Possible jacoud’s arthropathy-Plain Xray

37 yr old known case of Lupus complaints of pain in pain in 3^rd digit and Knee. Resident-professor series by Dr MGK Murthy

1.      What do they show?

PIP joint shows soft tissue shadow around the articulation  without joint widening or erosions or significant deformity

MCP joints are normal. Bone density is normal

Knee shows apparently reduced  joint space and soft tissues on medial aspect with focal lucency of lateral tibial condyle with reduced femoropatellar joint space as well

2.      How do we interpret?

In known case lupus, jacoud’s arthropathy is the first diagnosis to be considered

3.      What is it?

It is typically nonerosive, progressive, deforming polyarthropathy, typically involving MCP joints , PIP joints of digits , wrists and knees. It was originally described in  recurrent Rheumatic fever

4.      What is the difference with other Rheumatoid which is classical synovitis?

Yes , that is the point , it is non synovitis arthropathy. It has been proven on MR that there is no synovial inflammation or fluid or widened joint spaces , yet produces deformities

5.      How does it produce?

Ligament and muscle laxity along with atrophy plays the vital role

6.      what is unique in this case?

MCP joints are normal ,there is no significant deformities and soft tissues as well as muscles are not appreciably atrophied , lateral tibial condyle shows focal lucency with no segonds fracture

7.      How do we proceed and how do we explain?

The symptoms in this case are of short duration , and I presume , it is jacouds arthropathy  - very early  and needs  periodic review  to see the progress. Lucency of tibial condyle could be explained by steroid  effect or weight bearing symmetrical normal variant finding

8.      Would you advise MRI?

No it is clinically known case and radiologically not conflicting, and hence MR is not indicated. In fact what would help is  lab data including parat hormone levels, and periodic good quality digital X -rays of the joints involved