title: Effects of cyclosporin A on the development of osteonecrosis in rabbits.
abstract: BACKGROUND
  Osteonecrosis (ON) of the femoral head is a serious complication in patients who have undergone organ transplantation. Introduction of cyclosporin A has resulted in lower-dosage steroid treatment and a decrease in the occurrence of ON. We examined the effect of cyclosporin A on the development of ON in rabbits.
  
  
  METHODS
  In experiment A, rabbits were given cyclosporin A and 20 mg/kg methylprednisolone acetate. The control group was given 20 mg/kg methylprednisolone acetate only. Experiment B was then performed to mimic the clinical situation in which the use of cyclosporin A and lower steroid doses resulted in a decrease in occurrence of ON. In Experiment C, the effects of treatment with cyclosporin A only on development of ON were examined. 4 weeks after injection, bilateral femora and humeri were examined histopathologically for ON.
  
  
  RESULTS
  Cyclosporin A increased the incidence of ON in rabbits when given in combination with steroid (p = 0.04). No ON lesions were observed in rabbits treated with cyclosporin A alone.
  
  
  CONCLUSIONS
  Our findings suggest that the clinically reported reduction in occurrence of ON following the use of cyclosporin A is probably attributable to the lower steroid doses used.
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kyushu University, Higashi-ku, Fukuoka, 812-8582, Japan. keitamiya@jcom.home.ne.jp
authors.forename: Keita
authors.initials: K
authors.lastname: Miyanishi
authors.forename: Takuaki
authors.initials: T
authors.lastname: Yamamoto
authors.forename: Takahiko
authors.initials: T
authors.lastname: Irisa
authors.forename: Akihisa
authors.initials: A
authors.lastname: Yamashita
authors.forename: Goro
authors.initials: G
authors.lastname: Motomura
authors.forename: Seiya
authors.initials: S
authors.lastname: Jingushi
authors.forename: Yukihide
authors.initials: Y
authors.lastname: Iwamoto
mesh_terms: D000818:Animals; D016572:Cyclosporine / Q000008:administration & dosage*; D004305:Dose-Response Relationship, Drug; D005271:Femur Head Necrosis / Q000139:chemically induced / Q000209:etiology* / Q000517:prevention & control; D005938:Glucocorticoids / Q000008:administration & dosage; D007166:Immunosuppressive Agents / Q000008:administration & dosage*; D008775:Methylprednisolone / Q000008:administration & dosage; D016377:Organ Transplantation / Q000009:adverse effects*; D011817:Rabbits
chemical_list: D005938:Glucocorticoids; D007166:Immunosuppressive Agents; D016572:Cyclosporine; D008775:Methylprednisolone