Key Insights On Adjunctive Procedures With Transmetatarsal Amputations

Valerie L. Schade, DPM, AACFAS

   La Fontaine and co-workers reported on 28 patients (28 feet) who underwent a percutaneous Achilles tendon lengthening for treatment of a recurrent ulceration, which developed after a TMA.25 The follow-up period was 29 months. A total of 24 feet (85.7 percent) healed their recurrent ulceration. The reason for continued non-healing of the remaining four ulcerations was not reported. Six patients (21.4 percent) developed new ulcerations. Five of these ulcerations occurred on the plantar central heel and were related to over-lengthening of the Achilles tendon. One ulceration occurred on the plantar lateral aspect of the foot and was likely secondary to a forefoot varus deformity, which was not addressed.25

Addressing The Residual Varus Deformity After TMAs

While an Achilles tendon lengthening procedure has become a common adjunctive procedure to a TMA, few have published on tendon balancing procedures to address a residual varus deformity resulting from a TMA. Some studies have discussed the use of a split anterior tibial tendon transfer to correct a residual varus deformity. However, no studies to date have reported on the results of this procedure to prevent or treat a recurrent ulceration following a TMA.19,23

   Currently, there are published results for only three surgical techniques employed as adjunctive procedures to a TMA to correct a residual varus deformity of the foot and prevent recurrent ulceration. These three techniques are: 1) intramedullary screw placement; 2) flexor hallucis longus and extensor digitorum longus tendon transfers; and 3) peroneus brevis to peroneus longus tendon transfer.14,23,26-28

Pertinent Tips On Intramedullary Screw Fixation

Surgeons would perform intramedullary screw fixation while the residual foot is held in a neutral position. One would insert the screw down the residual first metatarsal into the rearfoot, ensuring that the distal tip of the screw does not enter the ankle joint and that the head of the screw is seated well within the residual first metatarsal. Then cover the distal residual first metatarsal with autogenous or allogenic bone graft substitute or the muscle belly of the abductor hallucis to prevent hardware exposure should the incision dehisce or have delayed healing.

   Using an intramedullary screw has an advantage with there being no need for additional incision placement. Potential complications include infection, hardware migration, iatrogenic fracture and recurrent ulceration. Intramedullary screw fixation results in static correction of a varus deformity of the residual foot. One must take care to ensure the residual foot is held in a neutral position as the midfoot will be stiff postoperatively and any varus or valgus position of the residual foot could result in recurrent ulceration.14,23

Can Tendon Balancing Procedures Have An Adjunctive Impact?

In regard to flexor hallucis longus and extensor digitorum longus tendon transfers, surgeons transfer the flexor hallucis longus and the tendon slips of the extensor digitorum longus to the residual first and fourth metatarsal respectively via drill holes. One then secures these transfers while the residual foot is held in a neutral position to create a dynamic correction of varus deformity of the residual foot. This procedure has the same advantage as intramedullary screw placement with no need for additional incisions.14,28

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