Femoral neck anteversion: A comprehensive Indian study

Background: The femoral neck anteversion has important implications. Since these values are not documented for our population, we undertook this study to define this for Indian population. Methods: FNA was calculated on 300 dry femora by the Kingsley Olmsted method, and prospectively on otherwise normal living adults by CT method (n=72 hips), by biplanar radiography (n=138 hips) and clinically (n=138 hips). Results: The mean FNA by CT was 7.4° (SD 4.6°) and more than 75% of cases were between 3.4° and 11.4°. The mean FNA by X-ray method was 11.5° (SD 5.4°) and more than 71% of cases were between 6.5° and 16.5°. The mean, clinically, was 13.1° (SD 4.6°) and almost 75% of cases were between 9.1° to 17.1°. The mean FNA on dry femora has been calculated as 8.1° (SD 6.6°) and almost 62% of cases were between 3.1° to 13.1°. The mean FNA on right side was statistically significantly 1.7° less than on the left side. Statistically significant difference between the sexes was found only by the dry bone method (F>M = 3°). Conclusions: Considering CT to be most accurate on living subjects, FNA in our study has been found to be 7.4° (SD 4.6°). It is 4 -12° lower than most of the western studies by all these methods. Readings are 4.1° higher by the X-ray method and 5.7° by the clinical method. Correlation and regression equations have also been formed between the various methods and the clinical method correlates better than the X-ray method to the CT method.