Pathologic and metabolic responses of experimental osteoarthritis to estradiol and an estradiol antagonist.

Tamoxifen, an estradiol antagonist, and estradiol were separately evaluated in a rabbit experimental osteoarthritis. Cartilage from anatomically defined regions of individual rabbit knees was assayed for sulfate and thymidine incorporation. Tamoxifen reduced erosive osteoarthritic pathology, while estradiol worsened it. There was no effect on the incidence of osteophytes. Metabolic studies in organ culture showed no changes relating to treatment. The results suggest that specific medical therapy for osteoarthritis is within the realm of possibility.