Prevalence of radiographic parameters on CT associated with femoroacetabular impingement in a Chinese asymptomatic population

Background: Imaging evaluation of femoroacetabular impingement (FAI) plays a major role in early diagnosis and treatment, preventing irreversible degenerative changes in hip joints.

Purpose: To investigate the anatomical parameters associated with FAI in a Chinese asymptomatic population by computed tomography (CT) and to evaluate the prevalence of the radiographic features of cam and pincer types in Chinese patients.

Material and methods: We reviewed the CT images of 470 hips in 235 Chinese patients who underwent abdominal and pelvic CT scans for reasons unrelated to hip symptoms at our hospital between February and October 2017. The following measurements were made on each hip joint: acetabular version angle (AV); anterior acetabular sector angle (AASA); posterior acetabular sector angle (PASA); the lateral center edge angle (LCE); the alpha angle (AA); and femoral head-neck offset (FHNO).

Results: Significant differences in all parameters were seen between men and women. Young men and elderly women showed more retroversion in our study. LCE, AA, and FHNO were all larger in men than women. The data showed 25% of female joints and 34.5% of male joints had at least one predisposing factor for FAI using measurement parameters by CT images in Chinese asymptomatic patients, and the prevalence of pincer lesion (19.1%) was larger than cam lesion (9.1%).

Conclusion: Morphological features associated with FAI are also present in Chinese asymptomatic patients. The threshold values for abnormal parameters should be reconsidered based on gender, age, and other factors in order to improve the accuracy of diagnosis.