The measurement of femoral anteversion has been a subject of interest and debate. Femoral anteversion is defined as the angle formed by the bicondylar plane and a plane passing through the center of the neck and femoral head. The angle of anteversion in humans exhibit a wide range (-25o
) with the mean varying from 8o
. Many methods for measuring femoral anteversion have been proposed each with its own merits and demerits. Our aim was to evaluate the validity of the Parallax method for measuring femoral anteversion and compare the results with Direct measurement and Biplane radiography - the method of Ogata et al
Materials and Methods: This is a Prospective study conducted at our institute with a total of 50 dried femur specimens obtained from the department of anatomy. Bones with obvious deformities in the proximal portion were excluded from the study. The anteversion angle was calculated by three methods:
1. Direct measurement – taken as the reference value against which the values of the other two methods can be compared.
2. Parallax method
3. Biplane radiography – the method of Kosuke Ogata et al.
Results: Considering direct measurement of anteversion by the Kingsley-Olmsted method as the most accurate method, the mean anteversion was found to be 11.235o, Range: -12o to 37o. 5(10%) femurs were retroverted. 3(6%) were in neutral version. 32(64%) were in the range 1o to 20o of anteversion. 10(20%) femurs showed anteversion more than 20o.
Conclusion: The parallax method is comparable to biplanar radiography in terms of safety, availability, cost and accuracy. The patient can lie with the hips extended and in neutral rotation and the radiographs can be taken. Therefore the “Parallax Method” seems to be a viable alternative to the biplanar method especially in complicated and difficult situations.