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Computed Tomography-Based Robotics Are More Accurate than Manual Instruments in Achieving Sagittal Alignment Targets
Spencer H Summers1, Paraic S Cagney2, Tyler R Youngman3
1Department of Orthopaedic Surgery, Hospital for Special Surgery, West Palm Beach, Florida.
Background:
Implant malalignment may predispose patients to implant failure or pain following total knee arthroplasty (TKA). Previous studies indicate that robotically-assisted total knee arthroplasty (RA-TKA) can achieve coronal alignment targets more accurately and precisely than manually instrumented total knee arthroplasty (M-TKA). The purpose of this study was to evaluate the accuracy of RA-TKA versus M-TKA in achieving predetermined coronal and sagittal alignment targets in TKA.
Methods:
A total of 201 RA-TKAs performed by three high-volume, fellowship-trained surgeons between June 2021 and June 2022 were compared to a historical control of 365 M-TKAs performed between 2013 and 2017 by the same surgeons. Coronal and sagittal component alignments were assessed using standing antero-posterior and lateral radiographs. Included measurements were femoro-tibial angle (FTA), medial distal femoral angle, proximal tibial angle, femoral sagittal angle, tibial sagittal angle, anterior condylar offset, and posterior condylar offset ratio. Normal and outlier ranges were determined from prior studies. The proportions of outliers were compared using univariate analyses.
Results:
The RA-TKA was more accurate than M-TKA in achieving all four sagittal alignment targets and two of the three coronal alignment targets. The RA-TKA group exhibited fewer radiographic outliers for distal femoral angle (zero versus 2.5%; P = 0.03), proximal tibial angle (one versus 10.1%; P < 0.001), femoral sagittal angle (7.0 versus 15.6%; P < 0.01), tibial sagittal angle (5.0 versus 14.3%; P < 0.01), anterior condylar offset (8.5 versus 30.6%; P < 0.01), and posterior condylar offset ratio (1.5 versus 9.5%; P < 0.01). Patients in the RA-TKA group had a higher proportion with no radiographic outliers (58.2 versus 35.2%; P < 0.001) and a lower incidence of ≥ two outliers (5.5 versus 25%; P < 0.001) compared to the M-TKA group.
Conclusions:
The RA-TKA is more effective than M-TKA in achieving coronal and sagittal alignment, potentially enhancing surgical outcomes.
