Is a marker‑ball (fiducial) radiograph used for Mako robotic‑assisted total hip arthroplasty or for conventional total hip replacement?

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Last updated: September 14, 2026 • View editorial policy

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Marker Ball Radiographs for Mako vs. Conventional Total Hip Arthroplasty

Marker ball (fiducial) radiographs are used for Mako robotic-assisted total hip arthroplasty, not for conventional total hip replacement. The marker ball serves as a calibration reference for the robotic system's preoperative CT-based planning and intraoperative registration 1.

Technical Workflow Distinction

Mako Robotic-Assisted THA

  • Requires preoperative CT imaging with specific protocols (mean effective radiation dose 8.3 mSv) 1
  • Uses fiducial markers/checkpoint systems for registration and spatial mapping 2, 3
  • The marker ball placement is critical for the robotic system to accurately translate the preoperative CT plan into intraoperative execution
  • Arrays with reflective discs are placed on anatomical landmarks during surgery for real-time tracking 3

Conventional THA

  • Uses standard AP pelvis radiographs only (mean effective radiation dose 0.174 mSv) 1
  • No marker balls or fiducial markers required 1
  • Traditional templating relies on magnification markers placed at the level of the greater trochanter, though these have been shown to be inaccurate (mean error 6%, range -5% to 15%) 4
  • Assuming 20% magnification for all patients is actually more accurate than using magnification markers 4

Clinical Context

The distinction matters because:

  • Radiation exposure differs substantially: Mako's CT-based approach delivers approximately 48 times more radiation than conventional radiographs 1
  • Marker ball placement accuracy is critical for robotic cases - misplacement compromises preoperative templating and increases operative complexity 5
  • Recent audit data shows that with targeted education, marker ball placement compliance can reach 80% (entirely visible and correctly positioned between femurs, inferior to symphysis pubis) 5

Important Caveat

While Mako robotic assistance demonstrates superior radiographic accuracy (smaller deviations in acetabular anteversion and inclination, 98.1% vs 82.7% within Lewinnek safe zone), this does not translate to improved short-term functional outcomes compared to conventional techniques 2. The technical precision comes at the cost of longer operative time (77.8 vs 65.0 minutes) 2.

References

4
Research

Inaccuracies in the Use of Magnification Markers in Digital Hip Radiographs.

Clinical orthopaedics and related research, 2016

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This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.