Year: 2025
Type: article
Abstract: BACKGROUND: Hoffa fractures remain biomechanically challenging due to their intra-articular location and limited fixation surface. The influence of posterior muscle forces-particularly from the gastrocnemius-on interfragmentary motion has not been adequately addressed in previous experimental studies. This study aimed to assess the impact of simulated gastrocnemius traction on interfragmentary motion in Hoffa fracture fixation. METHODS: Patient-specific synthetic femora with anatomically realistic type I Hoffa fractures were manufactured from CT data using validated polyurethane-based materials. High-strength-fiber loops were embedded at the anatomical gastrocnemius insertion sites to simulate posterior muscle traction. Eight specimens with and eight without simulated gastrocnemius force (300 N constant pull) were tested under progressively increasing cyclic axial loading. Interfragmentary motion was captured via 3D motion tracking and analyzed for displacement and rotation. RESULTS: Specimens with simulated muscle force exhibited significantly altered motion patterns compared to controls. Muscle traction reversed the direction of gap opening, increased gap twisting at higher loads (up to - 3.0°, p ≤ 0.005), and modified shear displacement and localized gap expansion. Despite these differences in fragment kinematics, no significant differences in construct failure load were observed (p = 0.599). CONCLUSION: Simulated gastrocnemius traction substantially influences interfragmentary motion in Hoffa fractures under axial load, even in the absence of changes in failure load. This study presents a novel test setup combining patient-specific fracture morphology and anatomically integrated muscle simulation, providing a transferable and physiologically relevant platform for future biomechanical investigations of distal femur fractures.
Authors: Marianne Hollensteiner, Marlene Stallinger, Christof Hofmann, Mischa Mühling, Markus Greinwald, Sabrina Sandriesser, Dirk Baumeister, Peter Augat
Language: English
Subfield: Epidemiology
Field: Medicine
Domain: Health Sciences
Open Access status: hybrid
Estimated APC paid: $2,490
OpenAlex ID: W4416212322