title: [Biomechanical research of dynamic sleeve three-wing screw in fixing femoral neck fracture of different angles].
abstract: OBJECTIVE
  To explore the biomechanical stability 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 clinical application.
  
  
  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 degrees. All cut ends were fixed with dynamic sleeve three-wing screw. Instron-8874 servohydraulic mechanical testing machine was used to fixed the specimens which simulated united standing, at the rate of 10 mm/minute and linear load 0-1200 N at 11 key points. The strain values of principal pressure side and principal tension side under different loads were measured.
  
  
  RESULTS
  There was a peak at 6th point in the 1200 N load. The strain values at Pauwels angles of 30, 50, and 70 degrees were (-1657 +/- 171), (-1879 +/- 146), and (-2147 +/- 136) microepsilon; showing significant differences (P < 0.01). The strain values of principal pressure side and principal tension side of the femoral neck became higher with the increasing Pauwels angle under the same load, showing significant differences (P < 0.01). The strain values became higher with the increasing load under the same Pauwels angle (P < 0.01).
  
  
  CONCLUSIONS
  Dynamic sleeve three-wing screw has good biomechanical stability for treatment of femoral neck fracture. It explains theoretically that the fracture is more unstable with the increasing Pauwels angle.
authors.affiliation: Department of Orthopaedics, General Hospital of Tianjin Medical University, Tianjin, 300052, P.R. China. yangyang-8686@163.com
authors.forename: Yang
authors.initials: Y
authors.lastname: Yang
authors.forename: Xinlong
authors.initials: X
authors.lastname: Ma
authors.forename: Jianxiong
authors.initials: J
authors.lastname: Ma
authors.forename: Zhibin
authors.initials: Z
authors.lastname: Wang
authors.forename: Baoyi
authors.initials: B
authors.lastname: Ma
mesh_terms: D001696:Biomechanical Phenomena; D001863:Bone Screws; D005265:Femoral Neck Fractures / Q000601:surgery*; D005593:Fracture Fixation, Internal / Q000295:instrumentation*; D006801:Humans; D016268:Internal Fixators; D008875:Middle Aged