Early Radiographic and Clinical Outcomes of Robotic-Arm-Assisted Versus Conventional Total Knee Arthroplasty

2. Materials and methods 2.1 Study design Our study was a prospective, multicenter and randomized controlled trial that was approved by the Institutional Review Board of Peking University Third Hospital (IRB # 2022-134-02), the First Affiliated Hospital of Shandong First Medical University (IRB # 2022-QX-S003-01) and Chifeng Municipal Hospital (IRB # 2022-LLSCGVK4-101-06). All patients had provided written informed consent.

2.2 Patient recruitment From November 2022 to May 2023, a total of 130 patients were randomized into two groups - 65 patients underwent robotic-assisted TKA and 65 underwent conventional TKA. The inclusion criteria were as follows: older than 18 years old and younger than 80 years old with knee osteoarthritis undergoing primary and unilateral TKA; after receiving both an oral and a written explanation of the study protocol, they provided written informed consent that they were willing to complete all of the assessments and potential interventions. The exclusion criteria were as follows: patients with infection, severe systemic disease (severe diabetes, severe osteoporosis, severe muscle loss, etc.), neuromuscular dysfunction of lower limbs, who are allergic to metal implants, participated in other clinical studies, whose knee joint has been fused for a long time without pain or deformity, unable to tolerate surgery on a systemic assessment, women who are pregnant or breastfeeding, or who expect to give birth during the clinical period, and there are other factors that affect the efficacy of observation in this study. All operations were performed by experienced surgeons for the conventional and robotic-assisted groups at three hospitals. All patients who underwent TKA with the robotic-assisted or conventional operations underwent the radiologic and clinical assessment.

Main effectiveness evaluation index The main evaluation index of the knee navigation and positioning system clinical trial was the proportion of subjects whose mechanical axis of the femoris deviated from the mechanical axis of the tibia by ≤3° on the full-length lower extremity weight-bearing X-ray at 6 weeks (±2 weeks) after surgery.

X-ray shooting requirements: Full-length weight-bearing X-ray of both lower limbs, that is, X-ray of both lower limbs including hip joint, full length of femur, knee joint, full length of tibia and fibula and ankle joint taken by the patient in the standing state. Key points: The patient stands upright on the camera frame, the back is close to the camera frame, the hands naturally droop, the knee joint is as straight as possible, the feet are the same width as the shoulders, and the internal rotation is about 15°, so that the small head of the fibula overlaps with the tibia nearly one-third, and the patella is pointed vertically in front.

The lower limb force line was evaluated by non-surgeon.