Triangular supporting fixation: an innovative surgical approach for intertrochanteric fractures of the femur--Evidence from a biomechanical study / 中华创伤骨科杂志

ABSTRACT

Objective:To compare the biomechanical properties between triangular supporting fixation and conventional dynamic hip screw (DHS) fixation in the treatment of femoral intertrochanteric fractures.Methods:Eight pairs of 16 femoral specimens with an average death age of 51.9 years were used in this study. After thawing, they were randomly divided into an experimental group ( n=8) and a control group ( n=8) according to the left or right laterality. They were made models of femoral intertrochanteric fracture of AO 31-A1 type with strain gauges pasted. The experimental group was subjected to fixation with double triangu-lar supporting and the control group conventional DHS fixation to achieve anatomical reduction. The specimens were then mounted onto a biomechanical testing machine and subjected to loading till 400 N at a rate of 10 N/s. The values of overall deformation of the specimens and strain at 16 selected sites were recorded and compared between the 2 model groups. Results:Under the load of 400 N, the overall deformation was (0.31±0.13) mm for the experimental group and (0.49±0.21) mm for the control group, showing a significant difference ( t=-2.456, P=0.023). The strain values in front of femoral neck, upon front fracture line, at inferior-lateral, inferior-median and inferior-interior sites of front fracture line, at the root of anterior fixation screw, below medial femoral neck fracture line, behind femoral neck, at superior-lateral, superior-median and superior-interior sites of posterior fracture line, below posterior fracture line, at superior and inferior roots of posterior fixation screw, at points parallel to the fixation screw in front of and behind femoral shaft were, respectively, -244.90, 13.16, -71.77, -124.38, -366.89,121.62, -10.94, -166.00, -54.93, -367.38, -608.93, -69.09, 326.50, 133.14, 52.97, and -185.82 in the experimental group and -24.62, -40.39, -36.99, -120.97, -486.38, 99.20, 35.36, -205.67, -74.30, -566.01, -1, 085.40, -77.41, 334.34, 114.08, 38.50, and -235.74 in the control group. Internal fixation failure occurred in one specimen in the control group after 1,759 cycles of loading but in none in the experimental group. Conclusion:For femoral intertrochanteric fractures, double triangular supporting fixation may result in less overall deformation and is more consistent with the normal biomechanical conduction of the femur than conventional DHS fixation.