[Histomorphometric study of osteoporosis in rheumatoid arthritis]

A histomorphometric study of osteoporosis in rheumatoid arthritis was performed on thirty-eight specimens from the proximal tibial metaphysis, which were obtained during total knee arthroplasty. Fourteen specimens from the proximal tibial metaphysis of osteoarthritis patients were also histomorphometrically studied, and the osteoporosis in rheumatoid arthritis was compared with it in osteoarthritis. In nine rheumatoid arthritis patients, specimens from the iliac bone were obtained, and the difference between the generalized osteoporosis and the juxta-articular osteoporosis was evaluated. The proximal tibial metaphysis in rheumatoid arthritis was usually represented by a fairly low bone area and by thin mean trabecular thickness. No correlations were seen between histomorphometric parameters and the age at operation, the age of onset and the duration of disease. However, in patients of long duration (over 20 years), the bone area was very low and mean trabecular thickness was thin. In one parameter (scalloped surface) which shows bone resorption, there was a high correlation between generalized osteoporosis and juxta-articular osteoporosis in rheumatoid arthritis. There was no significant difference between rheumatoid arthritis and osteoarthritis in bone area and mean trabecular thickness. However, the scalloped surface of rheumatoid arthritis was significantly higher than it of osteoarthritis.