Three-dimensional computed tomography of the hip in the assessment of femoroacetabular impingement

Abstract

Femoroacetabular impingement secondary to the cam effect is thought to be associated with an insufficient anterior concavity in the sagittallaxial plane of the femoral head-neck junction. Using three-dimensional computed tomography the anterior and posterior concavity of the femoral head-neck junction was assessed in 36 painful non-dysplastic hips (30 patients). The mean age of the symptomatic hips was 40.7 with 13 females and 17 males. Eighteen out of the 36 hips had a pistol grip deformity. Magnetic resonance gadolinium arthrography was performed to assess for labral and cartilage lesions. Alpha and beta angles measuring the anterior and posterior femoral head-neck junction concavities were also determined in 20 asymptomatic hips (12 patients; mean age 37, 5 females and 7 males) using three-dimensional computed tomography. The mean alpha angle for the symptomatic and the control group were: 66.4 versus 43.8 0, = 0.001), and for the beta angle 40.2 versus 43.8 0, = 0.01 l), respectively. All but one of the symptomatic hips had a labral tear with 61% of these hips having associated cartilage damage. Three-dimensional computed tomography represents an accurate tool to quantify the femoral head-neck concavity providing a non-invasive assessment of hips at risk of femoroacetabular impingement.

Incidence of Radiographic Cam-Type Impingement in Young Patients (<50) After Femoral Neck Fracture Treated with Reduction and Internal Fixation

“…The definition of a pathologic alpha angle varies across the literature [1,3,6,19], but on review of all definitions, prevalence in the general populations has been reported 14-17% [11,12]. Our series demonstrated a 46% prevalence of abnormal alpha angle in 31B fractures with a 63% prevalence in type the 31B3 subgroup.…”

Radiological Assessment of Femoroacetabular Impingement Morphology Using Computed Tomography in an Asymptomatic Young Population

“…Consensus is required on the threshold values with regard to what is normal and abnormal in all of the imaging modalities. For example, the threshold value of the AA has been suggested to be 50°based on the MRI (21), and 55°based on the CT (22). However, the reliability of its measurement and reproducibility have been questioned (23).…”

Femoroacetabular Impingement: Evidence of an Established Hip Abnormality

“…This could enhance understanding of the underlying hip disease in a patient and sensitize the treating physician so that he or she could recognize the importance of subtle deformities. Other imaging modalities (eg, bone scintigraphy [ 43 ]) have not yet been fully evaluated.…”