The rheumatoid disease can affect the whole foot. However commonly it affects the forefoot. It causes inflammation of the joints of the toes which leads to subluxation and dislocation of the toes. It destroys the joint cartilages due to inflammation. This causes callosities in the ball of the toes and clawing. The big toe deviates sideways and a severe bunion can develop.
Treatment is forefoot arthroplasty which inolves excision of the metatarsal heads and fusion of the first MTP joint.
In the hindfoot rheumatoid arthritis can cause valgus deformity. Tibialis posterior tendon could rupture aggravating the deformity. This leads to midfoot and subtalar arthritis. Treatment often is tripe fusion.
Total ankle replacement is a good option for patients with ankle involvement provided they don’t havd much of varus or valgus deformity.
These operations are commonly performed for painful stiff joints as in osteoarthritis and rheumatoid arthritis. Pain arises when two apposing bones which have lost their joint cartilage rub against each other.
Joints commonly affected that need fusion are big toe MTP (metatarsophalangeal), PIP (proximal interphalangeal), DIP (distal interphalangeal). Midfoot and hindfoot arthritis can be treated with triple fusion. Ankle joint sometimes needs fusing if joint replacement is not possible.