Septic arthritis of the knee joint secondary to adjacent chronic osteomyelitis of the femur in an adult.

The present report describes a case of septic knee arthritis secondary to reactivated chronic osteomyelitis. The osteolytic lesion observed on the initial radiographs resulted in further imaging studies including CT and MRI, which confirmed the diagnosis. Based on the patient's history, physical findings and imaging studies, we performed open debridement rather than arthroscopic surgery in order to treat the infected intraarticular knee joint and ream the femur intramedullary canal. Additionally, an antibiotic-impregnated cement rod was inserted into the medullary cavity to fill the dead space and eradicate the infection. A high index of suspicion combined with adequate comprehension of initial plain radiographs is essential for accurate diagnosis of septic knee arthritis with adjacent chronic osteomyelitis.