# Investigation of the Frequency of Femoroacetabular Impingement Using Computed Tomography Images

## TL;DR

This study examines how common femoroacetabular impingement is in Turkey using CT scans and specific measurements.

## Contribution

The study provides prevalence data for cam and pincer-type femoroacetabular impingement in Turkey using standardized CT measurements.

## Key findings

- Cam-type FAI prevalence was 25.3%, pincer-type FAI was 25.3%, and mixed-type FAI was 23.8%.
- Alpha angle ≥55° was observed in 46.5% of patients.
- Femoral head neck offset <8 mm was found in 38.8% of patients.

## Abstract

Objective: The aim of this study is to investigate retrospectively the prevalence of cam and pincer-type femoroacetabular impingement (FAI) in the adult patient population in Turkey using proven measurement methods on computed tomography (CT) images of the patients.

Methods: This study included 273 patients between the ages of 20 and 51. Previously taken CT images of the patients were retrospectively reviewed. Alpha angle (AA), femoral head neck offset (FHNO), lateral centre-edge angle (LCEA), and acetabular version angle (AVA) measurements were made on these images. In addition, the patients were evaluated for the presence of the crossover sign.

Results: Of the patients, 160 (58.6%) were male, 113 (41.4%) were female, and the mean age of the patients was 36.21±9.05 (20-51) years. While CS was seen in 15% (41 patients) of the patients, it was not seen in 85% (232 patients). As a result of the measurements, the AA average was 55.43°±10.17°, FHNO average was 8.19±1.91 mm, LCEA average was 35.22°±6.59°, and AVA average was 17.71°±5.19°. AA was measured at 55° and above in 46.5% (127 patients), and FHNO was measured below 8 mm in 38.8% (106 patients). LCEA was measured at 40° and above in 21.6% of patients (59 patients), and AVA was measured at less than 15° in 29.7% of patients (81 patients).

Conclusion: In the measurements we made using accepted diagnostic accuracy methods, the prevalence of FAI was found to be cam type at 25.3%, pincer type at 25.3%, and mixed type at 23.8%. Although it varies between societies, FAI is a common morphological change in the general population. FAI syndrome is diagnosed by supporting this change with the clinic. When making this diagnosis, unnecessary treatments can be prevented by considering the prevalence of FAI in societies.