title: Sheep model for fracture treatment in osteoporotic bone: a pilot study about different induction regimens.
abstract: OBJECTIVE
  Various regimens to induce osteoporosis in sheep were compared to establish a large animal model for further studies of fracture healing and fracture treatment in severe osteoporosis.
  
  
  METHODS
  Prospective, randomized animal study (six months' duration).
  
  
  METHODS
  Eight sheep (seven to nine years old) were divided into four treatment groups of two animals each.
  
  
  METHODS
  Group 1: Ovariectomy (OVX) + calcium/vitamin D-restricted diet (O + D); Group 2: Ovariectomy + daily injection of steroids (O + S); Group 3: Ovariectomy + daily injection of steroids + calcium/vitamin D-restricted diet (O + D + S); Group 4: Control, untreated.
  
  
  METHODS
  Preoperatively and every 2 months, the bone mineral density (BMD) was determined by quantitative computed tomography (QCT) bilaterally at the distal tibia. Bone structural parameters were determined from iliac crest biopsy specimens using micro-CT. In vitro torsional stiffness of tibia segments was measured.
  
  
  RESULTS
  The control group showed a slight increase in BMD with time. The greatest decrease in BMD was seen in Group 3, with a decrease of 55 percent in cancellous bone and 7 percent in cortical bone. In the iliac crest biopsy specimens, trabecular number decreased 19 percent, trabecular thickness decreased 22 percent, and bone volume fraction decrased 37 percent during the 6 months. The torsional strength and stiffness of the tibia showed a difference of approximately 50 percent between Group 3 and the control group.
  
  
  CONCLUSIONS
  The induction of severe osteoporosis in sheep is best possible by combined treatment with ovariectomy, calcium/vitamin D-restricted diet, and steroids. There is a good relationship between density, structural parameters, and mechanical properties of bone.
authors.affiliation: AO Research Institute, Davos, Switzerland.
authors.forename: C A
authors.initials: CA
authors.lastname: Lill
authors.forename: A K
authors.initials: AK
authors.lastname: Fluegel
authors.forename: E
authors.initials: E
authors.lastname: Schneider
mesh_terms: D015502:Absorptiometry, Photon; D000818:Animals; D015519:Bone Density / Q000502:physiology; D001861:Bone Regeneration; D017610:Calcium Compounds; D003131:Combined Modality Therapy; D004032:Diet; D004195:Disease Models, Animal; D005260:Female; D005598:Fractures, Spontaneous / Q000209:etiology* / Q000628:therapy; D007085:Ilium / Q000000981:diagnostic imaging; D008297:Male; D010024:Osteoporosis / Q000139:chemically induced* / Q000150:complications* / Q000175:diagnosis / Q000628:therapy; D010052:Ovariectomy / Q000379:methods*; D010865:Pilot Projects; D011446:Prospective Studies; D011897:Random Allocation; D012016:Reference Values; D012756:Sheep; D013256:Steroids; D016896:Treatment Outcome; D014807:Vitamin D
chemical_list: D017610:Calcium Compounds; D013256:Steroids; D014807:Vitamin D