Unicondylar Knee Arthroplasty in the U.S. Patient Population: Prevalence and Epidemiology

December 28, 2018 | Surgery

Erik Nathan Hansen, MD ; Kevin L. Ong PhD ; Edmund Lau, MS ; Steven M Kurtz, PhD ; Jess H. Lonner, MD

TAKE-HOME POINTS

Prior publications on prevalence of unicondylar knee arthroplasty (UKA) in the United States using a single database may have underestimated the “true” number of cases performed.
For the time periods analyzed, a total of 5,235 and 23,310 UKA procedures were identified from the 5% Medicare and MarketScan databases, respectively.
Rates of UKA generally increased until 2008, after which there was a decline through 2012.
Gender and year of operation were found to be significantly associated with UKA rate.
Males ages 55-64, 65-69, and 70-74 were the only age-gender groups whose UKA rates appear to be trending upward.

Our data indicate that only approximately 5% of UKA patients were non-white and another 5% were from lower socioeconomic status. These findings have been observed in multiple other studies looking at the epidemiology of total joint replacement in the United States.²⁹ Bolognesi and colleagues²³ reported that although “non-white race” patients made up 12% of the general Medicare sample they were analyzing, these patients accounted for only 5% and 3% of the total knee arthroplasty and unicompartmental knee arthroplasty populations, respectively. Although it is beyond the scope of this paper to delve into the reasons for this discrepancy, it may be related to differences in access to care, healthcare literacy, and trust of patients in the healthcare system.^30,31

Our study, like all those based on administrative claims, has several notable inherent limitations. Coding inaccuracies as well as the potential for systematic bias (eg, underreporting) may affect the accuracy of our results. Although the MarketScan Commercial Research Database (Truven Health Analytics) includes nationally representative information for >180 million patients covered with private insurance, it is possible that we have missed some patients who underwent UKA during the time period investigated. However, we feel that the number missed is probably small and does not affect our conclusions in any meaningful manner.

CONCLUSION

This novel analysis of 2 separate administrative claims databases, which more accurately captures all patients undergoing UKA, indicates that there has been a steady increase in the rate of the procedure over the past decade and that a significant proportion of the surgeries were performed in younger (<65 years) patients. Understanding the accurate trends in the use of UKA on a national scale is important for legislative bodies, healthcare administrators, as well as physicians. Furthermore, given the increasing rates of UKA in patients <65 years old, and the increased burden on implants for withstanding increased activities and repetitive loads, it remains imperative to strive to optimize materials, implant designs, and surgical techniques to enhance implant durability.