title: [An in vitro biomechanical evaluation of effect of augmentation pedicle screw fixation with polymethylmethacrylate on osteoporotic spine stability].
abstract: OBJECTIVE
  To ascertain whether augmentation pedicle screw fixation with polymethylmethacrylate (PMMA) can enhance the stability of unstable thoracolumbar burst fractures of osteoporotic spine.
  
  
  METHODS
  Six fresh frozen female osteoporotic spines (T10-L5) were harvested and an anterior and posterior column unstable model of L1 was made. Each specimen was fixated with plate and the stability test were performed by flexion, extension, axial rotation and lateral bending. The test of fatigue was done with MTS 858. The tests were repeated after screws were augmented with PMMA. To compare the biomechanical stability of 6 different conditions: a. normal specimens (control), b. defect model fixed with plate, not augmented and not fatigued, c. after fatigued, not augmented, d. screws augmented with PMMA, not fatigued, e. after augmented and fatigued.
  
  
  RESULTS
  In b., d. and e. conditions, the ranges of motion (ROM) were 6.23 +/- 1.56, 4.49 +/- 1.00, 4.46 +/- 1.83 in flexion and 6.60 +/- 1.80, 4.41 +/- 0.82, 4.46 +/- 1.83 in extension. There was no significant difference (P > 0.05), they were significantly smaller than those in a. and c. conditions (8.75 +/- 1.88, 1.47 +/- 2.25 and 8.92 +/- 2.97, 12.24 +/- 3.08) (P < 0.01).
  
  
  CONCLUSIONS
  The results demonstrated that augmentation pedicle screws fixation with PMMA can increase the stability of osteoporotic spine.
authors.affiliation: Department of Orthopaedic Surgery, Shajing People's Hospital, Shenzhen, Guangdong, 518104, P. R. China.
authors.forename: Shicai
authors.initials: S
authors.lastname: Fan
authors.forename: Shixue
authors.initials: S
authors.lastname: Liu
authors.forename: Yuexing
authors.initials: Y
authors.lastname: Deng
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D001843:Bone Cements; D015519:Bone Density; D001863:Bone Screws; D002102:Cadaver; D005260:Female; D006801:Humans; D016268:Internal Fixators; D008159:Lumbar Vertebrae / Q000502:physiology / Q000601:surgery*; D008875:Middle Aged; D009038:Motion; D010024:Osteoporosis / Q000503:physiopathology / Q000601:surgery*; D019904:Polymethyl Methacrylate; D011859:Radiography; D013123:Spinal Fusion / Q000295:instrumentation* / Q000379:methods; D013131:Spine / Q000000981:diagnostic imaging / Q000601:surgery; D016896:Treatment Outcome
chemical_list: D001843:Bone Cements; D019904:Polymethyl Methacrylate