Early Revision Analysis of Robotic-Arm Assisted and Manual Unicompartmental Knee Arthroplasty

Background:The purpose of this study was to evaluate hospital admissions for revision surgeries associated with robotic-arm assisted unicompartmental knee arthroplasty (rUKA) vs. manual UKA (mUKA) procedures.Methods:Patients ≥18 years of age who received either a mUKA or a rUKA procedure were candidates for inclusion and were identified by the presence of appropriate billing codes. Procedures performed between March 1st, 2013 and July 31st, 2015 were used to calculate the rate of surgical revisions occurring within 24-months of the index procedure. Following propensity matching, 246 rUKA and 492 mUKA patients were included. Revision rates and the associated costs were compared between the two cohorts. The Mann-Whitney U test, was used to compare continuous variables, and fisher’s exact tests was used to analyze discrete categorical variables.Results:At 24-months following the primary UKA procedure, patients who underwent rUKA had fewer revision procedures (0.81% [2/246] vs. 5.28% [26/492]; p=0.002), shorter mean LOS (2.00 vs. 2.33 days; p>0.05), and incurred lower mean costs for the index stay plus revisions ($26,001 vs. $27,915; p>0.05) than mUKA patients. Length of stay at index, and index costs were also lower for rUKA patients (1.77 vs. 2.02 days; p=.0047) and ($25,786 vs. $26,307; p>0.05).Conclusions:Study results demonstrate that patients who underwent rUKA had fewer revision procedures, shorter LOS, and incurred lower mean costs (although not statistically different) during the index admission and at 24-months post-operative. These results could be important for payers as the prevalence of end-stage knee OA increases alongside the demand for cost-efficient treatments.