Takao Hotokebuchi

Diagnostic criteria for non-traumatic osteonecrosis of the femoral head A MULTICENTRE STUDY

Six major and seven minor diagnostic criteria have been developed by the Japanese Investigation Committee for osteonecrosis of the femoral head (ONFH). We have carried out a multicentre study to clarify these. We studied prospectively 277 hips in 222 patients, from six hospitals, who had ONFH and other hip pathology and from whom histological material was available. We identified five criteria with high specificity: 1) collapse of the femoral head without narrowing of the joint space or acetabular abnormality on radiographs, including the crescent sign; 2) demarcating sclerosis in the femoral head without narrowing or acetabular abnormality; 3) a cold-in-hot appearance on the bone scan; 4) a low-intensity band on T1-weighted images (band pattern); and 5) evidence of trabecular and marrow necrosis on histological examination. With any combination of two of these criteria, the sensitivity and specificity of the diagnosis were 91% and 99%, respectively.

Osteoconductivity of thermal-sprayed silver-containing hydroxyapatite coating in the rat tibia

A silver-containing hydroxyapatite (Ag-HA) coating has been developed using thermal spraying technology. We evaluated the osteoconductivity of this coating on titanium (Ti) implants in rat tibiae in relation to bacterial infection in joint replacement. At 12 weeks, the mean affinity indices of bone formation of a Ti, an HA, a 3%Ag-HA and a 50%Ag-HA coating were 97.3%, 84.9%, 81.0% and 40.5%, respectively. The mean affinity indices of bone contact of these four coatings were 18.8%, 83.7%, 77.2% and 40.5%, respectively. The indices of bone formation and bone contact around the implant of the 3%Ag-HA coating were similar to those of the HA coating, and no significant differences were found between them (bone formation, p = 0.99; bone contact, p = 0.957). However, inhibition of bone formation was observed with the 50%Ag-HA coating. These results indicate that the 3%Ag-HA coating has low toxicity and good osteoconductivity, and that the effect of silver toxicity on osteoconductivity depends on the dose.

Osteoporosis and years since menopause

In Fukuoka Prefecture, in south-western Japan, a regional screening program for osteoporosis was conducted from 1994 to 1995. The screening level in the bone mineral density (BMD) at the distal non-dominant radius was equal to or less than two standard deviations below age-specific mean (≤ −2.0 SD). In 1177 examinees with natural menopause (mean age: 61.4, range: 42–88), 56 of those who were screened were subsequently radiologically confirmed by orthopedic specialists to have osteoporosis (case group). They were then compared with 802 normal BMD (≥ −1.0 SD) women (reference group) with their lifestyle and reproductive characteristics. The adjusted odds ratio (OR) and its 95% confidence interval (CI) were calculated using a logistic regression model. A significant increase in the ORs for osteoporosis based on the number of years since menopause was observed for 7–13 years since menopause (OR=2.3; 95% CI: 1.0–5.4) compared with <7 years, however, no increasing trend in risk was evident in 14+ years since menopause (OR=1.4; 95% CI: 0.4–5.1). Thus, the elevated risk continued up to around 10 years since menopause. These findings are consistent with previous studies that reported an alternation in the calcium metabolism and bone loss related to the length of time after menopause. Both the childhood and current milk consumption were also associated with a decreased risk: ORs were 0.4 (95% CI: 0.2–0.9) and 0.5 (95% CI: 0.3–1.0), respectively.