We evaluated 5 thumbs in 5 patients who underwent radial polydactyly reconstruction using the “on-top plasty” technique between 1998 and 2003. This technique was used when it was felt that neither thumb possessed adequate proximal and distal structures to provide a functional and aesthetically pleasing thumb. Our study group included 1 Flatt type III and 4 Flatt type VII thumbs. The average age at time of surgery was 1.4 years and at final follow-up was 13.5 years. Subjective patient evaluation, objective outcomes values, and validated patient-oriented outcome measures were obtained.


There was no soft tissue loss and union was achieved in all thumbs with no further surgery required in any thumb. Mean flexion-extension arc for the metacarpophalangeal joint was 60° (range, 10° extension to 70° flexion) and at the interphalangeal joint was 19° (range, 25° extension to 35° flexion). Mean percentage of age-matched norms for lateral, tripod, and tip pinch were 47.0%, 45.9%, and 47.8%, respectively. Mean grip strength was 54.2% of age-matched norm. The mean Pediatric Quality of Life Inventory (PedsQL) score for parent questionnaires was 89.0 and for teen/child questionnaires was 89.1. The Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire revealed a mean score of 4.3.


For patients with radial polydactyly in which neither thumb possesses adequate distal and proximal components, the on-top plasty is a reliable method of polydactyly reconstruction with durable results at longer than 10 years’ follow-up.

Type of study/level of evidence Therapeutic V.