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Robotic Assisted UKA

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.


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