Epidemiology, demographics, and natural history of congenital hip disease in adults.

This study examined the epidemiology and demographics of congenital hip disease in 468 (660 hips) patients who were examined between 1970 and 1996. In 356 (54%) hips, the diagnosis was secondary osteoarthritis due to congenital hip disease, and in 272 (41%) hips, the diagnosis was idiopathic osteoarthritis. In the remaining 32 (5%) hips, the diagnosis was uncertain. Of the hips with congenital hip disease, 170 (47.7%) hips were dysplastic, 85 (23.9%) had low dislocation, and 101 (28.4%) high dislocation. The majority of patients with congenital hip disease were women (338 [95%] hips). The natural history of the three types of congenital hip disease was studied in 157 patients (202 hips: 102 dysplastic, 42 low dislocation, and 58 high dislocation) who had received no treatment before the initial examination. Average length of follow-up was 17 years. In dysplastic hips, the disease remained undiagnosed until the onset of symptoms at an average age of 34.5 years. In patients with low dislocation, pain had started at an average of 32.5 years due to progressive degenerative arthritis within the false acetabulum. In patients with high dislocation, in the presence of a false acetabulum, pain started at an average age of 31.2 years, while in its absence, pain started at an average age of 46.4 years due to muscle fatigue. These findings suggest dysplasia, low dislocation, and high dislocation in adults are the results of untreated dysplasia, subluxation, and complete dislocation in infancy, respectively.