Page 100 - The value of total hip and knee arthroplasties for patients

Chapter 6
Introduction
There is strong evidence that total knee ar throplasty (TKA) and total hip ar throplasty (THA) are cost-effective procedures for alleviating pain and increasing physical function in osteoarthritis patients [1-3]. Although satisfaction rates are generally high, it is estimated that still 7-34% of patients are dissatisfied or report still having pain or physical limitations 6-12 months after surgery[4-6].The majority of these remaining complaints cannot be explained by technical factors like loosening of the prosthesis.As an increase of the number of joint arthroplasties is expected for the upcoming years [7], absolute numbers of patients with remaining complaints will thus probably also increase. Another recent development is that patients’ evaluations of care processes and outcomes play a prominent role in the financial compensations of hospitals. Both these trends make seeking pre-operative factors that can explain outcomes, resulting in a better selection of patients for surgery currently a priority in orthopedics.
One of the factors that may contribute to the variability in outcomes of TKA and THA are patients’ expectations about the outcome of surgery [8;9]. Patients’ outcome expectations are defined as “improvements that patients believe will be achieved” [10]. Previously, studies in many fields have shown that these expectations are associated with outcomes[11-13]. In TKA and THA however, mixed results have been found in studies examining the relationship between expectations and outcomes[14;15]. In previous studies on patients’ expectations for TKA and THA the aim has been either to describe and quantify patients’ expectations[16;17] or to investigate the association between preoperative outcome expectations and postoperative outcomes[18-21], or the association between fulfilment of expectations and outcomes[22;23]. Statistical models presented in these articles have been mainly association models, in which the authors seek to estimate the relationship between expectations and outcomes as accurate as possible. For TKA and THA however many other factors have been found to be also associated with outcomes, for example pre-operative pain and function[24;25] mental health[25;26], body mass index[27], comorbidity[26;28], age[24;25], female gender[25;27] , radiological abnormalities[29] Probably a combination of these factors best identifies those at risk of poor outcome, rather than just one of these factors. So far, however, patient’s expectations have rarely been included as a candidate variable in multivariable prediction models for outcomes of TKA and THA. The first aim of
98