Musculoskeletal ImagingOsteitis
inflammation of a bone, in which the haversian canals and usually the medullary cavity are involved. Commonly bone enlargement, tenderness and an aching pain are noted. Whereas
osteomyelitis implies an infection of bone and bone marrow, infective (suppurative) osteitis refers to contamination of the bone cortex, either in isolated cases or comcomitantly with
osteomyelitis.
Osteitis occurs under a variety of circumstances; it is seen in leprosy, yaws and congenital or acquired syphilis. Radiation therapy may also induce an osteitis or osteonecrosis.
In ankylosing spondylitis, osteitis is characterized by an enthesopathy at the discovertebral junction associated with erosion, sclerosis and syndesmophytosis. These abnormalities, termed Romanus lesions, produce an abnormal loss of concavity of the anterior vertebral surface, with a squared contour and shiny corner sign.
Osteitis condensans ilii
and osteitis pubis are two conditions occurring predominantly as complications of pregnancy (
Fig.1) (
Fig.2). In the former, a well-defined triangular sclerosis occurs on the ilac aspect of the
sacroiliac joint, with bone eburnation on the inferior portion of the bone. A "low back" syndrome or "fibrositis" syndrome may be recognized in some patients. Osteitis condensans ilii may be related to mechanical stress across the sacroiliac joint and increased vascularity in pregnancy, although other causes have also been suggested. A relationship to ankylosing spondyitis may exist.
Osteitis pubis
involves the
symphysis pubis and may occur in women after delivery, in both sexes after pelvic surgery or in athletes of either sex. It may also be seen in patients with psoriatic arthritis and compression of the obturator nerve or after radiation therapy. On radiographs patients have mild to severe subchondral bone irregularity with
osteolysis.
Ankylosis may ensue after
resolution of the sclerosis.
Osteitis condensans of the clavicle
is not a complication of pregnancy but shares some features with osteitis condensans ilii and osteitis pubis. Pain and swelling, with bone eburnation, may occur over the medial end of the
clavicle. This abnormality may be initiated by mechanical stress from strenuous activity. On radiographs, bone sclerosis, mild bone enlargement and osteophytes on the inferior margin of the
clavicle may be noted. (See
clavicle (III:1), Fig. 1). Scintigraphy and
CT scanning are helpful in documenting the extent of bone involvement.
Leprous osteitis
usually involves the small bones of the face, the hands and the feet and occurs after extension of the infection from overlying dermal and muscosal sites.
Osteitis fibrosa cystica
is the classic bone abnormality in hyperparathyroidism. This entity is characterized by peritrabecular bone marrow fibrosis, particularly near the sites of active bone formation or resorption. The resorption cavities with fibrous stromas are termed dissecting osteitis. The osteofibrosis is associated with localized cysts or brown tumours. Frequently osteitis fibrosa cystica is superimposed on the lesions of rickets and osteomalacia. In the healing phase, a rugger-jersey spine may be evident.
Other forms of osteitis include osteitis deformans (Paget's disease) and osteitis fibrosa disseminata (fibrous dysplasia).
DR/RB
DR/RB