Prevalence of Radiographic Signs of Pincer Deformities in Asymptomatic Indian Individuals: A Retrospective Analysis

Femoroacetabular impingement (FAI) is the result of abnormal contact between the proximal femur and the acetabulum rim. Pincer impingement is the result of a globally deep acetabulum, focal anterior overcoverage or less commonly posterior overcoverage. The presence of radiological signs of femoroacetabular impingement (FAI) is not necessarily associated with symptoms. The study aims to find the prevalence of such signs in asymptomatic adult individuals.

Data of 714 patients (1428 hips) who have undergone PBH-AP (Pelvis Both hip- Anterior-Posterior view) radiograph for conditions unrelated to the disorders of the hip were taken for study. We evaluated the images for the presence of a cross-over sign (COS) and ischial spine sign (ISS) and measured Lateral Central-Edge (LCE) angle (Wiberg) and Tonnis angle (TA).

Mean age was 33.4 ± 9.8 years. Positive cross-over signs and ischial spine signs were seen in 26.6% and 13.9%, respectively; LCE angle > 40° in 25.5% and Tonnis angle ≤ 0° in 13.5% patients. 36.7% of patients showed atleast one radiological sign of acetabulum overcoverage. There was a significant difference in means of the values of LCE angle and Tonnis angle between males and females (2.9 and - 1.2, respectively). There was no significant difference in prevalence of COS and ISS among the two genders.

This study shows that there is higher prevalence of radiographic signs (36.7%) of pincer deformity among asymptomatic adults. Therefore, new clinical studies are required to clarify the actual significance of these findings.