The Effect of Remnant Metatarsal Parabola Structure on Transmetatarsal Amputation Primary Healing and Durability

Although generally considered to be both a durable and functional procedure for limb preservation, the transmetatarsal amputation (TMA) has high rates of complication, failure, revisional operation, and progression to more proximal amputation. The objective of this investigation was to determine the effect of remnant metatarsal parabola structure on healing outcomes following TMA. A retrospective chart review was performed of subjects undergoing a complete TMA with primary closure. We considered 4 patterns of remnant metatarsal parabola structure. TMA pattern type 1 was a normal parabola with the remnant second metatarsal extending furthest distally and slightly longer than the remnant first and third metatarsals with a gradual lateral taper. TMA pattern type 2 was the first metatarsal remnant extending furthest distally with a gradual lateral taper. TMA pattern type 3 was a relatively long fifth metatarsal remnant without the presence of a gradual lateral taper. And TMA pattern type 4 was a relatively short first metatarsal remnant with a relatively long second metatarsal with a gradual lateral taper. Seventy-three transmetatarsal amputations in 73 subjects met selection criteria. Thirty-nine (53.4%) amputations healed primarily at 90 days. No statistically significant differences were observed between groups with respect to the 90-day primary healing rate (p = .571) or 1-year ambulation rate without wound recurrence or reoperation (p = .811). These results might indicate that the remnant metatarsal structure does not have an effect on transmetatarsal amputation outcome. It is our hope that these results add to the body of knowledge and lead to further investigations into outcomes of limb preservation surgical interventions.