Robotic-assisted technology does not influence functional outcomes among obese and morbidly obese total knee arthroplasty patients

Trends and epidemiology in robotic-assisted total knee arthroplasty: Reduced complications and shorter hospital stays

INTRODUCTION

This study provides an in-depth analysis of the immediate postoperative outcomes and implications or robotic-assisted total knee arthroplasty (RA-TKA) compared with conventional TKA (C-TKA), particularly with regard to mortality, complications, hospital stay and costs, drawing from a comprehensive nationwide data set.

METHODS

The Nationwide Inpatient Sample (NIS) database, the largest all-payer inpatient healthcare database in the United States, was used to identify all patients who underwent RA-TKA or C-TKA from 2016 to 2019. A total of 527,376 cases, representing 2,638,679 patients who underwent elective TKA were identified, of which 88,415 had RA-TKA. To mitigate potential variations and selection bias in baseline characteristics between the two groups, a propensity score-matched analysis was employed to further balance and refine our data set, resulting in 176,830 patients evenly distributed between the groups. Analysis was performed according to demographics, immediate post-operative complications, and economic data, including payor class, length of stay and total charges.

RESULTS

There was a marked shift towards RA-TKA, from an initial 0.70% in 2016 to a notable 7.30% by 2019. Patients who underwent RA-TKA were slightly younger (66.2 ± SD years), compared to the C-TKA group (66.7 ± SD years). Hospital stay was 1.89 days and 2.29 days for RA-TKA and C-TKA, respectively. Charges metrics revealed slightly higher charges for RA-TKA. Less postoperative complications were found in the RA-TKA group, such as blood loss, anaemia, acute kidney injury, venous thromboembolism, pulmonary embolism, pneumonia and surgical wound complication. Even following the propensity score matching, these findings remained consistent and statistically significant.

CONCLUSIONS

RA-TKA use in the United States has grown substantially in the last few years and has been associated with significantly reduced immediate post-operative complications and length of hospital stay compared to C-TKA, offering safer surgical management for TKA patients. Further studies on the short- and long-term outcomes of RA-TKA would improve the understanding of the full potential of this technology.

LEVELS OF EVIDENCE

Level III.

Robotic-Assisted Total Knee Arthroplasty in Obese Patients

Background

Robotic-assisted systems have gained popularity in total knee arthroplasty (TKA). The purpose of this study was to evaluate operative characteristics and radiographic outcomes of obese patients undergoing robotic-assisted TKA.

Methods

A retrospective review of consecutive cases performed by a single surgeon was performed from January 1, 2016, to January 31, 2022. Adult patients with body mass index ≥35 kg/m2 who underwent primary TKA using a computed tomography-assisted robotic system were compared to patients who underwent primary TKA using conventional instrumentation. Demographics, preoperative and postoperative radiographic measurements, and intraoperative outcomes were compared between cohorts. In total, 119 patients were identified, 60 in the robotic-assisted cohort and 59 in the conventional instrumentation cohort.

Results

Age, body mass index, and estimated blood loss were not significantly different between the cohorts. The robotic-assisted cohort experienced longer tourniquet times (93.3 vs 75.5 minutes, P < .001). Preoperative hip-knee-ankle angle (HKA) was similar between the robotic-assisted and conventional cohorts (8.4° ± 4.9° vs 9.3° ± 5.3°, P = .335). Postoperative HKA was 2.0° ± 1.4° in the robotic-assisted group and 3.1° ± 3.23° in the conventional group (P = .040). The proportion of patients with postoperative HKA > 3° of varus or valgus was 9 of 60 (15.0%) in the robotic-assisted cohort compared to 18 of 59 (30.5%) using conventional instrumentation (P = .043).

Conclusions

Obese patients treated with robotic-assisted TKA had postoperative alignment closer to neutral and fewer postoperative radiographic outliers than patients treated with conventional instrumentation. The results of this study support use of robotic-assisted technologies in TKA, particularly in obese patients.