Does Rheumatoid Arthritis affect the feet?
In some patients, the feet may be the first manifestation of RA, although this can be difficult to recognize because synovitis in the MTPs is difficult to assess. The “MTP” squeeze test, where the forefoot is squeezed by the examiners’ hand, may provide a clue to synovitis if there is tenderness in any of the MTPs with this maneuver. In addition, over 33% of patients develop significant foot deformities during the course of RA. The most common deformity is claw toe or hammer toe. This is caused by inflammation of the MTP joints leading to subluxation of the metatarsal heads. When this problem occurs, the patient has difficulty fitting his or her toes into the shoe because the tops of the toes rub on the shoe box, resulting in callous or ulcer formation. Additionally, because the soft tissue pad that normally sits underneath the metatarsal heads is displaced, the heads of the metatarsal bones are no longer cushioned and become very painful to walk on, frequently resulting in calluses on the inferior surface of the foot. Patients commonly complain that it feels as though they are walking on pebbles or stones. Arthritic involvement of the tarsal joints and subtalar joint can result in flattening of the arch of the foot and hindfoot valgus deformity.