A newly custom coordinate system used for preoperative planning of robotic-assisted total knee arthroplasty

Preoperative planning is critical for total knee arthroplasty (TKA) performed with surgical robots, as it involves establishing a coordinate system to calculate the angle values of the components. This coordinate system serves as a reference during the surgical planning stage. This study aimed to develop a newly custom coordinate system suitable for integration with a surgical robot system.

The "Skywalker" surgical robot system was used to import computed tomography (CT) images of the entire lower extremities from 50 patients diagnosed with osteoarthritis. Three-dimensional reconstruction was subsequently performed. The TKA component was positioned at a fixed angle using the newly developed custom coordinate system. The angle values of the components, based on the standard CT coordinate system, were then recorded without altering their positioning. These values were analyzed to assess the differences between the two coordinate systems.

The mean and standard deviation values for the coronal, sagittal, and transverse plane positioning of the femoral component (absolute value of error) were 0.004° ± 0.020°, 0.006° ± 0.024°, and 0.158° ± 0.186°, respectively. Similarly, the mean and standard deviation values for the coronal, sagittal, and transverse plane positioning of the tibial component (absolute value of error) were 0.544° ± 0.452°, 0.042° ± 0.076°, and 0.348° ± 0.445°, respectively.

This newly developed custom coordinate system can be employed for preoperative planning in Skywalker surgical robot system-assisted TKA, particularly for patients with significant positional abnormalities in their CT scans.