BIOMECHANICAL ANALYSIS OF FEMORAL NECK FRACTURE FIXATION IN SYNTHETIC BONE

OBJECTIVES: To analyze the results of biomechanical assays of the fixation of Pauwels type II femoral neck fractures in synthetic bones, using two parallel cannulated screws or three cannulated screws in an inverted pyramid formation. METHODS: Ten Brazilian-made synthetic bones were divided into 2 groups. Groups A and B utilized three and two cannulated screws, respectively, after osteotomy in the middle third of the femur, perpendicular to the axis of the femoral neck, simulating a Pauwels type II femoral neck fracture. The resistance of these fixations was analyzed by compression on the axis of the force resulting from hip compression, simulated with a manual hydraulic press. The T-test and post hoc analysis were used to compare the groups, and the significance criterion adopted was p < 0.05. RESULTS: In group A, which used fixation with three screws, synthesis failure was seen at a mean force of 526 N. In group B, which used two screws, the mean force was 466 N. The results presented a statistically significant difference (p = 0.02). CONCLUSION: The osteosynthesis of femoral neck fractures in synthetic bone fixated with two screws presented inferior results to fixation with three screws. Level of Evidence III; Case-control study.