A Geographic Zone Method to Describe Intra-articular Pathology in Hip Arthroscopy: Cadaveric Study and Preliminary Report

Purpose: Our purpose was to develop an alternative method to divide the acetabulum and femoral head into different zones based on anatomic landmarks clearly visible during arthroscopy to facilitate reporting the geographic location of intra-articular injuries. Methods: Two vertical lines are positioned across the acetabulum aligned with the anterior and posterior limits of the acetabular notch. A horizontal line is positioned aligned with the superior limit of the notch perpendicular to the previous lines. The lines divide the acetabulum into 6 zones. Numbers are assigned to each zone in consecutive order. Zone 1 is the anterior-inferior acetabulum. The numbers progress around the notch until zone 5 is assigned to the posterior-inferior acetabulum. Zone 6 is the acetabular notch. The same method is applied to the femoral head. Six experienced hip arthroscopists were instructed in the zone and clock-face methods and were asked to identify and describe the geographic locations of lesions at the acetabular rim, acetabular cartilage, and femoral head in the same cadaveric specimen. Results: The zone method was more reproducible than the clock-face method in the geographic description of intra-articular injuries on the acetabulum and the femoral head. Conclusions: Among a group of expert hip arthroscopists, the zone method was more reproducible than the clock-face method. Clinical Relevance: The presented method divides the acetabulum into 6 different zones based on the acetabular notch. The zones are the same for right- and left-side hips. The same method is applied for the femoral head allowing, for the first time, a geographic description of pathology.