[Radiologic evaluation of cup placement variation in conventional total hip arthroplasty]

Area of Science:

• Orthopedic Surgery
• Biomedical Engineering
• Radiology

Background:

• Acetabular cup positioning is critical for total hip arthroplasty (THA) success.
• Variations in implant placement can lead to suboptimal outcomes.
• Assessing factors influencing cup positioning is essential for improving surgical techniques.

Purpose of the Study:

• To determine the variability of acetabular cup inclination and anteversion in conventional THA.
• To investigate factors (surgeon experience, implant type, operated side) influencing cup positioning accuracy.
• To evaluate the deviation from target angles (45° inclination, 20° anteversion).

Main Methods:

• Radiological assessment of acetabular cup position in 950 patients undergoing cementless THA.
• Analysis of surgeon qualifications, operated side, and implant model for correlation with positioning.
• Investigation of tolerable deviations from the intended radiological angles.

Main Results:

• Mean inclination was 48.7° (SD 7°), with a wide range (28°-75°).
• Mean anteversion was 18.6° (SD 9°), with a wide range (-9° to 50°).
• Only 22.7% of cups were within ±5° of target; 34.5% were outside ±10°.

Conclusions:

• Conventional THA implantation techniques result in significant variability in acetabular cup orientation.
• Surgeon experience, implant model, and operated side did not significantly impact positioning accuracy.
• Computer-aided navigation offers potential for enhanced accuracy and reproducibility in THA cup placement.