Abstract

Background Enthesial reaction, as a stress or disease marker, has been a generalized perspective, largely untested as to its veracity. Perhaps valid with soft tissue visualization by computerized tomography or magnetic resonance imaging, examination of standard radiographs reveals minimal evidence of enthesial reaction. The current study seeks to assess the disease-specificity of enthesial reaction by examining the primary evidence that of disease-related variation in its presence in defleshed skeletons. Methods Defleshed skeletons were evaluated macroscopically (in a manner blinded according to disease diagnosis) to assess presence of enthesial reaction. The skeletal sample included individuals diagnosed on the basis of clinical and previously validated non-enthesial reaction-based criteria as having spondyloarthropathy, calcium pyrophosphate deposition disease (CPPD) and diffuse idiopathic skeletal hyperostosis. These diseases are classically considered predisposed to enthesial reaction. They were contrasted with those which are not (rheumatoid arthritis and healthy individuals). The latter cohort was developed by excluding individuals with diseases that could have an enthesial component (e.g., renal disease, hypertrophic osteoarthropathy). Sixty-six macroscopically examined sites were assessed (ANOVA) individually and also according to established scoring systems. Results Prevalence of enthesial reaction at individual sites was indistinguishable, with notable exception of posterior iliac spine, ischial tuberosity and lateral elbow largely spared in healthy individuals, greater trochanter was more commonly affected in spondyloarthropathy and CPPD and distal lateral femoral sparing occurred in rheumatoid arthritis. Limited scoring systems performed poorly. Conclusions Macroscopic bone manifestation of enthesitis has insufficient prevalence variation among diseases to be useful in distinguish among them. Absence of macroscopic evidence of significant enthesial reaction explains the inadequacy of plain radiographs in its recognition. Enthesitis appears to be predominantly a soft tissue phenomenon, analogous to dactylitis.

Authors and Affiliations