University of Oxford researchers have introduced the novel approach of lifetime risk, which measures the risk of revision surgery following joint replacement, rather than the traditional method of survival rates. The evidence challenges the increasing trend for more total hip replacements and total knee replacements to be done in the younger patient group.
Total hip arthroplasty (THA) and total knee arthroplasty (TKA) are safe and effective surgical procedures for advanced degenerative osteoarthritis. Traditionally, the success of total hip and knee arthroplasty has been determined by the measurement of survival.
Lee Bayliss at the Nuffield department of orthopaedics, rheumatology, and musculoskeletal science, NIHR Biomedical Research Unit, University of Oxford and colleagues now introduce the use of lifetime risk as a novel approach to illustrate the risk of revision surgery following joint replacement.
Lifetime risk data, which describe the probability of an event occurring over the course of a lifetime, is useful to patients, clinicians, and other health-care professionals because it is easier to convey and understand than the commonly used survival rates.
Summary
Background: Total joint replacements for end-stage osteoarthritis of the hip and knee are cost-effective and demonstrate significant clinical improvement. However, robust population based lifetime-risk data for implant revision are not available to aid patient decision making, which is a particular problem in young patient groups deciding on best-timing for surgery.
Methods: We did implant survival analysis on all patients within the Clinical Practice Research Datalink who had undergone total hip replacement or total knee replacement. These data were adjusted for all-cause mortality with data from the Office for National Statistics and used to generate lifetime risks of revision surgery based on increasing age at the time of primary surgery.
Findings: We identified 63 158 patients who had undergone total hip replacement and 54 276 who had total knee replacement between Jan 1, 1991, and Aug 10, 2011, and followed up these patients to a maximum of 20 years. For total hip replacement, 10-year implant survival rate was 95·6% (95% CI 95·3–95·9) and 20-year rate was 85·0% (83·2–86·6). For total knee replacement, 10-year implant survival rate was 96·1% (95·8–96·4), and 20-year implant survival rate was 89·7% (87·5–91·5). The lifetime risk of requiring revision surgery in patients who had total hip replacement or total knee replacement over the age of 70 years was about 5% with no difference between sexes. For those who had surgery younger than 70 years, however, the lifetime risk of revision increased for younger patients, up to 35% (95% CI 30·9–39·1) for men in their early 50s, with large differences seen between male and female patients (15% lower for women in same age group). The median time to revision for patients who had surgery younger than age 60 was 4·4 years.
Interpretation: Our study used novel methodology to investigate and offer new insight into the importance of young age and risk of revision after total hip or knee replacement. Our evidence challenges the increasing trend for more total hip replacements and total knee replacements to be done in the younger patient group, and these data should be offered to patients as part of the shared decision making process.
Authors
Lee E Bayliss, David Culliford, A Paul Monk, Sion Glyn-Jones, Daniel Prieto-Alhambra, Andrew Judge, Cyrus Cooper, Andrew J Carr, Nigel K Arden, David J Beard, Andrew J Price
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