Dorsal Approaches to the Middle Part of the Foot

Dorsal Approaches to the Middle Part of the Foot‌

 

 

The middle part of the foot extends from the calcaneocuboid and talonavicular joints to the tarsometatarsal Lisfranc joints. All these bones and joints are superficial and can be approached directly by dorsal, medial,

lateral, and plantar approaches. Operations in this area (which are performed rarely) usually involve surgery on the insertions of the four powerful muscles that, together, are responsible for controlling inversion and eversion of the foot. These muscles are the tibialis anterior, which inserts into the medial surface and undersurface of the medial cuneiform bone, and into the adjoining part of the base of the first metatarsal bone; the peroneus longus, which inserts into the lateral side of the medial cuneiform bone; the peroneus brevis, which inserts into the base of the lateral side of the fifth metatarsal bone; and the tibialis posterior, which inserts into the tuberosity of the navicular bone, the inferior surface of the medial cuneiform bone, the intermediate cuneiform bone, and the bases of the second, third, and fourth metatarsal bones (see Figs. 12-55, 12-58, and 12-62).

The middle part of the foot is the target of various specialized procedures for the treatment of muscle imbalance, mobile flatfoot, and an accessory navicular bone. It is also approached for open reduction and internal fixation of fractures in and around Lisfranc joint, and for local tarsal fusion. Only the general surgical approaches are considered here, because the details of operative technique and indications are beyond the scope of this book.

 

Position of the Patient

 

Place the patient supine on the operating table. Dorsomedial approaches and medial approaches are carried out with the leg in its natural position of slight external rotation, whereas dorsolateral approaches require internal rotation of the limb, which is achieved by placing a sandbag under the buttock. For all procedures, exsanguinate the limb either by elevating it for 3 to 5 minutes or by applying a soft rubber bandage. Then, inflate a tourniquet (see Fig. 12-31).

 

Landmarks and Incisions

Landmarks

To palpate the first metatarsal cuneiform joint, feel along the medial border of the foot in a distal to proximal direction. The first metatarsal flares slightly at its base to meet the first cuneiform.

Continue moving proximally along the medial border of the foot to reach the tubercle of the navicular. The medial side of the talar head is immediately proximal to the navicular. It can be located by inverting and

everting the forepart of the foot. The motion that occurs between the talus and the navicular is palpable (Fig. 12-67).

Palpate the base of the fifth metatarsal by feeling along the lateral side of its shaft in a distal to proximal direction until its flared base is reached; this is the styloid process, into which the peroneus brevis muscle inserts (Fig. 12-69).

Incisions

Make a longitudinal incision directly over the area to be exposed. Use a dorsomedial incision to expose the talonavicular joint, the navicular-medial cuneiform joint, and the first metatarsocuneiform joint, and to reveal the insertions of the tendons of the tibialis anterior and tibialis posterior muscles (see Fig. 12-67). Use a dorsolateral incision to expose the calcaneocuboid joint and the base of the fifth metatarsal (see Figs. 12-63 and 12-69).

If access to both the medial and lateral sides of the tarsus is required, it is better to make two separate longitudinal incisions centered over the structures to be explored. Separate incisions nearly always are required for the open reduction in fractures of Lisfranc joint.

Transverse incisions are used best for wedge tarsectomy.

 

Internervous Plane

 

There are no internervous planes in these approaches. Longitudinal incisions avoid damaging cutaneous nerves. Certain major reconstructive operations, such as wedge tarsectomy, necessarily cut cutaneous nerves, leaving portions of the dorsum of the foot partially anesthetic.

 

Surgical Dissection

 

Cut down directly onto the structures that are to be exposed, taking care to avoid any cutaneous nerves that can be identified. Try to make sure that skin flaps are as thick as possible; minimize retraction as much as possible. The structures of the dorsum of the foot nearly all are subcutaneous. Take care to avoid damaging the insertions of the four powerful invertors and evertors of the foot (Figs. 12-68 and 12-70).

 

 

Figure 12-67 Incision for exposure of the middle part of the foot. Make a longitudinal incision directly over the area to be exposed. A dorsomedial incision exposes the talonavicular joint, the navicular-medial cuneiform joint, and the first metatarsocuneiform joint.

 

 

Figure 12-68 Develop the skin flaps. Note the insertions of the tibialis anterior and posterior muscles. Incise the joint capsules of the talonavicular joint, the navicular-medial cuneiform joint, and the first metatarsocuneiform joint according to the demands of the surgery.

 

 

Figure 12-69 A dorsolateral incision exposes the calcaneocuboid joint and the base of the fifth metatarsal.

 

 

Figure 12-70 Develop the skin flaps on the lateral side of the middle part of the foot. Note the tendon of the peroneus brevis as it inserts into the base of the fifth metatarsal. The joint capsule of the calcaneocuboid joint can be incised, if necessary.

 

How to Enlarge the Approach

 

These approaches can be extended proximally. On the lateral side, extend the incision posteriorly and then up behind the posterior border of the lateral malleolus; this exposes not only the lateral side of the ankle joint but also the posterior part of the subtalar joint and the calcaneocuboid joint (see sections describing the posterolateral approach to the ankle and lateral approach to the hindpart of the foot).

On the medial side, extend the incision up behind the medial malleolus, curving it to a point midway between the medial malleolus and the Achilles tendon. This extension exposes those structures that pass around the back of the medial malleolus. It is used commonly in the treatment of clubfoot, but its safety is controversial; the neurovascular

bundle must be protected (see the section regarding the posteromedial approach to the ankle).