OVERVIEW

Regardless of the type of tarsal coalition present, once the condition becomes symptomatic, it rarely resolves with nonoperative care. Traditional management has been with immobilization of the foot to decrease symptoms, but the beneficial effects thus obtained usually are not long-lasting. Although this treatment may temporarily decrease the soreness in the foot, the reactive tenderness in the lateral calf musculature, and the generalized lower limb dysfunction and aching, symptoms recur. Rarely, therefore, do I recommend immobilization of the limb in either a child or an adult for definitive treatment purposes. If marked foot and limb tenderness is present, immobilization can be used initially until definitive surgical plans are put into effect.

EXAMINATION AND DECISION MAKING

Tarsal coalition is one condition that the clinician can diagnose standing at the door of the examination room. Typically, when the patient is seated, the foot normally drops into a position of equinovarus. With a rigid hindfoot, the foot is held in valgus; if the deviation is unilateral, it is particularly easy to diagnose. Examination of the foot while the patient is standing, walking, sitting, and lying down is recommended. When a person with a normal foot is sitting, a natural equinovarus posture is present in the foot as it relaxes. This is not the case with a tarsal coalition because the foot is held in a more rigid position of neutral dorsiflexion with slight valgus (Figure 30-1). The peroneal tendons often are visible because of ongoing contraction, but true peroneal “spasm” does not occur. The peroneal musculature may be tender and certainly tight as a result of subtalar joint irritation, but true spasm does not occur. The decision for surgery, and for a specific type of surgery, is based on the flexibility of the foot, the presence of arthritis, the type of coalition, and function of the remaining foot. The spectrum of clinical deformity associated with coalition is very broad, and when rigidity is present, marked compensatory changes may be seen in the hindfoot and forefoot (Figure 30-2).

Figure 30-1 Note the severe unilateral flatfoot deformity. In children, very little other than a rigid tarsal coalition will be associated with or cause this unilateral deformity.

Figure 30-2 The spectrum of deformity with coalition is considerable. A, The right foot in this adolescent was rigid. B, Note, however, the marked elevation of the first metatarsal and the compensatory flexion of the hallux. Once the hindfoot deformity is corrected, the forefoot supination will worsen, and additional correction must be anticipated.

Arthritis of the foot is rare in a child in association with either a subtalar or calcaneonavicular coalition. The beaking of the talonavicular joint appears naturally as a result of traction on the anterior capsule of the ankle on the neck of the talus and does not in any way imply the presence of arthritis. Arthritis can occur, however, as indicated by the common finding of subtalar arthritis in adults with a middle facet coalition. Early arthritis is caused by previous surgery or may be associated with extreme rigidity, even in the child. An important point in this context is that presence of motion in the hindfoot does not rule out a coalition. Careful examination of the foot will show that most of this motion originates from either a transverse tarsal or the ankle joints. True subtalar motion is not normal and usually is absent, particularly with a middle facet coalition.

It is not easy to examine the hindfoot for true motion when the peroneal tendons are contracting. In patients who have severe stiffness, determination of how much true motion is present in the foot and how much the peroneal muscles are limiting subtalar motion is worthwhile. If the peroneal muscles are tight, I block the peroneal nerve at the fibular neck with a short-acting local anesthetic and then reexamine the foot. After peroneal nerve blockade has been achieved, the foot frequently is much easier to examine, the rigidity of the hindfoot previously noted is no longer present, and the surgery can be planned correctly. A diagnostic blockade of the subtalar joint or the sinus tarsi is not very helpful in these patients. Sometimes the coalition is not visible on radiologic evaluation, and, rarely, even with magnetic resonance imaging (MRI) and computed tomography (CT) scanning, the coalition is difficult to visualize (Figure 30-3).

Figure 30-3 The patient was a 14-year-old girl who experienced constant pain in the sinus tarsi. A and B, Appearance of the foot on the plain radiograph and magnetic resonance imaging scan (not shown) was normal, with no evidence of a calcaneonavicular coalition. C, At surgery, the standard approach to the sinus tarsi was used. D, The head of the talus was identified. E and F, The large fibrocartilaginous band extending from the neck of the calcaneus to the navicular was then easily identified and resected.

Whenever possible, I attempt resection of a coalition rather than an arthrodesis. Certainly, in the presence of arthritis of the hindfoot joints, an arthrodesis will be necessary, but in my experience, the arthrodesis is overused as a treatment modality in both adults and children. If arthrodesis is performed, a triple arthrodesis is indicated only with extensive deformity, which includes the subtalar and transverse tarsal joints as well as arthritis. A triple arthrodesis is therefore not required for correction of a middle facet coalition unless additional disease is present in the transverse tarsal joint. An interesting example of this problem, occurring in an adolescent patient with severe bilateral coalition, is presented in Figure 30-4. Not only was the hindfoot fixed in valgus, but the midfoot also was severely abducted. This was a double middle facet–calcaneonavicular coalition (see Figure 30-4). Rarely do I perform an arthrodesis for a calcaneonavicular coalition, even in adults.

Figure 30-4 Certain deformities defy resection. A, Bilateral rigid foot deformities with a double coalition (calcaneonavicular and middle facet) in a skeletally mature adolescent patient. B, Radiographic changes were confirmed by a computed tomography scan (not shown). C, A triple arthrodesis was the only realistic surgical alternative. The osteophyte present on the dorsal neck of the talus, which should have been removed at this procedure, and was resected subsequently owing to impingement against the deep peroneal nerve and discomfort with shoes.

The onset of pain in adults with a calcaneonavicular coalition often follows a minor episode of trauma. This condition is the subject of frequent dispute in worker’s compensation claims. Imaging studies in affected patients clearly show a tarsal coalition, which was previously asymptomatic; as a result of a minor twist or trauma, the condition becomes symptomatic. Excision of a calcaneonavicular coalition in the adult is still worth the effort. Provided that no degenerative changes are present and the foot is not too rigid, resection can restore a surprising degree of mobility, with good relief of symptoms. This procedure is not appropriate, however, for symptomatic subtalar coalition in the adult, which usually requires a subtalar arthrodesis.

It has been stated that “a middle facet coalition in a child can be excised if it involves less than 50%.” I do not agree with this statement, and regardless of the extent of the coalition, I perform a resection of the entire coalition. The outcome with resection of the middle facet coalition depends more on the flexibility and deformity of the remainder of the foot. The problem with a complete coalition is not with the ability to resect it but with the adaptive changes that have taken place over time in the subtalar joint and the remainder of the foot (Figure 30-5).

Figure 30-5 A middle facet coalition can manifest as a mass on the medial hindfoot. A and B, In this adolescent patient, the mass was so large that the presenting clinical manifestation was not a stiff foot but a tarsal tunnel syndrome secondary to compression of the tibial nerve. C and D, Appearance on computed tomography scans. E, At surgery, the large bony coalition was excised. Note the retraction of the flexor digitorum longus and flexor hallucis longus to expose the joint after removal of the coalition.

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The Modified Ludloff Metatarsal Osteotomy Hallux Varus Correction of Lesser Toe Deformity Peroneal Tendon Injury and Repair Subtalar Arthrodesis Arthrodesis of the Hallux Metatarsophalangeal and Interphalangeal Joints

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