Robotic-Assisted Total Hip Arthroplasty (R-THA)

Robotic-Assisted Total Hip Arthroplasty (R-THA)

Prepared by Dr. Kayahan KARAYTUG

1) Overview

Robotic-assisted total hip arthroplasty (R-THA) uses computer planning and robotic guidance (most commonly robotic-arm + haptic boundary control) to improve the accuracy and reproducibility of component placement and restoration of hip biomechanics.

Goal: optimize cup position, leg length, offset, and combined anteversion, while reducing variability compared with manual instrumentation.

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2) Why It Matters

Potential advantages

• More consistent acetabular cup inclination/anteversion and improved “safe zone” attainment
• Better control of leg length discrepancy (LLD) and offset restoration
• More standardized workflow for preoperative planning and intraoperative execution

Key limitation

• Evidence for clear clinical superiority (PROMs, revision, dislocation) remains mixed; benefits may be most relevant in complex anatomy and for reducing outliers rather than changing averages.

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3) Platforms and Planning Concepts

Common system types

• CT-based planning (most common in hip robotics): 3D pelvis/femur model → planned cup/stem parameters.
• Imageless/fluoro-based navigation (less common for full hip robotics, more navigation-oriented): intraoperative registration without preop CT.

Core planning targets

• Cup inclination/anteversion
• Combined anteversion (cup + stem)
• Leg length and offset
• Hip center of rotation
• Impinge-free ROM simulation (system dependent)

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4) Indications

R-THA can be used for standard primary THA, but it is especially attractive in cases where avoiding outliers matters:

Common indications

• Primary osteoarthritis with a goal of consistent biomechanics
• Developmental dysplasia of the hip (DDH) / abnormal acetabular anatomy
• Post-traumatic arthritis / distorted landmarks
• Spinopelvic considerations (patients with stiffness/imbalance where cup position is critical)
• Surgeon preference for precision and workflow standardization

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5) Contraindications and Practical Exclusions

Absolute/strong relative

• Active infection (same as standard THA)
• Inability to safely place trackers/pins (severe bone fragility at pin site, high fracture risk)

Practical limitations

• When required imaging (e.g., CT) is contraindicated or not feasible
• Severe deformity or metalwork that prevents reliable registration (platform dependent)
• Resource constraints (time, equipment availability, team training)

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6) Surgical Workflow (Typical Robotic-Arm R-THA)

Step 1 — Preoperative planning

• CT acquisition → 3D reconstruction
• Plan cup size/position, stem parameters, leg length/offset targets

Step 2 — Registration

• Pelvic registration and tracker placement
• Match intraoperative landmarks to the preoperative model

Step 3 — Acetabular preparation

• Robotic arm constrains reaming within the planned boundary (haptics)
• Cup implanted to planned inclination/anteversion

Step 4 — Femoral preparation

• Manual or system-assisted femoral work (platform dependent)
• Final stem/head selection to hit length/offset targets

Step 5 — Verification

• Intraoperative check of LLD/offset, ROM/impingement, and stability

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7) Outcomes: What the Evidence Suggests

Component positioning

• Consistently shows improved accuracy/precision of acetabular component placement vs conventional techniques across many studies.

Functional outcomes (PROMs)

• PROM differences are often small or inconsistent in short-term follow-up; a frequent theme is fewer outliers, not always higher mean scores.

Complications

• Dislocation/revision differences are not uniformly proven; long-term multicenter data is still evolving.

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8) Learning Curve and Operating Time

• Early adoption typically increases operative time and requires team training + standardized setup.
• Efficiency improves as the team gains experience and “robot days”/case clustering is used.

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9) Costs and Value

Cost drivers

• Capital cost + annual maintenance
• Disposable instruments/consumables
• Imaging cost (if CT-based)
• Early increased OR time

Potential offsets

• Reduced variability/outliers
• Shorter length of stay and discharge advantages in some settings (results vary by institution and pathway)
• Value is highly volume-dependent and workflow-dependent

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10) Complications and Pitfalls (Robotics-Specific)

• Tracker/pin site issues (pain, rare fracture, loosening)
• Registration errors → inaccurate execution despite “robotic precision”
• Pelvic motion/shift after registration
• CT-based planning mismatch vs intraoperative reality (positioning, landmark quality)
• Technical downtime / system failure (must be ready to convert to manual)

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11) Pearls and Pitfalls (OrthoRico Style)

Pearls

• Invest in registration quality (garbage in → garbage out)
• Use robotics to control outliers (cup position, LLD, offset)
• Standardize the room: same setup, same roles, same sequence

Pitfalls

• Over-trusting the plan without verifying stability/ROM
• Poor landmark acquisition or loose trackers
• Ignoring spinopelvic mechanics when setting cup targets

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References (Suggested, 7 items)

1. Clement ND, et al. Robotic-assisted total hip arthroplasty: a systematic review.
2. Robotic-assisted THA vs conventional THA – systematic review and meta-analysis (Arch Orthop Trauma Surg, 2024).
3. Systematic review/meta-analysis of RCTs comparing robotic/navigated vs conventional THA (2024).
4. Robotic arm-assisted THA and acetabular component position: case-control evidence (2022).
5. Economic impact & workflow efficiency of robotic hip/knee arthroplasty (PMC, 2025).
6. Troubleshooting robotics during THA/TKA (Orthop Clin North Am, 2024).
7. Imageless/navigation vs conventional arthroplasty evidence synthesis relevant to precision outcomes (context for “navigation vs robot” discussions).