Background MRI may have utility for examining neonatal hips. To date, MRI measurements of hip dimensions have only been characterized on post-mortem imaging. The aim of this study was to compare measurements made on left and right neonatal hips.
Methods Neonatal hips were imaged at 3T. Acetabular width and depth were measured using methods described by Whitby (J. Ped. Ortho. J Pediatr Orthop 2007; 27:898). In addition, femoral head DWI was used to calculate apparent diffusion coefficient (ADC). For each measurement the left and right were compared using within subject coefficient of variation (WS CV).
Results 44 neonates were imaged. Median (IQR) gestational age at birth was 36 weeks (range 25–42 weeks), 13 less than 32 weeks gestation; median gestational age at scanning was 41 weeks (range 37–46). 18 babies had HIE of whom 13 were cooled. Mean (SD) and WS CV (95% CI) for the following measurements were: Femoral head ADC 1.87 (0.094) on Right, 1.87 (0.099) on Left, WS CV 2.42 (2.12–2.72); acetabular width 17.1 (1.6) on Right, 17.0 (1.6) on Left, WS CV 3.50 (3.02–3.96); acetabular depth 3.81 (0.81) on Right, 3.81 (0.81) on Left, WS CV11.6 (10.1–13.1); acetabular width: depth ratio 4.66 (1.0) on Right, 4.66 (1.1) on Left, WS CV 13.6 (11.9–15.2).
Conclusions In this diverse group of babies the variation between sides was minimal. Analysing a single hip should be sufficient in this population.