Oblique Osteotomy for the Correction of the Zigzag Deformity of Wassel Type IV Polydactyly

Background: Surgical treatment of Wassel type IV thumb polydactyly is technically challenging, especially when it has a zigzag deformity. However, the authors obtained good operative results by performing oblique osteotomy with autologous fat graft in 30 patients. Methods: After removal of the extra digit, the radially deviated distal phalanx was corrected by performing oblique osteotomy at the proximal phalanx. Free fat tissue was grafted to the areas with soft-tissue deficiency. Surgical outcomes were evaluated in terms of the thumb length ratio compared to the normal counterpart, the angulation between the proximal phalanx and the distal phalanx, and the Tada score. As a negative control, the data of 46 type IV polydactyly patients without a significant axis deviation were evaluated. Results: The thumb length ratio was maintained from 0.96 ± 0.06 preoperatively to 1.01 ± 0.07 4-year postoperatively. The angulation improved from 30.84 ± 14.78 degrees to 11.03 ± 7.67 degrees. In comparison, the length ratio and angulation of the control group changed from 0.97 ± 0.04 to 0.98 ± 0.02, and from 19.46 ± 8.27 degrees to 14.10 ± 6.61 degrees, respectively. The Tada scores were 5.3 ± 0.88 in the oblique osteotomy group and 6.59 ± 0.62 in the control group, both of which were graded as good. Conclusions: Oblique osteotomy with autologous fat graft is a good surgical option for treating the Wassel type IV polydactyly with zigzag deformity. This technique allows sufficient axis correction without bone shortening, and it provides adequate soft-tissue contouring. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, III.