Prediction of hip joint centre location from external landmarks

Abstract

The approaches to predicting the hip joint centre (HJC) location of Tylkowski's group and Andriacchi's group were evaluated for accuracy and validity in children and adults of both sexes. Using Tylkowski's approach, we found that the three-dimensional (3-D) HJC location in adults (expressed as a percentage of the distance between the anterior superior iliac spines (ASIS)) was 30% distal, 14% medial, and 22% posterior to the ASIS, and predicted the HJC location to within 3.3 cm of the true location with 95% certainty. Using Andriacchi's approach, we found that the HJC was located in the frontal plane distal and lateral to the midpoint of a line between the ASIS and pubic symphysis, and varied from 2.2 cm distal and 0.78 cm lateral in girls to 4.6 cm distal and 1.7 cm lateral in men. A more accurate method of estimating the 3-D HJC location combined a modification of Andriacchi's approach (estimating frontal plane location of HJC) with a modification of Tylkowski's approach (estimating HJC location posterior to a frontal plane), and could predict the HJC location in adults to within 2.6 cm of the true location with 95% certainty.