The Treatment Of Femoral Neck Fracture Using The Intramedullary With Extramedullary Internal Fixation

Objectives: The femoral neck fracture is one of the old-age common fractures. It accounts for 3.6% of all fractures. Because of the specialty of the vascular supply to femoral head, it would be injured easily when the fracture took place. This not only affected the fracture healing but also would produce ischemic necrosis of femoral head easily. The morbidity of the femoral head ischemic necrosis is 10-25%. Many scholars have made a lot of study on treatment of the femoral neck fractures since Smith-Person created tri-flange nail in 1931. All kinds of internal fixations were in clinical use. The rate of the healing of the femoral neck fractures was obviously improved, but the morbidity of post-operative femoral head ischemic necrosis was fairly high yet. The retinacular arteries would be injured easily when the femoral neck fracture took place, which would cause a significant decrease in total blood flow of the femoral head. And incidence of post-traumatic femoral head necrosis was chiefly related to the remaining vascular supply to the femoral head and the ability to repair. Therefore, the treatment of femoral neck fracture should be early anatomic reduction and rigidly internal fixation .The compressed screw was used to fix the femoral neck fracture previously, all of three compressed screws needed to pass through the femoral neck marrow cavity. This would produce the femoral neck marrow disruption andthe pressure of the bone marrow cavity increased, which would add to the blood supply obstacle of the femoral head. In order to reduce the damage, this experiment improved the traditionally internal fixation, only one screw passed through the femoral neck, and two other screws did not. The purpose of this study was to compare the treatment of the femoral neck fracture using the intramedullary with extramedullary internal fixation with the traditionally internal fixation in animals and evaluate the possibility of treating femoral neck fracture with this method and provide experimental basis in clinical use.Methods: 12 goats were used in this study. They were operated into experimental modals of femoral neck displace fractures. One side of the fractures was fixed using intramedullary with extramedullary internal fixations, The other side was fixed with intramedullary internal fixation. In 12 animals with femoral neck fractures 99mTc-MDP scintimetry was performed before operation and 4, 6, 8, 12 weeks after operation. The amount of isotope uptake was estimated with the aid of a dedicated computer system. Regions of interest (ROI) of equal size were selected in the femoral head and shaft. The uptake ratios (head: shaft) were calculated. At the same time, radiograph was carried out. At 4, 8, 12 weeks 4 animals were sacrificed each time. Results were revealed in histology,radiography,scintimetry and gross observation. The functional indexes were analyzed in statistics treatments. Paired t-test was used.Results :(1) x-rays indicated that all of the femoral neck fractures, except one side, were healed. The curved screw at the femoral calcar was found in the experimental side. (2) Observed from cross-section of the femoral neck, the disruption of the marrow cavity of experimental side was less than that of the control side. (3) The blood supply to the femoral head began to be restored. The reconstructing speed of the experimental side femoral head vascular supply was faster than that of control side. The repair of bone was accelerated inthe experimental side. At 4 and 6 weeks the post-operative uptake ratios (head: shaft) of experimental side was significant greater than that of control side (P<0.01). There was the same result of observation in histology.Conclusions: The internal fixation stability of the intramedullary with extramedullary internal fixations was steadier than that of traditionally internal fixation. The intramedullary with extramedullary internal fixations method not only could reduce damage of the femoral neck marrow cavity made by the screws but also could avoided the pressure...