This is a plain English summary of an original research article
A one-stage knee replacement procedure to treat an infected prosthetic knee may offer similar outcomes for most people as the more commonly used two-stage procedure. Re-infection was seen in 7.6% of people after one-stage revision surgery, compared to 8.8% after a two-stage procedure. Other outcomes, such as range of motion, were also similar.
This review of observational studies described different techniques and approaches and because of the way this information was gathered there are some uncertainties as to whether these are now used or if other factors were important too.
An infection is one of the most serious complications of knee replacement surgery. Using one-stage revision surgery to treat suitable patients would reduce hospital time and improve patient experience. Patient selection will remain important and patient registries could be used to monitor outcomes.
Why was this study needed?
Knee replacement surgery (arthroplasty) replaces a damaged or diseased knee with an artificial joint. More than 70,000 knee replacements are carried out in England and Wales each year, and the number is rising.
One of the most devastating complications of knee replacement is an infection of the artificial joint. Infections impact on quality of life and may lead to amputation. Treatment often requires revision surgery, where the knee prosthesis is replaced.
Revision surgery can take a one- or two-stage approach. The two-stage process requires one operation to remove the prosthesis and associated infected material then at least six weeks wait, during which time the infection is treated, before reinsertion of a new prosthesis. In the one-stage approach the knee prosthesis is replaced after meticulous removal of potentially infected material.
While the two-stage process is associated with lengthy hospitalisation, poor mobility and pain between operations, it remains the preferred approach because it is thought to be better to ensure infection is completely eradicated before inserting a new prosthesis. This review investigated whether in all the studies currently undertaken, there are differences in re-infection rates and other outcomes between the one- and two-stage strategies.
What did this study do?
This was a systematic review and analysis of 118 observational (cohort) studies conducted in patients with infected knee prostheses treated by one- or two-stage revision surgery. Ten one-stage studies (423 participants) were included and 108 two-stage studies (5,129 participants). Observational studies were used because no trials were identified. Infection rates were indirectly compared across the studies.
Studies were from Europe, North America, Asia and the Pacific. Many of the studies were old and small (24 were published before 2000; only seven had more than 100 participants). Average follow-up was around one year. Studies were considered to be of moderate to good quality – quality scores ranged from 9 to 15 on a 16 point scale. However, because these are observational studies they can only provide at best weak evidence of cause and effect.
What did it find?
- The rates of re-infection after surgery were similar. The rate after one-stage surgery was 7.6% (95% confidence interval [CI] 3.4% to 13.1%), and after two-stage surgery 8.8% (95% CI 7.2% to 10.6%).
- Re-infection rates remained similar when the authors looked only at sub-groups of studies with certain characteristics. Sub-groups were selected on: geography, age, use of a spacer and spacer type (technical aspects of two-stage surgery), type of fixation used (cemented or cementless), size of study, and quality of study.
- Clinical outcomes of knee scores and range of motion were similar for both one- and two-stage surgeries. However, these were not reported for all studies.
What does current guidance say on this issue?
Guidelines published in the Journal of Antimicrobial Chemotherapy recommend that a one-stage procedure can be considered for people with good soft tissue and bone stock who do not require bone grafting. In addition, antibiotic-impregnated cement should be used and the infecting organism should have been identified and be likely to be susceptible to oral antibiotics. Otherwise, and for the majority of cases, two-stage revision is recommended.
Some individual trusts have local guidelines. For example, Nottingham University Hospitals NHS Trust recommends that the decision should be based on whether the person is high risk and how easy it is to treat the infecting organism.
All guidelines emphasise that management must be tailored to the individual.
What are the implications?
The data suggest that the one-stage approach may be as effective as the two-stage approach. The evidence is limited though, particularly with regard to the one-stage procedure, and prone to bias given its observational nature. However, a randomised controlled trial is unlikely to be feasible due to the difficulties with blinding, randomisation and the huge sample size that would be needed. The observational evidence covered in this review is the best currently available.
Two stage surgery is immensely disruptive for patients, typically necessitating three months or more of limited mobility and inability to work. Costs are high due to repeat operating theatre time and prolonged physiotherapy.
The one-stage procedure appears to be safe and effective in low risk patients, would be more convenient for the patient and could provide savings for the NHS through reduced hospitalisation time.
Citation and Funding
Kunutsor SK, Whitehouse MR, Lenguerrand E, et al. Re-Infection Outcomes Following One- And Two-Stage Surgical Revision of Infected Knee Prosthesis: A Systematic Review and Meta-Analysis. PLoS One. 2016;11(3): e0151537.
This project was funded by the National Institute for Health Research Programme Grants for Applied Research program (project number RP-PG-1210-12005).
Kallala RF, Vanhegan IS, Ibrahim MS, et al. Financial analysis of revision knee surgery based on NHS tariffs and hospital costs does it pay to provide a revision service? Bone Joint J. 2015;97-B(2):197-201.
Minassian AM, Osmon DR, Berendt AR. Clinical guidelines in the management of prosthetic joint infection. J Antimicrob Chemother. 2014;69 Suppl 1:i29-35.
NHS Choices. Knee replacement. London: NHS Choices; 2014.
NICE. Mini-incision surgery for total knee replacement. IPG345. London: National Institute for Health and Care Excellence; 2010.
Nottingham Antimicrobial Guidelines Committee. Guideline for the treatment of prosthetic joint infections. Version 2.0. Nottingham: Nottingham University Hospitals NHS Trust; 2014
Toms AD, Davidson D, Masri BA, Duncan CP. The management of peri-prosthetic infection in total joint arthroplasty. J Bone Joint Surg Br. 2006;88(2):149-55.
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