We searched Medline and PubMed from January, 1970, to December, 2010, with the search term “knee” in combination with “replacement”, “joint”, “total”, “partial”, “arthroplasty”, “cemented”, “outcomes”, “effectiveness”, “cost-effectiveness”, “epidemiology,” and “survivorship”. We concentrated on results from randomised trials and registries. We mostly selected publications from 2006–11, but did not exclude commonly referenced, and important older publications. Review articles are cited to
SeminarKnee replacement
Introduction
Knee replacement was first widely done in the 1970s and 1980s and is now generally regarded as an effective and cost-effective treatment for end-stage knee arthritis. As with many surgical implants, the first devices were designed and introduced by surgical innovators in collaboration with industry. The regulatory framework for new implants varies worldwide but has been generally much less rigorous than it is for new drugs. Therefore, proof of safety of implanted materials is needed rather than evidence of clinical effectiveness.
Most published reports of outcomes of knee-replacement surgery are small single-surgeon or single-centre case series. These reports are often from the personal practice of the surgeon-inventor of the implant, which introduces bias and a potential conflict of interest. In the past 40 years, the number of implants available on the market has substantially proliferated, often with little or no evidence of effectiveness or cost-effectiveness. In this Seminar, we focus on ways to improve decision making for surgery and how to provide high quality evidence for the effectiveness of different implants.
Section snippets
Epidemiology
Knee-replacement surgery is an increasingly common procedure: more than 650 000 total knee replacements (TKRs) were done in the USA in 2008,1 more than 77 500 in the UK in 2009,2 and 103 601 in South Korea between 2002 and 2005.3 The number of replacements has been increasing every year in developed countries. In the USA, rates have risen from 31·2 per 100 000 person-years (95% CI 25·3–37·1) in 1971–76, to 220·9 (206·7–235·0) in 2008.4 Rates for women in the UK have also increased from 43 per
Indications for surgery and decision making
Success of surgery depends on selection of patients for joint replacement. The key indications for knee replacement are generally agreed to be end-stage knee arthritis and persistent severe pain (panel).10, 11, 12, 13 Patients with these problems do not gain much from arthroscopic surgery, and osteotomy around the knee is usually only considered in patients younger than 55 years.14 Generally, patients undergoing knee replacement have end-stage radiographic disease, but the decision to operate
Assessment of surgery outcome
Outcomes of knee replacement are traditionally assessed by survival analysis with revision as an endpoint.20, 48, 49, 50 Assessment of clinical, usually physical, variables is also often included. Although survival analysis is crucial, analysis with revision as the only endpoint can underestimate problems; patients can remain with pain or poor function without necessarily undergoing revision TKR. As many as 20% of patients might continue to endure knee pain or have problems after TKR.51, 52, 53
National joint-replacement registries
National joint-replacement registries are now one of the best and most important sources of comparative data for knee-replacement surgery.80, 81, 82 They not only provide data for individual implants, but also establish variation in outcome related to patient characteristics, surgical techniques, and surgeon experience.83, 84, 85 The initial focus of the first national registry, the Swedish knee-replacement project, was to collect data for short-term complications. However, modern knee surgery
Future trends
For all governments and health-care systems, provision of and funding for research into long-term degenerative conditions such as arthritis is an issue.40, 47, 117, 118, 119 Priority action should be taken to distribute resources relative to health need to prevent inequities in access to services. Health needs vary in a population according to the demographic characteristics of local communities. Health-care commissioners need estimates of service use and health needs to provide services
Conclusion
Joint-replacement surgery is one of the most successful examples of innovative surgery and has resulted in substantial quality-of-life gains for people with end-stage arthritis. The pioneering days of knee-replacement surgery have probably ended, and future emphasis should first be on improvement of patient selection for surgery and reductions in variability in provision of surgery through education, training, and the use of well designed decision aids. Second, long-term monitoring of outcomes
Search strategy and selection criteria
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