Objective To explore the biomechanical stabil ity of dynamic sleeve three-wing screw for treatment of femoral neck fracture and to provide theoretical basis for choosing dynamic sleeve three-wing screw in cl inical appl ication. Methods Nine human cadaveric femurs were selected and divided randomly into 3 groups (n=3), excluding deformities, fractures, and other lesions. The central neck of the specimens were sawn with hand saw respectively at Pauwels angles of 30, 50, and 70°. All cut ends were fixed with dynamic sleeve three-wing screw. Instron-8874 servohydraul ic mechanical testing machine was used to fixed the specimens which simulated uni ped standing, at the rate of 10 mm/minute and l inear load 0-1 200 N at 11 key points. The strain values of princi pal pressure side and princi pal tension side under different loads were measured. Results There was a peak at 6th point in the 1 200 N load. The strain values at Pauwels angles of 30, 50, and 70° were (—1 657 ± 171), (—1 879 ± 146), and (—2 147 ± 136) με; showing significant differences (P lt; 0.01). The strain values of princi pal pressure side and princi pal tension side of the femoral neck became higher with the increasing Pauwels angle under the same load, showing significant differences (P lt; 0.01). The strain values became higher with the increasing load under the same Pauwels angle (P lt; 0.01). Conclusion Dynamic sleeve three-wing screw has good biomechanical stabil ity for treatment of femoral neck fracture. It explains theoretically that the fracture is more unstable with the increasing Pauwels angle．
