Nail–Plate Constructs for Treating Distal Femur Fractures: A Systematic Review of Biomechanical Studies

The biomechanical efficacy of nail–plate constructs (NPCs) used in the treatment of traumatic distal femur fractures (DFFs) remains understudied compared to traditional approaches. This systematic review examines the biomechanical efficacy of NPCs compared to alternative approaches for the surgical fixation of DFFs to guide surgical decision-making and improve patient outcomes. This systematic review searched the PubMed, CINAHL, MEDLINE, Web of Science, and SPORT Discus databases from inception until 24 January 2024. Inclusion criteria were biomechanical studies that involved nail–plate combination constructs for DFFs. Six observational studies were included. Of the included studies, five studies utilized synthetic bone models in testing, and one study used both synthetic and cadaveric bone models. All studies found NPCs to have significantly higher axial and torsional stiffness and resistance to loading than distal lateral femoral locking plate (DLFLP) constructs. The 11 mm NPCs were significantly stiffer than the 9 mm NPCs under torsional and axial loading. Only one of two studies found NPCs to have greater axial stiffness than dual-plate (DP) constructs. NPCs and DP constructs had greater torsional and axial stiffness than the plate-only or DP with medial distal tibial plate constructs. NPCs had less displacement and torque than the plate- or nail-only constructs under axial and torsional loads. NPCs demonstrate superior axial and torsional stiffness and resistance to mechanical loads compared to DLFLP. The varying performance between 11 mm and 9 mm NPCs suggests that construct diameter plays a role in mechanical stability. NPCs and DP constructs performed better than plate-only constructs. Future research should explore the impact of varying nail diameters and plate configurations on stability, as well as the clinical efficacy of NPCs across different patient populations, particularly those with varying bone densities, to better understand their performance in real-world scenarios.