Soft tissue balancing procedure with CASC assessment system for postaxial polydactyly and curled fifth toe deformity

Postaxial polydactyly, accounting for 80% of foot polydactylies, is often complicated by curled fifth toe deformity. Existing treatments neglect residual curly toe correction due to concerns about added surgical trauma. This study introduces a novel soft-tissue balancing technique utilizing polydactylous tendons without additional incisions.

Twenty-two children (mean age: 13.18 months) with postaxial polydactyly and reducible curled fifth toe were included. A new classification system categorized deformities: Type I (PIPJ flexion/inversion), Type II (MTPJ flexion/inversion), and Type III (combined). During polydactyly excision, residual extensor and flexor tendons were transferred to reconstruct balanced insertions on the fifth toe according to deformity type. Outcomes were evaluated using the non-imaging Clinical Assessment System for Curled fifth toe (CASC), assessing curvature angle, soft tissue tension, static appearance, and functional impact.

Significant improvements were observed postoperatively:PIPJ angle decreased from 33.36°±9.23° to 1.14°±0.96° (p<0.001), MTPJ angle decreased from 10.96°±6.94° to 0.63°±0.73° (p<0.001), Static appearance: All patients achieved fully exposed nails (preoperative: 0%), Aggregated CASC grade reduced from 7.57±2.13 to 2.10±0.30 (p<0.001) CONCLUSION: Polydactyly excision combined with tendon transfer balancing effectively corrects curled toe deformities without additional incisions, yielding excellent functional and aesthetic outcomes. The technique leverages existing anatomical resources, minimizing surgical morbidity.