A new assembly of locking compression plate of low elastic modulus for fixation of femoral comminuted fractures: a biomechanical study

Abstract

Objective To compare the stress and its distribution between our self-designed new assembly of locking compression plate (NALCP) of low elastic modulus versus conventional locking compression plate (LCP) in fixation of femoral comminuted fractures. Methods Six pairs of cadaveric femur were used to create models of middle femoral comminuted fracture. The femoral fracture models were fixated respectively by NALCP of Ti2448 with low elastic modulus (E=30 Gpa) (NALCP group) and conventional LCP of Ti-6Al-4V with high elastic modulus (E=110 Gpa) (LCP group). Axial and torsion loads were applied on the models in the 2 groups to simulate those on one leg when a person slowly walks. The relative maximum displacements on the X, Y and Z axes of fracture fragments, and the maximum and average strains of the plate were recorded in the 2 groups. Nephograms of strain distribution were made for the 2 groups. The results of fatigue test under axial loads were recorded for NALCP group. Results Both the axial and torsion loading tests showed significantly larger principal and average strains in NACLP group than in LCP group (P 0.05). The plate strain nephograms for the 2 groups showed consistent strain distributions. The plates in NALCP group survived 1,000,000 fatigue tests under axial loads, without any deformation, loosening or breakage. Conclusion As our NALCP of low elastic modulus may be better in stress transmission and distribution, it can effectively reduce the effect of stress-shielding and promote bone healing. Key words: Femoral fractures; Fracture fixation, internal; Biomechanics; Elastic modulus