Effects of pre-surgical interventions on chronic pain after total knee replacement: A systematic review and meta-analysis of randomised controlled trials

Objective
Nearly 100,000 primary total knee replacements [TKR] are performed in the UK annually. The primary aim of TKR is pain relief, but 10-34% of patients report chronic pain. The aim of this systematic review was to evaluate the effectiveness of pre-surgical interventions in preventing chronic pain after TKR.
Design
MEDLINE, Embase, CINAHL, The Cochrane Library and PsycINFO were searched from inception to December 2018. Screening and data extraction were performed by two authors. Meta-analysis was conducted using a random effects model. Risk of bias was assessed using the Cochrane tool and quality of evidence assessed by GRADE.
Primary and secondary outcomes
Pain at six months or longer; adverse events.
Interventions
Presurgical interventions aimed at improving TKR outcomes. 
Results
Eight RCTs with data from 960 participants were included. The studies involved nine eligible comparisons. We found moderate quality evidence of no effect of exercise programmes on chronic pain after TKR, based on a meta-analysis of 6 interventions with 229 participants (SMD 0.20, 95% CI -0.06 to 0.47, I² = 0%). Sensitivity analysis restricted to studies at overall low risk of bias confirmed findings. Another RCT of exercise with no data available for meta-analysis showed no benefit. Studies evaluating combined exercise and education intervention (n=1) and education alone (n=1) suggested similar findings. Adverse event data were reported by most studies, but events were too few to draw conclusions.  
Conclusions
We found low to moderate quality evidence to suggest that neither pre-operative exercise, education nor a combination of both is effective in preventing chronic pain after TKR. This review also identified a lack of evaluations of other pre-operative interventions, such as multi-modal pain management, which may improve long-term pain outcomes after TKR.