Comparison of femoroacetabular impingement-related radiographic features in a convenience sample of Japanese patients with and without herniation pits
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To examine the prevalence of herniation pits (HPs) and to evaluate differences in radiographic features related to femoroacetabular impingement—a hip disorder with abnormal abutment between the acetabulum and femur—between hips with and without HPs in a convenience sample of Japanese patients.
Materials and methods
We reviewed 1,178 hips on each side (695 men, 483 women; mean age, 58.2 years) using computed tomographic images. The radiological assessments of hip morphology were performed by measuring the lateral center edge angle, acetabular index, acetabular version, alpha angle, and femoral head-neck offset. HPs were defined as the round or oval cystic lesions surrounded by sclerotic bone located below the anterior femoral neck cortex.
Intraclass and interclass reproducibility of all radiographic measurements was acceptable (ICC: 0.71–0.98). The prevalence of HPs was 13.9 % in all subjects and was significantly higher in men (18.1 %) than in women (7.8 %; p < 0.001). HPs were larger in male (p < 0.001) and elderly subjects (p < 0.005). In subjects with HPs, the alpha angle was larger and femoral head-neck offset and offset ratio were smaller in the cohort overall and in men. Logistic regression analysis revealed the association between radiological cam-type FAI and HPs in all subjects (odds ratio: 1.86, p < 0.001).
We revealed the prevalence of HPs and showed it has a predilection for men in this Japanese cohort. Femoral head asphericity or small head-neck offset was more common in subjects with HPs than those without HPs.
KeywordsHerniation pits Femoroacetabular impingement Three-dimensional morphology Computed tomography Hip morphology
None of the authors received financial support for this study.
Compliance with Ethical Standards
Conflict of Interest
The authors declare that they have no conflict of interest.
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
Institutional Review Board approval was obtained for this study and in accordance with the requirements of a retrospective review; informed consent was not required.