Associations between alpha angle and herniation pit on oblique axial magnetic resonance imaging in asymptomatic hip joints of adults / 中国组织工程研究

ABSTRACT

BACKGROUND:Recent studies have found that femoral neck angleαin patient with femoral neck hernial fossa increased significantly. However, whether the femoral neck hernia fossa can be used as imaging diagnostic indicator for femoroacetabular impingement syndrome remains controversial. OBJECTIVE:To evaluate the association between alpha angle and herniation pit in asymptomatic hip joints, influencing factors of the above indexes, and to provide evidence for the diagnosis of hip impingement syndrome. METHODS:Adults with asymptomatic hip joints from September 2013 to December 2015 were retrospectively studied. Alpha angles were measured on oblique axial MRI images. The incidence and size of herniation pit were determined by MRI. Size measures, prevalence, and statistical analyses were conducted regarding its association with age, gender, laterality (right or left hip). Intra-and inter-observer consistency was determined by intra-class correlation coefficient. RESULTS AND CONCLUSION:(1) 105 patients with asymptomatic hips were included, and 185 sides of hip MRI images were obtained. The range of age was 18-80 years old. The prevalence of herniation pit in asymptomatic hips was 21.6%. (2) The range of alpha angle was 27.6°–65.0°. Alpha angles of hip joints of 17 cases were ≥ 55°. (3) There was no association between alpha angle≥55° and the size of herniation pit (P>0.05). The prevalence of herniation pit was not correlated with age, gender and affected side (P=0.160, 0.157, 0.110). Inter-observer consistency of alpha angle was 0.523 between first measurements of first vs. second observer, respectively. Intra-observer consistency of alpha angle was 0.654, respectively. (4) There is no association between alpha angle ≥ 55 degrees and presence of herniation pit or demographic variables (age, gender and affected side). The presence of herniation pit and the increased alpha angle need to be interpreted with caution. Clinical symptoms and other examinations should be used in the diagnosis of hip impingement syndrome.