Study On Biomechanical Characters And Clinical Value Of Revolving Self-lock Nail Versus Normal Two Operative Therapy For Humeral Shaft Fracture

Objective:The treatment of the humeral shaft fracture is the debating focus in clinical study .The object was to evaluate the biomechanical characters and clinical value of revolving self-lock nail (RSLN) versus 1ocked intramedullary nail(LIN)and dynamic compressive plate(DCP) so as to Find an effective methods for the treatment of humeral shaft fractures.Methods:(1)Biomechanical Experiment: 12 humerus specimens picked out the flexible tissue and the other disease were divided into three groups randomly, each of which was made into the same standard humeral shaft fracture models and was internally fixed by RSLN, LIN and DCP respectively. Axial compression test, three-point bend test and twist test were made and the results were got and analyzed.(2)Clinical material: 89 patients were treated humeral shaft fracture in our hospital from september,2004 to December,2006.All patients were respectively treated with one of 3 internal fixations.30 cases were stabilized with RSLN, 35 cases DCP, and 24 cases LIN. The three groups were compared for operative time ,volume of blood loosing , fracture healing time and healing rate, postoperative complications, the functional results of shoulder and elbow joint.Result:(1)Experiment results: It indicated that RSLN was poorer to LIN after axial compression test ,anti-twist test except three-point bend test, but the biomechanical effect of fixing humeral shaft fracture with RSLN is better than that of DCP ,and its stress shielding rate is lowest, which might meet biomechanic needs.(2)Clinical outcomes: All patients were followed up for 9～24 months ,mean 16 months. The operation time, volume of blood, fracture healing time and healing rate, postoperative complications of RSLN groups were shorter than that of DCP and LIN groups(p<0.05).The functional results of shoulder and elbow joint in RSLN groups were superior to those in LIN groups (p<0.05) ,but had no obvious difference with those in DCP groups (p>0.05) .Conclusion:The design of RSLN accords with the humerus medullary cavity shape and biomechanics of human body, and a new kind of intramedullary nails which has good properties of flexible fixation and firm fixation. It can diminish the stress shelding and allow functional exercises early ,and has many other advantages, such as less trauma and good results, reasonable structure and simple manipulation,without X-ray guidance。SLIN is an effective method for the treatment of humeral shaft fractures and worthy of popularization.