Femoral anteversion - Reliability and clinical significance of different investigation techniques in children and adolescents

In order to investigate the correlation between different methods of AV-determination and to assess their reliability, we compared the results of clinical and sonographic examination with computed tomography and magnetic resonance imaging in 21 children (41 hips) preoperatively. The mean anteversion angles obtained by computed tomography (34.0 degrees+/-13.7 degrees) appeared larger than the clinical (27.7 degrees+/-8.5 degrees), sonographic (25.6 degrees+/-8.0 degrees) and MRI-values (23.2 degrees+/-12.8 degrees), which can be explained by the different measurement techniques. The inter-rater as well as intra-rater reliability was high in MRI (Pearson's correlation coefficient r=0.97 and r=0.97) and CT (r=0.99 and r=0.96) but slightly less in sonography (r=0.88 and r=0.88) and clinical investigation (r=0.47 and r=0.77). For routine use in screening of femoral anteversion clinical and sonographic methods are sufficiently accurate. But in determining the exact amount of torsion preoperatively and in planning of rotation osteotomies in children MRI and CT determination are superior. As magnetic resonance imaging requires no radiation dosage, shows non-ossified cartilaginous structures and proved its high reliability, it could replace other techniques in the future for that purpose.