Lower Extremity Function in Arthritis

Abstract: The aim of this thesis was to develop and apply self-registered and observed measures of physical function in people with arthritis in the lower extremity. In Paper I, 181 subjects from the Swedish Knee Arthroplasty Register who were satisfied with their primary knee arthroplasty were studied. 44% of the medical records included reports of pain in the replaced knee at the same time as the patients had declared that they were satisfied with their primary operation. Most patients can be trusted to decide when there is a problem with the operated knee. Only 2 of 181 satisfied patients with primary knee arthroplasty were revised as a result of routine follow-up, 132/181 called the healthcare services themselves when there was a problem with the revised knee. In Papers II, I adapted a self-administered questionnaire used for people with knee injury and knee osteoarthritis (OA) to patients with chronic inflammatory arthritis and lower extremity problems. Focus groups and 119 in-patients were included for the validation process. The Rheumatoid and Arthritis Outcome Score (RAOS) is a valid, reliable and responsive questionnaire for assessment of multidisciplinary care. In Paper III, validity and reliability of ten functional performance tests were studied in a cohort of 285 meniscectomized subjects at risk of or with early stage knee OA. The tests "maximum number of knee-bendings in 30 seconds" and "one-leg hop for distance" were capable of discrimination with regard to age, sex and symptoms and had good test-retest reliability. In Paper IV, change in observed physical function, and the predictive value of knee pain and radiographic knee OA for change in observed physical function were studied. Observed physical function (the two tests from Paper III) was assessed twice (mean 7 years) in 173 meniscectomized subjects and 47 control subjects. Radiographic knee OA and knee pain predicted worse deterioration in observed physical function, controlled for age, sex and body mass index (BMI). Similar factors influenced a decline in observed physical function whether the subject had a meniscectomy or not. From this thesis I conclude that a single question of satisfaction is not a valid measure of lower extremity function. The Rheumatoid and Arthritis Outcome Score (RAOS) is a valid, reliable and responsive questionnaire for lower extremity function in people with chronic inflammatory arthritis. "One-leg hop for distance" and "maximum number of knee-bendings in 30 sec" are valid and reliable tests for lower extremity function in people with knee injury and knee osteoarthritis. Observed physical function decline already in midlife and the deterioration is predicted by radiographic knee OA and knee pain.