Nickel-titanium Memory Alloy Development And Fork Wrist Scaphoid Internal Fixation Biomechanical Testing

[objective]to design a new internal fixator for scaphoid waist fractures-Nickel titanium memory alloy fork scaphoid internal fixation (Nickel titanium memory alloy fork scaphoid internal fixation, NT-SAF), and carries on the biomechanical test. For new design rationality of the holder and further clinical application to provide the corresponding clinical basis.[method]1.48adult dry hand navicular and36blocks of adult wet hand navicular bone specimens, carefully observe its morphology and blood pressure trace, vernier caliper parts of the scaphoid measurement in detail, in the process of the anatomical observation of wrist joint anatomical structure, to hand scaphoid fracture internal fixation devices and surgical approaches of internal fixation devices to provide anatomical basis.2. According to the specimen measured by experimental data, the size of the design of general adult scaphoid fork Nitinol alloy scaphoid fracture internal fixation, and additional can effectively enhance the fixed effects and resistance to use design of tooth hooked a rotating shift.3. The biomechanical strength experiment:take32specimens of adult scaphoid, simulate the scaphoid waist fractures, randomly divided into4groups (n=8); Needle was respectively using intramedullary fixation (group A), gram the place needle screw fixation (group B), Herbert screw fixation (group C) and the NT-SAF fixed (group D), scaphoid fracture reduction and internal fixation, and test the fixed strength. Fatigue experiments:24adult upper limb specimens (elbow), simulation of scaphoid waist fractures, were randomly divided into3groups (n=8); Needle was separately in the place nail fixation group (E). Herbert screw fixation (group F) and the NT-S AF fixed group (G), on the wrist of applying98n vertical longitudinal compressive load, and simulate the wrist flexion, back stretch movement, movement range for palm bow might30°,5°～in100,500,1500and2000times the separation and lateral displacement is measured with the distance.[results]strength experiment:A, B, C, D group specimen fracture separation of1mm and2mm clearance required traction respectively (15.14+/-0.29),(20.34-0.43):(36.11+/-0.37),(76.11-0.52) and N (64.89+0.55),(120.73-0.60);(65.62+/-0.62),(130.15-0.54) N, compared with A, B group, group D each index difference had statistical significance (P<0.05), there was no statistically significant difference between the D and C group (P>0.05). Fatigue experiments:group G fracture end of shifting the separation distance compared with group E, F, each index difference had statistical significance (P<0.05). Wrist joint circular movement after500, there have "steps" group G scaphoid fracture displacement were compared with group E, the difference had statistical significance (P<0.05); Wrist joint circular movement after1500times, compared with group F, G group differences were statistically significant (P<0.05).[Conclusion]1. The nickel titanium memory alloy fork scaphoid internal fixation (NT-SAF) biomechanical properties can meet the clinical application.2. The NT-SAF conforms to the wrist scaphoid anatomical features, the complex shape-a lever structure can effectively fixed scaphoid fracture end, and two-way pressure, unique additional on the arm of the barb dentate to further strengthen the stability of the fixed structure, and prevent the effect of rotating shift.