Background Imaging has an essential role in the new spondyloarthritis (SpA) classification criteria for axial but not for peripheral manifestations. We evaluated the impact of imaging findings for identification and treatment decisions in patients with peripheral spondyloarthritis (pSpA) and controls (non-SpA).
Methods Patients with pSpA (Assessment of SpA international Society criteria, n=30) and non-SpA (n=30), aged <45 years, with painful heels or knees, were recruited. Conventional radiography, grey-scale ultrasound including power Doppler (US/PDUS) and MRI of symptomatic areas were performed to assess inflammatory and structural changes. Mann-Whitney U test was used for group comparisons.
Results In total, 105 painful entheses (71 heels, 34 knees) in 60 patients were examined. Differences between diagnoses were found for symptom duration (pSpA: 17.2±27.5 vs non-SpA: 4.4±4.3 months), human leucocyte antigen B27 prevalence (67% vs 13%) and gender distribution (53.3% vs 20% male, respectively), all P<0.05. Logistic regression analysis for baseline differences showed that chronic changes (erosions and calcification) in the heel were more frequent in pSpA versus non-SpA by US/PDUS (62.5% vs 28.6% patients and 59.5% vs 26.5% entheses, P<0.05). Inflammatory changes in heel or knee by US/PDUS and MRI could not differentiate between non-SpA and pSpA.
Conclusions Differentiation between pSpA and non-SpA was only possible based on structural but not inflammatory changes in the heels and knees of symptomatic patients. US/PDUS was superior to MRI for this purpose. These findings imply that pSpA is associated with erosive changes at enthesitic sites, while inflammation and susceptibility are of minor influence for the development of erosions and calcification to pSpA.
- magnetic resonance imaging
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Part of this work was presented at the ACR meeting 2013.
Contributors XB: idea, study organisation, patient examination, statistical analysis, writing of manuscript. JB: idea, study organisation, writing of manuscript. UK, HA, FD, MI, LK, CK, DK, ES, ES-B and FR: recruitment of patients, comments on manuscript. FR: study organisation.
Funding This study was supported by an unrestricted research grant from Pfizer Germany after an independent external project review process. The grant was used for performance of the imaging techniques, laboratory examinations and data documentation.
Disclaimer Pfizer had no influence on study design, protocol, patient selection, treatment, interpretation of results or writing of the manuscript.
Competing interests None declared.
Ethics approval Ethical Committee of the Ruhr-University of Bochum, Germany.
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement No additional data are available.
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