Case Report on Steroid-induced Bilateral Femoral Head Osteonecrosis with Concomitant Hip Septic Arthritis in Primary Membranous Nephropathy.

INTRODUCTION: Concomitant femoral head osteonecrosis and hip joint septic arthritis is rare. Membranous nephropathy is an immune-mediated glomerular disease producing nephrotic syndrome in adults. Patients take glucocorticoids or immunosuppressants during treatment of this condition. We report the first case of a patient with nephrotic syndrome during treatment developing concomitant hip septic arthritis and femoral head osteonecrosis with an opportunistic pathogen seen in gastrointestinal tract.

CASE REPORT: A 37-year-old gentleman on treatment with high-dose prednisolone and mycophenolate for nephrotic syndrome developed bilateral hip pain and was diagnosed as osteonecrosis of femoral head. He underwent core decompression of both hips. Suspected concomitant septic arthritis noted in the magnetic resonance imaging was missed. Post decompression Citrobacter species was aspirated from the left hip and was then managed by debridement and antibiotics. Five years later, he developed secondary osteoarthritis with protrusio-acetabuli subsequent to septic sequelae and underwent total hip replacement without any reactivation till last follow-up.

CONCLUSION: Concomitant septic arthritis with femoral head osteonecrosis should be considered when treating patients on steroids or immunosuppressants. An elevated erythrocyte sedimentation rate and C-reactive protein in a patient with osteonecrosis warrants additional investigations, including ultrasound-guided aspiration and culture, before core decompression or any surgical intervention even in immunocompetent patients.