Morphological findings in joint cartilage after osmic acid treatment.

Punch biopsy specimens from the cartilage of the lateral condyle of the femur in 29 patients suffering from rheumatoid arthritis were taken during surgical synovectomy of knee joints and investigated by light or electron microscopy. Eleven patients had never received osmic acid injections in this particular joint, whereas 18 had had such injections 1-24 months prior to surgery. By light microscopy only minor differences could be seen between controls and cartilage treated with osmic acid, whereas with electron microscopy, increased amounts of dark-staining cell debris were visible in samples taken after osmic acid treatment. The perilacunar matrix appeared normal. There was no irregularity of collagen fibres at the surface of the cartilage. It is concluded that osmic acid causes limited superficial damage to the cartilage. The question whether this is of any clinical consequence in the form of subsequent degenerative joint disease, must be solved by clinical follow-up studies.