title: An experimental study on transpedicular screw fixation in relation to osteoporosis of the lumbar spine.
abstract: In order to elucidate the relationship between the severity of osteoporosis and the fixation strength of a pedicle screw, screw pull-out tests were performed using cadaveric lumbar vertebrae. The severity of osteoporosis was evaluated by the Jikei osteoporosis grading scale (Jikei method), bone mineral density, and microdensitometry. When a 7.0-mm screw was used, the pull-out force of the screw was 1,056.4 N in the normal group (as determined by the Jikei method), while it was 495.6 N in the Grade I osteoporosis and 269.5 N in the Grade II osteoporosis groups, respectively. There were also positive correlations between the pull-out force and bone mineral density and each parameter of the microdensitometry method. When bone cement was used in an osteoporotic vertebra, twofold stronger pull-out force was obtained in comparison to that obtained without bone cement.
authors.affiliation: Department of Orthopaedic Surgery, Jikei University School of Medicine, Tokyo, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Soshi
authors.forename: R
authors.initials: R
authors.lastname: Shiba
authors.forename: H
authors.initials: H
authors.lastname: Kondo
authors.forename: K
authors.initials: K
authors.lastname: Murota
mesh_terms: D000368:Aged; D001696:Biomechanical Phenomena; D001843:Bone Cements; D001863:Bone Screws; D002102:Cadaver; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D008159:Lumbar Vertebrae / Q000601:surgery*; D008297:Male; D010024:Osteoporosis / Q000503:physiopathology / Q000601:surgery*; D013123:Spinal Fusion / Q000295:instrumentation
chemical_list: D001843:Bone Cements