title: Teriparatide increases the insertional torque of pedicle screws during fusion surgery in patients with postmenopausal osteoporosis.
abstract: OBJECTIVE
  The object of this study was to examine the efficacy of preoperative teriparatide treatment for increasing the insertional torque of pedicle screws during fusion surgery in postmenopausal women with osteoporosis.
  
  
  METHODS
  Fusion surgery for the thoracic and/or lumbar spine was performed in 29 postmenopausal women with osteoporosis aged 65-82 years (mean 72.2 years). The patients were divided into 2 groups based on whether they were treated with teriparatide (n = 13) or not (n = 16) before the surgery. In the teriparatide-treated group, patients received preoperative teriparatide therapy as either a daily (20 μg/day, n = 7) or a weekly (56.5 μg/week, n = 6) injection for a mean of 61.4 days and a minimum of 31 days. During surgery, the insertional torque was measured in 212 screws inserted from T-7 to L-5 and compared between the 2 groups. The correlation between the insertional torque and the duration of preoperative teriparatide treatment was also investigated.
  
  
  RESULTS
  The mean insertional torque value in the teriparatide group was 1.28 ± 0.42 Nm, which was significantly higher than in the control group (1.08 ± 0.52 Nm, p < 0.01). There was no significant difference between the daily and the weekly teriparatide groups with respect to mean insertional torque value (1.34 ± 0.50 Nm and 1.18 ± 0.43 Nm, respectively, p = 0.07). There was negligible correlation between insertional torque and duration of preoperative teriparatide treatment (r(2) = 0.05, p < 0.01).
  
  
  CONCLUSIONS
  Teriparatide injections beginning at least 1 month prior to surgery were effective in increasing the insertional torque of pedicle screws during surgery in patients with postmenopausal osteoporosis. Preoperative teriparatide treatment might be an option for maximizing the purchase of the pedicle screws to the bone at the time of fusion surgery.
authors.affiliation: Department of Orthopaedic Surgery, Kitasato University School of Medicine, Sagamihara, Kanagawa;
authors.forename: Gen
authors.initials: G
authors.lastname: Inoue
authors.forename: Masaki
authors.initials: M
authors.lastname: Ueno
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Nakazawa
authors.forename: Takayuki
authors.initials: T
authors.lastname: Imura
authors.forename: Wataru
authors.initials: W
authors.lastname: Saito
authors.forename: Kentaro
authors.initials: K
authors.lastname: Uchida
authors.forename: Seiji
authors.initials: S
authors.lastname: Ohtori
authors.forename: Tomoaki
authors.initials: T
authors.lastname: Toyone
authors.forename: Naonobu
authors.initials: N
authors.lastname: Takahira
authors.forename: Masashi
authors.initials: M
authors.lastname: Takaso
mesh_terms: D015502:Absorptiometry, Photon; D000368:Aged; D000369:Aged, 80 and over; D015519:Bone Density; D050071:Bone Density Conservation Agents / Q000627:therapeutic use*; D001863:Bone Screws; D005260:Female; D006801:Humans; D008159:Lumbar Vertebrae / Q000601:surgery; D015663:Osteoporosis, Postmenopausal / Q000188:drug therapy* / Q000601:surgery*; D013123:Spinal Fusion / Q000379:methods*; D019379:Teriparatide / Q000627:therapeutic use*; D013904:Thoracic Vertebrae / Q000601:surgery; D019415:Torque; D016896:Treatment Outcome
chemical_list: D050071:Bone Density Conservation Agents; D019379:Teriparatide
keywords: BMD = bone mineral density; PINP = procollagen Type I N-propeptide; PTH = parathyroid hormone; fusion surgery; insertional torque; osteoporosis; pedicle screw; technique; teriparatide