Skeletal Radiology

, Volume 40, Issue 2, pp 167–172 | Cite as

Herniation pits in the femoral neck: a radiographic indicator of femoroacetabular impingement?

  • Jin Ah Kim
  • Ji Seon Park
  • Wook Jin
  • Kyungnam RyuEmail author
Scientific Article


The purpose was to assess the significance of herniation pits in the femoral neck for radiographic diagnosis of femoroacetabular impingement (FAI). Eighty hips in 62 patients (bilateral in 18) with neutral pelvic orientation were enrolled. Herniation pits were diagnosed when they were located at the anterosuperior femoral neck, close to the physis, and with a diameter of >3 mm. The five radiographic signs of FAI were used: lateral center edge angle (LCE) >39°, acetabular index (AI) ≤0, extrusion index (EI) <25%, acetabular retroversion, and pistol-grip deformity. Patients with radiographs suggesting FAI were retrospectively correlated with their clinical symptoms. Positive radiographic signs were observed in 7 hips with LCE, 7 with AI, and 80 with EI criteria. Only 3 hips out of 80 (3.8%) showed all of the signs. The acetabular retroversion and pistol-grip deformity were seen in 12/80 and 3/80 hips, respectively. The total number of hips that met radiographic criteria for FAI, including pincer type and cam type, was 18 (23%). However, none of these hips were clinically diagnosed with FAI. All symptomatic hips (11/80) presented only with nonspecific pain, and 2 hips out of 11 showed radiographic signs of FAI. The low frequency of positive radiographic signs suggesting FAI with related symptoms among patients with herniation pits suggests that herniation pits have limited significance in the diagnosis of FAI. Therefore it can be concluded that an incidental finding of herniation pits does not necessarily imply a correlation with FAI.


Herniation pit Femoroacetabular impingement Radiographic diagnosis 



Femoroacetabular impingement


Lateral center edge angle


Acetabular index


Extrusion index



This research was supported by a grant from the Kyung Hee University Research Fund (grant KHU-20071609).

Conflict of interest statement

The authors declare that they have no conflicts of interest, financial or otherwise, to report.


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Copyright information

© ISS 2010

Authors and Affiliations

  • Jin Ah Kim
    • 1
  • Ji Seon Park
    • 1
  • Wook Jin
    • 2
  • Kyungnam Ryu
    • 1
    Email author
  1. 1.Department of Radiology, Kyung Hee University Medical CenterKyung Hee UniversitySeoulKorea
  2. 2.Department of Radiology, East-West Neo Medical CenterKyung Hee UniversitySeoulKorea

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