BIOMECHANICAL EVALUATION OF FIXATION METHODS IN PATELLAR FRACTURES (AO 34-C3): AN IN VITRO ANALYSIS

Objective: To describe the biomechanical outcomes of five different fixation models, namely: tension band wiring (TB), anterior star-shaped locking plate (PS), lateral orthogonal locking plates (LP), and two additional models using BT and LP combined with a circumferential cerclage wire around the patella, referred to as BTO and PSO, respectively, in a comminuted patellar fracture (AO34C3). Methods: This study analyzed, using the finite element method (FEM), the following variables: total displacement, fragment displacement, maximum and minimum principal stresses, and total and localized von Mises stresses, under loading conditions of 1,500 N (R1) and 3,000 N (R2). Results: Results were presented as absolute values and percentiles, as well as through observational analysis of individual stress distributions. From a biomechanical perspective, critical results in both absolute and percentile values were observed for most variables in the TB group compared with the PS and LP groups. While maximum and minimum principal stresses were similar among groups, differences in intensity and location were found for total and localized von Mises stresses. In addition, the inferior pole of the patella exhibited critical stress conditions across all groups. Conclusions: Tension band wiring demonstrated inferior outcomes compared with locking plates. Biomechanical benefits were observed with the use of two orthogonal locking plates compared with an anterior locking plate; however, both constructs still showed deficiencies in stabilizing the distal pole of the patella.