Osteoarthritis of the midfoot may be treated initially with nonoperative measures, which include nonsteroidal anti-inflammatory medication, a custom-molded insert, and a rocker bottom–soled shoe. If this treatment fails, then arthrodesis of all the symptomatic joints with restoration of the arch and alignment of the weight-bearing surface is the recommended treatment. Patients can expect to have improvement with respect to both pain and function after arthrodesis.
Midfoot arthritis may be caused by inflammatory arthritis, degenerative arthritis, or posttraumatic arthritis.
The goals of treatment of midfoot arthritis include pain relief, correction of the deformity, and preservation of function.
Studies have shown that tarsometatarsal motion is greatest for the fourth and fifth metatarsals. Minimal motion occurs at the first, second, and third tarsometatarsal joints.
Following injuries to the tarsometatarsal (Lisfranc) joint, posttraumatic arthritis and planovalgus deformity are common.
Roentgenographic findings of degenerative arthritis do not correlate with clinical findings.
The function of the orthosis and shoe modification is to decrease the compressive forces across the midfoot joint, decrease the motion through this segment, provide better shock absorption, and redistribute load from any bony prominences.
Steroid injection may be both diagnostic and temporarily therapeutic when evaluating midfoot arthritis.
Adequate reduction correlates with better outcome. When mechanical alignment is not markedly distorted, this can be brought about by an in situ fusion. When the mechanical alignment is markedly distorted, reduction may be brought about by an open technique.
The need for a midfoot fusion occurs at the first, second, and third metatarsal bases and is uncommonly needed in the lateral two rays. The lateral tarsometatarsal joints are included in the fusion if they are painful, demonstrably arthritic, and malaligned. An alternative treatment is a resection arthroplasty of these joints.
The technique of using a medial buttress plate for midfoot arthrodesis allows for reliable fusion and correction of residual deformity.
Many different surgical techniques exist for midfoot arthrodesis.
Complications include nonunion and malunion.
Nerve injuries are common in the foot because of the close relation of the cutaneous nerves and the soft-tissue retraction required for exposure. Careful planning of the incisions to avoid stretching, particularly to the deep peroneal nerve, is important. Injuries to these tissues may also increase the risk of causalgia syndromes and reflex sympathetic dystrophy.
Adjacent joints may develop degenerative changes following a midfoot arthrodesis. These may or may not be symptomatic.
Donor site pain from harvest of iliac crest bone graft may occur, and local bone graft is an alternative.
Wound healing has not been a problem in surgical arthrodesis of the midfoot in late reconstruction.
HISTORY/INTRODUCTION/SCOPE OF THE PROBLEM
Midfoot arthritis is a condition that is difficult to treat either by nonoperative or operative means. Midfoot arthritis may be primary, inflammatory, or posttraumatic. It is not uncommon that these patients have deformity and disabling pain. When conservative treatment fails, arthrodesis of the midfoot is indicated. Probably the most common cause of midfoot arthritis is the result of injuries to the tarsometatarsal (Lisfranc) joint. The reported incidence of symptomatic posttraumatic degenerative arthritis at the tarsometatarsal joint varies from none to greater than 50% of the treated injuries.
Arthrosis of the midfoot is uncommon in the midfoot and the literature suggests it is usually posttraumatic. The reported incidence of symptomatic degenerative arthritis after tarsometatarsal fracture-dislocations is 0% to 58%. Davitt et al. demonstrated that in the patient with primary arthrosis of the midfoot, there is a clear association between midfoot arthrosis and a functionally long second metatarsal. They suggest a possible mechanical cause for midfoot arthrosis.
CLINICAL SYMPTOMS EXAMINATION
Patients with midfoot arthritis most often present with pain and deformity. Midfoot pain is the most frequent complaint. Patients have pain with weight-bearing in the dorsal midfoot and arch, particularly during push-off. Quite often the patient presents with deformity, which is appreciated with the patient weight-bearing. The foot is in a pes planus deformity with forefoot abduction. The deformity can cause cosmetic concerns and/or interfere with shoe wear, which can be a problem. Examination reveals tenderness at the midfoot joints, especially with stress at the tarsometatarsal joints (dorsiflexion/plantarflexion, twisting of midfoot, and forced forefoot abduction). Radiographs are helpful to confirm these findings. Subtle joint space narrowing in the tarsometatarsal and naviculocuneiform joints may be detected with standard weight-bearing radiographs of the foot ( Fig. 32-1 ). The anteroposterior and lateral radiographs may show a break in the physiologic talar declination angle demonstrating the forefoot abduction and planovalgus deformity in the midfoot.
