Pain and pain management following manual versus robotic assisted unicondylar knee arthroplasty

Abstract

Aims

The adoption of robotic assistance for unicondylar knee arthroplasty (UKA) is increasing, driven by reports of improved implant positioning. However, its impact on short-term patient outcomes remains debated. This study aimed to compare postoperative pain, opioid consumption, and length of hospital stay between manual (maUKA) and robotic-assisted (raUKA) procedures in a large, real-world cohort.

Materials and methods

We retrospectively identified 1369 opioid-naïve patients undergoing medial, unilateral UKA at a single institution between 2019 and 2023 (417 manual, 952 robotic). We collected data on Numeric Pain Rating Scale (NRS) scores, opioid consumption in morphine milligram equivalents (MMEs), and length of hospital stay. Multivariable linear regression was used to compare outcomes while controlling for patient-level confounders.

Results

After multivariable adjustment, we found no statistically significant difference between the manual and robotic groups in length of hospital stay (p = 0.6206) or total 90-day opioid consumption. Patients in the raUKA group reported slightly higher pain scores at the first postoperative measurement (Estimate −0.7, p < 0.001); however, no significant differences were observed in average, minimum, or maximum in-hospital pain scores. There was no significant difference in total inpatient opioid consumption.

Conclusion

In this large single-institution analysis, robotic assistance was not associated with improvements in postoperative pain, opioid use, or length of hospital stay compared to the manual technique. These findings suggest that potential benefits of robotic UKA related to implant accuracy may not translate to improved short-term clinical outcomes, a crucial consideration in the context of technology acquisition and healthcare costs.