New Robotic Knee Surgery: Does Implant Type Affect Alignment Accuracy?

This is a single-center, prospective, double-blinded, randomized controlled trial (RCT) conducted at the Department of Orthopaedics & Traumatology, The Duchess of Kent Children's Hospital (DKCH), Hong Kong. The study aims to evaluate the accuracy of postoperative knee alignment relative to preoperative planning when using two different commercially available total knee arthroplasty (TKA) implant systems (Attune and Persona) in conjunction with a novel CT-based robotic surgical system (KUNWU® Robotic Surgical System, Yuanhua Robotics, Perception & AI Technologies Limited, Hong Kong).

Randomization and Blinding Eligible participants will be randomized in a 1:1 ratio to receive either the Attune or Persona implant using a computer-generated randomization sequence. Allocation concealment will be maintained using sequentially numbered, opaque, sealed envelopes. The study is double-blinded: participants and outcome assessors will be blinded to implant allocation. The operating surgeon cannot be blinded due to the inherent differences in implant instrumentation and design.

Surgical Procedure All surgeries will be performed by a single surgical team using the KUNWU® robotic system. Preoperative planning will be based on CT-derived 3D models of the patient's knee joint, allowing for individualized determination of implant size, positioning, and alignment targets. Intraoperatively, the robotic system provides real-time haptic feedback and bone resection guidance to execute the preoperative plan. The choice of implant (Attune or Persona) is the only variable; all other aspects of the surgical procedure, including approach, soft tissue balancing, and postoperative rehabilitation protocol, will be standardized across both groups.

Assessments and Follow-up Schedule Participants will undergo a series of clinical and radiological assessments at specified time points throughout the study.

Imaging Assessments:

Computed Tomography (CT) scans will be performed preoperatively and once postoperatively to assess knee alignment.

Standard X-rays will be taken preoperatively, and at 3 months, 6 months, 12 months, and 24 months postoperatively.

Clinical Assessments:

All clinical outcome assessments will be administered by a blinded assessor. Assessments will take place preoperatively, and at 6 weeks, 3 months, 6 months, 12 months, and 24 months postoperatively. The following validated instruments will be used:

Pain Assessment: Visual Analog Scale (VAS) for pain

Functional Assessment: Forgotten Joint Score (FJS) and Knee Injury and Osteoarthritis Outcome Score, Junior (KOOS, JR)

Quality of Life Assessment: Short-Form-12 (SF-12) health survey

Safety Monitoring:

All intraoperative and postoperative complications, including but not limited to infection, dislocation, and need for revision surgery, will be documented throughout the follow-up period. Length of hospital stay and cost-effectiveness data will also be collected.

Summary of Assessment Schedule:

In summary, CT scans are performed twice (preoperatively and postoperatively), while X-rays are performed at five time points (preoperatively, 3 months, 6 months, 12 months, and 24 months). Clinical outcome assessments using VAS, FJS, KOOS, JR, and SF-12 are conducted at six time points (preoperatively, 6 weeks, 3 months, 6 months, 12 months, and 24 months). Complications are monitored at all postoperative visits from 6 weeks through 24 months.

Inclusion criteria

• Adults aged 18 years and older.
• Diagnosis of symptomatic knee osteoarthritis requiring total knee replacement.
• Ability to give informed consent.
• Feasibility of using the two types of implants

Exclusion criteria

• Severe radiographic knee OA (Kellgren-Lawrence grade 4) or severe knee pain (VAS>80mm/100 mm) that could not tolerate further conservative management