Metatarsal Protrusion Distance and Its Influence on Recurrent Ulceration Rates After Partial First-Ray Amputations: A Retrospective Study.

BACKGROUND

Recurrent ulceration is a common problem after partial first-ray amputations. Loss of the first metatarsophalangeal joint contributes to altered biomechanics and increased pressure on the foot. This may increase risk of adjacent ulcerations and additional amputations. Preserving first-ray length maintains the metatarsal parabola and limits transfer lesions, but few data support this. We aimed to evaluate the incidence of ulceration after partial first-ray amputations and to assess the association between metatarsal protrusion distance and recurrent ulceration.

METHODS

Thirty-two consecutive patients underwent unilateral partial first-ray amputation at various levels along the first metatarsal, and the metatarsal protrusion distance was measured after surgery. Incidence of ulceration was evaluated on the ipsilateral foot. We hypothesized that patients with a longer first metatarsal were less likely to ulcerate again on the ipsilateral foot.

RESULTS

Fourteen patients (43.8%) ulcerated again after partial first-ray amputation. Mean time to ulceration was 104 days. Active smoking status was associated with increased risk of another ulceration (P = .02), and chronic kidney disease was associated with a decreased risk of recurrent ulceration (P = .03). The average metatarsal protrusion distance for patients who ulcerated again after surgery was 36.1 mm versus 25.9 mm for patients who did not (P = .04). Logistic regression analysis of the receiver operating characteristic curve demonstrated an ideal cutoff length for recurrent ulceration of 37 mm (area under the curve = 0.7381). Patients with a protrusion distance greater than 37 mm were nine times as likely to ulcerate again (95% CI, 1.7-47.0).

CONCLUSIONS

Partial first-ray amputations can be a good initial salvage procedure to clear infection and prolong bipedal ambulatory status. Unfortunately, these patients are prone to recurrent ulceration. Significant loss of first metatarsal length is a poor prognostic indicator for recurrent ulceration.