Postoperative and Long-Term Patient-Reported Outcomes of Type A Ulnar Polydactyly.

Background: Type A ulnar or postaxial polydactyly describes a well-developed supernumerary small finger, which may have self-image and functional sequelae even after reconstructive surgery. The authors aimed to characterize postoperative outcomes and substantiate the clinical relevance of the Congenital Upper Limb Differences Ulnar Polydactyly (CUP) Classification.

Methods: All cases at 2 major pediatric hospitals from 2012 through 2022 were reviewed. Surgeons classified preoperative radiographs using the CUP Classification. Complication rates were compared using chi-square or Fisher exact tests. Patient-reported outcomes included the Patient and Observer Scar Assessment Scale, Australian Hand Difference Register aesthetics scale, and Patient-Reported Outcomes Measurement Information System (PROMIS); descriptive analyses considered minimum clinically important differences.

Results: Sixty-four hands of 42 patients underwent surgery (mean age, 15.1 ± 12.2 months). Operative techniques aligned with the CUP reconstructive pathway. Late complications varied significantly by CUP subtype ( P < 0.001), occurring most commonly in A3 (divergent metacarpophalangeal) and A5 (duplicated metacarpal) cases. Differences centered on functional complications, including subjective functional concerns, flexion contractures, and limited flexion (each P ≤ 0.02). Nineteen patients or caregivers completed questionnaires on average 5.9 years postoperatively. Most agreed that surgery improved their hand appearance (median 5 of 5) and endorsed happiness with their hand appearance (median 4 of 5). Approximately half believed that their hands could look better. Patients or caregivers reported good scar quality. Regarding function, mean PROMIS Upper Extremity scores fell more than a minimum clinically important difference below pediatric norms, especially for older children or adolescents (ages 8 to 18 years). Self-reported PROMIS Peer Relationships scores were within normal limits.

Conclusions: Most patients were pleased with postoperative results, but many reported room for aesthetic and functional improvement. This study corroborated the clinical relevance of the CUP Classification.

Clinical question/level of evidence: Therapeutic, IV.