Biomechanical Evaluation of Hoffa Fractures

: Introducing Muscle Forces into Osteosynthesis Assessment

Abstract

Hoffa fractures are rare intra-articular injuries of the distal femur that present a biomechanical challenge in surgical treatment. Previous studies have focused mainly on axial loading tests and have neglected the influence of the gastrocnemius muscle, which attaches to the posterior femoral condyles. The aim of this study was therefore to investigate the effects of simulated muscle forces on the stability of Hoffa fractures for the first time. For this purpose, patient-speci c PuReBone models of a Ho a fracture were produced based on CT data and fixed with three anteroposterior (A-P) screws. Cyclic axial loading was then applied with increasing forces up to more than 2000 N, combined with a constant simulated muscle pull of 300 N. Fracture gap movements were recorded using a 3D camera system. The results show that the simulated muscle pull has a significant inuence on interfragmentary motion. At lower axial loads, a stabilizing effect was observed, whereas higher loads resulted in progressive destabilization. This highlights the strong clinical relevance of muscular inuences in biomechanical studies. Despite several limitations, such as the assumption of constant muscle forces, the use of simpli ed menisci, and differences between PuReBone models and real bone, the ndings remain informative. They provide novel insights into the role of muscular forces in Ho a fractures. Future studies should focus on optimizing the experimental setup and validating the results on human specimens to improve clinical transferability.

Date of Award	2025
Original language	German (Austria)
Supervisor	Andreas Schrempf (Supervisor) & Marianne Hollensteiner (Supervisor)