CT assessment of herniation pits: prevalence, characteristics, and potential association with morphological predictors of femoroacetabular impingement.

The purpose of this study was to evaluate whether there is a correlation between the presence of herniation pits (HPs) and morphological indicators of cam and pincer femoroacetabular impingement (FAI) based on computed tomography (CT) examinations. CT studies of the pelvis obtained from 200 patients were retrospectively analysed for the presence of HPs and morphological abnormalities of the femoral head and acetabulum. As an indicator for cam FAI, we used the angle alpha, describing the anterior femoral head-neck junction. As an indicator for pincer FAI, we measured the acetabular coverage and the acetabular orientation. Student's t-test was used for statistical analysis. HPs were identified in 85 of the 200 patients. HPs were predominantly found in the superior portion of the proximal anterior femoral neck; some were located in the inferior portion. The angle alpha was significantly larger by 10% in the group with HPs. A correlation between the presence of HPs and morphological indicators of pincer FAI was not found. In conclusion HPs are not only located in the superior portion of the proximal anterior femoral neck, but also in the inferior portion. There is an association between the presence of HPs and a high value of angle alpha.