Biomechanical Assessment of Femur Fracture Fixation Using Modified Locking Compression Plate Made of Biodegradable and Non-Biodegradable Materials Under Physiological Loading During Healing Phases.

Abstract

Transverse femoral fractures heal through a complex secondary healing process, often stabilized using locking compression plates (LCPs) that maintain compression across an interfragmentary gap. Conventional LCPs made of non-biodegradable Ti-alloys provide adequate mechanical support but can induce stress-shielding in newly formed callus and bone, necessitating revision surgeries. To address this, Mg-based biodegradable LCPs have been actively investigated. However, their clinical translation and commercial adoption remain limited, primarily due to concerns regarding their lower mechanical strength and fixation stability compared to Ti-alloys. Embossed structure-based LCP (ELCP) was designed previously to enhance its mechanical performance. However, its biomechanical feasibility under physiological loading across different fracture healing phases has not yet been systematically evaluated. In the present study, fractured femur models for two fixation strategies, a conventional LCP (M2) and the ELCP (M3), were developed. These strategies were tested using three candidate biomaterials (one non-biodegradable material, Ti-alloy, and two biodegradable materials, Mg-alloy and PLA/50% Mg composite). Three physiological loading conditions corresponding to the healing and early repair phases were applied. The results showed that although Ti-alloy-based conventional LCPs provided superior fixation strength, Mg-alloy-based ELCPs also performed substantially better than conventional LCPs, as reflected by high safety factors ranging from 1.81 to 3.42, unlike composite-based plates. Moreover, Mg-alloy-based ELCPs exhibited higher interfragmentary strain (within or above the ideal strain range) in the callus compared to Ti-alloy-based LCPs, which might promote faster callus strengthening. Thus, Mg-alloy-based ELCPs could represent a viable alternative to conventional LCPs by offering adequate fixation strength while potentially reducing stress-shielding.