Biomechanical Study of the Stiffness of the Femoral Locking Compression Plate of an External Fixator for Lower Tibial Fractures

Abstract

Background: A locking compression plate (LCP) of the distal femur is used as an external fixator for lower tibial fractures. However, in clinical practice, the technique lacks a standardized approach and a strong biomechanical basis for its stability. Methods: In this paper, internal tibial LCP fixator (Group IT-44), external tibial LCP fixator (Group ET-44), external distal femoral LCP fixator (Group EF-44, group EF-33, group EF-22), and conventional external fixator frame (Group CEF-22) were used to fix the unstable fracture models of the lower tibial segment, and anatomical studies were performed to standardize the operation as well as to assess the biomechanical stability and adjustability of the distal femoral LCP external fixator by biomechanical experiments. Results: It was found that the torsional and flexural stiffness of the group EF-44 and group EF-33 were better than those of the group IT-44 and group ET-44 (p<0.05); the flexural stiffness of the group EF-22 was similar to that of the group IT-44 (p>0.05); and the compressive stiffness of all three EF groups was better than that of the group ET-44 (p<0.05). In addition, the flexural and compressive stiffnesses of the three EF groups decreased with the decrease in the number of screws (p<0.05), while the torsional stiffnesses of the three groups did not differ significantly between the two adjacent groups (p>0.05). In the last point, the group ET-44 had the worst stability (P<0.05). Conclusions: The study shows that the distal femoral LCP has good biomechanical stability and adjustability, and it is superior to the tibial LCP as an external fixator for distal tibial fractures, as long as the technique is used in a standardized manner according to the anatomical studies in this article.