Numerical evaluation of internal femur osteosynthesis based on a biomechanical model of the loading in the proximal equine hindlimb.
Authors: Lang Jan J, Li Xinhao, Micheler Carina M, Wilhelm Nikolas J, Seidl Fritz, Schwaiger Benedikt J, Barnewitz Dirk, von Eisenhart-Rothe Ruediger, Grosse Christian U, Burgkart Rainer
Journal: BMC veterinary research
Summary
# Editorial Summary: Biomechanical Assessment of Equine Femoral Fracture Fixation Femoral fractures remain a significant clinical challenge in equine surgery, with primary implant stability being critical to fracture healing outcomes, yet the actual physiological forces acting through the equine hindlimb during weight-bearing have not been thoroughly characterised. Researchers used finite element analysis coupled with a musculoskeletal model to simulate realistic loading conditions in the standing horse and evaluate how four different diaphyseal fracture patterns—transverse, two oblique orientations, and a gap fracture—respond to intramedullary nail fixation. The gap fracture generated the highest stresses on the implant system (compressive stress of −348 MPa and tensile stress of 197 MPa), predominantly concentrated in the screws adjacent to the fracture line, though all stress values remained within material strength limits across all fracture configurations. The native femur's highest stress concentrations occurred distally to the femoral head and proximally along the caudal condyles, providing insight into anatomically vulnerable regions. These findings suggest that intramedullary nail fixation with appropriate screw placement can provide sufficient primary stability for common diaphyseal fracture types, offering a biomechanical framework to guide surgical decision-making and potentially improve outcomes in equine femoral fracture repair.
Read the full abstract on PubMed
Practical Takeaways
- •Intramedullary nailing with screws appears biomechanically sound for equine femoral fracture repair across common fracture patterns in standing horses.
- •Gap fractures (non-contact fragments) represent the greatest challenge to implant performance, though still within safe material limits.
- •This modeling approach provides a foundation for optimizing surgical technique and implant design, potentially improving outcomes in this historically challenging fracture type.
Key Findings
- •A finite element analysis model successfully predicted load distribution in the standing horse femur using physiological stance conditions.
- •Intramedullary nail fixation with screws demonstrated sufficient stability for all four fracture types analyzed (transverse, oblique medial-lateral, oblique anterior-posterior, and gap fractures).
- •Gap fractures generated the highest stresses in implant material (maximum compressive stress -348 MPa, tensile stress 197 MPa), but material strength was not exceeded.
- •Fracture-adjacent screws experienced the highest stresses in the implant for all fracture types.