[Roentgenological and histomorphological studies of the knee joint in rheumatoid arthritis].

In order to study the disease process of rheumatoid arthritis in the knee joint, clinical and roentgenological analysis as well as histomorphological study of the proximal tibia taken at total knee arthroplasty procedure were carried out. The natural course of eight patients who had been followed 12.7 years on an average were studied in respect to range of motion, swelling, pain, instability of the knee joints along with radiographical appearance of the knee joints and other locations such as hand, spine and other major joints. There were two extreme types: one which led to obvious joint instability and one which ended up with joint contracture. The majority of the cases, however, fell between the two types. These three groups well corresponded to the three types proposed earlier by Katsube: unstable, stiff and standard types, respectively. For the roentgenological analysis, 148 knees of 80 preoperative patients were also subjected. The findings included osteoporosis, abnormal femoro-tibial angle, osteophyte formation, bone destruction with or without osteosclerosis. There were apparent bone destruction and a tendency toward valgus demormity in the unstable type, whereas apparent osteoporosis and little osteosclerosis of the tibial plateau were found in the stiff type. In the standard type, there were osteophyte formation and osteosclerosis of the tibial plateau as usually seen in osteoarthritic knees. For the histomorphological study, 30 patients were given tetracycline hydrochloride preoperatively for tetracycline labeling and total of 38 knees were thus examined. The specific findings in the unstable type included severe pannus formation and bone absorption, and those in the stiff type were severe osteoporosis with articular cartilage degeneration and decreased mineralization. No specific findings were observed in the standard type.