Lateral center-edge angle

Dr Zishan Sheikh et al.

The lateral center-edge angle is a radiographic measurement of femoral head bony coverage by the acetabulum. It has primarily been described in assessing for acetabular dysplasia but can also be used in femoroacetabular impingement.

It is calculated on AP pelvic radiographs by using drawing a best fit circle for the inferior and medial margins femoral head. The angle is then measured between two lines drawn from the center of the circle, one running vertically along the longitudinal axis of the pelvis and the other to the acetabular sourcil edge.

It was originally described by Wiberg in 1939 and has since been shown superior to the extrusion index in measuring femoral head undercoverage. 

Normal range

Values greater than 20 degrees but less than 40 degrees are considered within the normal range 1.

Increased lateral center-edge angle
  • pincer type impingement
Reduced lateral center-edge angle
  • acetabular dysplasia
Pitfalls
  • cannot be measured in patients with abnormal femoral heads due to previous injury or avascular necrosis
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Article information

rID: 62982
Synonyms or Alternate Spellings:
  • Wiberg's lateral centre-edge angle

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