Impact of prior knee surgery on change in knee pain, quality of life, and walking speed following supervised education and exercise therapy: an analysis of 30,545 people with knee osteoarthritis

To investigate the impact of prior knee surgery on changes in outcomes following an 8-week supervised patient education and exercise therapy program in patients with knee osteoarthritis. Patients were classified according to knee surgery in the most affected knee joint (yes/no) prior to enrolment in the Good Life with osteoArthritis in Denmark (GLA:D^®) program. Between-group differences in outcome changes from baseline to 3 months follow-up were evaluated using linear regression stratified by sex. Outcomes were knee pain intensity (VAS, 0-100 mm), joint related quality of life (Knee Injury and Osteoarthritis Outcome Score Quality of Life subscale score (KOOS QOL, 0-100)) and walking speed (40-m fast-paced walk test). To evaluate clinically relevant between-group differences, proportions of patients reaching a threshold of minimal important change in the surgery and non-surgery groups were compared. Among 30,545 patients, 27% (n, 8254) had prior surgery in the most affected knee. The prior surgery and the non-surgery group experienced improvements in all outcomes with minor between-group differences in change in pain intensity (males, 0.03 95% CI - 0.9 to 1.0; females, 1.3 95% CI 0.6 to 2.1); KOOS QOL (males, 0.3 95% CI - 0.4 to 0.9; females 0.02 95% CI - 0.5 to 0.5); and walking speed (males, 0.01 95% CI - 0.01 to 0.02; females 0.01 95% CI 0.003 to 0.02). The responder analysis showed no clinically relevant between-group differences in improvements. Previous knee surgery does not seem to modify the clinical outcome following exercise therapy and patient education in patients with knee osteoarthritis.