Clinical characteristics of avascular necrosis in patients with Behçet disease: a case series and literature review

Avascular necrosis (AVN), also known as osteonecrosis, is characterized by death of the osteocytes due to inadequate blood supply caused by various mechanisms. The hip is the most common affected joint followed by knee. Incidence of AVN in rheumatic diseases is variable and high corticosteroid (CS) therapy is a known major risk factor for development of AVN. Data on the AVN in Behçet disease (BD) are limited. The purpose of this study is to examine the clinical and treatment characteristics of BD patients with diagnosis of AVN. Retrospective medical records of 337 BD patients were reviewed. Nine BD patients with AVN were detected. The clinical data of these patients with AVN have been reviewed. All patients had MRI of the symptomatic joints compatible with AVN. All of the nine patients who were diagnosed with AVN were male. Median duration of BD was 7 years. Median time between diagnosis of BD and detection of AVN was 3 years (1–16 years). Multiple joints were involved in seven patients. Six patients had bilateral knee AVN. Six patients had vascular BD. The median time interval between initial CS dose and AVN development was 24 months (range = 2–100). The median highest daily CS dose was 64 mg/day (range = 32–80) and median cumulative CS dose prior to AVN was 18 g. All of patients had intravenous pulse steroids. CS treatment, smoking and vascular involvement may predispose to AVN in patients with BD. According to this cohort, AVN in BD frequently tended to be in the knee joint and bilateral.