Interosseous tendon inflammation (ITI) has been described in rheumatoid arthritis (RA). Whether ITI occurs in at-risk individuals before the onset of clinical synovitis is unknown.
Objectives To investigate, by MRI, ITI in anti-cyclic citrullinated peptide (CCP)-positive at-risk individuals (CCP +at risk) and to describe the anatomy, prevalence and clinical associations across the RA continuum.
Methods Hand MRI was performed in 93 CCP + at risk, 47 early RA (ERA), 28 established ‘late’ RA (LRA) and 20 healthy controls (HC) and scored for ITI, flexor tenosynovitis (TSV) and RA MRI scoring at the metacarpophalangeal joints (MCPJs). Cadaveric and histological studies were performed to explore the anatomical basis for MRI ITI.
Results The proportion of subjects with ITI and the number of inflamed interosseous tendons (ITs) increased along the disease continuum (p<0.001): 19% of CCP +at risk, 49% of ERA and 57% of LRA had ≥1 IT inflamed . ITI was not found in any HC. ITI was more frequently identified in tender MCPJs compared with nontender MCPJs (28% vs 12%, respectively). No IT tenosynovial sheath was identified in cadavers on dissection or histological studies suggesting MRI findings represent peritendonitis. Dye studies indicated no communication between the IT and the joint.
Conclusions ITI occurs in CCP + at-risk individuals and can precede the onset of clinical synovitis. The ITs may be important nonsynovial extracapsular targets in the development and progression of RA.
- early rheumatoid arthritis
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Handling editor Josef S Smolen
Contributors KM recruited patients, collected and analysed the data and wrote the manuscript. MADA designed the study and helped prepare the manuscript. ER scored the MRI scans. EMAH led the statistical analysis. LH recruited patients and collected data. IM, MP, JRM, JN and EN performed the cadaveric and histological studies. JLN was one of the study clinicians. ALT and JEF recruited patients and collected clinical data. AJG and PE designed and led the study. All coauthors read and revised the manuscript.
Funding The study was supported by the National Institute for Health Research (NIHR) Leeds Clinical Research Facility.
Competing interests None declared.
Patient consent for publication Not required.
Ethics approval NHS Health Research Authority National Research Ethics Service Committee Yorkshire & the Humber – Leeds West.
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement No additional unpublished data are currently available.