Robotic knee replacement tailored for varus (bow-legged) knees

Total Knee Arthroplasty in Varus Deformity

This study will test whether using weight-bearing CT scans and robotic surgery to tailor alignment improves outcomes for adults with one-sided varus knee osteoarthritis.

Quick facts

• Phase: NA
• Study type: Interventional
• Enrollment: 300 (estimated)
• Ages: 18 Years and up
• Sex: All
• Sponsor: I.M. Sechenov First Moscow State Medical University (other)
• Locations: 1 site (Moscow)
• Trial ID: NCT07465484 on ClinicalTrials.gov

What this trial studies

Participants with unilateral, advanced varus knee osteoarthritis will receive total knee arthroplasty performed with an active robotic surgical system, with alignment decisions informed by multislice CT and weight-bearing (vertical) CT comparisons to the opposite limb. The study will quantify physiological versus pathological varus under load and use those measurements to guide mechanical or kinematic alignment choices. Investigators will develop an algorithm for selecting alignment strategy based on the degree of varus deformity and follow patients for 12 months after surgery. Outcomes will focus on limb alignment, pain, and functional recovery.

Who should consider this trial

Good fit: Adults over 18 with unilateral grade 3–4 knee osteoarthritis, varus deformity (>3° or HKA <177°), BMI under 35, ASA score ≤III, able to consent and complete 12 months of follow-up are ideal candidates.

Not a fit: People with severe ligament instability or major bone defects, prior knee reconstructions, impaired weight-bearing of the opposite leg, metal implants in the lower extremities, or very high BMI (>40) are unlikely to benefit from this approach.

Why it matters

Potential benefit: If successful, patients could get more precise alignment during knee replacement, potentially improving pain relief and implant function.

How similar studies have performed: Robotic total knee arthroplasty and kinematic versus mechanical alignment approaches have shown promising but mixed results in prior studies, while using weight-bearing CT to define physiological varus is relatively novel.

Eligibility criteria

Inclusion Criteria:

1. Patients over 18 years of age with grade 3-4 knee osteoarthritis (according to Kellgren-Lawrence) and pain score of 5 or higher on a 10-point VAS scale.
2. Varus deformity of the lower limb (HKA angle \<177°, or varus \>3°)
3. Anesthesia risk according to the ASA scale of no more than III.
4. BMI less than 35 kg/m2.
5. Patient must be monitored throughout the entire study period (12 months).
6. Patient must be mentally competent and compliant.
7. Patient must provide written informed consent to participate in the study.

Exclusion Criteria:

1. Body mass index \> 40 kg/m².
2. Instability of the collateral ligaments of the knee joint requiring the installation of ligamentous systems, presence of primary severe bone defects.
3. Impaired weight-bearing ability of the contralateral limb.
4. Presence of metal implants or foreign bodies in the lower extremities.
5. Previous knee interventions, such as reconstruction of the knee ligament apparatus, or corrective osteotomies of the femur and tibia.
6. Patient refusal to participate in the study.
7. Patient failure to comply with the recommendations of the treating physician or the prescribed regimen.

Where this trial is running

Moscow

• University clinical hospital №1 I.M.Sechenov First Moscow State Medical University. The Department of Traumatology, Orthopedics and Disaster Surgery — Moscow, Russia (RECRUITING)

Conditions: Knee Osteoarthritis, Knee Osteoarthritis in Varus, Kinematic and Mechanical alignment, Weight-bearing CT