The metatarsophalangeal and interphalangeal joints of the second and third toes are most regularly involved in polyarthritic rheumatoid arthritis of the feet (Fig. 10.26). Of these joints, involvement of the metatarsophalangeal joint frequently heralds the disease. Pinhole scintigraphy is useful for first making the diagnosis and then assessing the individual pathological change in the toes. In the early stage, tracer accumulates conspicuously in and around the metatarsophalangeal joints, obscuring the articular spaces (Fig. 10.26). The tracer uptake appears expansive as opposed to the slender uptake of the normal digits (Fig. 4.39). In young patients the growth cartilages in the digits delimit rheumatoid change to the juxta-articular bones (Fig. 10.27). The sesamoid bones at the first metatarsal head are occasionally involved in rheumatoid arthritis, manifesting as characteristic "hot" nodule(s) (Fig. 10.27A). However, since the normal sesamoid bones also concentrate tracer due to articular movement (Fig. 4.39), their differentiation requires keen clinical judgment. It may be of help to remember that rheumatoid arthritis affects plural joints as opposed to the singular occurrence of the physiological uptake in the sesamoids. Following osteolysis and ankylosis joints become closed and articular malalignment, subluxation, and deformity may result. In the mutilating type, besides subluxation or dislocation, shortening or telescoping of digits may be seen.
Was this article helpful?