Current Considerations In Performing Transmetatarsal Amputations
The gastrocnemius recession to correct equinus avoids an incision through a potentially diseased Achilles tendon secondary to diabetes mellitus and maintains the integrity of the tendon near the insertion of the triceps surae.19,30-33 In addition, the gastrocnemius recession decreases the risks that are associated with the percutaneous tendo-Achilles lengthening such as over-lengthening and risk of tendon rupture leading to a calcaneal gait and with possible subsequent heel ulceration.17,34,35
In addition to ankle equinus, a varus rotation of the foot often occurs. To correct a varus forefoot when performing a TMA, the surgeon can transfer the peroneus brevis tendon attachment to the peroneus longus and anchor the flexor hallucis longus to the remaining first metatarsal base to aid in resisting the forces of the tibialis tendons.36-38
Lateral loading of the foot can often lead to increased pressure over the prominent base of the fifth metatarsal leading to a common site of tissue breakdown. If the fifth metatarsal requires removal, one can transfer the peroneus brevis tendon to the cuboid to prevent inversion. Also, a split tibialis anterior tendon transfer or complete transfer helps to reduce the varus component of the forefoot.3,37,39
While not ideal, in certain cases involving an open “guillotine” type TMA, negative pressure wound therapy can assist as a bridging therapy to prepare the wound for closure and results in fewer secondary amputations.40
Diabetic peripheral neuropathy can lead to chronic non-healing ulcerations that increase the risk of limb loss. Closing these wounds and preserving a functional limb from major amputation are the ultimate goals to prevent early mortality and subsequent morbidity. The TMA is a foot sparing procedure that can keep a patient active with a limb. With careful attention to patient selection, healing criteria and surgical planning, the TMA can provide limb salvage from major amputations and significantly increase the quality of life in this patient population.
Dr. Johnson is a Chief Resident at the Hennepin County Medical Center in Minneapolis.
Dr. Rogers is the Associate Medical Director for the Amputation Prevention Center at Valley Presbyterian Hospital in Los Angeles. Dr. Rogers is the Chair of the Foot Council for the American Diabetes Association (ADA).
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.