MAUI, HAWAII – Inflammation of the hand interosseous tendons found on MRI is a novel target in efforts to preempt the development and progression of rheumatoid arthritis, Paul Emery, MD, said at the 2019 Rheumatology Winter Clinical Symposium.
He and his coinvestigators have previously shown there is a high prevalence of interosseous tendon inflammation in the hands of patients with established RA, but now they’ve demonstrated that this phenomenon also occurs in anti–cyclic citrullinated peptide (CCP)–positive individuals at increased risk for RA, even before onset of clinical synovitis.
This finding is consistent with the notion that, even though RA is classically considered a disease of the synovial joints, the joint involvement is a relatively late phenomenon in the disease development process and extracapsular structures may be important early targets of RA-related inflammation. Indeed, the MRI finding of tenosynovitis of the wrist and finger flexor tendons is known to be the strongest predictor of progression to arthritis in patients with recent-onset arthralgia or other musculoskeletal symptoms but no clinical synovitis, according to, professor of rheumatology and director of the University of Leeds (England) Musculoskeletal Biomedical Research Center.
Because the interosseous muscles of the hands play a critical role in hand function – pianists and other musicians not infrequently present to rheumatologists with overuse injuries of the muscles and their tendons – Dr. Emery and his coworkers decided to take a comprehensive look at interosseous tendon inflammation across the full spectrum of RA and pre-RA. They conducted a retrospective study of clinical and hand MRI data on 93 CCP-positive patients who presented with new-onset musculoskeletal symptoms but no clinical synovitis; 47 patients with early RA, all of whom were disease-modifying antirheumatic drug–naive; 28 patients with late RA as defined by at least 1 year of symptoms, anti-CCP and/or rheumatoid factor positivity, a Disease Activity Score in 28 joints (DAS28) of 3.2 or more, plus a history of exposure to one or more DMARDs at the time of their hand imaging; and 20 healthy controls.
The key finding is that the proportion of subjects with MRI evidence of interosseous tendon inflammation rose along the advancing RA continuum. It was present in 19% of the CCP-positive patients without clinical synovitis; 49% of the DMARD-naive early RA group; 57% of the late RA group; and in none of the healthy controls. Moreover, the number of inflamed interosseous tendons per patient also increased with RA progression.
A total of 12% of 507 nontender metacarpophalangeal joints showed MRI evidence of interosseous tendon inflammation, as did 28% of 141 tender ones (Ann Rheum Dis. 2019 Mar 23.).
As part of the study, Dr. Emery and coinvestigators performed cadaveric dissections that demonstrated that the interosseous tendons don’t possess a tendon sheath and don’t directly communicate with the joint capsule.
A prospective study is warranted in order to confirm the observed association between interosseous tendon inflammation and clinical and subclinical synovitis and to establish the predictive value of hand MRI as a harbinger of RA, he noted.
Dr. Emery reported having no financial conflicts regarding his presentation.