title: The biomechanical effect and clinical application of a Ni-Ti shape memory expansion clamp.
abstract: METHODS
  The study involves three phases: a clinical study of 30 patients, a biomechanical study to assess the expansion force of a recovering-shape memory expansion clamp, and a biomechanical study using cadaveric specimens to assess the pullout strength of the shape memory expansion clamp as a function of the shape of the clamp.
  
  
  OBJECTIVE
  To evaluate the biomechanical effect and clinical application of the shape memory expansion clamp.
  
  
  BACKGROUND
  The major complication of anterior cervical decompression and fusion was graft dislodgement and pseudarthrosis. Improvement of the shape of bone graft and fusion technique could not eliminate the problem completely. The authors designed the shape memory expansion clamp by using the characteristic of Ni-Ti shape memory alloy and first applied it in an anterior cervical operation.
  
  
  METHODS
  The expansion force of recovering of the shape memory expansion clamp was measured in a biomechanical study. Eight fresh human cadaver cervical spine specimens were used to assess the pullout strength of the shape memory expansion clamp as a function of the shape of the clamp. The shape memory expansion clamp had been used to fix rotated circular grafts in 30 cases with cervical spine injuries or cervical spondylosis after anterior decompression.
  
  
  RESULTS
  The expansion force of the shape memory expansion clamp in recovery was 4.65-27.96 N, and the pullout strength was 8.82-20.58 N. Bone fusion was achieved in all 30 cases. Dislocation of bone graft, loosening of clamp, or kyphotic deformity had not occurred.
  
  
  CONCLUSIONS
  The expansion force and the pullout strength of the partially recovered shape memory expansion clamp were determined biomechanically. The clinical study demonstrated that the shape memory expansion clamp is safe and effective.
authors.affiliation: Department of Orthopedics, Xinqiao Hospital, Third Military Medical University, Chongqing, China.
authors.forename: F
authors.initials: F
authors.lastname: Mei
authors.forename: X
authors.initials: X
authors.lastname: Ren
authors.forename: W
authors.initials: W
authors.lastname: Wang
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging / Q000293:injuries* / Q000503:physiopathology; D005069:Evaluation Studies as Topic; D005260:Female; D005593:Fracture Fixation, Internal / Q000295:instrumentation*; D006801:Humans; D016268:Internal Fixators; D008297:Male; D008875:Middle Aged; D016103:Spinal Fractures / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome