Comparison of the cost-effectiveness and safety between staged bilateral total knee arthroplasty and simultaneous bilateral total knee arthroplasty: a retrospective cohort study between 2001 and 2022.

INTRODUCTION: A substantial proportion of Hong Kong's aging population suffers from osteoarthritis in both knees. Bilateral total knee arthroplasty (BTKA) is a surgical option for addressing this condition and can be performed via two approaches: simultaneous (SimBTKA) and staged (StaBTKA) bilateral TKAs. We compared the cost-effectiveness and safety of these two methods in our institution. METHODS: We retrospectively reviewed 2,372 patients (SimBTKA, 772; StaBTKA, 1,600; female, 1,780; male, 592; mean age at SimBTKA, 70.4 ± 7.99 years; mean age at StaBTKA, 66.4 ± 7.50 years; p < 0.001) who underwent bilateral TKA in our institution from 2001 to 2022. Patients were categorized according to surgical approach. Patients undergoing BTKA in our institution were included. Particularly for SimBTKA, patients were assessed by anesthetists to be medically fit before undergoing SimBTKA according to their age, American Society of Anesthesiologists status, and osteoarthritis severity. Primary outcome was the length-of-stay (LOS) after surgery. Secondary outcomes were the 30-day unintended readmission, intensive care unit (ICU) admission, and death. RESULTS: SimBTKA had a short mean total LOS (acute hospital + rehabilitation center; SimBTKA, 13.09 days; StaBTKA, 18.12 days; p < 0.001) and mean LOS in acute hospital (SimBTKA, 7.70 days; StaBTKA, 10.42 days; p < 0.001). However, no significant difference was found in mean LOS in rehabilitation centers (SimBTKA, 5.47 days; StaBTKA, 6.32 days; p > 0.05) between the two approaches. The 30-day unintended readmission rate was low in SimBTKA (SimBTKA, 2.07%; StaBTKA, 3.30%; OR = 1.60; p > 0.05) but statistically insignificant. SimBTKA was less costly than StaBTKA by US$8,422.22. per patient. No significant differences in ICU admission and death rates were found (p > 0.05) between the two groups. CONCLUSION: SimBTKA had a shorter LOS and lower cost than StaBTKA and comparable complication rates. Therefore, SimBTKA should be indicated in medically stable patients.

Reducing edge loading and alignment outliers with image-free robotic-assisted unicompartmental knee arthroplasty: a case controlled study.

BACKGROUND: Survivorship of medial unicompartmental knee arthroplasty (UKA) is technique-dependent. Correct femoral-tibial component positioning associates with improved survivorship. Image-free robotic-assisted unicompartmental knee arthroplasty enables preoperative and intraoperative planning of alignment and assessment of positioning prior to execution. This study aimed to compare the radiological outcomes between robotic-assisted UKA (R-UKA) and conventional UKA (C-UKA). METHODS: This retrospective case control study involved 140 UKA (82 C-UKA and 58 R-UKA) performed at an academic institution between March 2016 to November 2020, with a mean follow-up of 3 years. Postoperative radiographs were evaluated for mechanical axis and femoral-tibial component position. Component position was measured by two methods: (1) femoral-tibial component contact point with reference to four medial-to-lateral quadrants of the tibial tray and (2) femoral-tibial component contact point deviation from the center of the tibial tray as a percentage of the tibial tray width. Baseline demographics and complications were recorded. RESULTS: There was a higher mean component deviation in C-UKA compared with R-UKA using method 2 (17.2% vs. 12.8%; P = 0.007), but no difference in proportion of zonal outliers using method 1 (4 outliers in C-UKA, 5.1% vs. 1 outlier in R-UKA, 1.8%; P = 0.403). R-UKA showed no difference in mean mechanical alignment (C-UKA 5° vs. R-UKA 5°; P = 0.250). 2-year survivorship was 99% for C-UKA and 97% for R-UKA. Mean operative time was 18 min longer for R-UKA (P < 0.001). CONCLUSION: Image-free robotic-assisted UKA had improved component medio-lateral alignment compared with conventional technique.