Background: Functional outcome and patient satisfaction after total knee arthroplasty can be variable. Up to 20% of patients have been reported to not be entirely happy with their knee replacement. Psychological factors, in particular illness perception – a patient’s beliefs about their illness – have been found to predict recovery from a range of conditions. Few studies have examined their impact within the orthopaedic context.

Aim: The aim of this study was to investigate the impact of psychological factors, including illness perception, anxiety and depression, on postoperative recovery and functional outcome after total knee arthroplasty.

Patients and Methods: 100 patients from two centres, who underwent a primary total knee arthroplasty for osteoarthritis between 2004 and 2006, took part in this prospective cohort study.

Before surgery patients were asked to complete a psychological questionnaire consisting of Revised Illness Perception Questionnaire (IPQ-r), Hospital Anxiety and Depression Scale (HADS) and Recovery Locus of Control (RLOC). Knee function was assessed preoperatively, at six weeks and one year using Oxford Knee Score (OKS) and range of motion (ROM).

Results: The mean OKS improved significantly at six weeks and further at one year. The mean ROM showed little change in the first six weeks, but was significantly improved at the one-year follow-up.

The psychological factors Consequences, Illness Coherence, Emotional Representation and HADS Anxiety showed a statistically significant correlation with the OKS at six weeks, the factors Consequences and HADS Anxiety and HADS Depression with the OKS at one year. We found no correlation with range of motion at six weeks, but ROM at one year was statistically significantly correlated with the factors Consequences and HADS Depression.

This indicates that patients who believed that their illness had less impact on their personal lives and patients with lower scores on the anxiety and depression scale showed a lower OKS and higher ROM at one year, indicating a better functional outcome.

Hierarchical regression analysis showed that, after controlling for demographics and baseline scores, the factor consequences explained 7% of the variance in ROM at one year. HADS Anxiety and Depression had a significant impact on OKS and accounted for 13.7% of the variance of OKS at one year.

Discussion: Recovery from TKA surgery can be difficult to predict. This study showed that functional outcome can be significantly influenced by psychological factors. These should be taken into account when considering patients for TKA surgery. Improving patient education, looking at home environment and social network as well as addressing anxiety and depression may help to improve overall outcome after TKA surgery.