medwireNews: Patients undergoing unicompartmental knee arthroplasty (UKA) have shorter hospital stays and fewer early complications than those receiving total knee arthroplasty (TKA) but are more likely to need a revision within 5 years, results of a large meta-analysis show.
The findings are based on data from 60 studies published in the past 20 years that compared outcomes of primary UKA with TKA in adult patients with osteoarthritis. These included seven publications from six randomized controlled trials (RCTs), 17 studies using data from national joint registries and databases, and 36 cohort studies.
Hannah Wilson (University of Oxford, UK) and co-authors say that “TKA and UKA are both viable options for the treatment of isolated unicompartmental osteoarthritis,” and therefore the results of their study “should be available to patients as part of the shared decision making process in choosing treatment options.”
For all three study types included in the analysis, the length of hospital stay was significantly shorter for the patients who underwent UKR compared with those who received TKR, by 1.20 days in the RCTs, 1.43 days in the database studies, and 1.73 days in the cohort studies.
In terms of early complications, both the RCTs and database studies showed a significantly lower risk for myocardial infarction after UKA than TKA, at risk ratios (RRs) of 0.33 and 0.22, respectively, while the database trials also showed a significantly lower risk for venous thromboembolism (RR=0.39) and cerebrovascular accident (RR=0.34) with UKA than with TKA.
The risk for death from any cause within 45 days of operation was significantly lower with UKA than TKA (RR=0.27) in the database studies, but the researchers note that no early deaths were reported among patients in the RCTs or cohort trials in either treatment group.
Rates of early reoperation for any reason were significantly lower after UKA than TKA in the cohort studies (RR=0.45) but not in the RCTs or database studies. By contrast, revision rates within 5 years were significantly higher after UKA than after TKA in all three study groups, with RRs of 5.95, 2.50, and 3.13, recorded in the RCTs, database studies, and cohort studies, respectively.
The researchers also found that patient-reported outcome scores for pain did not differ between the two operation techniques in any of the three study groups, but significantly better functional outcomes, indicating a better clinical outcome, were achieved after UKA than after TKA in patients included in the database and cohort studies.
Writing in The BMJ, Wilson et al say that patients who need to decide which treatment option to pursue will benefit from the current analysis.
“Their final decision will hinge on the relative value they place on the advantages and disadvantages of each treatment option,” the researchers write.
Wilson and team also note that “many UK knee surgeons do not [currently] perform UKA, preferring to use TKA as their sole treatment option. As the case for UKA as a viable treatment option increases, more surgeons could offer UKA or refer to appropriate specialists.”
They conclude: “If such changes in patient and clinician preference occur, then the proportion of UK primary knee arthroplasties performed as UKA could increase from the present level of 8%.”
By Laura Cowen
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