Two versus 3 lag screws for fixation of long oblique proximal phalanx fractures of the fingers: a cadaver study.

Abstract

To compare 2- versus 3-screw fixation for oblique fractures of the proximal phalanx in a cadaver model that simulates active finger motion. We experimentally cut the proximal phalanges of the index, middle, and ring fingers of 9 cadaveric hands. Five fingers were assigned to a control group with no fixation, and 22 were fixed with either 2 or 3 lag screws. One digit was excluded because of iatrogenic fracture during preparation. The fingers were fitted with a differential variable reluctance transducer that measured maximum interfragment displacement while the fingers were subjected to 2,000 full flexion and extension cycles to simulate a 6-week active motion protocol. Analysis of variance revealed a significant difference between the control group and both the 2- and the 3-screw group. The 2- and 3-screw group average displacements were not significantly different. Both of these groups were equivalent with a power of 90%. Biomechanical stability during simulated active motion protocol did not differ in simulated proximal phalanx fractures treated with 2 lag screws or 3. Fracture fixation using 2 screws may be more cost and time effective and, therefore, more attractive to the surgeon, even when 3 screws can be placed. Furthermore, surgeons may consider using 2 screws rather than resorting to plate fixation when 3-screw fixation is not possible for these types of fractures.