Minimally Invasive Intramedullary Screw Versus Plate Fixation for Proximal Phalanx Fractures: A Biomechanical Study

Purpose To compare the maximum interfragmentary displacement of short oblique proximal phalanx (P1) fractures fixed with an intramedullary headless compression screw (IMHCS) versus a plate-and-screws construct in a cadaveric model that generates finger motion via the flexor and extensor tendons of the fingers. Method We created a 30 degrees oblique cut in 24 P1s of the index, middle, ring, and little fingers for 3 matched pairs of cadaveric hands. Twelve fractures were stabilized with an IMHCS using an antegrade, dorsal articular margin technique at the P1 base. The 12 matched-pair P1 fractures were stabilized with a radially placed 2 0-mm plate with 2 bicortical nonlocking screws on each side of the fracture. Hands were mounted to a frame allowing a computer-controlled, motordriven, linear actuator powered movement of fingers via the flexor and extensor tendons. All fingers underwent 2,000 full-flexion and extension cycles. Maximum interfragmentary displacement was continuously measured using a differential variable reluctance transducer. Results The observed mean displacement differences between IMHCS and plate-and-screws fixation was not statistically significant throughout all time points during the 2,000 cycles. A 2 one-sided test procedure for paired samples confirmed statistical equivalence in fracture displacement between fixation methods at the final 2,000-cycle time point. Conclusions The IMHCS provided biomechanical stability equivalent to plate-and-screws for short oblique P1 fractures at the 2,000-cycle mark in this cadaveric model. (C) 2021 by the American Society for Surgery of the Hand. All rights reserved.

Automated summary

This study compared the maximum interfragmentary displacement of short oblique P1 fractures fixed with an intramedullary headless compression screw (IMHCS) versus a plate-and-screws construct in a cadaveric model. The results demonstrated that both fixation methods provided equivalent biomechanical stability after 2,000 cycles in this study.