Nonseptic monoarthritis: Imaging features with clinical and histopathologic correlation

Diagnosis of septic arthritis requires aspiration and analysis of joint flu id. However, nonseptic articular disorders are fairly common and represent a significant diagnostic and therapeutic challenge. Such disorders include gout, Milwaukee shoulder, rapidly destructive articular disease, amyloid ar thropathy, hemophilic arthropathy, primary synovial osteochondromatosis, pi gmented villonodular synovitis, neuropathic arthropathy, and foreign-body s ynovitis. The clinical signs of articular disease, which include pain, swel ling, and limitation of motion, are often nonspecific and can overlap with those of osseous or extraarticular disorders. Many articular processes have characteristic radiologic appearances that allow definitive diagnosis, Rad iography is an important part of the evaluation of patients with articular disease. However, magnetic resonance (MR) imaging is the method of choice f or characterizing the various disorders and assessing the full extent of os seous, chondral, and soft-tissue involvement. AAR imaging can exquisitely d emonstrate joint effusions, synovial proliferation, articular cartilage abn ormalities, sub,chondral bone, ligaments, muscles, and juxtaarticular soft tissues. Although a wide spectrum of noninfectious processes may involve th e joints, careful analysis of the imaging findings and correlation of these findings with the patient's clinical history can suggest a more specific d iagnosis in most cases. Awareness and understanding of the underlying histo pathologic findings aids in interpretation of MR images.