Outcomes of primary total knee arthroplasty: the impact of patient-relevant factors on self-reported function and quality of life

Purpose. To identify factors associated with functional recovery and outcome 1 year after total knee arthroplasty (TKA). Methods. In the prospective follow-up study, all the patients (n = 75, aged 60-80 years) underwent primary TKA. Assessments were performed preoperatively and 12 months after surgery. The main measures were the Western Ontario and McMaster Universities OA Index (WOMAC) and the 15D. The clinical examination included analyses of comorbidity and a detailed knee examination. Age-standardised population values of the 15D and the Outcome Measures in Rheumatology-Osteoarthritis Research Society International (OMERACT-OARSI) criteria were used as indices of response. Results. Osteoporosis, pain, gender, age and preoperative function of the opposite knee accounted for 29.9% of the variance in the change in the WOMAC function score. A preoperative score of the 15D below the age-standardised population level, pain, higher age and pulmonary disease reduced the possibility to reach the HRQOL level of the general population. Osteoporosis decreased the likelihood of achieving responder status according to the OMERACT-OARSI criteria. Conclusion. The baseline preoperative score of the 15D strongly associated with the achieved level of HRQOL after TKA. The findings of the present study highlight the multifactorial nature of health status in TKA.