MEASUREMENT OF ANTEVERSION OF THE FEMORAL-NECK IN CHILDREN BY MRI AND EVALUATION BY COMPARISON WITH CT AND ULTRASOUND

Purpose: Anteversion of the femoral neck was measured by MRI in 19 children (37 hips) preoperatively before femoral rotation osteotomies. Material and methods: The results of this new technique were compared with values for anteversion obtained by CT and ultrasound. The measurements were performed independently by two observers to determine the correlation between the three different methods and to assess their reliability. Results: It was possible to show a high correlation coefficient (Pearson) between MRI and CT (r = 0.77) as well as MRI and sonography (r = 0.81). The mean angles obtained by CT (34 degrees, range + 5 to + 82 degrees) and ultrasound (25.6 degrees, range + 10 to + 40 degrees) appeared larger than the MRI values (mean angle 23.2 degrees, range 0 to + 65 degrees), which can be explained by the different measurement techniques. Mean inter- and intra-variability was low for MRI (r = 0.97 and r = 0.97) and CT (r = 0.99 and r = 0.96) but slightly higher for sonography (r = 0.88 and r = 0.88). MRI is a new reliable and precise method to evaluate femoral anteversion that does not require ionising radiation. Conclusion: MRI is recommended for preoperative planning of paediatric femoral rotation osteotomy patients.