Stress fracture of the fused lumbo-dorsal spine in ankylosing spondylitis. A report of three cases.

According to Romanus and Yd#{233}n (1955) the first description of a locally destructive lesion involving both surfaces of a vertebral body in ankylosing spondylitis was in an article by Andersson (1937) reporting two cases. Since then there have been occasional reports of similar lesions, notably by Edstr#{246}m (1940) and Forestier, Jacqueline and Rotes-Querol (1956). Both of these authors commented on the radiological resemblance to tuberculosis, but the pathology of the “destructive lesions” was not established. In 1952 Baggenstoss, Bickel and Ward reported four patients in an article entitled “Rheumatoid granulomatous nodules as destructive lesions of vertebrae”, and presented a detailed histological account based, however, on the single case of rheumatoid arthritis ; the other three were cases of ankylosing spondylitis in which no histology was available. In their own words “the lesions were presumed to be caused by similar rheumatoid granulomatous bodies” . That this presumption is erroneous was well stated by Lorber, Pearson and Rene (1961 ), who reported another histologically documented case of rheumatoid granulomatous nodules found in vertebrae. In their equally well documented case of ankylosing spondylitis “a different type of destructive lesion was found”, and they pointed out that these lesions “are not nearly as rare as they are in rheumatoid arthritis”. In 1969 Kanefield and his colleagues described three cases in ankylosing spondylitis and gave good evidence that the lesion might represent a response to delayed union or nonunion of a fracture. In the last three years we have seen three cases in ankylosing spondylitis that lend support to Kanefield’s proposition. We report them in view of their relative rarity, and explain why we believe these lesions are not truly destructive but rather a failure to reconstruct as in non-union.