Background/Purpose:

Osteonecrosis is a serious comorbidity of systemic lupus erythematosus (SLE).  The reported frequency of symptomatic osteonecrosis in SLE is variable, ranging from 4% to 15%. 

The aim of this study is to provide an update of the prevalence, patterns and outcomes of symptomatic osteonecrosis in SLE. 

Methods:

SLE patients with osteonecrosis were identified from the Lupus Clinic Database containing patients with 4 ACR criteria of SLE or 3 criteria and a biopsy diagnostic of lupus.  Osteonecrosis was defined as those patients with clinical symptoms and confirmed osteonecrosis by imaging (x-ray, bone scan, CT, MRI).  Demographic and clinical data of affected patients were collected prospectively, stored in an Oracle database and analyzed using descriptive statistics. 

Results:

Of the 1729 patients with SLE registered in the database as of 1970, 235 patients (13.6%) developed symptomatic osteonecrosis.  86.0% were female, with a mean age of 34.8 ± 12.8 years at first osteonecrosis diagnosis.  This involved a total of 542 joints, 383 joints of which were identified at the time of first osteonecrosis occurrence.  The mean time from diagnosis of SLE to diagnosis of first osteonecrosis was 8.2 ± 8.1 years, and the time from first osteonecrosis diagnosis to second osteonecrosis diagnosis was 3.4 ± 4.8 years. 

111 out of 235 (47%) patients had multiple site involvement at first osteonecrosis occurrence, affecting from 2 to 6 sites.  At the time of first diagnosis affected sites included the hip (245), knee (86), shoulder (28), ankle (15), wrist (3), other joints (3) and elbow (2).   Those that progressed to surgical intervention included: hip 131/245 (53.5%), knee 18/86 (19.8%), wrist 1/3 (33.3%), shoulder 1/28 (3.6%), ankle 0/15 (0%), elbow 0/2 (0%), and other joints 1/3 (33%).  The mean time from osteonecrosis diagnosis to surgery of the hip was 3.8 ± 5.5 years, while the mean time from osteonecrosis diagnosis to surgery of the knee was 5.5 ± 6.2 years.

Conclusion:

To our knowledge, this is the largest cohort of SLE patients with symptomatic osteonecrosis.  Osteonecrosis continues to be a significant comorbidity of SLE as 13.6% of patients developed symptomatic osteonecrosis.  In patients developing osteonecrosis, the presentation occurred after 8.2 ± 8.1 years of SLE disease duration.  47.2% of patients had multiple site involvement at first ON diagnosis.  Large weight-bearing joints, including the hip and knee, were most frequently involved.  The majority of hips required surgical intervention. Better strategies to prevent this serious complication are needed.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/osteonecrosis-in-systemic-lupus-erythematosus-prevalence-patterns-and-outcomes/