Acetabular component position of the noncemented total hip endoprosthesis after previous Chiari pelvic osteotomy

The aim of the study was to determine the validity of acetabular component position of the noncemented total hip endoprosthesis after Chiari pelvic osteotomy.

The study involved 75 patients operated on at the Institute of Orthopedic Surgery "Banjica" in the period from 1990-2009. The first group consisted of 39 patients (46 hips) who underwent Chiari pelvic osteotomy and also later the implantation of a noncemented total hip endoprosthesis. A control group consisted of 36 patients (47 hips) who underwent total hip arthroplasty due to degenerative hip dysplasia.

In the previously operated patients the centre of rotation of the hip was on the average placed more proximally, while in the control group of patients the position of the acetabular component was closer to the anatomical one. In the group of patients after Chiari osteotomy the mean acetabular cup abduction angle rated 41.8°±9.8°, while in the control group this value was on the average higher (45.4°±8.6°).

There was a significant difference between the studied groups in relation to the distance between the acetabular component of endoprosthesis and the acetabular teardrop (t=-2.763; p=0.007). No statistically significant difference was determined in the mean value of the angle of acetabular abduction component of endoprosthesis between the studied groups of patients (t=1.878; p=0.064).

Acetabular component position of the total hip endoprosthesis was not compromised by anatomic changes of the acetabulum caused by Chiari pelvic osteotomy.