THE NATURAL COURSE OF ARTHROSIS OF THE KNEE

The aim of this study was to describe the course of untreated or conse rvatively treated arthrosis of the knee joint. Of 265 patients present ing with knee pain who had weightbearing radiographs taken between 197 0 and 1973, 132 (33 men and 99 women) responded to and participated in a clinical followup 20 years later using the Hospital for Special Sur gery score and new weightbearing radiographs. Arthrosis was defined as an equal to or greater than 50% joint space narrowing. In 75 of 132 k nees of Ahlback Class 0 (57%) and 20 of 52 knees of Ahlback Class I (3 9%), the classification remained unchanged. The Hospital for Special S urgery score at followup was compared with the Ahlback classes in the 1970s for the 110 cases for which surgery was not done. A higher Ahlba ck class at the time of presentation was associated with lower functio nal score (Hospital for Special Surgery) 20 years later. In addition, in the contralateral knee a reduction of joint space may occur. In the arthrosis group with total joint space reduction or attrition there w as a clinical and radiographic deterioration that would merit surgical intervention to avoid unnecessary loss of function. However, in knees with equal to or greater than 50% joint space reduction (Ahlback I) a nd pain, a considerable number (39%) did not deteriorate radiographica lly during a 20-year period, and 25% remain free of pain. It appears t hat the long-term prognosis of mild knee arthrosis is not necessarily poor. A substantial number of these patients will not have progression of the arthrosis.