Effects of lateral opening wedge and medial closing wedge distal femoral osteotomies on axial load stability

Background: The stability of the current distal femoral osteotomy is insufficient for early weight bearing and bone healing. The purpose of this study was to test the stability of medial closing wedge- (MCW-) and lateral opening wedge-distal femoral osteotomies (LOW-DFO), which have improved with the recent advances in technology. Methods: We used composite bone models with MCW-DFO, improved with biplanar osteotomy technique and a Tomofix (TM) MDF plate, or LOW-DFO improved with biplanar osteotomy technique, a Tomofix (TM) LDF plate, and a beta-TCP bone substitute, BONISH (R) graft. A cyclic axial loading test was employed to evaluate the strain on a plate and hinge point. The breaking axial load was measured. Results: Tensile strain on the plate produced by cyclic axial loading was significantly lower for LOW-DFO (2.0 +/- 0.8 MPa) than for MCW-DFO (3.9 +/- 1.6 MPa, P< .05). Compressive strain on the hinge point produced by cyclic axial loading was lower for LOW-DFO (6.6 +/- 2.9 MPa) than for MCW-DFO (7.7 +/- 4.6 MPa,). The maximum breaking axial load was significantly higher for LOW-DIO (5511 +/- 945 N) than for MCW-DFO (4303 +/- 518 N, P < .05). Conclusions: LOW-DFO improved with recent advanced technology was superior to MCW-DFO improved with advanced technology in both cyclic axial loading test and breaking axial load test. This suggests that LOW-DIO facilitates earlier weight bearing and bone healing than does MCW-DFO. (C) 2020 Elsevier B.V. All rights reserved.