Balance Between Mechanical Stability and Mechano-Biology of Fracture Healing Under Volar Locking Plate.

The application of volar locking plate (VLP) is promising in the treatment of dorsally comminuted and displaced fracture. However, the optimal balance between the mechanical stability of VLP and the mechanobiology at the fracture site is still unclear. The purpose of this study is to develop numerical models in conjunction with experimental studies to identify the favourable mechanical microenvironment for indirect healing, by optimizing VLP configuration and post-operative loadings for different fracture geometries. The simulation results show that the mechanical behaviour of VLP is mainly governed by the axial compression. In addition, the model shows that, under relatively large gap size (i.e., 3-5 mm), the increase of FWL could enhance chondrocyte differentiation while a large BPD could compromise the mechanical stability of VLP. Importantly, bending moment produced by wrist flexion/extension and torsion moment produced from forearm rotation could potentially hinder endochondral ossification at early stage of healing. The developed model could potentially assist orthopaedic surgeons in surgical pre-planning and designing post-operation physical therapy for treatment of distal radius fractures.