MEASUREMENT OF FEMORAL ANTEVERSION BY MAGNETIC-RESONANCE-IMAGING - EVALUATION OF A NEW TECHNIQUE IN CHILDREN AND ADOLESCENTS

Anteversion of the femoral neck was measured by magnetic resonance ima ging (MRI) in 19 children (37 hips) preoperatively before femoral rota tion osteotomies. The results of this new technique were compared with values for anteversion obtained by computed-tomographic (CT) scanning and ultrasound. In order to determine the correlation between the thr ee different methods and to assess their reliability, the measurements were performed independently by two observers at different times. The re was a high correlation (Pearson's correlation coefficient) between MRI results and CT scan (r = 0.77) as well as MRI and sonography (r = 0.81), although the mean anteversion angles obtained by computerized t omography (34.0 degrees, range 5-82 degrees) and ultrasound (25.6 degr ees, 10-40 degrees) were larger than the MRI values (23.2 degrees, 0-6 5 degrees), which can be explained by the different measurement techni ques. Mean inter-rater as well as intra-rater reliability was high for MRI (r = 0.97 and r = 0.97) and CT (r = 0.99 and r = 0.96) but slight ly less for sonography (r = 0.88 and r = 0.88). MRI is a novel method for evaluating femoral anteversion that does not require ionizing raia tion, allows a precise anatomical measurement and reliable results. MR I is recommended for preoperative planning of pediatric femoral rotati on osteotomy cases.