The Experimental Study On Biomechanics Of Sliding Bone Graft

Objective: In the study, discussion on the best methods of the sliding bone graft by researching the ratio of arc length of the grooved bone block and circumference of femor at the fracture line and the grooved bone block the fixation methods which have an effect on the stability of the fractures fixation provides the theory for the clinic.With the rapid expansion of the traffic and economy, high energy injury bring about more and more patients with complicated wound, III degree open fractures or comminuted fractures. Wrong selection of the treatment methods and prematurity of weight-bearing exercise increase the amount of the patients with delay union, nonunion, and even permanent disability. Nonunion is one of the frequent complications, with the incidence rate 5% to 10%, which has become a big problem for the orthopedist. The cause of nonunion is complicated.There are many factors, and it is hard to treat, frequently secondary operation is needed, which brings large damage to the spirit, physiology and economy of the patients. The cause for nonunion involves local blood supply, infection, bone facture and soft tissue injure being severe and stress interference. For the patients with nonunion, the broken ends of fractured bone often encounter bone resorption, ends hardening, pulp cavity closure, consequently disunion is found in some patients. For the past few years, a good many researchs have been carried on nonunion. Therefore the knowledge of nonunion is deepened, therapeutic tool gets renewal, and the therapy results is improved. Now clinical treatments for nonunion involves cutting and refreshing the ends of fractured bone, reposition, stably fixation and bone grafting. Bone grafting is a effective methods for nonunion. Nowadays there are many bone grafting style, such as the fracture bone ends surrounding bone grafting, attachment bone grafting, percataneous marrow injection, spongy bone insert bone grafting, sliding bone graft, muscle bone stem bone grafting, mobilized bone with blood vessel stem bone grafting and so on. Sliding bone graft has unique superiority in treating nonunion. This study is to explore the best groove methods for sliding bone graft through the biomechanical experiment, and to provide reference data for clinical treatment.Methods:1 The biomechanical experiment on the three different ratios between the arc length of grooved bone block and circumference of femor at the fracture line30 fresh isolated porcine shaft of femur specimen were selected. The muscle and soft tissues were rejected. And visual study and X-ray films were taken to preclude destruction of bone, tumor, tubercle, anatomical variations and so on. Radish fractures were made artificially between middle and inferior segments. Fixed the femur laterally with the plate. The specimen were divided to 3 groups at random, with 10 per group. Bilateral groove was made at ventri-broken ends of the fracture femur, and the two sides had different length, the length of the shorter is the diameter of the femor at the fracture, and the longer is 2 times the shorter. The ratios of the grooved bone block's arc length and circumference of femor at the fracture line were 1/5,1/4 and 1/3 respectively. Transpositon was made, and the longer grooved bone block was made stepping over the fracture line. The femur was fixed with self-made tongs. The specimen were put in CSS-44020 biomechanics experiment machine, and tested by vertical compression and three-point bending mechanical property, and the homologus load and displacement. Experimental data was analyzed by statistics software SPSS17.0.2 The biomechanical experiment on grooved bone blocks with none fixation, screw fixation and plate fixation20 fresh isolated porcine shaft of femur specimen were selected. The muscle and soft tissues were rejected. And visual study and X-ray films were taken to preclude destruction of bone, tumor, tubercle, anatomical variations and so on. Radish fractures were made artificially between middle and inferior segments. Fixed the femur laterally with the plate. The specimen were divided to 2 groups at random, with 10 per group. The specimen were grooved with the best ratios of the first experimental results. The grooved bone blocks of the first group were fixed with screws and the second group were fixed with plates. The experimental data of grooved bone block with none fixation was used first experimental data. The femur was fixed with self-made tongs. The specimen were put in CSS-44020 biomechanics experiment machine, and tested by vertical compression and three-point bending mechanical property, and the homologus load and displacement. Experimental data was analyzed by statistics software SPSS17.0.Results:1 the biomechanical experiment on the three different ratios between the arc length of grooved bone block and circumference of femor at the fracture lineWe found that: At the vertical compress load of 600N, the comparison has no significant difference(P>0.05). At the three-point bending load of 250N: On the inside, the comparison among the three groups has no significant difference (P>0.05); On the outside, the comparison among the three groups has no significant difference (P>0.05); On the front side, the comparison among the three groups has no significant difference (P>0.05); On the behind side, the comparison between 1/5 group and 1/4 group has no significant difference (P>0.05), but the comparison between 1/5, 1/3 and 1/4 group has significant difference(P<0.05), the 1/5 group and 1/4 group is better than the 1/3 group.2 The biomechanical experiment on grooved bone block with none fixation, screw fixation and plate fixationWe found that: At the vertical compress load of 600N, the comparison has no significant difference(P>0.05). At the three-point bending load of 250N: On the inside, the comparison among the three groups has no significant difference (P>0.05); On the outside, the comparison between the group of screw fixation and the group of plate fixation has no significant difference (P>0.05), the comparison between the groups of screw fixation, plate fixation and the group of none fixation has significant difference(P<0.05), the groups of screw fixation and plate fixation are better than the group of none fixation; On the front side, the comparison between the group of screw fixation and the group of plate fixation has no significant difference (P>0.05), the comparison between the groups of screw fixation, plate fixation and the group of none fixation has significant difference(P<0.05), the groups of screw fixation and plate fixation are better than the group of none fixation; On the behind side, the comparison between the group of none fixation and the group of screw fixation has no significant difference (P>0.05), the comparison between the groups of none fixation, screw fixation and the group of plate fixation has significant difference (P<0.05), the group of plate fixation is batter than the groups of none fixation and screw fixation.Conclusion:1 It can gain a good biomechanical stability when the ratio of the arc length of the grooved bone block and the circumference of femor at the fracture line of the femur are 1/4 and 1/5.2 The grooved bone block with plate fixation is the best, the second is screw fixation, and the grooved bone block with none fixation is poor.