Description
The aim of our study was to compare lower limb alignment, 3D femoral and tibial component placement after preoperative planning and after final implantation. It was hypothesized that robotic arm‐assisted total knee arthroplasty (RA‐TKA) using additionally a gap‐balancing instrumentation will show high accuracy in executing the planning in component placement throughout the range of knee motion.
104 patients underwent robotic-arm assisted total knee arthroplasty (RA-TKA) at a single center (44 M, 60 F) were included. The mean age was 69.38 +8,99. Data was collected prospectively. A cruciate retaining cemented design was implanted in all cases using the MAKO® robotic system. Lower limb alignment during the full ROM was recorded prior bony resection and finally after implantation of the components. A ligament tensioner was inserted to measure the extension and flexion gap using 200N. The components were adjusted to preserve the joint line and lower limb alignment with a range of 5 degrees. The component placement was analyzed based on 3D CT images after planning and final placement in sagittal, coronal and axial view.
The femoral component was less valgus of 0,68°+1.44° in the coronal plane (p<0.001), 0.65°+1.96° less externally rotated referenced to the surgical TEA in the axial plane (p=0.001) and less flexion of 0,86° +1.81° referenced to the sagittal plan (p<0.001). In the tibial components were more varus of 0.16°+0.86° in the coronal plan (p=0,056) and an increased posterior slope of 0.46° +0.98° in the sagittal plan (p<0.001). The intra-op mean alignment was 4,37°, 3,36°, 3,77°, 3,55° and 2,91° in the native knee and 1,24°, 0,77°, 1,03°, 1,11° and 1,51° with the final component placed, respectively.
Depending on the analysis during surgery, respecting the native joint line, the study demonstrated Robotic‐assisted TKA helps to achieve the target of alignment and component placement very close to the planning. It allows optimal component placement of off‐the‐shelf implants respecting patient's specific anatomy. The clinical relevance of these changes require further studies.
