Takuaki Yamamoto

Subchondral insufficiency fracture of the femoral head in younger adults

We report two cases of subchondral insufficiency fracture of the femoral head observed in younger adults without any history of overexertion. In both cases, MRI revealed an irregular, discontinuous low-intensity band on the T1-weighted images. Both patients were treated operatively, and histological examination confirmed the diagnosis of subchondral fracture. A diagnosis of subchondral insufficiency fracture needs to be put in as one of the diagnoses in younger patients with a hip pain.

Dose effects of corticosteroids on the development of osteonecrosis in rabbits.

Objective The relationship between dose of corticosteroids and the prevalence of osteonecrosis (ON) has not been established. We examined the dose effects of corticosteroids on the development of ON in a rabbit model. Methods Rabbits were injected once intramuscularly with 1 (12 rabbits), 5 (12 rabbits), 20 (20 rabbits), and 40 (25 rabbits) mg/kg of methylprednisolone acetate (MPSL) into the right gluteus medius muscle. Four weeks after the MPSL injection, the proximal and distal parts of both the femora and humeri were histopathologically examined for the presence of ON. Hematological examinations were performed before and after the corticosteroid injection. Results In rabbits with 1, 5, 20, and 40 mg/kg MPSL, the incidence of ON was 0, 42%, 70%, and 96%, respectively. The dose of MPSL showed a significant association with the incidence of ON. Histologically, reparative tissues around the ON sites were observed in the rabbits with 5 mg/kg MPSL, but not observed in rabbits with 20 and 40 mg/kg MPSL. On hematological examination, hyperlipidemia and thrombocytopenia were most apparent in the rabbits receiving 40 mg/kg MPSL. Conclusion The study suggested that the dose of corticosteroids plays an important role in the development of ON in rabbits. The repair process was also found to be influenced by the dose of corticosteroids. Corticosteroid-induced hyperlipidemia and thrombocytopenia seemed to be associated with the incidence of ON.

Subchondral insufficiency fracture of the femoral head in a patient with systemic lupus erythematosus

Osteonecrosis of the femoral head (ON) has been recognised as a relatively common complication in patients with systemic lupus erythematosus (SLE) who have received corticosteroids, with a reported prevalence of around 30%.1 Recently, subchondral insufficiency fracture of the femoral head (SIF) has been reported as a differential diagnosis in patients suspected of having osteonecrosis.2–4 We describe the clinicopathological features of a patient with SLE with a history of corticosteroid treatment, who developed SIF.nnA 55 year old woman had a 32 year history of SLE, which had been treated with corticosteroids (8 mg/day). She had a history of hypothyroidism, arthritis in both shoulders, skin rash, pericarditis, and pleuritis, but had no history of smoking or drinking. The body mass index indicated she was overweight (27.4 kg/m2).nnOver the past 5 years she had developed stiffness and discomfort in the right hip, and over the past 2 months the hip pain had got worse. …

Effects of cyclosporin A on the development of osteonecrosis in rabbits.

Backgroundu2003Osteonecrosis (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. Methodsu2003In 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. Resultsu2003Cyclosporin 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. Interpretationu2003Our 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.

Rapid destruction of the hip joint in osteoarthritis

Rapidly destructive arthrosis of the hip joint (RDA) is commonly seen in elderly females with unilateral involvement, which has been reported to occur in a joint that initially appears normal.1–3 We describe a case of osteoarthritis, which underwent rapid destruction of the hip joint over a period of 2 months.nnA 62-year-old woman presented with mild left hip pain of recent onset. Her height was 157 cm and body weight was 49 kg. Her body mass index indicated she was in the normal range (19.9 kg/m2). No evidence of infection, inflammatory arthropathies or neuropathy was noted. She had a history of Hashimoto disease, asthma …

Risk factors for developing osteonecrosis after prophylaxis in steroid-treated rabbits.

Objective Both abnormal lipid metabolisms and coagulopathy have been suggested to be associated with the development of steroid-induced osteonecrosis (ON). We examined plasma risk factors for development of steroid-induced ON in rabbits after prophylaxis with a lipid-lowering agent and/or an anticoagulant. Methods Seventy adult male rabbits were injected intramuscularly once with 20 mg/kg methylprednisolone acetate. Fifty-five rabbits received prophylaxis with probucol (a lipid-lowering agent; n = 20) or warfarin (an anticoagulant; n = 14) or both (n = 21). Probucol and warfarin were administered beginning 1 to 2 weeks prior to steroid injection. Two weeks after steroid injection, the bilateral femora and humeri were examined histopathologically for the presence of ON. Based on a logistic regression model, laboratory variables before steroid injection were assessed to determine whether they demonstrated any association with the risk of ON. Results Twenty-one rabbits developed ON. In the univariate analyses, significant positive associations were observed between plasma concentrations of triglyceride and low-density lipoprotein and the risk of development of ON. In the multivariate model, only the plasma triglyceride level suggested a positive association. Even after adjusting for probucol and warfarin use, the plasma triglyceride level was still suggested to be a predictor for development of ON. Rabbits with higher baseline triglyceride levels had a more pronounced triglyceride increase in their response to steroids. Conclusion Our study suggests that, after prophylaxis with probucol and/or warfarin, plasma triglyceride level is associated with the development of steroid-induced ON in rabbits.

Effects of Tacrolimus (FK506) on the Development of Osteonecrosis in a Rabbit Model

The present study examined the effects of tacrolimus (FK506) on the development of osteonecrosis in rabbits. In Experiment A, rabbits were given FK506, and also given a single dose of steroid. Control rabbits were given the same dose of steroid only. In Experiment B, rabbits were given FK506 and a reduced dose of steroid. The results showed that addition of FK506 did not change the number of rabbits with osteonecrosis when an identical steroid dose was given. When the steroid dose was reduced, the osteonecrosis incidence significantly decreased (p < 0.01). These results suggest that the clinically reported decrease in the osteonecrosis incidence following the introduction of FK506 is most likely attributable to the lower doses of steroids.

Early MRI findings of the acetabulum and femoral head in a dysplastic hip resulting in a rapid destruction of the hip joint

We documented a case of rapidly destructive arthrosis of the hip joint (RDA), in whom abnormal findings were observed not only in the femoral head but also in the acetabulum on magnetic resonance images (MRI) in the early stage. Radiographs made 1xa0month after the onset of pain showed a slight narrowing of the joint space. MRI obtained 2xa0months after the onset detected small foci of low signal intensity in the subchondral area of the femoral head on the T1-weighted images, and a linear pattern of high signal intensity in the lateral side of the acetabulum on the T2-weighted images. During the 17-month follow-up period, this case eventually underwent massive destruction of the femoral head as well as the acetabulum.