Challenging the Parabola Paradigm Post-Transmetatarsal Amputation
Summary: This oral abstract presented at the 2025 APMA National conference, led by Craig J. Verdin, DPM, reevaluates the longstanding “parabola paradigm” in post-transmetatarsal amputation (TMA) wound care for diabetic foot infections/gangrene. Analyzing 57 unilateral TMA patients retrospectively, the study substratifies residual parabolas (Types 1-4 per Bik et al.) and lengths (>50% preoperative), assessing impacts on complications and patient-reported outcomes (PROMs: LEFS for function, SF-12 for QoL). Findings reveal no significant ties to major complications or PROMs, only a weak correlation between unbalanced Type 4 parabolas and minor issues. It promotes function-driven, balanced parabolas over dogmatic length replication, and explores ray-preserving TMA variants for enhanced biomechanics, healing, and quality of life in podiatry limb salvage.
Key Highlights:
- Retrospective review of 57 TMAs at Georgetown University Hospital (2 years); no effect of parabola shape/length on major complications or PROMs/QoL.
- Weak correlation (p<0.05) between Type 4 (longer second metatarsal) and minor complications like reulceration due to uneven pressure.
- Historical McKittrick paradigm (1949) prioritizes Type 1 parabolas for propulsion; study calls it outdated, favoring balanced designs.
- Alternatives: Ray-preserving TMAs (e.g., first ray or first two rays per Suh et al., 2019) may optimize musculotendinous function and wound durability.
- Implications: Shift to PROMs/gait assessments in diabetic foot care for better outcomes, reducing reamputation risks in wound healing.
Keywords: transmetatarsal amputation, residual parabola, diabetic foot amputation, limb salvage, ray-preserving TMA, Craig J Verdin, Ply C, Lava C