The natural history of severe osteoarthritis of the knee in patients awaiting total knee arthroplasty

The disabling symptoms of osteoarthritis of the knee can be dramatically improved with joint replacement. The aim of this study was to examine the change in pain and physical function that occurs in patients with osteoarthritic knees awaiting total knee replacement. Data was collected prospectively from a cohort of 124 consecutively recruited patients at three stages of assessment over a mean of 24 months (range 9–32 months). The patients were assessed at the time of referral by the general practitioner, when first assessed by the orthopaedic consultant, and just before surgery. At each visit, the patients were examined and the American Knee Score and Oxford Knee Score completed by the patient. The function element of the American Knee Score deteriorated significantly from the time of referral till the time of first orthopaedic consultation (P=0.005) and also from the time of referral to the time of surgery (P=0.006). The pain element of the American Knee Score improved from the time of referral till the time of orthopaedic assessment (P=0.011). The change in Oxford knee scores between the time the patient was put on the waiting list and the time of surgery was not statistically significant (P=0.30). Our study shows that for patients referred with severe osteoarthritis of the knee, both the American Knee Scores and Oxford Knee Scores deteriorate significantly prior to surgery, although most of this change is not during their time on the waiting list. The time from referral by the general practitioner (GP) to orthopaedic assessment by the consultant was l.8–14.2 months (average 9.8 months) and from the time of orthopaedic assessment, i.e. when seen by the consultant and placed on the waiting list to the time of surgery was 9.1–22 months (average 13.3 months). We have shown that the pain and functional elements of the American Knee Score behave independently to the total score. This research therefore questions the current emphasis on surgical waiting times instead of patient symptoms and physical function in determining the timing of surgery.