Accuracy considerations in navigated cup placement for total hip arthroplasty

Area of Science:

• Orthopaedic Surgery
• Medical Technology
• Surgical Navigation

Background:

• Acetabular component malpositioning is a significant issue in total hip arthroplasty (THA).
• Computer-assisted orthopaedic surgery (CAOS) technologies aim to enhance surgical accuracy and patient outcomes.
• Existing navigation systems include CT-based, fluoroscopy-based, and image-free approaches.

Purpose of the Study:

• To comprehensively analyze the accuracy of computer-assisted acetabular cup placement.
• To evaluate a hybrid navigation approach combining image-free and fluoroscopic technologies for THA.
• To compare in vitro, mathematical, and in vivo data for accuracy assessment.

Main Methods:

• A hybrid navigation approach utilizing pointer-based digitization and bi-planar fluoroscopy was employed.
• Mathematical modeling, in vitro testing, and an in vivo clinical trial were conducted.
• Accuracy was assessed by measuring deviations in cup inclination and anteversion.

Main Results:

• In vitro testing showed maximum deviations of 3.6° for inclination and 3.8° for anteversion.
• The maximum difference between intraoperative and postoperative measurements was 4° for inclination and 5° for anteversion.
• Statistical simulations confirmed these findings under worst-case scenarios.

Conclusions:

• The hybrid navigation system provides accurate acetabular cup placement, reducing variability within the surgical safe zone.
• Proper utilization of CAOS technology can improve THA outcomes.
• Surgeons must be aware of potential error sources and learning curves associated with CAOS implementation.