TY - JOUR
T1 - The frog-leg lateral radiograph accurately visualized hip cam impingement abnormalities
AU - Clohisy, John C.
AU - Nunley, Ryan M.
AU - Otto, Robert J.
AU - Schoenecker, Perry L.
PY - 2007/9
Y1 - 2007/9
N2 - Radiographic evaluation of the anterolateral femoral head-neck junction is essential in diagnosing cam femoroacetabular impingement. We hypothesized the frog-leg lateral radiograph can accurately assess femoral head-neck offset abnormalities associated with cam femoroacetabular impingement. We reviewed the radiographs of 61 hips treated for cam impingement and 24 asymptomatic control hips. To characterize the anatomy of the femoral head-neck junction, the femoral head sphericity, the α-angle of Nötzli et al, and head-neck offset were measured on all radiographs. Asphericity of the femoral head was detected more frequently in hips with impingement on all radiographic views when compared with control hips. The average α-angle was greater in hips with impingement on all views, with the greatest difference between hips with impingement and control hips seen on the frog-leg lateral view (65° for hips with impingement versus 47° for control hips). The average head-neck offset was decreased in hips with impingement on all views. The greatest difference between groups was seen on the frog-leg lateral view (6.6 mm for hips with impingement versus 9.3 mm for control hips). The frog-leg lateral radiograph provides accurate visualization of the femoral head-neck offset in patients being evaluated for femoroacetabular impingement.
AB - Radiographic evaluation of the anterolateral femoral head-neck junction is essential in diagnosing cam femoroacetabular impingement. We hypothesized the frog-leg lateral radiograph can accurately assess femoral head-neck offset abnormalities associated with cam femoroacetabular impingement. We reviewed the radiographs of 61 hips treated for cam impingement and 24 asymptomatic control hips. To characterize the anatomy of the femoral head-neck junction, the femoral head sphericity, the α-angle of Nötzli et al, and head-neck offset were measured on all radiographs. Asphericity of the femoral head was detected more frequently in hips with impingement on all radiographic views when compared with control hips. The average α-angle was greater in hips with impingement on all views, with the greatest difference between hips with impingement and control hips seen on the frog-leg lateral view (65° for hips with impingement versus 47° for control hips). The average head-neck offset was decreased in hips with impingement on all views. The greatest difference between groups was seen on the frog-leg lateral view (6.6 mm for hips with impingement versus 9.3 mm for control hips). The frog-leg lateral radiograph provides accurate visualization of the femoral head-neck offset in patients being evaluated for femoroacetabular impingement.
UR - http://www.scopus.com/inward/record.url?scp=34548436557&partnerID=8YFLogxK
U2 - 10.1097/BLO.0b013e3180f60b53
DO - 10.1097/BLO.0b013e3180f60b53
M3 - Article
C2 - 17589367
AN - SCOPUS:34548436557
SN - 0009-921X
VL - 462
SP - 115
EP - 121
JO - Clinical orthopaedics and related research
JF - Clinical orthopaedics and related research
ER -