gms | German Medical Science

Introduction: Distal radius fractures (DRF) are one of the most common fractures and often treated by plate osteosynthesis, which are validated through biomechanical tests. A recent publication challenges the current standard biomechanical fracture model. The aim of the study was to develop a new model for DRF (AO-23.A3) and compare its biomechanical behavior to the current gold-standard.

Material and methods: Polyaxial angle-stable volar plates (ADAPTIVE, Medartis) were mounted on 10 pairs of fresh frozen radii. The osteotomy location (New: 10 mm wedge 8 mm / 12 mm proximal to the dorsal / volar apex of the articular surface; Gold-standard: 10 mm wedge 20 mm proximal to the articular surface) was alternated within each pair. Each specimen was tested in cyclic axial compression (increasing load by 100N per cycle) until failure or -3 mm displacement. Parameters assessed were displacement, work and stiffness calculated for each cycle and ultimate load.

Results: 7 female and 3 male pairs of radii aged 74.3 ± 9.0 years were tested. In most cases (7/10) the two groups showed similar mechanical behavior at low loads with increasing differences at increasing loads, which became significant at 700N. The new model showed greater displacement (p=0,044), more dissipated work (p=0.025) and lower stiffness values p=(0.009). The average final loads resisted were significantly lower in the novel model (860N ± 232N vs. 1250N ± 341N; p=0,001).

Conclusion: The herein introduced novel biomechanical fracture model for DRF better mimics the in-vivo fracture location and shows a significantly different biomechanical behavior with increasing loads when compared to the current gold-standard.