• Kenneth J Fellows, David Carmack, Joshuea Cameron, Donald Hope, and Daniel J Cognetti.
• Department of Orthopaedic Surgery, Brooke Army Medical Center, Ft. Sam Houston, TX 78234, USA.
• Mil Med. 2024 Sep 23.

IntroductionSurgeries within the Military Health System (MHS) are often performed by military physicians at External Resource Sharing Agreement (ERSA) hospitals to offload the operative demand at Military Treatment Facilities (MTFs). These agreements allow physicians flexibility in selecting where to treat military service members and other TRICARE beneficiaries. However, there is a paucity of military orthopedic literature comparing ERSA hospitals and MTFs. The objective of this study is to compare operative volume, efficiency, and orthopedic resident operative experience between an ERSA hospital and an MTF in military arthroplasty.Materials And MethodsA retrospective chart review was conducted for all surgeries performed between October 1, 2022 and July 31, 2023 by three military arthroplasty-trained surgeons at an MTF and two associated ERSA hospitals (denoted as ERSA-A and ERSA-B). Details recorded include spinal time-out time, spinal end time, in-room time, case start time, case stop time, and out-of-room time. These were used to calculate the total time in room (out-of-room time minus in-room time), case time (case stop time minus case start time), extra time in room (total time in room minus case time), and time between cases (in-room time minus out-of-room time of previous case). Lastly, we compared the average daily case volume and operative time between the facilities. Only primary joint replacements with properly documented time stamps were included in the efficiency analysis. Continuous variables were assessed for normality by the Shapiro-Wilk test. Non-normal data are presented as the median and interquartile range (IQR) and were analyzed using the Mann-Whitney U test (for two group comparisons) or the Kruskal-Wallis test (three or more groups) with Dwass-Steel-Chritchlow-Fligner pairwise comparisons. The associations between categorical variables were analyzed using the chi-squared test. Significance was set to P < .05. Statistical analyses were performed using SAS version 9.4 (Statistical Analysis Software, Cary, NC, USA). This study was classified as exempt human subjects research by the authors' institutional review board.ResultsAverage daily case volume was significantly higher at both ERSA-A (median of 3, IQR 2-4, P < .001) and ERSA-B (median of 2, IQR 2-3, P = .0075) compared to the MTF (median of 2, IQR 1-2). This translated to residents operating for a median of 270 minutes (IQR 170-398, n = 25 OR days) each operative day at ERSA-A compared to 234 minutes (IQR 131-304, n = 91 OR days) when at the MTF, which was not a significant difference (P = .21). Median case time was 26.5 minutes lower (P < .001), extra time in room was 5 minutes lower (P < .001), and time between cases was 67 minutes lower (P < .001) in the ERSA group as compared to the MTF group.ConclusionsUtilizing ERSAs can improve patient throughput and operative efficiency, which in turn enhances orthopedic resident operative experience. These findings suggest that the MHS should seek ways to improve operative efficiency at MTFs. Expanding ERSA contracts to reach a broader portion of TRICARE beneficiaries, including patients over 65 years of age and those with supplemental insurance, who are currently ineligible, should also be explored.© The Association of Military Surgeons of the United States 2024. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site–for further information please contact journals.permissions@oup.com.

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