Definition of bone necrosis by the pathologist

Abstract

Osteonecrosis is a common disorder that may go clinically unrecognized or may result in the collapse of the architecture of bone, determining severe anatomic alterations of the involved site. Osteonecrosis is not a specific disease entity, but rather the result of a number of conditions ultimately leading to an impairment of blood supply to the bone tissue, although there is evidence that modifications of bone remodelling activity and weakening of bone structure with formation of microfractures are implicated as well. According to the site involved and to the factors promoting its development, the morbid anatomy and histopathology of osteonecrosis show a different appearance. This review discusses the main skeletal manifestations of osteonecrosis, including subarticular avascular necrosis of the femoral head and of the knee, as well as osteonecrosis of the jaw.

Figure 1

Osteonecrosis following fracture of the femoral head. There is diffuse coagulative necrosis of marrow cells and osteocytic lacunae in bone trabeculae are empty (haematoxylin and eosin, 10x obj.).

Figure 2

Frontal section of a femoral head showing a wedge-shaped subarticular area of necrosis, which is well separated from the viable bone by a rim of granulation tissue. The convex shape of the femoral head is maintained.

Figure 3

A – Scanning view of a frontal section of an infarcted femoral head stained with haematoxylin and eosin. A subchondral fracture is present at the periphery of the infarcted area, which has caused the collapse of the articular surface. The trabeculae in viable bone adjacent to the infarct are thickened. B – Specimen radiograph of the same frontal section in A, showing the fracture line and the rim of bone sclerosis at the periphery of the infarct.

Figure 4

Frontal section of a femoral head showing severe deformity due to the progressive detachment of bone and cartilage fragments from the infarcted area.

Figure 5

Bisphosphonate induced osteonecrosis of the jaw. Haematoxylin and eosin stained section showing partially necrotic bone trabeculae, with lacunae containing viable osteocytes, necrotic osteocytes or showing empty lacunae. A severe inflammatory infiltrate is present in the inter-trabecular spaces (20x obj.).

Figure 6

Bisphosphonate-induced osteonecrosis of the jaw. Haematoxylin and eosin stained section showing completely necrotic bone trabeculae. Actinomyces colonies are present in the inter-trabecular spaces (20x obj.).