[Osteophyte formation in the knee joint: a radiological study].

Reported here are the results of a study on the significance of osteophyte formation in the osteoarthritic knee joint. The osteophyte formation was examined in a total of 795 cases involving 1040 joints. Of these, 415 cases (660 joints) had no symptoms of osteoarthritis of the knee joint (Group A); while the other 380 (380 joints) had primary osteoarthritis of the knee joint (Group B). The osteophyte location and osteophyte length were determined in all cases of Group A and Group B. The rate of annual increase in osteophyte length was determined in 224 cases (369 joints) of Group A (average study period: 7.1 years) and in 122 cases (122 joints) of Group B (average study period: 7.5 years). A special measuring unit called the "spur index" was devised for the present study to determine a corrected measurement of the osteophyte length; 1 spur index unit corresponded to 1/100 of the width of the proximal tibial articular surface. By using this spur index, measurements could be corrected for the magnifying effect of X-ray photography and for variations in the size of knee joints. On the assumption that age, obesity, arteriolosclerosis and femorotibial angle were factors that promoted the progression of osteoarthritis in the knee joint, the correlation between the osteophyte length and each of these factors was investigated. A significant difference in osteophyte length, and in the annual increase in osteophyte length, was found between Group A and Group B, but no difference between them with regard to osteophyte location. A significant correlation was found between the osteophyte formation and each of the above-mentioned factors. The correlation was strongest with the femorotibial angle followed by age, arteriolosclerosis and obesity, in that order.