Dorsal Approach for Morton Neuroma

Dorsal Approach for Morton Neuroma ‌

The dorsal approach to the web space allows pathology of web spaces to be explored. By far, the most common use of this approach is in the identification and excision of Morton neuromas. The approach is most commonly used for exploration of the cleft between the third and fourth toes, the most common site for Morton neuroma. Less common uses include drainage of web space infections, which are curiously much rarer in the foot than the hand.

Position of the Patient

Place the patient supine on the operating table. Apply a tourniquet either at the midpoint of the thigh or just above the ankle after the leg has been exsanguinated. Alternatively, use a soft rubber bandage to exsanguinate the foot, then use the bandage as a tourniquet at the ankle (see Fig. 12-81). Place a firm wedge or several pillows under the patient’s thigh to flex the knees, so that the foot lies flat on the operating table.

Landmarks and Incision

Palpate the metatarsophalangeal joint of the two adjacent toes by passively flexing and extending them. Separate the two toes of the affected web space. The easiest way to do this is to wrap a gauze swab around the adjacent toes and use it to pull the two toes apart. Make a dorsal longitudinal incision over the center of the web space starting at the distal end of the web and extending proximally some 2 to 3 cm beyond the level of the metatarsophalangeal joints (Fig. 12-86).

Internervous Plane

There is no internervous plane. No muscles or tendons are encountered in the approach.

Superficial Surgical Dissection

Incise the deep transverse metatarsal ligament in line with the skin incision initially with blunt dissection and then by opening a pair of scissors with the blades in the longitudinal plane. Division of the deep transverse metatarsal ligament will expose the neurovascular bundle (Figs. 12-87 and 12-88). The neuroma, if one is present, often bulges into the wound. To make it more prominent, apply digital pressure to the space between the

metatarsal heads, pushing your finger up on the plantar surface of the foot (see Fig. 12-88).

This surgical approach not only exposes the neuroma but also divides the deep transverse metatarsal ligament that many surgeons believe is the cause of the irritation in neuroma pathology.

Figure 12-86 Make a dorsal longitudinal incision over the center of the web space starting at the distal end of the web and extending proximally some 2 to 3 cm beyond the level of the metatarsophalangeal joints.

Figure 12-87 Incise the fascia in line with the skin incision.

Dang

The only danger in an approach to a single cleft is the digital nerve and vessel that are the target of the approach. Take care, however, to avoid cutting any dorsal cutaneous nerves that run under the incision.

The arterial supply to the toes runs closely with the nerves. If more than one cleft must be explored, take care to avoid disrupting the arterial supplies of the toes. Accidental incision of one digital artery does not render a toe ischemic, but if the second digital artery to the same toe is incised in the next web space, ischemia may result (see Fig. 12-58).

Excising a neuroma from a web space usually leaves the weight-bearing surface of the affected toes at least partially anesthetic, but trophic changes do not occur.

How to Enlarge the Approach

The approach is rarely enlarged and is used almost exclusively for specific web space pathology.