Biomechanical Study about Difference between Stainless Steel and Titanium Dynamic Hip Screws in Peritrochanteric Fractures of the Femur

Lee, Kwang Suk; Lee, In Hee; Woo, Kyung Jo; Park, Jong Hoon; Wie, Dae Gon

Abstract

Peritrochanteric fractures are common in the elderly, and the mortaliy and morbidity rates after conservative treatment of the fractures are usually high. In these fractures the internal fixation now allows the patient more rapid functional gain. It has been known that for stabilization of fracture the sliding hip screw is superior to other fixation devices. To investigate the biomechanical difference between two different materials of dynamic hip screw, eight intertrochateric and eight subtrochanteric femur fractures were artificially induced in human cadavers. Two femurs were used as the control. In eight cadaver intertrochanteric fractures (Group I), four of them were treated with stainless steel compression hip screw and four were treated with titanium compression hip screw. Eight cadaver subtrochanteric fractures (Group II) were divided by two groups as equal number. One group was treated with stainless steel compression hip screw and the other was treated with titanium compression hip screw with plate. Each femur was secured in a fixation device of the Instron and loaded in a vertical compression. Collapse or fixation failure during vertical compression were observed and recorded continuously in slow speed with deformation rate of 3mm/min. Biomechanical analysis of maximal loading force in the control and experimental two groups were performed. The results were as follows; 1. The mean maximal loading force was 625 kp in control group. 2. The mean maximal loading force in each 4 intertrochanteric fractures fixed with stainless steel DHS (dynamic hip screw) and plate was 92.59 kp, and with titanium DHS and plate was 71.57 kp. There was no statistical significance between stainless steel DHS and plate fixation and titanium DHS and plate fixation. (p>0.05) 3. The mean maximal loading force in each 4 subtrochanteric fractures fixed with stainless DHS and plate was 140.12 kp, and with titanium DHS with plate was 169.4 kp. There was no statistical significance between stainless steel DHS and plate fixation and titanium DHS and plate fixation. (p>0.05) 4. The breakage of metal implant was not occurred at the maximal loading force 600 kp in both group. There was no difference of fixability and stability according to the metal quality, as the results of the experiment of compression loading force to the stainless steel DHS and titanium DHS fixation on intertrochanteric and subtrochanteric fractures in cadaverous femurs.