ePoster #732 - ISHA Annual Scientific Meeting 2016

A New Comprehensive and Straightforward Radiological Classification for FAI

Alberto Fioruzzi, MD, Pavia ITALY
Alberto Acerbi
Valentina Ferrari, MD, Como ITALY
Andrea Fontana, MD, San Fedele Intelvi, Como ITALY

COF Lanzo Hospital, Lanzo d'Intelvi, Como, ITALY

FDA Status Not Applicable

Summary: We present a new simple classification for CAM and pincer deformities based on two planes radiological evaluation that shows excellent levels of inter- and intra-observers agreement for both deformities and demonstrated to be a useful tool in planning hip preservation surgery.

Abstract:
Purpose Radiological evaluation of Femoro-acetabular impingement (FAI) is based on single plane parameters such as the alpha angle or the center edge angle or complex software reconstruction. We present a new simple classification for CAM and pincer deformities based on two planes radiological evaluation. Our purpose was to determine the intra-observer and inter-observer reliability of a new classification for femoro-acetabular impingement based on radiographic landmarks. Methods A three view radiographic pelvic study of 30 hips with symptomatic FAI undergoing hip preservation surgery and 30 asymtomatic hips, was analyzed and classified by four different observers. We used our proposed classification to identify three different stages for the CAM and pincer morphotypes. Inter- and intra-observer agreement of classification was determined using average pairwise Cohen’s Kappa coefficient and Fleiss’ Kappa coefficient. Results The inter-observers agreement for the CAM morphotype was strong with an average pairwise Cohen’s Kappa of 0.846 ( range 0.734 - 0.929 ) and a Fleiss’ Kappa of 0.846. The average Kappa agreement for the Pincer classification was 0.922 ( range 0.764 - 0.944 ). The intra-observer agreement was 0.845 and 0.870 for CAM and Pincer types respectively. Conclusion The classification we propose quantifies the extent of femoral and acetabular bony deformities. The new classification system shows excellent levels of inter- and intra-observers agreement for both deformities. Mild dysplasia and pistol grip deformities were the most difficult cases to evaluate. This classification has demonstrated to be a useful tool in planning hip preservation surgery. Further studies are needed to correlate the classification itself with specific intraoperatory findings.