Femoroasetabular Sıkışma Tanısında Kullanılan Alfa Açısı ve Anterior Femoral Mesafe Ölçümlerinde Ultrasonografinin Etkinliği: Sağlıklı Bireylerde Manyetik Rezonans Görüntüleme ile Karşılaştırmalı Değerlendirme

Abstract

ABSTRACT Dr. Sinan BALCI. Validity of ultrasound in the measurements of alpha angle and anterior femoral distance used for diagnosis of femoroacetabuler impingement: Comparative assessment with magnetic resonance imaging in healthy individuals. Hacettepe University Medical Faculty Radiology Department. Ankara. 2015. Femoroacetabular impingement is a process characterized by various abnormalities of mechanical contact between femur and acetabulum whose pathogenesis is yet to be understood. It is a clinical entity especially encountered in young population and can cause early osteoartrhitis via degeneration of joint chondral surfaces within time. Abnormal morphology can be revealed with contributions of hip radiographs, computed tomography and magnetic resonance imaging. In routine clinical practice magnetic resonance imaging is the imaging modality of choice for diagnosis of the femoroasetabular impingement. Recently in literature, there are opinions advocating utilization of ultrasound for hip joint, femur head and neck for measurement of some parameters via predefined anatomical points. Quantitative parameters used for diagnosis of femoroasetabuler impingement are alpha angle and anterior femoral distance. The purpose of this study is to evaluate efficacy and reliability of ultrasound in measurements of these parameters with respect to magnetic resonance imaging which is used as gold standard imaging technique. Thirty five healthy people were enrolled in the study, of which 12 were women (34.3 %) and 23 were men (65.7 %). The age range was between 10 and 29 (median: 22). Both hip joints were evaluated by US and MRI for the study. Two researchers performed the measurements independently and in a blinded manner in respect to the other imaging method. There was no statistically significant difference between women and men for all measured parameters. Interobserver correlation coefficients were 0.528 (p = 0.001) for US alpha angle measurement, 0.539 (p = 0.001) US anterior femoral distance measurement; 0.753 (p < 0.0001) for MRI alpha angle measurement and 0.466 (p = 0.005) for MRI anterior femoral distance measurement. Statistically interobserver agreement was moderate for US measurements of alpha angle and anterior femoral distance, good for MRI measurement of alpha angle and moderate for MRI measurement of anterior femoral distance. When compared to MRI as standard of reference, US measurements were found statistically significantly different from MRI for both observers (alpha angle, p < 0.05; anterior femoral distance, p < 0.05). MRI is an objective and reliable imaging technique for measurement of alpha angle which is a quantative criterion, helpful for diagnosis of femoroacetabuler impingement. However measurement results obtained via US do not correlate with that of MRI. Therefore, US alone is not a reliable imaging technique for measurements of alpha angle and anterior femoral distance. Keywords: Femoroacetabular impingement, cam type, alpha angle, anterior femoral distance.