We searched MEDLINE and PubMed from Jan 1, 1970, to April 30, 2018, using the search term “knee” in combination with “replacement”, “joint”, “total”, “partial”, “arthroplasty”, “epidemiology”, “mortality”, “morbidity”, “outcomes”, “registry”, “enhanced-recovery”, “indications”, “effectiveness”, “cost-effectiveness”, “survivorship”, “follow-up”, “innovation”, “evaluation”, and “regulation”. We concentrated on results from randomised trials, registries, and large population cohort studies. We
SeriesKnee replacement
Introduction
Knee replacement surgery has been routinely done for more than 40 years and usage continues to grow worldwide. Its success is based on improving the quality of life for patients with knee arthritis by reducing pain and improving long-term function. However, 20% of patients are dissatisfied with the outcome of surgery, and research and development in the field focuses on this deficiency. This review concentrates on a number of topical areas in knee replacement, starting with the epidemiology of knee replacement and the variability in intervention rates alongside the indications for surgery. The increasingly important role of patient-reported outcomes and analysis of registry data is considered, together with an overview of the health–economic evidence relating to knee replacement. Enhanced recovery programmes are commonplace and have the potential to positively affect patient outcomes. Development of new implants and supportive technologies is continuously led by the industry, but more robust evidence to support their introduction is still required; we therefore review the regulatory requirements for assessment of new devices and strategies to ensure patient safety in this process.
Section snippets
Epidemiology of knee replacement
The use of knee replacement as a treatment for arthritis continues to increase. In the UK, more than 100 000 knee replacements are now done each year and a similar pattern of increased frequency is reported by many worldwide joint registries.1, 2, 3, 4, 5 Total numbers of procedures in the USA have now reached 700 000 per year, and the number is increasing as predicted despite periods of economic downturn (figure 1).6, 7 Projected analyses from different counties all suggest that, even with
Indications for knee replacement surgery
Total knee replacement has traditionally been offered to older patients with intolerable knee pain, unacceptable activity limitation with the loss of highly valued activities, and severe end-stage osteoarthritis of the joint.21 Historically, arthroplasty surgeons have been reluctant to operate on patients with either morbid obesity (because of the higher risk of perioperative complications), and on patients younger than 55 years (because of the increased likelihood of revision in their
Patient-reported outcome after knee replacement surgery
The evaluation of knee replacement has improved over time and the use of patient-reported outcome measures have become more common and influential. A recent systematic review showed 32 different measures that have been used for this purpose, with the Western Ontario and McMaster Universities Osteoarthritis (WOMAC), the Knee Injury and Osteoarthritis Outcome Score, and the Oxford Knee Score (OKS) widely used.34 These instruments have shown that knee replacement improves quality of life for the
Cost-effectiveness of knee replacement surgery
As one of the most commonly done elective procedures in the world, total knee replacement has not surprisingly been the subject of a substantial number of cost-effectiveness analyses. Using the health economists' favoured outcome measure—quality-adjusted life-years (QALYs)—these studies have typically estimated the ratio of incremental costs to health gain from total knee replacement to be between approximately £1000 and £12 000 for the average patient in different health-care systems, which is
Enhanced recovery after knee replacement surgery
Enhanced recovery programmes use a multimodal approach aimed at improving the care and subsequent clinical outcome for patients undergoing knee arthroplasty. First proposed in 1997,54 this approach aims to minimise the physiological and psychological stresses of surgery through the use of specific interventions throughout the care pathway.55 The principal components of enhanced recovery programmes can be broadly thought of in terms of preoperative optimisation of patients' comorbidities,
Patterns of implant use
Analysis of national registry data has become a cornerstone of assessment of knee replacement surgery, reinforced by improvements in data capture, as seen in the UK National Joint Registry (UK NJR).1 Data from all published registries show expanding usage of knee replacement over time, with women most likely to have surgery, and increasing numbers of patients younger than 60 years having surgery.1, 2, 3, 4, 5 Most implantations are cemented total knee replacements, with far fewer partial
Design of total condylar knee replacement
Posterior cruciate retaining or sacrificing total condylar knee designs remain the two most widely used total knee replacement options.1, 2, 3 Incremental design development continues, such as gender-specific and high-flex components, but evidence that these changes in component shape produce any meaningful improvement in outcome is sparse.75 Most knee replacements still use a metal on polyethylene-bearing surface and polyethylene wear remains a major cause of implant failure.1, 2, 4 Around 20
The regulation and evaluation of innovation in knee replacement surgery
The majority of medical devices and surgical implants, including knee replacements, are used without problem or concern, but in some situations problems have arisen. For example, in the use of metal-on-metal hip replacements in which modifications to design resulted in the production of excessive metal wear products, in some patients substantial local and sometimes systemic toxic effects were observed.91 As a result, the regulatory authorities throughout the world have begun to make changes to
Conclusion
Knee replacement surgery is a highly successful established technology, with good evidence of successful treatment outcome and long-term implant survival. A proportion of patients continue to have poor results and addressing this issue is the major challenge for improving care, particularly given the continued increase in worldwide usage and the increasing numbers of younger patients undergoing surgery. Continued incremental changes in implant design do not appear to have achieved any
Search strategy and selection criteria
References (100)
- et al.
Projected increase in total knee arthroplasty in the United States—an alternative projection model
Osteoarthritis Cartilage
(2017) - et al.
Future projections of total hip and knee arthroplasty in the UK: results from the UK Clinical Practice Research Datalink
Osteoarthritis Cartilage
(2015) - et al.
The lifetime risk of total hip and knee arthroplasty: results from the UK general practice research database
Osteoarthritis Cartilage
(2012) - et al.
Current and future impact of osteoarthritis on health care: a population-based study with projections to year 2032
Osteoarthritis Cartilage
(2014) - et al.
Utilization rates of knee-arthroplasty in OECD countries
Osteoarthritis Cartilage
(2015) - et al.
The effect of patient age at intervention on risk of implant revision after total replacement of the hip or knee: a population-based cohort study
Lancet
(2017) - et al.
Strategies to reduce variation in the use of surgery
Lancet
(2013) - et al.
The effect of BMI on 30 day outcomes following totaljoint arthroplasty
J Arthroplasty
(2015) - et al.
The association of pre-operative body pain diagram scores with pain outcomes following total knee arthroplasty
Osteoarthritis Cartilage
(2017) - et al.
Meaningful changes for the Oxford hip and knee scores after joint replacement surgery
J Clin Epidemiol
(2015)