A multiplanar radiography method for assessing cup orientation in total hip arthroplasty

Area of Science:

• Orthopedic Surgery
• Radiographic Imaging
• Biomedical Engineering

Background:

• Accurate acetabular cup orientation is crucial for successful total hip arthroplasty (THA).
• Patient-specific functional pelvic angles significantly impact THA outcomes and complication rates.
• Existing methods for assessing pelvic tilt and cup orientation have limitations in accuracy and invasiveness.

Purpose of the Study:

• To introduce and validate a noninvasive radiographic tool for determining patient-specific pelvic tilt angles.
• To accurately assess acetabular cup orientation (inclination and anteversion) relative to bony landmarks.
• To compare the accuracy and radiation dose of the new method against existing radiographic, fluoroscopic, and CT techniques.

Main Methods:

• Development of a novel, noninvasive radiographic tool for pelvic tilt and acetabular cup orientation assessment.
• Validation using a bone replica model with implanted hip components and digitized references.
• Verification with a cadaveric specimen to assess intraoperative and postoperative accuracy.
• Measurement of pelvic tilt, cup inclination, and anteversion with associated accuracy and standard deviations.

Main Results:

• Pelvic tilt measurement accuracy of 0.1 deg (SD 0.4 deg).
• Operative cup inclination accuracy of 0.6 deg (SD 0.4 deg) and anteversion accuracy of 2.5 deg (SD 0.6 deg).
• The method demonstrated superior accuracy compared to existing radiographic and fluoroscopic techniques.
• Lower radiation exposure compared to computed tomography (CT) methods.

Conclusions:

• The proposed radiographic method is a feasible and accurate tool for assessing acetabular cup placement.
• It allows referencing consistent bony landmarks preoperatively, intraoperatively, and postoperatively.
• This technique offers significant advantages for both clinical practice and research in total hip arthroplasty.