title: Bone marrow fat cell enlargement and a rise in intraosseous pressure in steroid-treated rabbits with osteonecrosis.
abstract: The etiology of steroid-induced osteonecrosis (ON) is unclear. This study was designed to determine whether bone marrow fat cell size, intraosseous pressure, and blood flow rate differed between steroid-treated rabbits with ON and those without. Twenty-nine rabbits were intramuscularly injected once with 20 mg/kg of methylprednisolone acetate (MPSL), and five rabbits were injected once with physiologic saline (PS) as a control. Intraosseous pressure and blood flow rate in the proximal femur were determined before and at 2 weeks after the injection. After these measurements, both femora and humeri were histopathologically examined for the presence of ON, and size of bone marrow fat cells were morphologically examined. At 2 weeks after steroid injection, the intraosseous pressure was significantly higher in rabbits with ON than in those without (p = 0.0251), and the blood flow rate had decreased significantly more in rabbits with ON than in those without (p = 0.0051). The size of the bone marrow fat cells was significantly (p = 0.0004) larger in rabbits with ON (diameter, 63.5 +/- 5.8 microm) than in those without (diameter, 53.3 +/- 6.9 microm). Injection of PS (5 rabbits), 1 (10 rabbits), 5 (10 rabbits), and 20 (10 rabbits) mg/kg of body weight of MPSL showed that a larger dose of steroid increased both fat cell size and prevalence of ON. These results suggest that bone marrow fat cell enlargement and a rise in intraosseous pressure may be important when considering the pathophysiology of steroid-induced ON in rabbits.
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Miyanishi
authors.forename: T
authors.initials: T
authors.lastname: Yamamoto
authors.forename: T
authors.initials: T
authors.lastname: Irisa
authors.forename: A
authors.initials: A
authors.lastname: Yamashita
authors.forename: S
authors.initials: S
authors.lastname: Jingushi
authors.forename: Y
authors.initials: Y
authors.lastname: Noguchi
authors.forename: Y
authors.initials: Y
authors.lastname: Iwamoto
mesh_terms: D017667:Adipocytes / Q000187:drug effects / Q000473:pathology*; D000818:Animals; D001783:Blood Flow Velocity / Q000187:drug effects; D001854:Bone Marrow Cells / Q000187:drug effects / Q000473:pathology*; D048429:Cell Size / Q000187:drug effects; D004195:Disease Models, Animal; D005269:Femur / Q000098:blood supply / Q000187:drug effects / Q000503:physiopathology; D008297:Male; D008775:Methylprednisolone / Q000031:analogs & derivatives* / Q000633:toxicity; D000077555:Methylprednisolone Acetate; D010020:Osteonecrosis / Q000139:chemically induced / Q000473:pathology* / Q000503:physiopathology*; D011312:Pressure; D011817:Rabbits
chemical_list: D000077555:Methylprednisolone Acetate; D008775:Methylprednisolone