Avascular necrosis of bone in systemic lupus erythematosus

IntroductionAvascular necrosis (AVN) is a major cause of morbidity in SLE. Several factors have been associated with the development of osteonecrosis in SLE but corticosteroid therapy has been the most consistent. Many factors such as thromboembolism, fat embolism, thrombophilia, hypofibrinolysis, intramedullary haemorrhage, vasculitis and increased bone marrow pressure are related to corticosteroid-induced osteonecrosis.Aim of the workTo determine the prevalence of avascular necrosis (AVN) of bone in patients with systemic lupus erythematosus (SLE) and to study the predictive factors for AVN in patients with SLE and its association with other SLE disease manifestations.Patients and methodsOne hundred consecutive SLE patients, diagnosed according to the updated American College of Rheumatology criteria (ACR), were studied. A full medical history and rheumatologic examination were administered to all patients. Laboratory and serologic tests were also carried out. Systemic disease activity was scored using the systemic lupus erythematosus disease activity index (SLEDAI). Cases of symptomatic AVN were identified by plain X-ray and magnetic resonance imaging (MRI). Comparisons between groups of patients with and without AVN, and associations between groups were analyzed by the t-test, Pearson correlation as well as multiple regression models to study the predictive factors for AVN in patients with SLE.ResultsAVN was detected in 15% (n = 15) of SLE patients. Osteonecrosis of one hip joint was highly predictor for the other (p = 0.000). Cumulative corticosteroid dose, Gait disturbance, myalgia and hypertension are the clinical predictors of AVN (p = 0.000, 0,000, 0.001, 0.000), respectively, in the regression analysis model. Haemoglobin and proteinuria were the laboratory predictive (p = 0.000, 0.000), respectively.ConclusionsLupus patients are at high risk for avascular necrosis (AVN), this risk extended to those on high dose corticosteroid of which patient's screening should be considered and closely monitored by sensitive techniques such as MRI.