Joints
3.1
Monoarthritis
1. Trauma – pointers to the diagnosis are: (a) the history, (b) the presence of a fracture, and (c) a joint effusion, especially a lipohaemarthrosis.
4. Rheumatoid arthritis* – occasionally. Also juvenile idiopathic arthritis.
5. Pyogenic arthritis – commonest joints affected are the hip, knee and small joints of the hands and feet. 15% of those due to Staphylococcus aureus and 80% of those of gonococcal aetiology involve two or more joints. The joint may be radiographically normal at first presentation.
6. Tuberculous arthritis – insidious onset with radiological changes present at the time of first examination. Erosions first develop at peripheral non-contact points of the joint.
7. Pigmented villonodular synovitis* – most commonly at the knee.
8. Sympathetic – a joint effusion can occur as a response to a tumour in the adjacent bone.
Demertzis, J. L., Rubin, D. A. MR imaging assessment of inflammatory, crystalline-induced, and infectious arthritides [Review]. Magn Reson Imaging Clin N Am. 2011; 19(2):339–363.
Murphey, M. D., Vidal, J. A., Fanburg-Smith, J. C., Gajewski, D. A. Imaging of synovial chondromatosis with radiologic–pathologic correlation [Review]. Radiographics. 2007; 27(5):1465–1488.
3.3
Arthritis with osteoporosis
2. Juvenile idiopathic arthritis.
3. Systemic lupus erythematosus*.
6. Reiter’s syndrome* – in the acute phase.
3.4
Arthritis with preservation of bone density
2. Calcium pyrophosphate arthropathy – see Calcium pyrophosphate dihydrate deposition disease*.
6. Reiter’s syndrome* – in chronic or recurrent disease.
7. Neuropathic arthropathy* – especially in the spine and extremities.
3.5
Arthritis with a periosteal reaction
1. Juvenile idiopathic arthritis*.
5. Rheumatoid arthritis* – in less than 5% of patients.
3.6
Arthritis with preserved or widened joint space
1. Early infective or inflammatory arthritis – because of joint effusion.
2. Psoriatic arthropathy* – due to deposition of fibrous tissue.
3. Acromegaly* – due to cartilage overgrowth.
