Abstract
Background
The inherently high stiffness of locked plate constructs is increasingly recognized as a potential cause of deficient healing observed in patients with periarticular locked plating systems.
The objective of this study is to perform a biomechanical comparison of distal femur locked plating systems.
Methods
Biomechanical study using bone substitutes in a distal femur fracture model (OTA/AO 33-A3). Four different locked plate fixation systems were compared (AxSOS, LCP, PERI-LOC, POLYAX). Eight bone implant constructs of each plating system were evaluated in a multiple testing model to examine static failure, stiffness under static and cyclic loading and cyclic fatigue.
Results
The implant systems made of titanium alloy (POLYAX & LCP) supported smaller torsional stiffness values under static loads and smaller axial stiffness values under cyclic loads compared with the implant systems made of stainless steel (PERI-LOC & AxSOS). All bone implant constructs reached the cyclic failure criterion of 10 degrees displacement at the fracture area within the third load level (>50000 cycles) except for the LCP which failed earlier.
Conclusion
The tested four different locked plating systems differ significantly in terms of stiffness and load to failure. Two of the clinical available systems differed almost 100% in stiffness values. And one system differed almost 100% in fatigue strength. For clinical use, this knowledge is essential for the practicing orthopaedic surgeon.
