Several studies have reported an association between osteonecrosis (ON) and septic arthritis, mainly in the pediatric population with sickle cell disease (SCD). However, it is unclear whether the association applies to adults.

To report a case of femoral head ON (ONFH) in an adult with sickle cell anemia (SCA) complicated by septic arthritis.

Male patient, 20 years-old, with SCA, on Hydroxyurea 28 mg/kg/day and folic acid 5 mg/day, baseline hemoglobin (Hb) of 8 g/dL, Hb S 80.7%, Hb A2 2.6% and fetal Hb 16.7%. He underwent attendance due to pain in the right hip and was diagnosed with ONFH, affecting over 50% of the joint, associated with joint effusion, with no orthopedic surgical indication. After 20 days of discharge, he returned due to refractory pain and he had no fever. On the 10th day of hospitalization, he underwent mechanical debridement and osteotomy. He was diagnosed with septic arthritis caused by S. aureus and S. epidermidis and received antibiotic therapy, with progressive pain improvement. Currently, he is scheduled for total hip arthroplasty.

ON is a common complication of SCD due to episodes of ischemia and reperfusion in susceptible joints. Clinical includes hip pain, reduced joint range, and gait alterations. The femoral region is highly affected due to its poor blood supply, susceptibility to high mechanical load, and increased joint wear propension. In patients with SCD, bacterial opsonization is dysfunctional, leading to systemic inflammation and oxidative stress, which can increase the susceptibility to infections, justifying the association of ONFH with osteomyelitis and septic arthritis, a situation more commonly described in the pediatric population and rare in adults like the presented patient. The most common microorganism found in septic arthritis of patients with SCD is Salmonella, followed by enteric gram-negatives, but in the reported case, S. aureus and S. epidermidis were isolated. Bone decompression to stimulate revascularization of the femoral head may alleviate symptoms in the early stages of ONFH. Historically, poor operative outcomes have discouraged many individuals with SCD and ONFH undergoing hip arthroplasty. If surgical management is chosen, perioperative treatment should be done with adequate hydration, oxygenation, and pain control, along with advanced surgical techniques, so it may improve quality of life. Regarding septic arthritis, surgical debridement and joint irrigation are indicated.

The overlapping of septic arthritis and osteonecrosis has a clinical picture that will not always be typical in adult individuals and may result in late diagnosis and higher morbidity and mortality. The complaint of pain should not be dismissed as just another painful crisis; hematologists must take into consideration other complications associated with avascular necrosis, such as septic arthritis and osteomyelitis.