CHAPTER 11 Correction of Crossover Toe Deformity

SURGICAL APPROACH

Crossover toe deformity cannot be corrected in the same way as for a claw toe or hammertoe. If correction is undertaken using a standard metatarsophalangeal (MP) joint release with arthroplasty of the interphalangeal (IP) joint, the deformity will invariably recur, because the associated contracture is in the transverse plane. Ideally, stability in the transverse plane should be enhanced, but at the same time, flexibility of the MP joint and control of any sagittal plane instability should be maintained. To some extent, the success of the operation will depend on the cause of the deformity. The pathogenesis of this condition is assumed to involve a rupture of the lateral collateral ligament, followed by some degree of rupture of the plantar lateral volar plate, followed by dorsomedial deviation.

If the crossover deformity is associated with a long second metatarsal, then the second metatarsal should be shortened. Shortening the metatarsal relieves the medial joint contracture because pressure is taken off the intrinsic tendons, as illustrated in Figure 11-1. In this case, the patient presented for treatment 1 year after bilateral hallux valgus correction. An interesting observation is that recurrent hallux valgus did not develop, despite the lack of anatomic barriers to valgus drift of the hallux (see Figure 11-1, A and B). The lesser toe deformities were treated with shortening osteotomies of the lesser metatarsals. The alignment initially was not ideal but improved somewhat with taping of the toes into varus for 3 months after surgery (see Figure 11-1, C).

Figure 11-1 A and B, Valgus deformity at 1 year after bilateral hallux valgus correction. Of note, recurrent hallux valgus did not develop in this time period, although there was nothing to stop the valgus drift of the hallux. The lesser toe deformities were treated with shortening osteotomies of the metatarsals. C, The alignment was not ideal, but taping of the toes into varus for 3 months postoperatively resulted in some additional improvement.

Treating a crossover toe deformity as a claw toe will lead to prompt recurrence of deformity (Figure 11-2). Repair of the ruptured lateral collateral ligament and volar plate is technically difficult and probably unrealistic. For the repair to be performed, the suture must be inserted into the lateral collateral ligament without restraint of the joint and creation of a dorsiflexion contracture. To approach the plantar aspect of the MP joint with a transverse or longitudinal incision is very difficult, because the plantar joint does not correspond with the plantar skin crease. Techniques for repair of the lateral collateral ligament have been described; an important consideration in the surgical evaluation, however, is the underlying cause of the ligament rupture. If the rupture is the result of wear against the base of the third toe phalanx or from a long metatarsal, will a simple repair correct the deformity? This outcome is very unlikely, and an attempt at an anatomic repair, versus a simpler procedure such as a tendon transfer or a shortening of the metatarsal head, is not worth the effort. In elderly patients, when the MP joint is severely subluxated, with crossover of the toe on the hallux and asymptomatic hallux valgus, amputation of the toe may be a very reasonable option. The hallux does not drift further, because it typically is abutting the third toe already, and the removal of the painful second toe generally is a very successful procedure for the patient (Figure 11-3).

Figure 11-2 Recurrent second toe deformity in a patient who underwent a bunionectomy and distal metatarsal osteotomy for correction of hallux valgus and a second proximal interphalangeal joint resection arthroplasty for correction of a presumed claw toe. This was a crossover toe deformity, however, and cannot be treated in the same way as for a claw toe.

Figure 11-3 A and B, The patient was a 77-year-old woman who presented with a grade IV crossover toe deformity associated with a painless hallux valgus. C, The second toe was amputated without worsening of the hallux deformity.

COMPONENTS OF SURGICAL CORRECTION

Incision and Dissection

The incision begins at the MP joint, with an adequate soft tissue release of the dorsal and medial contracture. The extensor hood is identified and is incised longitudinally medial to the extensor digitorum longus tendon, which is retracted laterally. The attachment of the extensor hood to the base of the proximal phalanx must be maintained, and a transverse dorsal capsulotomy is performed. On the dorsal-medial aspect of the MP joint the collateral ligament is now released. This can be cut at its attachment to the proximal phalanx or the metatarsal head, but the volar plate ligament should be maintained.

Extensor Digitorum Brevis Tendon Transfer

If the instability of the toe is predominantly in the transverse and not the sagittal plane, then the extensor digitorum brevis (EDB) tendon transfer, rather than a flexor-to-extensor tendon transfer, is preferred. The EDB tendon and the extensor digitorum longus tendon are identified proximally and dissected free of each other by means of a longitudinal split of the extensor hood with Metzenbaum scissors, as shown in Figure 11-4. In this case, after the proximal interphalangeal (PIP) arthroplasty, the toe is seen sticking up in the air and crossing over the hallux—a classic example of why some decompression of the MP joint is necessary. Some increase in the strength of plantar flexion of the toe is necessary using either a flexor-to-extensor tendon transfer or an extensor brevis tendon transfer. A 6-cm length of the EDB tendon is selected, and before division of the tendon, two nonabsorbable 4-0 sutures are inserted on either side of the tenotomy to stabilize the tendon after its division for transfer. A tenotomy is now performed in between these two sutures, and the distal portion of the EDB tendon is now gradually mobilized. It is dissected free more distally from the extensor hood. Its attachment to the extensor hood overlying the base of the proximal phalanx must be maintained (see Figure 11-4).