Understanding The Biomechanics Of The Transmetatarsal Amputation
There are a number of options for patients with a TMA. These options include toe fillers to aid in wearing normal shoe gear; below-ankle and combined below- and above-ankle orthoses; prostheses with carbon fiber plating; rigid rocker bottom soles; short shoes (length of residuum); ankle-foot orthoses; and total contact inserts. Various authors have proposed that these modalities aid in ambulation, including improved stability, increased gait velocity, a decrease in peak plantar pressures and improved function.38-40
Mueller and Strube advocate the full-length shoe, total contact insert and a rigid rocker bottom sole for most patients with diabetes and a TMA to optimize physical performance and walking speed.39 They report that patients do not tolerate the ankle-foot orthoses well and that short shoes are cosmetically unpleasing to some patients although they did not interfere with activities such as stair climbing as did the front of the full-length shoe.
Transmetatarsal amputation is a valuable surgery that can prevent major limb loss and minimize loss of function, optimizing the quality of life for patients who require limb salvage procedures. Optimizing foot length is ideal but one should not do this at the expense of insufficient debridement and poor cutaneous blood supply.
The biomechanical consequences of TMA are well known and podiatrists must address these in order to optimize healing, normalize gait and function, and minimize tissue breakdown and the need for subsequent surgeries, including re-amputation. Achieving initial healing and avoiding the need for subsequent debridement correlates significantly with the patient’s ability to ambulate and overall limb salvage.15
Dr. Gambardella is a Chief Resident in Podiatric Medicine and Surgery at the Yale-New Haven Hospital in New Haven, Ct.
Dr. Blume is an Assistant Clinical Professor of Surgery in the Department of Surgery and an Assistant Clinical Professor of Orthopaedics and Rehabilitation in the Department of Orthopaedics, Section of Podiatric Surgery at the Yale University School of Medicine in New Haven, Ct. Dr. Blume is a Fellow of the American College of Foot and Ankle Surgeons.