Estimation of the reference value of pubofemoral distance in normal infants by ultrasonography: A pilot study in Indian population

Abstract

Objectives: The objectives of this study were to determine the normal values of pubofemoral distance (PFD) and its variation with age, sex, and laterality of hip in infants in the Indian population. Material and Methods: The PFD was measured in 141 infants falling under Grafs categories I, IIa, and IIb (Males: 77 and Females: 64) divided into two groups comprising the neonatal group (<1 month) and postneonatal group (>1–12 months). PFD measurement and Grafs’ method of alpha- and beta-angle measurement were both performed at the same time by doing an ultrasound of the hip. Probe was placed in the coronal plane in lateral decubitus with the flexed position in a neutral position. PFD was measured between the superior pubic rami and femoral head epiphyses. Results: The average PFD in 141 infants (282 hips) was 3.23 ± 0.83 mm. It was 3.15 ± 0.79 mm in the neonatal group (88 patients) and 3.47 ± 0.84 mm in the postneonatal group (53 patients). In males, the average PFD was 3.29 ± 0.85 mm, and in females, it was 3.23 ± 0.81 mm. No significant difference was observed in the average PFD among the two sexes and between the left and right hips of both neonatal and postneonatal groups. Conclusion: The study demonstrates reference PFD values in infants aged 0–12 months in neonatal and postneonatal age groups. Mean PFD values were not significantly influenced by the laterality or sex of the patient in both groups, however, increased with age. Further studies need to be done however to find its values in the cases with developmental dysplasia of the hip to determine the cutoff in such cases.