Comparison of Three Internal Fixation Constructs for AO/OTA 33-A3 Distal Femoral Fractures: A Biomechanical Study
Wei Xie1, Hui Liu1, Shufen Chen1
1Department of Orthopaedics, The 909th Hospital, School of Medicine, Xiamen University, Zhangzhou 363000, China.
Background:
To compare the biomechanical performance of three internal fixation constructs for AO/OTA 33-A3 distal femoral fractures.
Methods:
Thirty AO/OTA 33-A3 synthetic distal femoral fracture models were constructed and randomly divided into three groups. Group A (dual-plate construct) was fixed with a medial locking plate combined with a less invasive stabilization system (LISS). Group B was fixed with a retrograde femoral nail (RFN) combined with an LISS (RFN + LISS construct), and Group C was fixed with a retrograde tibial nail (RTN) combined with an LISS (RTN + LISS construct). The axial displacement, axial stiffness, torsional displacement, torsional stiffness and maximum failure load of different internal fixation constructs were recorded and statistically analyzed.
Results:
In the axial compression test, the average stiffness of Group C was significantly higher than that of Groups A and B, and the average displacement of Group C was significantly smaller than that of Groups A and B. In the torsion test, the torsion degree of Group C was significantly lower than that of Groups A and B, and Group C had a higher torsional stiffness than Groups A and B. In the axial compression failure test, the average ultimate load (a displacement greater than 5 mm) of Group C was significantly higher than that of Groups A and B.
Conclusion:
The biomechanical strength of the RTN combined with a plate is higher than that of the RFN combined with plate and dual-plate constructs, which can be used as an internal fixation option for the treatment of comminuted distal femoral fractures.
