Abstract：Objective To perform a mechanical test of fresh cadaver specimens and compare the biomechanical properties of the novel minimal invasion dynamic hip plate (MIDHP) and the dynamic condylar screw (DCS) in treatment of subtrochanteric fractures of the femur. Methods All specimens were firstly used to simulate models of Seinsheimer type ⅡA subtrochanteric fractures of the femur, which were later divided into DCS group and MIDHP group. Based on experimental requirements, the femoral head and distal femur were embedded using self-freezing type dental base acrylic resin powder. Torsion strength test was given in the first place, succeeded by compression strength test. Finally, destructive test was made to record the limit load. All experimental data were analyzed statistically. Results Torsion strength test showed that specimens of both groups were basically stable as the reverse was within 3°. Torque for specimens in DCS and MIDHP groups was (3.16±0.13) N·m and (3.31±0.27) N·m respectively as the reverse was 1.5°. Both torque and torsion stiffness had no statistical significance between the two groups, and the anti-rotation features of the two internal fixations were similar. Compression strength test showed that compression stiffness of specimens in DCS group was (532.27±61.02) N/mm and (581.98±77.56) N/mm in MIDHP group at a load of 800 N, with evidently higher compression displacement and stiffness in MIDHP group (P<0.05). Destructive test showed the maximum load of specimens in DCS and MIDHP groups was (2 994.38±244.81) N and (3 322.13± 141.21) N respectively, far higher in MIDHP group (P<0.01). Conclusions MIDHP is characterized by reasonable design, strong anti-rotation property and anti-compression property over DCS. In comparison with DCS, MIDHP has biomechanical advantage in treatment of femoral subtrochanteric fractures, for it can be performed minimally invasive and is worthy of further application.
WENG Yi-min,SHUI Xiao-long,KONG Jian-zhong et al. Biomechanical study of novel minimally invasive dynamic hip plate for femoral subtrochanteric fractures[J]. CHINESE JOURNAL OF TRAUMA, 2013, 29(6): 556-560.
［3］Warwick DJ, Crichlow TP, Langkamer VG, et al. The dynamic condylar screw in the management of subtrochanteric fractures of the femur. Injury, 1995, 26(4):241-244.
［13］Rydell NW. Forces acting on the femoral head-prosthesis. A study of strain gauge supplied prostheses in living persons. Acta Orthop Scand, 1966, 37 Suppl 88:1-132.
［14］Elkholy AH. Design optimization of the hip nail-plate-screws implant. Comput Methods Programs Biomed, 1995, 48(3):221-227.
［15］Mavrogenis AF, Mavrogenis G, Stavropoulos NA, et al. Sliding screw implants for extracapsular hip fractures. J Long Term Eff Med Implants, 2012, 22(1):1-10.
