Histopathologic changes in arthroscopic synovial biopsies before and after open synovectomy in patients with chronic inflammatory joint diseases.

Synovial biopsies were taken from five preselected areas of knee joints in patients with chronic inflammatory joint diseases immediately prior to synovectomy as well as 6 and 12 months later. The histologic changes were assessed by evaluating 16 different parameters in each individual biopsy. When the 16 parameters were treated as a group there was a significant reduction (p less than 0.001) in inflammatory changes at 6 months, but a slight increase again after 12 months. This was expressed by a significant reduction in lymphocytes (p less than 0.025) and plasma cells (p less than 0.01). The reduction seen in macrophages was not significant (p greater than 0.05). The cellular infiltrates in the interstitial stroma were dominated by lymphocytes, plasma cells and macrophages preoperatively and by lymphocytes and macrophages following synovectomy. Fibrosis was a dominating feature before synovectomy, and it increased (p less than 0.025) following the operation, probably due to the surgical intervention. Before synovectomy the severity of inflammatory changes within each single joint varied, but none of the preselected areas was more prone to these changes than any other. Postoperatively at both 6 and 12 months the inflammatory parameters were more pronounced in the intercondylar area (p less than 0.025).