Flexor pollicis longus rebalancing: a modified technique for Wassel IV-D thumb duplication.

ABSTRACT

PURPOSE: To report a modified reconstructive technique for Wassel type IV-D thumb duplication that preserves and transfers the flexor pollicis longus (FPL) from the removed radial portion. METHODS: We analyzed the hands of 16 patients (average age, 2 y) with Wassel IV-D thumb duplication. Patients were treated with ablation of the radial thumb and reconstruction of the ulnar thumb by a series of soft tissue procedures, including FPL rebalancing. The postoperative range of motion and the alignment at the metacarpophalangeal and interphalangeal joints of the affected thumbs were compared with the preoperative measurements. RESULTS: Of 16 cases, 14 were observed for an average of 29 months. Motion at the interphalangeal joint and alignment at metacarpophalangeal and interphalangeal joints showed improvement after surgery. According to the Japanese Society for Surgery of the Hand scoring system, the results were excellent in 2 cases, good in 11, and fair in 1. A disadvantage of this technique proved to be restricted interphalangeal joint motion with an extension lag that averaged 14°. CONCLUSIONS: The FPL rebalancing technique with soft tissue stabilization of the metacarpophalangeal and interphalangeal joints can establish dynamic rebalance of the bifurcated FPL tendon in Wassel IV-D duplicated thumb. It shows excellent results in alignment and joint stability. The long-term results are under evaluation. TYPE OF STUDY/LEVEL OF EVIDENCE Therapeutic IV.