Robotic Assisted UKA

Robotic Assisted UKA

Prepared by Dr. Kayahan KARAYTUG

Robotic unicompartmental knee arthroplasty (R-UKA) is an evolution of traditional unicompartmental knee replacement, developed to improve component accuracy, reduce outliers, and enhance short-term recovery. It is indicated for isolated medial or lateral compartment osteoarthritis (Kellgren–Lawrence grade IV) when the remaining compartments are intact.
💡 Approximately 20% of knee OA cases are unicompartmental — most involve the medial side.

Robotic Unicompartmental Knee Arthroplasty (R-UKA)

Why Robotics?

Conventional UKA is highly technique-sensitive; even 2–3° of malalignment can shorten implant life. Robotic systems minimize this variability by integrating preoperative imaging, 3-D planning, and intra-operative feedback, allowing precise bone preparation and implant positioning.
💡 Accuracy translates to reproducibility and potentially longer survivorship.

Robotic Platforms

Common systems:

• MAKO (Stryker, NJ, USA) – most extensively validated
• Cuvis Joint ( Meril, India)
• NAVIO / CORI® (Smith & Nephew, MN, USA)
• ACROBOT (UK)

Systems are categorized as passive (navigational), semi-active, or active, depending on the degree of robotic autonomy.

Accuracy & Alignment

• R-UKA achieves superior coronal and sagittal alignment compared to manual UKA.
• Tibial slope variation and component overhang are significantly reduced.
• Fewer alignment deviations >2° are reported.
• Improved restoration of joint line and mechanical axis alignment.
  💡 Most alignment-related failures seen in conventional UKA are rare in robotic surgery.

Functional & Clinical Outcomes

• Early postoperative pain and opioid use are reduced.
• Faster return to daily activities and physiotherapy.
• Improved early range of motion and hospital discharge time.
• At 1-year, gait studies show more physiological motion patterns during stance phase.
• Mid-term outcomes (2–5 years) are comparable to conventional UKA in survivorship.
  💡 Robotic precision benefits early recovery, but long-term differences remain under investigation.

Implant Survivorship

• Short- to mid-term survival rates: ≈98–99% at 2–3 years.
• Failures in robotic series are rarely due to malalignment — mostly aseptic loosening or progression of arthritis in untreated compartments.
• Long-term (>10 years) data are still limited.
  💡 Accuracy may delay mechanical failure but cannot prevent disease progression.

Limitations & Considerations

• Higher cost and longer setup time.
• Requires specific training and case volume to justify system investment.
• Outcomes depend on surgeon experience, platform type, and patient selection.

Clinical Pearls

• Ideal candidates: isolated unicompartmental OA, intact cruciate ligaments, correctable deformity, BMI < 35.
• Avoid in: inflammatory arthritis, tricompartmental OA, fixed deformity > 15°, severe bone loss.
• Precision ≠ Perfection: robotic systems guide, but do not replace, surgical judgment.
• Integration with AI-based planning and patient-specific implants will likely define the next generation of R-UKA.

Summary

Robotic UKA enhances surgical precision, reproducibility, and early functional recovery compared to conventional techniques.
While radiographic and short-term clinical outcomes are consistently superior, long-term survivorship equivalence underscores the importance of patient selection, surgical skill, and individualized alignment goals.

References 

1. Cobb JP et al. J Bone Joint Surg Br. 2006;88-B:188–197.
2. Cool CL et al. J Arthroplasty. 2023;38(4):754–763.
3. Herry Y et al. Bone Joint J. 2022;104-B:325–333.
4. Bell SW et al. Knee Surg Sports Traumatol Arthrosc. 2021;29:1001–1012.
5. Pandit H et al. J Arthroplasty. 2020;35:S15–S22.