Introduction

Osteoarthritis (OA) of the knee with pain, reduced function and resulting lessened quality of life, affects many people above 50 years of age. Various drug treatments, physical therapy and complementary medicine constitute the main therapeutic components for this disease that affects people without relation to their socio-cultural, racial or cultural background. However, for approximately 20% of those with pain and loss of function, disability is sufficiently severe that surgery is a recommended treatment option.

A recent report, summarized here, has examined various aspects of total knee replacement (TKR) surgery, based on a literature review up to 1998 and published group consensus papers. The authors have formulated the following recommendations:

Is total knee replacement (TKR) an effective treatment for knee osteoarthritis?

Analyses of the results gathered from the literature review and published treatment guidelines clearly indicate that the answer to this question should be "yes", even in the absence of appropriately designed controlled randomized trials. This has been recently confirmed in a Swedish report on more than 27,000 operated cases, showing only 8% dissatisfaction with the procedure on a follow-up duration more than 15 years¹.

TKR is predominantly performed on patients having a diagnosis of OA, and in such patients it is efficacious in reducing pain and disability, thereby contributing to improve function and quality of life. An interesting finding of the review was a large variation in rates of TKR surgery per inhabitant between counties, countries and geographical areas of the world, in spite of documented even distribution of the disease world-wide. Thus, across broadly distributed geographical regions and a period of time since 1980, reported ranges in the USA vary from 200 to almost 1,000 per 100,000 inhabitants, falling to 13 to 25 in the UK, a 15- to 40-fold difference.

Although the extent of the difference has decreased over the period, these extreme area practice variations can be accounted for by several factors. Among these are differences in healthcare delivery systems, the knowledge and expertise regarding OA diagnosis and management, lack of evidence-based data, and the lack of standardized decision criteria for major knee surgery. It is interesting to add to this list the under-utilization of resources in the treatment of OA, as shown by the results of a UK survey questionnaire, that show that 2% (i.e. 2,000 per 100,000 population) had pain and disability consistent with a need for joint arthroplasty.

Why, then, are people not more frequently given TKR for osteoarthritis?

The consensus group meetings reviewed identified key qualitative components in the chain of events between the time a patient seeks help or advice to the time he or she provides informed consent to TKR surgery. These components include demographic factors (e.g. social class, ethnicity), social structures, personal expectations, perceived functional status, and co-morbidity (e.g. obesity, diabetes, cardiovascular disease). A general negative attitude towards OA or surgery and the belief that knee OA and pain are part of a normal, inevitable aging process may also contribute to under-utilization of TKR. The gatekeeper's role in facilitating the patient's referral to the orthopedic surgeon was considered important. In particular, the ability to make an early, correct diagnosis with an assessment of severity, a good, existing working relationship with a skilled surgical unit, and the presence of referral or other guidelines were all deemed of importance.

But do orthopedic surgeons agree on the criteria for recommending TKR?

Severity of joint disease assessed by pain intensity, functional impairment and imaging techniques was considered by the consensus panel as relevant, although no precise relative weighting was provided for these three 3 individual components of severity.

Similarly, disease-specific or generic, easy-to-use, functional instruments measuring patient outcome variables - such as pain and disability (e.g. the WOMAC²or Oxford 12-item questionnaire), patient health status (SF36) or quality of life (15D and Nottingham Health Profile) - are still under evaluation for their relevance to the individual patient's decision making process. Finally, availability of a qualified and experienced surgical team was an important determinant identified in a Canadian study, as well as economic considerations if the patient has to pay.

Conclusions and recommendations

There are presently only a few consensus official guidelines for TKR surgery around the world. Orthopedic surgeons have recently acknowledged the need to further document the benefits and risks associated with joint replacement in general and TKR in particular, with more focus on functional outcomes and the decision-making process³. Continuous emphasis should be given to educating patients and healthcare professionals on the assessment and management of OA.

TKR is now a well-established and effective treatment strategy for the OA patient. Availability of guidelines incorporating criteria for the TKR decision-making process and high-quality documentation on patient outcomes will be welcome, providing opportunity to pass on improved information on the expected benefits and the risks incurred by those many - and otherwise healthy - patients with knee OA who are looking for better physical function and an improved quality of life.