Surgery of the foot in rheumatoid arthritis
THE foot has been a long-neglected area in medicine, yet foot disorders, especially in association with rheumatoid arthritis, are common. Rheumatoid arthritis usually begins in the forepart of the foot, and the metatarsophalangeal joint often is the earliest joint in the body to demonstrate the characteristic erosion of bone.
Pathogenesis of deformity in the foot
There is early spreading of the forepart of the foot as the synovitis of the metatarsophalangeal joints distends the joint capsules and stretches the intermetatarsal ligaments. The intrinsic musculature may become affected, and has been shown by Duchenne1 to flex the metatarsophalangeal joints and to extend the interphalangeal joints. When the long flexors of the toes contract on the straight toes, they sling the heads of the metatarsals and prevent the forepart of the foot from dropping. He demonstrated that in the absence of function of lumbricales, the long flexors pull the toes into flexion; the metatarsal heads are no longer supported; and the proximal phalanges become dorsiflexed at the metatarsophalangeal joint, and the interphalangeal joints become flexed. The same mechanism is thought to be operating in the rheumatoid foot. Synovitis of the metatarsophalangeal joints furthers the dislocation of those joints and of the flexor tendons into the region between the metatarsal heads. When this occurs the metatarsal heads protrude into the sole of the foot; the fat pad atrophies; and calluses develop beneath the metatarsal heads and on the dorsa of the interphalangeal joints (Fig. 1). The patient experiences much discomfort while walking and . . .