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Int Orthop. 2012 Sep;36(9):1783-8. doi: 10.1007/s00264-012-1550-5. Epub 2012 May 3.

Experimental study of an original radiographic view for diagnosis of cam-type anterior femoroacetabular impingement.

Author information

1
Institut de l'Appareil Locomoteur, Rangueil University Hospital, Toulouse, France. cavaignac.etienne@gmail.com

Abstract

PURPOSE:

Primary paraclinical investigation to look for femoral morphological abnormality consistent with cam-type anterior femoroacetabular impingement (FAI) must include specific radiographic projections of the hip from the following: cross-table, frog-leg or Dunn (90° and 45° flexion). We use a frog-leg type view with fixed angles as described by Chiron, obtained with the patient in a supine position, with the hip in 45° flexion-abduction and 30° external rotation. The X-ray beam is anteroposterior and centred on the femoral head. We evaluated this view by comparing it with other views in common use.

METHODS:

In this experimental study, we created artificial radio-opaque morphological abnormalities secured onto normal femoral necks. The femurs were placed in relation to a fixed pelvis using orthogonal landmarks, in the positions of the various radiographic views. The digital radiographs were analysed by two observers. Nineteen femurs were included to reveal a difference of 5° between the alpha angle of Nötzli et al. [11] measured on the Dunn view and the frog-leg 45/45/30 view (Student's paired test).

RESULTS:

The highest mean values of the alpha angle of Nötzli were always obtained with the frog-leg 45/45/30 view (87.4°, 86.2°, 84.5°) and the lowest with the cross-table view. We found a mean difference of 8.95° with the 90° Dunn view (P = 0.00007), 3.44° with the 45° Dunn view (P = 0.004) and 13.47° with the cross-table view (P = 0.002).

CONCLUSIONS:

This experimental study confirmed the value of the frog-leg 45/45/30 view in assisting diagnosis of cam-type FAI.

PMID:
22552431
PMCID:
PMC3427436
DOI:
10.1007/s00264-012-1550-5
[Indexed for MEDLINE]
Free PMC Article

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