Archives of Orthopaedic and Trauma Surgery - 2026-05-09 - Journal Article
Robotic-assisted unicompartmental knee arthroplasty is associated with lower odds of prolonged hospitalization and no higher odds of high-charge admission during the index hospitalization.
Sun Q, Xu Y, Hong X, Dai M, Wang J, Xie H, Fu Z
Topics
Key Takeaway
Robotic-assisted UKA was associated with 25% lower adjusted odds of prolonged hospitalization (aOR 0.750) versus conventional UKA, with no significant difference in high-charge admission (aOR 1.007) in a national inpatient sample of 7,154 cases.
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Summary
This study used the National Inpatient Sample (2016–2022) to compare prolonged hospitalization (LOS ≥2 days), high-charge admission (TOTCHG ≥$72,321), and in-hospital mortality between RA-UKA and conventional UKA for medial compartment OA. On multivariable logistic regression with calendar year fixed effects, RA-UKA carried lower odds of prolonged LOS (aOR 0.750, 95% CI 0.647–0.870) and equivalent odds of high-charge admission (aOR 1.007, 95% CI 0.855–1.186). In-hospital mortality and inpatient complications were rare in both groups.
Key Limitation
The analysis is restricted to the index hospitalization, precluding assessment of 30-day readmission, revision rates, implant survivorship, or total episode-of-care cost — the outcomes most relevant to value-based purchasing decisions.
Original Abstract
BACKGROUND
Robotic-assisted unicompartmental knee arthroplasty (RA-UKA) may improve implant positioning, but its impact on index-hospitalization length of stay (LOS), billed charges, and early inpatient outcomes in routine practice remains unclear.
METHODS
Using the National Inpatient Sample (2016-2022), we identified primary medial UKA for osteoarthritis. RA-UKA was defined by ICD-10-PCS robotic-assisted lower-extremity procedure codes. Primary outcomes were prolonged hospitalization (LOS ≥ the 75th percentile, ≥ 2 days), high-charge admission (total hospital charges [TOTCHG] ≥ the 75th percentile, ≥ $72,321), and in-hospital mortality. We performed univariable comparisons and multivariable logistic regression adjusting for demographics, payer, admission type, hospital teaching status, comorbidities, and calendar year fixed effects (YEAR 2016-2022) using the unweighted NIS discharge sample.
RESULTS
Among 7,154 UKAs, 1,297 (18.1%) were RA-UKA and 5,857 (81.9%) were C-UKA. Median LOS was 1 day (IQR 1-2) in both groups; however, prolonged hospitalization (LOS ≥ 2 days) occurred less frequently in RA-UKA (412/1,297 [30.7%] vs. 2,162/5,857 [37.2%]; P < 0.001). In adjusted analyses including YEAR fixed effects, RA-UKA was associated with lower odds of prolonged hospitalization (aOR 0.750, 95% CI 0.647-0.870; P < 0.001) and was not associated with high-charge admission (TOTCHG ≥ $72,321; aOR 1.007, 95% CI 0.855-1.186; P = 0.993). In-hospital mortality and other inpatient complications were rare.
CONCLUSIONS
RA-UKA was associated with lower odds of prolonged hospitalization (LOS ≥ 2 days) and no higher odds of a high-charge admission (billed charges, TOTCHG) during the index hospitalization. Findings apply to the index hospitalization only.