Factors affecting surgical results of Wassel type IV thumb duplications.

The aim of this study is to review the outcomes of Wassel type IV thumb duplications with a minimum of one year follow-up, and to identify any factors that may compromise the quality of results. Forty one patients (42 thumbs) returned for assessment of thumb alignment, metacarpophalangeal joint and interphalangeal joint stability and motion; carpometacarpal joint motion; pinch and grip strengths; and thumb size. The subjective assessment considered thumb shape and contour, scarring, nail deformity and examiner and patient/parent satisfaction. The mean age at surgery was 16 months and the mean follow-up time was 79 months. Metacarpophalangeal joint and interphalangeal joint mal-alignment was present in 56% and 38% of cases, respectively. Interphalangeal ulnar collateral ligament laxity was significant. Metacarpophalangeal joint and interphalangeal joint motion was significantly decreased. Pinch and grip strength measurements were normal. A novel and comprehensive assessment scale is introduced, which revealed results of one (2.5%) excellent, 23 (59%) good, 14 (36%) fair and one (2.5%) poor. We consider that greater attention should be directed to the avoidance of mal-alignment and instability to improve these results.