Robotic-assisted total knee arthroplasty can attain highly accurate implantation. However, the target for optimal positioning of the components remains debatable. One of the proposed targets is to recreate the functional status of the pre-diseased knee. The aim of this study was to demonstrate the feasibility of reproducing the pre-diseased kinematics and strains of the ligaments and, subsequently, use that information to optimize the position of the femoral and tibial components. For this purpose, we segmented the pre-operative computed tomography of one patient with knee osteoarthritis using an image-based statistical shape model and built a patient-specific musculoskeletal model of the pre-diseased knee. This model was initially implanted with a cruciate-retaining total knee system according to mechanical alignment principles; and an optimization algorithm was then configured seeking the optimal position of the components that minimized the root-mean-square deviation between the pre-diseased and post-operative kinematics and/or ligament strains. With concurrent optimization for kinematics and ligament strains, we managed to reduce the deviations from 2.4 ± 1.4 mm (translations) and 2.7 ± 0.7° (rotations) with mechanical alignment to 1.1 ± 0.5 mm and 1.1 ± 0.6°, and the strains from 6.5% to lower than 3.2% over all the ligaments. These findings confirm that adjusting the implant position from the initial plan allows for a closer match with the pre-diseased biomechanical situation, which can be utilized to optimize the pre-planning of robotic-assisted surgery.

Implant malalignment during TKA may lead to suboptimal outcomes. Accuracy studies are typically performed with experienced surgeons; however, it is important to study less experienced surgeons when considering teaching hospitals where younger surgeons are operating. Therefore, the purpose of this study was to assess whether computer-assisted TKA (CATKA) allows for more accurate and precise implant position to plan when compared to manual TKA (MTKA) when the surgery is performed by less experienced surgeons.Two surgeons, currently in their fellowship training and having minimal CATKA experience, performed a total six MTKA and six CATKA on paired cadaveric knees. Computed tomography (CT) scans were obtained for each knee pre- and post- operatively. CT scans were analyzed to compare post-operative implant position to the pre-operative planned position. Mean system errors and standard deviations were compared between CATKA and MTKA for the femoral component sagittal, coronal, and axial planes and the tibial component in the sagittal and coronal planes. A 2-Variance testing was performed using an alpha=0.05.CATKA had greater accuracy and precision to plan than MTKA for: femoral axial plane (1.1o±1.1o vs. 1.6o±1.3o), coronal plane (0.9o±0.7o vs. 2.2±1.0o), femoral sagittal plane (1.5o±1.3o vs. 3.1o±2.1o), tibial coronal plane (0.9o±0.5o vs. 1.9o±1.3o) and tibial sagittal plane (1.7o±2.6o vs. 4.7o±4.1o). There was no statistical difference between surgical groups or between the two surgeons performing the cases.With limited CATKA experience, the fellows showed increased accuracy and precision to plan for femoral and tibial implant positions. Furthermore, these results are comparable to what has been reported for an experienced surgeon performing CATKA.