Unicondylar Knee Arthroplasty Has Fewer Complications but Higher Revision Rates Than Total Knee Arthroplasty in a Study of Large United States Databases

• Published in: The Journal of arthroplasty Vol. 34; no. 8; pp. 1617 - 1625
• Main Authors: Hansen, Erik N., Ong, Kevin L., Lau, Edmund, Kurtz, Steven M., Lonner, Jess H.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01-08-2019
• Subjects: complications; re-operation; revision; UKA; unicompartmental; unicondylar knee arthroplasty; unicondylar knee arthroplasty; UKA; unicompartmental; complications; re-operation; revision
• ISSN: 0883-5403; 1532-8406
• DOI: 10.1016/j.arth.2019.04.004

Unicondylar knee arthroplasty (UKA) has superior functional outcomes compared to total knee arthroplasty (TKA) with good mid-term and long-term survival data from high-volume institutions. We sought to quantify the risk of complications, re-operation/revision, hospital re-admission for any reason, and mortality of knee arthroplasty patients in the US patient population using 2 large databases.
UKA and TKA patients who were identified in the 2002-2011, 5% sample of Medicare data and 2004-2012 (June) MarketScan Commercial and Medicare Supplemental Databases were followed to evaluate the risk of complications, hospital re-admission for any reason, and mortality within 90 days of surgery. Survival probability defined by re-operation was calculated using the Kaplan-Meier method at 0.5, 2, 5, 7, and up to 10 years post-operatively.
Compared to UKA, complication rates for TKA patients were significantly higher, including wound complication, pulmonary embolism, stiffness, peri-prosthetic joint infection, myocardial infarction, re-admission, and death. Age was found to be a significant risk factor (P < .05) for all complications in the Medicare cohort, except stiffness (P = .839), and all complications in the MarketScan cohort, except re-admission (P = .418), whereas gender had a variable effect on complications based on age. Survivorship of UKA was lower than TKA at all time points. Additionally, younger age adversely affected implant survival. By 7 years post-surgery, UKA survivorship in the Medicare and MarketScan cohorts was 80.9% and 74.4%, respectively. In contrast, TKA survivorship for the same cohorts was 95.7% and 91.9% by the same time point.
Patients undergoing UKA have fewer post-operative complications and re-admissions than those undergoing TKA. However, patients undergoing UKA have a higher rate of re-operation and revision at up to 10 years of follow-up. It appears that age, as well as surgeon and hospital volume significantly impacts implant survivorship while gender does not have a relation.
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