Physical activity and health-related quality of life of patients with chronic knee pain after total knee replacement : analysis of the PEP-TALK trial

Background Chronic pain is a major challenge for some people after total knee replacement (TKR). The changing impact of this complication during the first post-operative year remains unclear. This analysis aimed to examine how physical activity and health-related quality of life (HRQoL) evolved over the first year after TKR for patients with and without post-operative chronic knee pain. Methods We conducted a secondary analysis of data from a randomised controlled trial (PEP-TALK), which tested the effectiveness of a behaviour change physiotherapy intervention compared with usual rehabilitation after TKR. Mean UCLA Activity Score and EQ-5D-5L for participants with and without chronic knee pain (14 points or lower in the Oxford Knee Score Pain Subscale (OKS-PS) at six months post-TKR) were compared at six and 12 months post-TKR. Results Data from 83 participants were analysed. For those with chronic knee pain, UCLA Activity Score remained unchanged between baseline to six months (mean: 3.8 to 3.8), decreasing at 12 months (3.0). Those without post-operative chronic knee pain reported improved physical activity from baseline to six months (4.0 vs 4.9), plateauing at 12 months (4.9). Participants with chronic knee pain reported lower baseline HRQoL (0.28 vs 0.48). Both groups improved health utility over one year. Of those without chronic pain at six months, 8.5% returned to chronic pain by 12 months. Conclusions Monitoring clinical outcomes after six months may be indicated for those at risk of chronic pain post-TKR. Further, sufficiently powered analyses are warranted to increase the generalisability of this exploratory analyses’ results