Evaluation of Intramedullary Olecranon Screw Fixation for Simple Olecranon Fractures: A Biomechanical Study

Abstract

The purpose of this study was to biomechanically evaluate the stability of the 6.5 mm intramedullary (IM) olecranon screw compared to locking compression plate fixation for Orthopedic Trauma Association/AO Foundation (OTA/AO) 2U1B1 olecranon fractures under cyclic range of motion of the elbow. Twenty paired elbows were randomized to either IM olecranon screw or locking compression plate fixation of a simulated OTA/AO 2U1B1 fracture. Pullout strength was tested by increasing force applied to the triceps and proximal fragment. Fracture gap displacement was measured using differential variable reluctance transducers as the elbow was cycled through a 135° arc of motion using a servohydraulic testing system. Analysis of variance revealed significant interaction between group and load on fracture distraction after the 500th cycle in three settings: between the plate at 5-pound load and screw at 35-pound load, the screw at 5-pound load and screw at 35-pound load, and between the plate at 15-pound load and screw at 35-pound load. The difference in the rate of failure between plate (2 of 80 samples) and screw (4 of 80 samples) was not statistically significant. For OTA/AO 2U1B1 olecranon fractures, a single 6.5 mm IM olecranon screw demonstrated similar stability when compared to the locking compression plates throughout range of motion testing. From a biomechanical perspective, 6.5 mm IM screws and locking compression plates have similar ability to maintain fracture reduction following simulated elbow range of motion exercises in OTA/AO 2U1B1 fractures, giving surgeons another option in the management of these fractures.