Key Insights On Adjunctive Procedures With Transmetatarsal Amputations
Surgeons would perform transfer of the peroneus brevis to the peroneus longus either through an incision on the lateral foot or distal lateral leg. One transects the peroneus brevis tendon via electrocautery and weaves it through the peroneus longus tendon in a Pulvertaft weave fashion while the residual foot is held in a neutral position. This results in dynamic correction of a varus deformity of the foot due to the increased pull on the medial aspect of the residual foot. The advantages of incision placement on the distal lateral leg, as opposed to the lateral foot, are increased healing potential — paramount in patients with vascular compromise — and the lack of need for reconstruction of the peroneal tendon sheath.14,27
Roukis and colleagues reported on a total of 29 patients (29 feet) who underwent a TMA.14 Twenty-seven patients (27 feet) had an equinus deformity present with 26 undergoing a percutaneous Achilles tendon lengthening or gastrocnemius recession. Twenty-two feet had a residual forefoot varus deformity with 17 feet undergoing correction. Surgeons used an intramedullary screw in five cases, performed flexor hallucis longus and extensor digitorum longus tendon transfers in five cases, and performed a peroneus brevis to peroneus longus tendon transfer in seven cases. The researchers did not perform tendon balancing procedures if they deemed them unnecessary or unfeasible due to limited regional perfusion.
Only three patients, none of whom underwent any tendon balancing procedures, ulcerated on the plantar lateral aspect of the residual foot with one requiring a Chopart amputation, one requiring a BKA and one cardiac-related death. The study authors reported no hardware infections with the use of intramedullary screw placement. One patient had transient eversion weakness after the peroneus brevis to peroneus longus tendon transfer. However, this resolved with self-directed physical therapy of performing daily dorsiflexion-eversion exercises of the residual foot. The study authors found no other complications.
The goal of any limb salvage procedure is to create a stable, plantigrade foot. One can protect the foot postoperatively in a shoe or brace, which allows maintenance of function while withstanding repeated stress that occurs during ambulation.
A TMA is effective in facilitating these goals as one can maintain limb length and protect the residual foot in shoe gear with a custom insert, with or without adjunctive bracing, for continued ambulation. The most common reported complications of a TMA are an equinus or equinovarus deformity of the residual foot and recurrent ulceration. Various researchers have also described these complications as the most common technique-based complications of a TMA. While the addition of an Achilles tendon procedure has become a common adjunctive procedure to a TMA, one also needs to address correction of the dynamic varus deformity of the residual rearfoot in order to minimize recurrent ulceration following a TMA.
Dr. Schade is the Chief of the Limb Preservation Service for the Madigan Healthcare System in Tacoma, Wa. She is an Associate of the American College of Foot and Ankle Surgeons.
Dr. Steinberg is an Associate Professor in the Department of Plastic Surgery at the Georgetown University School of Medicine in Washington, D.C. He is a Fellow of the American College of Foot and Ankle Surgeons.