Joint not involved in Rheumatoid arthritis?

Ans.(a) D.I.PRef : Harrison 19th ed. / 2142* Rheumatoid arthritis characteristically causes swelling of small joints in the hand like the P.I.P, M.C.P and the wrist joint bilaterally.* Isolated D.I.P joint involvement is seen in psoriatic arthropathy.* D.I.P joint involvement is also seen with osteo-arthritis but the involvement is with pain at the base of thumb. Knee joint is the commonest joint involved in these patients.