartment. Two approaches are available for use—the central and the ulnar approach.29,30

Landmarks and Incisions

Landmarks

Central Incision. Palpate the lateral humeral epicondyle just lateral to the olecranon process on the distal humerus and the radial styloid process of the radius on the radial aspect on the distal end of the radius.

Ulnar Incision. Palpate the medial humeral epicondyle, the large subcutaneous bony mass that stands out on the medial side of the distal end of the humerus and the ulna styloid process on the distal end of the ulna.

Incisions

Central Incision. Make a longitudinal incision extending from just below the lateral epicondyle of the distal humerus to the radial styloid process (Fig. 4-36A).

Ulnar Incision. Make a longitudinal incision extending from just below the medial epicondyle of the humerus to a point about 1.5 cm lateral to the ulnar styloid (Fig. 4-37).

Figure 4-36 A: To decompress the flexor compartments of the forearm begin by making a longitudinal incision extending from the lateral side of the elbow crease to the radial styloid process. B: Deepen the skin incision to reveal the fascia covering the superficial flexor muscles and incise that fascia on the ulnar border of flexor carpi radialis. C: Incise the fascia overlying flexor digitorum superficialis to decompress the deep layer of the flexor musculature.

Internervous Plane. There is no internervous plane for use. In the central approach, division of the deep fascia is usually done between the palmaris longus muscle and flexor carpi radialis both of which are supplied by the median nerve.

In the ulnar approach the intermuscular plane used lies between the flexor carpi ulnaris and the medial side of the flexor digitorum superficialis both of which are supplied by the ulnar nerve.

Superficial Surgical Dissection

Central Approach. Divide the fascia in line with the skin incision. Identify

the lacertus fibrosus just below the elbow and divide it carefully to decompress the median nerve. Identify the interval between the palmaris longus muscle and the flexor carpi radialis and gently develop this intermuscular plane (Fig. 4-36B).

Ulnar Approach. Incise the deep fascia in the line of the skin incision along the medial border of the flexor carpi ulnaris (Fig. 4-38).

Deep Surgical Dissection

Central Approach. Identify the muscle belly of flexor digitorum superficialis with its tendons emerging distally. Carefully divide the fascia overlying the anterior surface of the muscle (Fig. 4-36C).

Ulnar Approach. Develop a plane between the flexor carpi ulnaris and the flexor digitorum superficialis elevating the latter muscle. The median nerve should remain attached to the deep surface of the flexor digitorum superficialis. Move the ulnar nerve with the flexor digitorum superficialis. To do this ligate and divide any branches of the ulnar artery running into the flexor carpi ulnaris that tether the nerve to that muscle. Elevating the muscle will reveal the three deep muscles of the forearm—pronator quadratus, flexor pollicis longus, and flexor digitorum longus—all of which can be given an epimysiotomy (Fig. 4-39).

Figures 4-37 A: Ulnar approach for decompression of forearm compartment syndrome—make a longitudinal incision from the medial epicondyle of the humerus to the ulnat styloid. B: Incise the fascia overlying the flexor digitorum muscle to decompress the superficial flexor muscles.

Figure 4-38 Retract the flexor digitorum superficialis muscle radially to expose the ulnar nerve and vessels.

Figure 4-39 Expose the fascia covering the flexor digitorum profundus muscle and divide it longitudinally taking care to preserve the ulna nerve and vessels.

Figure 4-40 A: To decompress the posterior compartment, make a longitudinal incision overlying the posterior aspect of the forearm extending from the lateral humeral epicondyle to Lister tubercle. B: Incise the fascia overlying the posterior muscle mass in the line of the skin incision.

Dang

The median nerve and the ulnar neurovascular bundle are potentially at risk during these extensive exposures. A knowledge of anatomy is critical since internervous planes cannot be exploited.

Posterior Approach to the Forearm for Compartment Syndrome Decompression

The posterior approach to the forearm for decompression of a compartment syndrome is only used for this one surgical indication.

Landmarks and Incision

Landmarks. Palpate the lateral humeral epicondyle just lateral to the olecranon process and Lister tubercle which lies about one-third of the way across the dorsum of the wrist from the styloid process of the radius.

Incision. Make a longitudinal incision starting just below the lateral epicondyle of the humerus and ending just proximal to Lister tubercle (Fig. 4-40A).

Internervous Plane

No internervous plane is used in this approach as surgical dissection only involves the division of the deep fascia.

Superficial Surgical Dissection

Incise the deep fascia in line with the skin incision. The fascial edges should spring apart. Preserve the extensor retinaculi at the level of the wrist joint (Fig. 4-40B).

Dang

The posterior interosseous nerve runs in the substance of the supinator muscle. It should be safe if dissection is confined to simple division of the deep fascia.