[Pathomorphologic development of the dysplastic hip joint]

On the basis of findings published in the literature, morphologic changes seen among the author's patients were classified as anthropologic and teratologic dislocations. The anthropologic dislocations were sub-classified into four groups, identified as dysplasia, subluxation, severe subluxation and luxation. Their anatomic peculiarities were described and illustrated. One observation which appears important, and which has already been reported by other authors, is that the limbus is not an infolded free joint border; also, that even in cases of severe luxation the femoral head often does not go beyond the acetabular labrum, which is displaced far upward. A number of special features appear to be of major importance for therapy. Mechanically, a severe subluxation behaves in the same manner as a subluxation. No reduction maneuver is needed to reposition the joint. On plain radiographs, subluxation are often mistaken for luxations. In dislocated hips the tendon of the iliopsoas muscle lies between the anterior portion of the acetabulum and the femoral head. When the extremity is extended, the psoas tendon is an obstacle to reduction. The real articular obstacle to reduction is not the limbus (primary limbus) but the primary joint cavity, which is too narrow. The limbus is only an obstacle on the way to the primary acetabulum.