The aetiology of degenerative disease of the hip. A review of 400 cases.

Four-hundred and forty patients who presented for Total Hip Replacement to the Orthopaedic Hospital, Cappagh were included in this study. Each case was classified into radiographic and aetiologic groups on the basis of the patients history, the results of special investigations, and the radiographic appearance of the hips. This classification allowed a further differentiation into primary and secondary osteoarthritis. Primary or idiopathic osteoarthritis was the single most common aetiologic group. A surprisingly high percentage of patients with secondary osteoarthritis had congenital dysplasia. It is suggested that this faulty biomechanical situation is the initiator of subsequent joint degeneration due to stress loading on the supero-lateral border of the hip. The reasons why such changes may be delayed until the 6th and 7th decades are unclear but degeneration once started progresses quickly. The possible place of surgical correction of the underlying biomechanical fault in delaying or preventing the onset of osteoarthritis is demonstrated and discussed.