Brian P. Jacob, David C. Chen, Bruce Ramshaw, Shirin Towfigh (eds.) - The SAGES Manual of Groin Pain-Springer International Publishing (2016)

13. Imaging for Evaluation of Groin Pain
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Fig. 13.3. Two views of the right hip demonstrating the findings of mixed-type
femoroacetabular impingement. Pincer-type deformity can be diagnosed on the
anteroposterior view if there is evidence of acetabular overcoverage: in this case
the anterior acetabular wall is somewhat more lateral than the posterior wall,
forming a figure-of- eight. The modified Dunn view (patient lying supine with
feet flat on the table) allows for the evaluation of cam-type deformity, which is
due to asphericity of the femoral head. A circle is drawn within the confines of
the femoral head and an alpha angle measured between the axis of the femoral
neck and the point where the cortex of the neck first meets the head. This alpha
angle measured 65°, while normal is considered less than or equal to 50°.
of ten single view radiographs [ 1 ]. This is in comparison to natural background
levels of radiation, which averages an equivalent of about three
radiographs per year in the United States [ 2 ]. The significant drop in
radiation associated with CT has allowed for the application of dynamic
acquisition in some diagnostic circumstances.
Intravenous iodinated contrast material has also advanced substantially
since its early uses. Recent research suggests that the nonionic, low
osmolarity contrast formulations currently employed in CT are not a
causative factor in the development of nephropathy, particularly among
patients with normal renal function at baseline [ 3 , 4 ]. Rather, baseline