Imageless Navigation Versus Image-Based Navigation in Robotic-Assisted Total Knee Arthroplasty for Knee Osteoarthritis

The trial will include patients with end-stage osteoarthritis, qualified for Robotic-Assisted Total Knee Arthroplasty (RA-TKA). For each patient, a full-length standing radiograph will be taken with designated sensors. Based on these, a three-dimensional model of the knee joint will be generated, enabling preoperative planning and intraoperative navigation in the image-based mode. Patients who meet the criteria and provide informed consent will be included in the study. Immediately before surgery, patients will be randomly assigned by a computer programme to either the experimental or control group in a 1:1 ratio, remaining blinded to the chosen method. In the experimental group, RA-TKA will be performed using imageless navigation, whereas in the control group, it will be performed using image-based navigation. In both groups, the procedure will be performed by experienced specialists with several years of experience, according to a standardized protocol: a medial parapatellar approach with restricted kinematic alignment, using a medial congruent knee implant.

The total number of patients included in the study is planned to be 146, with 73 in the experimental group and 73 in the control group. The group size was calculated based on a power analysis; power level: 80%, significance level: α=0.05, minimal clinically important difference: 5 points on the Oxford Knee Score (OKS), standard deviation: 10 points on the OKS. The study's dropout rate is estimated at 15%.

Radiologic imaging, survey responses, and intraoperative records will be stored on physical disks and paper, as well as in a secure cloud-based database. All other records will be stored digitally only. Registry data will be compared with external data sources (medical records) every 6 months to assess their accuracy and completeness. A Linear Mixed-Effects Model will be used to account for correlation between OKS measurements in the same patient. Both Per-Protocol and Intention-to-Treat analyses will be reported. For comparing continuous variables, a t-test (if normally distributed) or a Mann-Whitney U test (if skewed) will be used. Categorical variables will be compared with Fisher's Exact Test or the Chi-squared test. A cost-minimization analysis will be conducted using economic data.

• Range of motion [Time frame: On admission to the hospital, the day after surgery, at 6 months, and at 12 months postoperatively.]
• Number of Participants achieving a planned postoperative limb alignment [Time frame: From enrollment to 12 months after surgery.]
• Postoperative radiographic results [Time frame: From enrollment to 12 months after surgery.]
• Postoperative pain assessed with a VAS scale [Time frame: Survey taken right before surgery, at 6 months, and at 12 months after surgery.]
• Time of the surgical procedure [Time frame: From the beginning to the end of the surgical procedure.]
• Estimation of perioperative blood loss [Time frame: Immediately after the end of the surgery.]
• Difference between preoperative and postoperative hemoglobin levels [Time frame: Hemoglobin levels will be measured within 2 weeks before surgery, as well as 24, 48 and 72 hours after surgery.]
• Postoperative complications [Time frame: From enrollment to 12 months after surgery.]
• Costs required for preoperative planning [Time frame: From one month before enrollment to 12 months after surgery.]
• Time required for preoperative planning [Time frame: From one month before enrollment to 12 months after surgery.]