Polydactyly of the thumb: a surgical plan based on ninety-five cases.

Preaxial polydactyly constitutes the most common group of congenital anomalies of the hand among the Chinese population of Hong Kong. Ninety-five cases from the Orthopaedic/Plastic and Reconstructive Surgery Unit, Princess Margaret Hospital, Hong Kong (March 1976 to March 1981), were reviewed. The cases were classified according to Wassel's classification (1969) into seven types. The most common category was type IV followed by types II, V, III, VII, I, and VI. The treatment of each type was analyzed. Bilhaut's procedure was satisfactory for type I, and a modified technique was used for types II and III. A method of shaving the incongruous articular cartilage was used in type IV. Removal of the extra digit and osteotomy of the metacarpal usually were required for type V. The experience with types VI and VII was too limited for assessment. Short-term results (1 to 6 years) have been satisfactory, but follow-up until skeletal maturity to assess the ultimate functional and cosmetic results is necessary.