Femoral and Patellar Radiographic Metrics Are Improved With Robotic-Assisted Total Knee Arthroplasty

Abstract

Background

Although robotic technology enhanced surgery does not directly address the patella, its associated improvement in knee reconstruction and flexion balance may result in improved patellar function and radiographs. In this retrospective observational analysis, we aimed to 1) compare patellar and femoral radiographic metrics between robotic-assisted and conventional total knee arthroplasty (RA-TKA and C-TKA) and 2) assess the correlation between these radiographic metrics and postoperative patient-reported outcomes in the RA-TKA cohort.

Methods

Fifty RA-TKAs were compared with 50 C-TKAs at an average 2.8 years of follow-up. Age, gender, body mass index, type of arthritis, preoperative range of motion, preoperative pain localization, type of implant, precut patellar thickness at the expected location of the apex, postcut patellar thickness at the same location, patellar button thickness, and length of stay were compared, along with patient reported outcome measures. Descriptive stats, t-tests, chi-squared, and Fisher’s exact tests were applied.

Results

A significantly lower postoperative patellar displacement (1.92 vs 3.16; P = .008) and posterior femoral overstuffing (21.97 vs 23.97; P = .017) were noted among the RA-TKA group. The RA-TKA group had a significantly smaller number of patients with patellar tilt >5 degrees (10% vs 32%; P = .013). The regression analysis of patellar and femoral radiographic metrics revealed no statistically significant correlation between radiographic metrics and majority of patient-reported outcomes within the RA-TKA cohort.

Conclusions

RA-TKA had better patellofemoral metrics than conventional TKA. The RA-TKA group showed a significant improvement in patellar displacement and posterior femoral overstuffing, and lower incidence of patellar tilt >5 degrees compared to the C-TKA cohort.