Does preoperative anxiety and depression predict satisfaction after total knee replacement?

Approximately one fifth of patients are not satisfied with the outcome of total knee arthroplasty (TKA). Preoperative variables associated with poorer outcomes are severity and chronicity of pain, psychological disease, poor coping strategies and pain catastrophisation. Psychological disease may be expressed as anxiety and depression. It is unclear whether anxiety and depression before TKA are constitutional or result from knee pain. The aim of this study was to explore the association of anxiety and depression with knee pain and function using specific outcome measures.

Forty consecutive patients undergoing TKA completed Hospital Anxiety and Depression Scale (HAD) and Oxford Knee Scores (OKS) preoperatively and at 3 and 6 months postoperatively.

The HAD and OKS significantly improved post-operatively (p<0.001). There was a greater change between the preoperative and postoperative scores in the OKS than the HAD. The severity of preoperative anxiety and depression was associated with higher levels of knee disability (coefficient -0.409, p=0.009). Postoperatively reduction in anxiety and depression was associated with improvement in knee disability after 3 (coefficient -0.459, p=0.003) and 6 months (coefficient -0.428, p=0.006).

The difficulty in interpreting preoperative anxiety and depression and the outcome of TKA is establishing whether they are the cause or effect of pain in the knee. As anxiety and depression improve with knee pain and function, this study suggests that knee pain contributes to the psychological symptoms and that a successful TKA offers an excellent chance of improving both.