Opponensplasty provides predictable opposable tripod pinch in toe transfer for proximal thumb ray defect reconstruction

Background: Thumb amputations proximal to the metacarpophalangeal joint inevitably result in destruction of the thenar musculature and secondary loss of opposition. Opposable tripod pinch is one of the essential goals in toe-to-thumb reconstruction. Pronation osteosynthesis is the traditional method of restoring opposition, but a simultaneous opponensplasty may turn this static process into a dynamic one. Methods: From 1992 to 2010, 19 toe-to-thumb transfers at and proximal to the metacarpophalangeal level with concomitant thenar muscle damage were examined. All underwent either pedicled groin flap (n = 16) or free flap (n = 3) surgery for amputation stump resurfacing. Nine transferred toes had a static opposition procedure with osteosynthesis by rotation of 30 to 60 degrees (group I). Ten transferred toes underwent an additional simultaneous opponensplasty to provide dynamic opposition (group II). Results: Seventy-eight percent (seven of nine) of group I and 100 percent of group II achieved opposable basic hand function and lateral pinch. In contrast, only 33 percent (three of nine) in group I regained tripod pinch grip compared with 90 percent (nine of 10) in group II, which was statistically significant (p = 0.02). Conclusions: Primary opponensplasty in toe transfers provides active restoration of opposition and significantly better restoration of tripod pinch, in comparison with static opposition with osteosynthesis. It is therefore recommended that primary opponensplasty be performed at the time of toe transfer in such injuries. Clinical Question/Level of Evidence: Therapeutic, III.