Femoroacetabular impingement (FAI) is a pathologic condition of the hip that leads to osteoarthrosis. The goal of the surgical hip dislocation is to correct the bony malformations to prevent the progression of osteoarthrosis. We investigated the topographical cartilage thickness variation in patients with FAI and early stage osteoarthrosis using an ultrasonic probe during surgical hip dislocation. We performed a prospective case-series of 38 patients (41 hips) that underwent surgical hip dislocation. The mean age at operation was 30.6 (range, 18–48) years. Indication for surgery was symptomatic FAI with 4 hips (10%) with pincer-type, 7 hips (17%) with cam-type, and 20 hips (73%) with mixed-type of FAI. Cartilage thickness was measured intraoperatively using an A-mode 22 MHz ultrasonic probe at 8 locations on the acetabular cartilage. The thickest acetabular cartilage was found in the weight bearing zone (range 2.8–3.5mm), whereas the thinnest cartilage was in the posterior acetabular horn (1.0–2.2 mm). In all hips, cartilage was thicker in the periphery area compared to the central area. In the anterior and posterior acetabular horn, the anterior area, and the superior area (central parts) a significantly decreased cartilage thickness in pincer-type compared to
