[Standardized analysis of acetabulum cup migration in hip endoprosthesis using digital image processing]

Area of Science:

• Orthopedic Surgery
• Biomedical Engineering
• Radiology

Background:

• Aseptic loosening is a common complication after total hip replacement.
• Current methods for measuring acetabular component migration are time-consuming and require specialized equipment, limiting their clinical utility.
• Early detection of migration is crucial for identifying aseptic loosening.

Purpose of the Study:

• To develop and validate a novel digital analysis software for measuring acetabular component migration.
• To assess the software's accuracy and reliability compared to conventional methods.
• To provide a clinically applicable tool for early detection of aseptic loosening.

Main Methods:

• Development of analysis software based on Nunn and Sutherland methods using digitized pelvic radiographs.
• Manual marking of five reference points on a computer screen for planar migration and cup inclination measurement.
• Correction for projection enlargement and patient rotational malpositioning.
• Intra-observer variability assessment using five acetabular cup types and a pelvis phantom in various positions.

Main Results:

• The digital method demonstrated low intra-observer variability (SD for migration: 0.2-0.4 mm; inclination: 0.8-1.4 degrees).
• Manual measurement showed higher variability (SD for migration: 0.4-0.8 mm; inclination: 0.8-1.2 degrees).
• Pelvis phantom measurements with digital evaluation yielded SDs for biplanar distances between 0.1-1.2 mm and inclination between 1.1-2.3 degrees.

Conclusions:

• The developed digital analysis software offers a reliable and efficient method for measuring acetabular component migration and inclination.
• This tool is suitable for routine clinical practice, enabling earlier detection of aseptic loosening.
• The software demonstrates high accuracy and low intra-observer variability, improving upon existing techniques.