Tendon Lengthening: Is It A Viable Option For Forefoot Ulcers?
Approximately 3 percent of the United States population has diagnosed diabetes mellitus.1 Diabetic foot problems, however, are the leading cause of amputation.2,3 The risk of amputation is 15 times greater in patients with diabetes than in other people.2 Up to 15 percent of patients with diabetes will require amputation.1,3 Over 50,000 amputations in patients with diabetes occur annually in the U.S.4 In one study of patients with diabetes mellitus, 84 percent of lower extremity amputations were preceded by foot ulcers.2
Among people with diabetes, about 15 percent will eventually have foot ulcers.1,5 In the absence of large vessel disease, diabetic forefoot ulcers result from the combination of neuropathy and abnormal mechanical stress.1,6,7 Deformity that increases stress on a portion of the foot can instigate ulceration in a patient with diabetic neuropathy.1,6,7 Peripheral neuropathy results in the loss of protective sensation and a lack of recognition of repetitive mechanical stress, which often cause forefoot ulcers in patients with diabetes.1,7
Diabetic motor neuropathy and glycosylation of collagen may contribute to calf tightness and decreased dorsiflexion of the ankle, which increase pressure on the forefoot.7,8 The high forefoot pressure is consistent with the most common locations (the plantar surface of the metatarsal heads and the hallux) of foot ulcers.7,8
Patients who have experienced previous foot ulceration have abnormally high pressures at healed ulcer sites.9 Plantar foot ulcers occur at sites of high pressure.7,10 The combination of neuropathy and decreased ankle dorsiflexion has been implicated in the cause of forefoot ulcers.7,11,12 One should reduce the risk of neuropathic ulceration of the forefoot by decreasing pressure on the forefoot.9 One may accomplish pressure relief via shoe modification, total contact casts (TCCs) and tendo-Achilles lengthening (TAL).13,14
Total contact casting is an effective technique for healing diabetic neuropathic foot ulcerations.5,15,16 However, separate studies have shown that between 20 percent (20 of 102) to 81 percent (21 of 26) of the ulcers healed by TCC have recurred in two years.15,16 Dorsiflexion of the metatarsal osteotomy also is effective in healing chronic neuropathic forefoot ulcers but has a much higher complication rate.17
Tendo-Achilles lengthening promotes healing of chronic foot ulcers in patients with neuropathy (see photos on page 26 and page 29).12,18,19 When researchers employed TAL, they found that healing occurred in patients who did not heal by TCC and there were fewer ulcer recurrences in patients who underwent TAL as compared to patients who had ulcers healed with TCC.18
Assessing The Impact Of TL Procedures On Plantar Forefoot Ulcers
We performed a study to assess the impact of tendon lengthening (TL) in treating patients with plantar forefoot ulcers. Between May of 1995 and October of 2002, we offered TL procedures to all patients who presented with plantar forefoot ulcers without active infection or gangrene. Twenty-four patients with one or more plantar forefoot ulcers agreed to undergo the TL procedure.