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

Abstract

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.

Parafoveal Chondral Defects Associated with Femoroacetabular Impingement

“…Additionally, characteristic femoral chondral fibrocystic changes, today called impingement cysts [11], previously named herniation pits, are localized at the head-neck junction distal to the physis and frequently visible radiographically [11,12,15,18]. Histologically these lesions consist of proliferative fibroblasts forming either dense fibrous tissue or gelatinous tissue.…”

How Useful Is the Alpha Angle for Discriminating between Symptomatic Patients with Cam-type Femoroacetabular Impingement and Asymptomatic Volunteers?

“…Volunteers were included if they were asymptomatic (no symptoms, no medical history in regard to abnormalities of the hip joint, negative impingement test, and internal hip rotation of greater than 25° at clinical examination by the same author who performed the assessment mentioned above) and were the osseous deformities at the femoral head-neck junction, but there has been some controversy about its accuracy for clinical use, because the validation of the alpha angle measurement revealed only moderate agreement after repeated measurements by the same reader and substantial interobserver differences (12,13). Moreover, researchers in several studies have shown that a substantial portion of the healthy young adult population exhibits some degree of cam-type deformities (14)(15)(16)(17).…”

Femoroacetabular impingement: presence of FAI-like features on conventional radiography in young patients presenting to primary care with hip pain

“…In this study, excessive acetabular coverage is defined as a lateral edge angle of .398 as suggested previously (14). This is at odds with a more recent study suggesting a cut-off of .448 (23).…”