Methods for correlating pathological and radiological findings in osteoarthrosis of the hip

Abstract

In primary osteoarthrosis of the hip, destruction of old cartilage and bone on the femoral head is accompanied by an attempt at repair and remodelling. On the superior surface of the femoral head this attempt at repair tends to be overwhelmed by the continued action of a destructive mechanism. In contrast, on the infero-medial, and sometimes on the lateral, surfaces, remodelling activity can form a layer of new bone external to the line of the old chondro-osseous junction; for the purpose of the present study, this new bone is distinguished from that in osteophytes projecting downwards below the level of the original edges of the femoral articular surface. Femoral heads from patients with primary osteoarthrosis of the hip vary a good deal in their naked-eye and radiological appearance. Methods are described by which this variability can be expressed in terms of contrasting changes of variable amounts of bony flattening and of bony expansion. The methods suggest a new or additional approach to radiological and pathological classifications of primary osteoarthrosis of the hip, based on recording the amounts of these two changes in femoral head contour in addition to features such as loss of radiological joint space, osteosclerosis, cyst formation, and osteophytic lipping. Difficulties inherent in this quantitative approach are discussed, but such difficulties do not invalidate the basic concept of the methods, which can also be applied to secondary osteoarthrosis and avascular necrosis.