What are the differences between various robotic Total Knee Replacement (TKR) systems?

Robotic Total Knee Replacement Systems

Based on the strongest available evidence, robotic-assisted TKA systems should not be routinely used over conventional TKA, as there is no demonstrated improvement in long-term clinical outcomes, survivorship, or complications, despite higher costs and longer operative times. 1

Guideline-Based Recommendation

The American Academy of Orthopaedic Surgeons provides strong evidence against using intraoperative navigation (which includes robotic systems) in TKA because there is no difference in outcomes or complications. 1 This represents the highest quality guideline evidence available and should guide clinical decision-making.

Types of Robotic TKR Systems

While multiple robotic platforms exist for TKA, they generally fall into two categories:

• Semi-autonomous systems that provide haptic feedback and constrain bone cutting within predetermined boundaries 2
• Image-guided robotic systems that use preoperative CT or intraoperative imaging for surgical planning 3

Evidence on Clinical Outcomes

Long-Term Effectiveness (13-Year Follow-Up)

The highest quality randomized controlled trial with 13-year follow-up comparing robotic-assisted TKA to conventional TKA in 1,348 patients found: 4

• No difference in Knee Society scores (93 vs 92 points, p=0.321) 4
• No difference in WOMAC scores (18 vs 19 points, p=0.981) 4
• No difference in range of motion (125° vs 128°, p=0.321) 4
• Identical aseptic loosening rates (2% in both groups) 4
• Identical 15-year survivorship (98% in both groups, p=0.972) 4
• No difference in complications including infection rates (0.6% in both groups) 4

Short-Term Outcomes (1-Year Follow-Up)

One comparative study in 36 patients who had robotic TKA on one knee and conventional TKA on the contralateral knee showed: 5

• Decreased hospital stay by 5.5 hours (p=0.03) 5
• Improved pain and stiffness subscores at 1 year (p=0.041 and p=0.007) 5
• Better early range of motion at 3,6, and 12 months (p<0.05) 5
• No difference in total WOMAC scores (p=0.061) 5

Technical Considerations

Advantages of Robotic Systems

• Improved component alignment precision, with more components within 2-3° of target alignment 3
• Quantifiable soft tissue balancing through range of motion 3
• Reduced alignment outliers compared to conventional techniques 3

Disadvantages of Robotic Systems

• Increased operative time for application and removal 1
• Higher costs without demonstrated long-term benefit 4
• Potential complications including pin-tract infections, peroneal nerve palsy, and pin-site fractures 4
• Requires additional training and resources 3

Clinical Decision Algorithm

For routine TKA cases:

• Use conventional instrumentation as the standard approach 1
• Conventional TKA achieves 89% good or excellent outcomes for pain and function up to 5 years 6

Robotic assistance may be considered only in:

• Research settings where outcomes are being systematically tracked 4
• Cases where the surgeon has extensive robotic experience and can demonstrate equivalent or better efficiency compared to conventional techniques 3

Common Pitfalls to Avoid

• Do not assume improved alignment translates to better clinical outcomes - the 13-year RCT definitively shows it does not 4
• Do not justify robotic use based on short-term improvements alone - these do not persist long-term and do not justify the additional cost 4, 5
• Do not use patient-specific instrumentation as an alternative - strong evidence shows PSI also provides no benefit over conventional instrumentation 1

Cost-Effectiveness

Robotic systems add substantial expense without improving long-term outcomes, making them not cost-effective for routine use. 4 The additional time and resources required cannot be justified by the current evidence base. 4