A Guide To Shoe Gear Selection Following A Transmetatarsal Amputation
Proper shoe gear/bracing and education on the importance of its use is essential in the long-term postoperative management of patients who have undergone a transmetatarsal amputation (TMA). Initial publications on shoe gear use after a TMA reported that patients did well with no more than the placement of lamb’s wool in the toe box of a standard shoe.1-5
However, in 1963, Bauman and colleagues noted that “a foot without toes is urgently in need of protection.”6 They performed a comparison study of six different combinations of shoe sole modifications and orthotics, and their ability to reduce plantar foot pressures. The authors found that shoes with a rigid sole reduced plantar forefoot pressures significantly during the late stance and push-off phases of gait. The addition of a rocker bottom sole with the apex at the center of the shoe was the most effective in reducing plantar forefoot pressures in the shortened or deformed foot.
Despite these findings, the use of a standard shoe with a filler in the toe box persisted. This was due to the perception that the functional capacity of a patient who had undergone a TMA was not significantly different than that of a non-amputee due to maintenance of a majority of the foot and the length of the limb.7
Mueller and co-workers found that patients who had undergone a TMA lacked stability.8-10 The authors hypothesized the primary mechanical reason for this was loss of the available moment arm length required to generate the plantarflexory force necessary for ambulation due to loss of the forefoot.
Spurred by these findings, Mueller and colleagues then compared the functional differences between transmetatarsal amputation patients and a non-amputee control group who were matched for age, gender, height, weight and body mass index.8-10 Patients with a TMA had a significantly decreased functional capacity in comparison to non-amputees, being particularly poor at performing activities that required body weight to shift to the front of the foot. These activities included reaching, climbing stairs and walking at a normal pace. Patients with a TMA also had walking speeds similar to patients with severe intermittent claudication.
Kelly and co-workers had similar findings when comparing patients with diabetes and a TMA to an age matched control group of non-amputees without diabetes.11 Peak plantar pressures were 16 percent higher and walking speed was 25 meters per minute slower in the patients with a TMA when ambulating in their normal shoe gear with lamb’s wool in the toe box.
Weighing The Efficacy Of Shoes, Orthoses And Bracing For TMA Patients
Mueller and colleagues performed a study to determine what combination of orthotics, shoe gear and/or bracing would be most efficacious in returning patients with a TMA to a more normal functional capacity postoperatively.10
The study involved 30 patients with a diagnosis of diabetes who had undergone a TMA. The mean age of the patients was 61.7 ± 4 years. The mean duration of diabetes was 19.9 ± 10.1 years. All patients had a fully healed TMA with a mean time of 27.4 ± 28.1 months since amputation and were able to ambulate without the use of an assistive device.