[Differential diagnosis of inflammatory arthritis of the hip joint]

The differential diagnosis of inflammatory arthritis of the hip covers a broad spectrum and includes in particular crystal arthropathies and systemic rheumatic diseases. The clinical examination of joint effusion of the hip may be difficult but diagnostic ultrasound should support an early diagnosis. Radiographs remain essential in the initial diagnostic evaluation but may be of limited value in early stages of the disease. Magnet resonance imaging may be helpful in addition for the detection of early arthritis.Basic laboratory diagnostics include blood count, determination of C-reactive protein level and erythrocyte sedimentation rate. If septic arthritis is suspected blood cultures should be taken. Joint aspiration should be attempted in all cases and especially in monoarthritis. Synovial fluid analysis includes white cell count, differential count, examination for crystals and microbiological diagnostics including direct stains and cultures. The most important differential diagnoses of inflammatory arthritis of the hip joint in adults are osteoarthritis, crystal arthropathies and systemic rheumatic diseases, such as spondyloarthritis.