Related Experiment Video
Updated: May 24, 2025
In Vitro Application of a Wireless Sensor in Flexion-Extension Gap Balance of Unicompartmental Knee Arthroplasty
Published on: May 5, 2023
Two-Year Outcome Comparison of a Matched Set of Total Knee Arthroplasties Performed With Robotic-Arm-Assisted
Kenneth A Gustke1, Peter Simon2
1Florida Orthopaedic Institute, Tampa, Florida; Department of Orthopaedic Surgery, University of South Florida College of Medicine, Tampa, Florida.
Background:
Alternative strategies in total knee arthroplasties (TKAs) have been developed to obtain improved outcomes utilizing implant realignment and positioning to balance the soft tissues while accepting a nonneutral mechanical alignment. The purpose of our study was to compare 2-year outcomes of a matched set of TKAs with soft-tissue gaps either "functional" balanced via robotic-arm-assisted changes to implant position and alignment prior to bone cuts (R-TKA) or manual instrument-adjusted mechanical alignment (M-TKA). We hypothesized that the R-TKA cohort would have superior patient outcomes.
Methods:
A consecutive series of 210 TKAs matched 2:1 by selecting patients in each cohort with no statistically significant preoperative differences in sex, age, American Society of Anesthesiologist physical status classification system score, Knee Society knee scores (KS-KS) and Knee Society function scores (KS-FS), range of flexion (ROF), and knee coronal alignment. There were 140 R-TKA and 70 M-TKA with the same implants that were reviewed. Tibial pressure sensors were used in all cases to verify balance. Postoperative KS-KS, KS-FS, and ROF were compared at 3 months and 2 years, and Forgotten Joint Scores (FJS) were obtained at 2 years.
Results:
Both groups achieved equivalent quantitative balance with the pressure sensors. The functional alignment-balanced R-TKA cohort had more component realignments (100 versus 35.7%), fewer soft-tissue releases (40 versus 61.4%), and statistically significant higher mean KS-KS, KS-FS, and ROF at 3 months and 2 years than the M-TKA group. The mean FJS was higher in the R-TKA group (66.3 versus 60.4), but this did not represent a statistical significance.
Conclusions:
A functional alignment balancing technique using robotic-arm assistance resulted in fewer soft-tissue releases and higher Knee Society outcome scores and knee flexion than with M-TKA at 3 months and 2 years, despite equivalent soft-tissue balance per the pressure sensors. The mean FJS at 2 years was greater, but not statistically significant.
