NEW METHOD OF ACETABULAR ORIENTATION MEASUREMENT IN THA

Abstract

Relevance. The correct implantation of acetabular component in total hip arthroplasty is an important factor for obtaining good outcomes and long-term survival of the prosthesis. The anteversion angle is one of the significant indicators for the three-dimensional orientation of the cup. The purpose of the study — to develope the method of calculating the anteversion angle of the acetabular component using postoperative anteroposterior radiographs of the hip and pelvis.The method. The authors used the projection ellipse formed by the opening of the prosthesis cup on the radiograph centered on the hip joint to calculate the desired value. The ratio sine of projectional diameter of the ellipse to its true diameter is a mathematical formula for finding the angle of anteversion. The comparison of the calculated index on anteroposterior radiographs centered on the hip joint and on the pelvis is necessary to identify the distinction between anteversion and retroversion of the acetabular component. In negative anteversion, or retroversion, the projectional diameter on the pelvic radiograph is larger than on the radiograph focused on the hip joint.Conclusion. Measuring of anteversion angle of acetabular component on postoperative radiograph allows to gain an optimal orientation of acetabular component which decreases postoperative complications rate. X-rays of any scale can be used for measurements while the ratio but not the absolute value of measured diameters is important for the result.

Keywords

• hip replacement
• acetabular component anteversion