title: Evaluation of delayed-image bone scintigraphy to assess bone formation after distraction osteogenesis in dogs.
abstract: OBJECTIVE
  To quantitatively assess distraction-induced bone formation in a crural lengthening model in dogs by use of delayed-image bone scintigraphy.
  
  
  METHODS
  12 mature Labrador Retrievers.
  
  
  METHODS
  Dogs were randomly allocated to 1 of 3 groups. A circular external skeletal fixation system was mounted on the right crus of each dog. Osteotomy of the distal portion of the tibia and fibula was performed in groups 1 and 2 and was followed by a lengthening procedure of 10 mm in the first group only. The third group served as sham-operated controls. Delayed-image bone scintigraphy with technetium-99m hydroxy methylene diphosphonate was performed 2, 4, and 6 weeks after surgery. Delayed-image-to-region-of-interest, delayed-image-to-crural, and delayed-image-to-femoral scintigraphic activity ratios were calculated. New bone formation was quantified by use of densitometric image analysis, and values for the scintigraphic ratios were compared.
  
  
  RESULTS
  In the distraction and osteotomy groups, delayed-image-to-region-of-interest and delayed-image-to-crural ratios increased significantly. Although densitometric image analysis revealed increased bone formation after distraction, the region-of-interest ratios and crural ratios were similar in both groups. All dogs had increased delayed-image-to-femoral ratios.
  
  
  CONCLUSIONS
  Delayed-image bone scintigraphy ratios were not effective at differentiating between the amounts of distraction-induced bone and osteotomy-induced bone. Metabolic bone activity in the adjacent femur was increased as a consequence of circular external skeletal fixator placement. Delayed-image bone scintigraphy was not adequately sensitive to quantitatively monitor bone formation but may be useful as an early predictor of bone healing.
authors.affiliation: Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands.
authors.forename: Lars F
authors.initials: LF
authors.lastname: Theyse
authors.forename: Herman A
authors.initials: HA
authors.lastname: Hazewinkel
authors.forename: Maarten
authors.initials: M
authors.lastname: Terlou
authors.forename: Yvonne W
authors.initials: YW
authors.lastname: Pollak
authors.forename: George
authors.initials: G
authors.lastname: Voorhout
mesh_terms: D000818:Animals; D004285:Dogs / Q000502:physiology*; D006614:Hindlimb / Q000254:growth & development; D010012:Osteogenesis / Q000502:physiology*; D019857:Osteogenesis, Distraction / Q000662:veterinary*; D011877:Radionuclide Imaging / Q000379:methods / Q000662:veterinary*; D019275:Radiopharmaceuticals; D013669:Technetium Tc 99m Medronate; D013997:Time Factors
chemical_list: D019275:Radiopharmaceuticals; D013669:Technetium Tc 99m Medronate