Descriptive epidemiology of mechanical hip pathology in adults under 50 years of age. Prospective series of 292 cases: Clinical and radiological aspects and physiopathological review

Summary Two hundred and ninety-two patients, aged between 16 and 50 years and presenting with mechanical hip pathology, were included in a prospective multicenter study. The descriptive study concerned the clinical examination and analysis of three X-ray views (AP pelvic, Lequesne false profile and lateral axial view). The series comprised 62% males, mean age 35 years, with 53% right side and 22% bilateral involvement. Initial trauma was reported in 19% of cases, and direct familial history of hip pathology in 20%. Seventy percent of the patients played sports, 30% were high-level athletes, and 17% played combat sports. The physical impingement sign was present in 18% to 65% of cases depending on the variant studied. On imaging ( n = 241), 62% of hips showed osteoarthritis, with 25% at the evolved stage. In the series, as a whole, there was a 35% rate of dysplasia, 63% of impingement and 5% of normal X-ray results. The radiologic impingement aspects were 58% cam-type, 19% pincer-type and 23% mixed. Twenty-two percent of dysplasia cases showed signs of associated impingement. Pain experienced exclusively in flexion/internal rotation/adduction on examination showed little sensitivity (20%) but considerable specificity (86%) for the main diagnosis of impingement. The links between impingement and dysplasia are discussed, and an integrative schema of all risk factors is put forward. Level of evidence IV, descriptive epidemiological study.