RA:
Marginal and central bone erosions is important clue
Symmetric
Fusiform soft tissue swelling
Common: MCPJ, PIPJ, IPJ of thumb
Uncommon: DIPJ, rare in absence of proximal changes
Earliest: 2nd and 3rd MCPJ and 3rd PIPJ
Radial aspect of MC head (on ulnar side normaly there is a slight irregularity)
Periarticular osteoporosis
Uniform decrease in joint space
No osteophytes
OA:
Any articulation
PIP, DIP more common than MCP
Osteophyte is hallmark of the disease
Uniform decrease in joint space
Interdigitation is important feature (i.e. if there is decrease in joint space, it should also occur centrally). If there is increase in joint space centrally, it is unlikely to be OA
EOA: (Inflammatory OA)
Erosions not always present
PIP, DIP more common than MCP
Central collapse more than OA
JCA:
Advanced changes in relatively young patient is important clue
CPPD:
Symmetric
Features are similar to OA, but commonly involves MCP
MCPJ, most commonly 2nd and 3rd in hemochromatosis, and 4th and 5th in idiopathic CPPD ??
Beak like osseous growths from radial aspect of metacarpal heads in hemochromatosis
Psoriasis:
DIPJ involvement is important clue - 'pencil in cup'
Single ray involvement is a feature
Whiskering is an important sign = proliferative arthropathy
Erosions tend to go peripherally
Periarticular osseous proliferation
Periostitis
Asymmetric
Minimal osteoporosis
Scleroderma:
DIPJ and to lesser extent PIPJ involvement with soft tissue calcification is important clue
Acroosteolysis is another important clue
Gout:
Asymmetric
DIPJ, PIPJ, MCPJ
Lobulated soft tissue masses, eccentric punched out extremely well defined erosions with overhanging edges are important clues
Joint space is usually preserved
No porosis
SLE:
Deforming non-erosive arthropathy is important clue
Symmetric
MCPJ and IPJ of all digits
Osteonecrosis at MCPJs
Radiographs may be normal even if there is clinically visible deformity. It is because as soon as the patient keeps the hand on the cassette, the deformity gets corrected!
Reiter's:
Similar to psoriasis
AS:
Exuberant osseous proliferation is important clue
Asymmetric
DIPJ may be involved
Also affects PIPJ, MCPJ, IPJ of thumb
Polymyositis:
Similar to scleroderma
Multicentric reticulohistiocytosis:
Extremely well defined erosions
I was listening to Dr Resnick when he told (Lords, London, 2007) that he has seen 2 or 3 cases of MRH in his life time. So never make a diagnosis of MRH, unless you know the histological diagnosis!!
Jaccouds arthropathy:
Rare
Associated with rheumatic fever
Non-erosive reversible arthropathy
Hyperparathyroidism:
Although not an arthritidis, never forget hyperparathyroidism in the differentials.
Subperiosteal or subchondral bone resorption
References:
Resnick et al, Bone and joint imaging, 3rd edition, Elsevier Saunders publications
