A Closer Look At Tendon Transfers For Crossover Hammertoe
We prefer a modified Girdlestone-Taylor procedure with an intact flexor digitorum longus tendon transfer.20 We prefer this biomechanical approach to stabilization of the second metatarsophalangeal joint and researchers have well documented the results of treatment with this method.21 In cases of the “crossover hammertoe,” the extensor is involved. In these cases, we also perform a modified Hibbs procedure (localized to the second digit only), which functions as a joint sparing procedure via release of the MPJ contractures via capsulotomy and transfer of the extensor digitorum brevis tendon into the distal stump of the extensor digitorum longus tendon.20
In a study of 44 patients by Ross and Faux, the authors’ results concluded that a combined flexor-to-extensor transfer and shortening phalangeal osteotomy is an effective means of reliably stabilizing the unstable lesser MPJ.22 As we described previously, the deformity does not pertain to the bone and we have noted continued success without performing any type of digital osseous procedure.
With respect to the theory that the second metatarsal is involved, we ask the following questions:
• When does a metatarsal become “long”? Are not most of these patients adults who have reached skeletal maturity?
• If so, how does the metatarsal become long? It is our opinion that it is a radiographic appearance of biomechanical faults and the position of the foot in relation to the X-ray beam.
• In the case of pes cavus, does the metatarsal look short (divergent from the weightbearing surface)?
• In cases of pes planus, doesn’t the metatarsal lie more parallel to the ground, leaving an impression of a long metatarsal? In reality, the metatarsal does not become short or long after skeletal maturity.
Another common thought is that the metatarsal is “plantarflexed.” In cases in which there was no previous history of trauma or surgery, this theory is also flawed. When a fully weightbearing patient has intact deep transverse intermetatarsal ligaments along with intact interosseous musculature (lumbricales and interossei), the deep transverse intermetatarsal ligament acts like a tie-bar system. Therefore, the metatarsal cannot plantarflex.23 Based on this information, it is our opinion that second metatarsal osteotomies are not needed.
If instability of the tarsal metatarsal and posterior muscle tightness exist, we will also perform a modified Lapidus with shear strain autologous calcaneal bone graft in combination with a gastrocnemius recession. The goal of the Lapidus is to restore the appropriate amount of weight under the first metatarsal and the two sesamoids. The result of performing a gastrocnemius recession in patients who present with a tight posterior muscle group is to unload the forefoot pressures (lesser metatarsals).
Pertinent Pearls Of The Authors’ Surgical Technique
Most crossover digit deformities are associated with an abnormal pull and biomechanics of the short and long flexors and extensors that have caused the toe to deform. The surgery must balance the flexors and extensors in order to prevent recurrence or continued progression of the deformity. As a matter of fact, once one removes the deforming force, a recurrence cannot happen. Opting for soft tissue techniques involving the short and long flexors and extensors may be more beneficial, especially in patients with significant compromise of the plantar plate. We do not think that plantar plate repairs or arthroplasties/arthrodesis are the indicated treatment choice to address this problem. Lastly, if the attempted soft tissue procedures would not succeed, the surgeon could always revert back to a bony procedure.