title: Enhancement of holding strength of cannulated screw supported with PMMA: a biomechanical study on femoral head [corrected].
abstract: OBJECTIVE
  The aim of this study was to evaluate the holding strength of cannulated screw with multiple holes on threaded area, supported with PMMA in femoral head.
  
  
  METHODS
  A total of 48 human femoral heads were divided into two groups after mineral density measurement with Q-CT. Seven-millimeter cannulated screws with multiple holes on threaded area supported with PMMA were used in the study group, while in the control group standard 7-mm cannulated screws were used. Each group was divided into three subgroups with eight femoral heads. Mineral density of each subgroup was equal to the other. Groups were compared in terms of pull-out, maximum extraction torque and cut-out.
  
  
  RESULTS
  In pull-out group, maximum holding strength (N) was measured, while axial pull-out of 0.5 mm/sec applied with Instron. Results showed meaningful significant difference (p < 0.011) between two groups. In cut-out group, femoral heads were placed into Instron and loading was started from 5 N at 2 mm per minute at first, and it was continued until a failure, at least 5 mm, of implant was observed. Results showed significant difference (p < 0.05) between two groups. In maximum extraction group, 4° per second reverse torque (Nm) was applied with torque meter. Highest torque value was measured during extraction time, and results showed very significant difference (p < 0. 001) between two groups.
  
  
  CONCLUSIONS
  The results of our new design of cannulated screw augmented with PMMA provided background data to clinical application.
authors.affiliation: Clinic of Orthopaedics and Traumatology, Baku Medical Plaza Hospital, Baku, Azerbaycan.
authors.forename: Reşad
authors.initials: R
authors.lastname: Zeynalov
authors.forename: İsmail
authors.initials: İ
authors.lastname: Ağır
authors.forename: Ahmet Hamdi
authors.initials: AH
authors.lastname: Akgülle
authors.forename: Barış
authors.initials: B
authors.lastname: Kocaoğlu
authors.forename: Mithat Selim
authors.initials: MS
authors.lastname: Yalçın
mesh_terms: D001696:Biomechanical Phenomena; D001843:Bone Cements / Q000627:therapeutic use*; D015519:Bone Density; D001863:Bone Screws; D005270:Femur Head / Q000503:physiopathology / Q000601:surgery*; D006801:Humans; D019904:Polymethyl Methacrylate / Q000627:therapeutic use*; D013314:Stress, Mechanical; D019415:Torque
chemical_list: D001843:Bone Cements; D019904:Polymethyl Methacrylate