Establishing boundaries of acetabular walls in total hip replacement

Introduction The term "acetabular walls" is used to describe the survival rate of total hip replacements (THR) and classifications of THR surgeries. With the experience accumulated in THR surgery, there is no information on establishing boundaries of the acetabular walls. ASPID is a classification system used to describe post‑traumatic acetabular deformities with no technique for establishing boundaries of acetabular walls. The objective was to demonstrate and provide a theoretical substantiation for a method establishing the boundaries of the acetabular walls in primary THR. Material and methods Pelvic computed tomography scans of five children aged 10–12 years and 30 pelvic preparations of adult bones without signs of acetabular dysplasia were used. Results Extraacetabular fixed anatomical landmarks were identified in 3D models from CT scans of pediatric pelvic bones with the planes dividing acetabulum into conditional walls separated by cartilage. The pelvic bones of 30 adults were scanned, and similar reconstructions performed to delineate boundaries of the acetabular walls. The proportional ratios and areas of each acetabular wall were determined in the pediatric and adult groups, and the results compared. The absence of statistical differences in the proportions of the superior, posterior and medial walls of the pediatric and adult acetabulum suggested high reliability of the method. Discussion There were insignificant statistical differences in the anterior acetabular wall fraction of children and adults and could be associated with a small quantity of measurements. The absence of statistical differences in the proportions of the superior, posterior and medial walls of the pediatric and adult acetabulum suggested the reliability of the method. A larger number of measurements to be performed by several specialists, determination of the Cohen's Kappa coefficient and statistical analysis of the results are essential for the validity of the method. Conclusion The method offered for establishing boundaries of the acetabular walls can be practical for scientific research, but cannot be used in routine practice due to its complexity and the need to use special software. The method can be recommended for describing post-traumatic deformities of the acetabular walls in cases where extraacetabular landmarks are not damaged or displaced.