In eight patients with so-called idiopathic degenerative arthritis of
the hip the acetabular labrum, at surgery, was found to lie in the
articulation between the femoral head and the acetabulum. In none of the
patients was there a history or roentgenographic evidence of congenital
dysplasia or congenital dislocation. None of the patients had had a closed
reduction or manipulation of the hip during infancy, childhood, or
adolescence. No patient had had a traumatic dislocation. The findings
suggest that the intra-articular labrum was a developmental abnormality and
we postulate that this abnormality was the cause of the degenerative
arthritis.