PURPOSE: The alpha angle is used to quantify in a single plane the head-neck junction deformity of cam @entity1743 ( @entity1743 ). When the deformity overlaps the superior retinaculum, @entity2738 in this area can jeopardise intra-articular vascular structures. This study proposes a new angular measure of the linear radial extension of @entity85 as a planning tool for bone resection and compares the accuracy of @entity2738 using open and arthroscopic surgery. METHODS: Twenty-five symptomatic @entity1 operated on for @entity1743 were included in this study. Radial magnetic resonance imaging (MRI) was done before and after surgery. Bi-dimensional coordinates of the vascular foramina and radial extension of the deformity (omega angle) were measured. This extension was correlated with the vascular foramina location and alpha-angle value. Accuracy of resection and hip function were evaluated before and after surgery. RESULTS: The cam lesion frequently extended posteriorly. No relation between values of alpha and omega angles was found. Cam resection was complete in 88  % of cases; there was a significant improvement in outcome score after surgery. CONCLUSIONS: This study showed that alpha angle, measured in one plane, was not a predictor of the radial extension of @entity85 . To achieve a full resection, it was frequently necessary to extend the @entity2738 over the retinacular area. Pre-operative determination of the omega angle and location of the vascular foramina helped improve cam resection safety and accuracy.

Morphologic and angular planning for cam resection in XXXX : value of the omega angle.

@entity1 :: ('9606', 'Species') :: ['patients'] @entity85 :: ('MESH:D009140', 'Disease') :: ['cam deformity'] @entity1743 :: ('MESH:D057925', 'Disease') :: ['femoro-acetabular impingement', 'FAI'] @entity2738 :: ('MESH:D005271', 'Disease') :: ['femoral head osteoplasty']
@entity1743 :: (MESH:D057925,Disease) :: ['femoro-acetabular impingement']
