THE EFFECT OF PSYCHOLOGICAL FACTORS ON OUTCOME FOLLOWING TOTAL KNEE REPLACEMENT

Abstract

This study investigates the role of pre-operative mental health on outcome following Total Knee Replacement.

Patients were recruited as part of a prospective, observational study of the outcomes of primary total knee replacement for osteothritis in centres in the United Kingdom (6 centres), United States (4 centres) and Australia (2 centres). Independent, research assistants recruited eligible patients, collecting clinical history and examination data pre-operatively, 3 and 12 month post surgery. The SF-36, WOMAC, patient satisfaction and demographic data were obtained by self-administered questionnaires.

We recruited 862 eligible patients and have completed 12-month data on 742 patients (86%). Mean age was 70 years (SD 10), 59% were female, 50% were from the UK, 30% from the USA and 20% from Australia. In linear regression models, the significant correlates of preoperative mental health (in decreasing order of significance) were: low preoperative WOMAC function (Std B 8, 2; p< 0. 0001), self reported depression (Std 8 7. 6; p< 0, 0001), female gender (Std 13 2. 9 p=0, 004), older age (Std 13 2, 9; p=0. 004), other comorbid conditions (Std 3 2. 8; p=0, 005) and low income (Std B 23; p-0, 03). 12 months following surgery, low pre-operative mental health was a significance predictor of worse WOMAC pain and function (p< 0. 0001). The linear regression models adjusted for preoperative pain and function, age, sex, comorbid conditions, country and centre within country. With the exception of the pre-operative WOMAC pain and function score, low pre-operative mental health was the strongest of worse outcome 12 months after TKR.

Low pre-operative mental health is a highly significant predictor of worse outcome one year after Total Knee Replacement. It may be possible to identify patients with poor mental health before surgery using the SF36 mental health score as well as self-reported depression. This may allow for effective treatment of their mental health problems prior to TKR and/or highlight the need for extra rehabilitation input to improve outcome following surgery.