Initial treatment should be nonsurgical, which includes the use of nonsteroidal anti-inflammatory drugs (NSAIDs), custom orthoses, and/or a rocker-bottom shoe. The function of the orthosis and shoe modification is to decrease the compressive forces across the midfoot joints, decrease the motion through this segment, provide shock absorption, and redistribute load from any bony prominence. Smita Rao et al. showed that the use of a full-length carbon foot plate was accompanied by a favorable redistribution of pressure resulting in unloading of the midfoot, when compared with the traditional three-fourths length insert. Steroid injections may be both diagnostic and temporarily therapeutic. Fluoroscopic guidance is helpful to deliver the steroid directly to the involved articulation(s) because these are small joints.
OPERATIVE TREATMENT, SURGERY
An arthrodesis is indicated if severe pain persists despite the use of an orthosis and anti-inflammatory drugs. The goals of surgical treatment include relief of pain, correction of the deformity, and preservation of function with a solid arthrodesis ( Fig. 32-2 ).
A key issue is the selection of the joints to be fused and to satisfy these goals without making the midfoot unnecessarily rigid. Plain radiographs and clinical examination are a guide to which joints are symptomatic but are not precise. Joint space narrowing, osteophytes, and other typical changes of osteoarthritis are seen (see Fig. 32-1 ). A bone scan may be a helpful diagnostic tool to identify the involved articulations. This view is not held by all authors because bone scans are not very specific. When a bone scan is made, there is often diffuse uptake throughout the midfoot, often in locations that are painless. These scans are very sensitive to osseous turnover from osteoarthrosis, but these findings do not always coincide with painful joints. Sobel and Mann do not recommend a bone scan to determine the extent of the arthrodesis.
Computed tomography (CT) scan of the midfoot can be difficult to interpret. Differential anesthetic blocks may be helpful, particularly in cases in which the bone scan indicates arthritis in what seems to be an asymptomatic joint. The medial column of the Lisfranc joint, that is, the first through third metatarsals with all cuneiforms, will be fused as a block in most instances. If the fourth and fifth tarsometatarsal-cuboid joints or the talonavicular joints are not symptomatic, they should not be included in the fusion. These regions are more mobile.
Tarsometatarsal fractures, fracture dislocations, and other midfoot injuries are commonly associated with midfoot collapse. These injuries often result in a residual planus or planovalgus deformity with forefoot abduction. This deformity not only results in shoe wear problems, callosities, and gait alterations, but it is also a less mechanically efficient foot.
The decision whether to do an in situ versus correction osteotomy is controversial. Johnson and Johnson made no attempt to correct any existing incongruence of the tarsometatarsal joints in their series. They believed that correction of the deformity at time of arthrodesis did not seem to have significant advantages over an in situ arthrodesis. On the other hand, in Sangeorzan series, reduction of residual deformity was the most significant prediction of a good outcome. It is believed by most authors that by gaining reduction and restoring the normal longitudinal arch of the foot, a more mechanically sound plantigrade foot is achieved. It is believed that symptoms from residual deformity are significant enough to warrant correction. These patients often complain of fatigue from walking on a pronated foot and pain and callosities on the inferior medial aspect of the midfoot from increased weight-bearing in this area.
Surgical management is indicated when conservative measures fail. The recommended surgical treatment of degenerative arthritis of the midfoot is arthrodesis. A variety of arthrodesis techniques have been described, including bone grafting with staples, Steinman pins, tension band wires, screws, dowels, medial, dorsal, and plantar plates, and external fixators.
In Situ Arthrodesis
An in situ arthrodesis is indicated for patients who have slight deformity and osteoarthrosis that is limited to the medial column. The operation is performed in the supine position under tourniquet hemostasis. Following elevation of the limb and exsanguination with an Esmarch bandage, a longitudinal incision is made over the interval between the first and second metatarsals ( Fig. 32-3 ). Parallel incisions are made over the other joints as needed. Once the incision is made, care is taken to identify and protect the superficial and deep peroneal nerves, the dorsalis pedis artery, and the vertical descending arterial branch into the first web space. After the involved joints are exposed, the capsules are opened and all fibrous tissue is removed. Digital traction and plantar flexion of the forefoot allows distraction of the joints and aide to visualization. The cartilage and the subchondral bone are removed with sharp osteotome. A debridement is continued until viable bone is visible on both sides of the surface of the joint. Any gap or defect that is created is filled with morcellized cancellous bone graft ( Fig. 32-4 ). Our preference is to harvest cancellous bone from the iliac crest. It is also possible to harvest small amounts of bone locally, but the author’s preference, especially if several joints are involved, is the more reliable iliac crest. The graft is morcellized and packed into the defect created by excising the articular surfaces. Most often reduction is achieved by surgical manipulation of the involved bone under direct vision. The arthrodesis sites are rigidly fixed with 3.5-mm cortical screws after properly aligning the distal bone with respect to the more proximal segment. The alignment is critical. Typical radiographs are shown in Figure 32-5 .