Summary

A claims data analysis, comparing robotic-arm assisted (rUKA) to manual (mUKA) unicompartmental knee arthroplasty, found reduced costs among patients who underwent rUKA. Compared to manual UKA, robotic-arm assisted UKA procedures experienced lower revision rates and average total spending (including index and revision) at 24-months.

Abstract

Introduction

Robotic technologies have been introduced to enhance the outcomes of unicompartmental knee arthroplasty (UKA). One robotic technology for unicompartmental knee arthroplasty (rUKA) has been shown to lead to more accurate component positioning to plan with significantly lower median errors for all component parameters, and a shorter inpatient length of stay (LOS) when compared to manual unicompartmental knee arthroplasty (mUKA). In addition, it has been associated with lower early post-operative pain scores, improved patient outcomes, and satisfaction indices when compared to mUKAs. However, no studies on a general population have been published.

Methods

This was a longitudinal retrospective analysis of an administrative claims database designed to evaluate hospital admissions for revision surgeries associated with rUKA and mUKA procedures. Patients at least 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. Cases were propensity matched 2:1 to control for outside confounding factors at index. A total of 738 health plan patients were selected for inclusion in the analysis: 246 patients underwent rUKA and 492 patients underwent mUKA. 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=0.0017), shorter mean LOS during their revision (2.00 vs. 2.33 days; p>0.05), and incurred lower mean costs for the index stay plus revision(s) ($26,001 vs. $27,977; p>0.05). Length of stay at index, and index costs were also lower for patients who underwent rUKA (1.77 vs. 2.02 days; p=0.0047) and ($25,786 vs. $26,307; p>0.05).

Discussion

Study results demonstrate that patients who underwent rUKA had fewer revision procedures, shorter LOS, and incurred lower mean costs at 24-months. These results are likely to become even more important for payers and providers as the prevalence of end-stage knee OA increases alongside the demand for cost-efficient options for treatment.