[Radiographic changes of the calcaneus in the framework of chronic polyarthritis]

Plain films of the calcaneus of 768 patients with confirmed rheumatoid arthritis were examined retrospectively with reference to inflammatory rheumatic changes. 42 patients (5.5%) showed an erosion of the posterior upper calcaneal margin related to an Achilles bursitis. In three patients there were additional plantar erosions. The Achilles bursitis was bilateral in 50% of cases, particularly in patients in stages 2 and 3 according to Steinbrocker. In the majority of bilateral cases (62%) the size or shape of the lesions was asymmetrical. Our observations indicate that involvement of the os calcis is not uncommon in rheumatoid arthritis; routine examination of this bone would appear to be indicated even in patients without symptoms. Since the defect is unilateral in half the patients, unilateral occurrence of an erosive lesion cannot be regarded as a criterion for a bacterial-inflammatory bursitis. Contrary to the symmetrical involvement of joints in the hands in rheumatoid arthritis, defects in the calcaneus are often unilateral or asymmetrical.