title: Changes over time in callus formation caused by intermittently administering PTH in rabbit distraction osteogenesis models.
abstract: BACKGROUND
  Changes over time in the callus during intermittent administration of parathyroid hormone (PTH) were studied in rabbit distraction osteogenesis models.
  
  
  METHODS
  Models of distraction osteogenesis in Japanese white rabbits were created, and distraction osteogenesis (total length: 10.5 mm) was performed for 2 weeks. Simultaneously with the start of distraction, 30 rabbits received 4 weeks of subcutaneous administration of 30 μg/kg of PTH(1-34), teriparatide, (P-group: n = 15) or saline (N-group: n = 15) every other day. The tibias of five rabbits were dissected at 6, 8, and 10 weeks after surgery to perform bone mineral density (BMD), peripheral quantitative computed tomography (pQCT), and mechanical testing.
  
  
  RESULTS
  The mean BMD had no significant differences over time at 6, 8, and 10 weeks after surgery between the P-group and the N-group. On pQCT, the P-group had significant increases in total bone cross-sectional area of the callus compared to the N-group at 8 and 10 weeks after surgery. On mechanical testing, the P-group's absorption energy had not changed at 6 weeks after surgery compared to the N-group, but it had significantly increased at 8 weeks. At 10 weeks after surgery, the N-group's absorption energy rapidly increased, and the difference between the two groups disappeared.
  
  
  CONCLUSIONS
  The intermittent administration of PTH(1-34), teriparatide, for 4 weeks every other day from the start of distraction had the potential to shorten the callus maturation period in the rabbit distraction osteogenesis models.
authors.affiliation: Kyorin University, School of Medicine, 6-20-2 Sinkawa, Mitaka, Tokyo, 181-8611, Japan. ohh.tetsu@hotmail.co.jp.
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Ohata
authors.affiliation: Kyorin University, School of Medicine, 6-20-2 Sinkawa, Mitaka, Tokyo, 181-8611, Japan. maruizo@yahoo.co.jp.
authors.forename: Hideto
authors.initials: H
authors.lastname: Maruno
authors.affiliation: Kyorin University, School of Medicine, 6-20-2 Sinkawa, Mitaka, Tokyo, 181-8611, Japan. ichimura@ks.kyorin-u.ac.jp.
authors.forename: Shoichi
authors.initials: S
authors.lastname: Ichimura
mesh_terms: D000818:Animals; D015519:Bone Density / Q000187:drug effects; D050071:Bone Density Conservation Agents / Q000008:administration & dosage*; D002146:Bony Callus / Q000000981:diagnostic imaging / Q000187:drug effects*; D004353:Drug Evaluation, Preclinical; D023421:Models, Animal; D019857:Osteogenesis, Distraction; D011817:Rabbits; D019379:Teriparatide / Q000008:administration & dosage*; D014057:Tomography, X-Ray Computed; D016474:Weight-Bearing
chemical_list: D050071:Bone Density Conservation Agents; D019379:Teriparatide