Musculoskeletal ImagingSystemic lupus erythematosus
a connective tissue disorder characterized by significant immunological abnormalities and involvement of multiple organ systems, including the musculoskeletal system. Initial clinical manifestations most frequently include constitutional symptoms and signs (malaise, weakness, fever, anorexia and weight loss) and
articular (polyarthritis) and cutaneous (skin rash) findings. Characteristic and significant musculoskeletal abnormalities in patients with systemic lupus erythematosus may include
myositis, symmetric
polyarthritis,
deforming nonerosive arthropathy, subchondral
cysts, spontaneous
tendon weakening and rupture,
osteonecrosis, soft tissue
calcification,
osteomyelitis,
septic arthritis and miscellaneous other abnormalities.
Joint symptoms and signs are of variable severity and are most frequent in the small joints of the hand, knee, wrist and shoulder. On radiographs soft tissue swelling and periarticular osteoporosis are observed; cartilage and bone destruction is rare.
The deforming nonerosive arthropathy usually causes little functional disability and is completely reducible, although some patients develop chronic fixed deformities (Fig.1). Swan neck deformity, boutonniere deformity and hallux valgus can also be seen.
In the joints, capsular and ligamentous laxity, contracture and muscular imbalance lead to abnormalities that are similar to those occurring in patients with rheumatic fever. Spontaneous rupture of tendons, especially the Achilles, quadriceps and patellar tendons, takes place almost exclusively in patients who have been given systemically or locally administered steroids.
osteonecrosis typically involves the femoral head but may also affect the humeral head, femoral condyles, tibial plateau, talus, and even the small bones of the hand, the wrist and the foot. Administration of steroids is suspected to be the cause in many cases.
Patients with systemic lupus erythematosus exhibit an unusually high frequency of bacterial and mycotic infections. On radiographs the presence of a large or increasing joint effusion and progressive cartilaginous and osseous destruction should raise the possibility of articular infection.
Insufficiency fractures may also occur, with a distribution similar to that in rheumatoid arthritis.
DR/RB
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a. AP radiograph of the hand demonstrates ulnar deviation at the metacarpophalangeal joints. Considerable ulnar subluxation at the second matacarpophalangeal joint also is present.
b. Oblique radiograph of the second metacarpal head demonstrates a small marginal erosion (arrow).
(Courtesy of Jon Robins, MD, Alverado Community Hospital)
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Systemic lupus erythematosus, Fig.1 (a) | | Systemic lupus erythematosus, Fig.1 (b) | |