The following is a summary of “Interosseous tendon inflammation in the hands of patients with clinically suspect arthralgia: analysis of MRI data from a prospective cohort study,” published in the July 2023 issue of Rheumatology by Dijk et al.
Interosseous tendon inflammation was observed for the first time with MRI in patients with rheumatoid arthritis and at-risk individuals with detectable anti-citrullinated protein antibodies, leading to the hypothesis that interosseous tendon inflammation precedes clinical arthritis. To better understand the role of interosseous tendon inflammation in the development of rheumatoid arthritis, the researchers examined the frequency of interosseous tendon inflammation in healthy individuals and in those with arthralgia that was clinically suspected of progressing to rheumatoid arthritis (i.e., clinically suspect arthralgia), as well as the association of interosseous tendon inflammation with other symptoms of inflamed joint tissues and with clinical arthritis development. Contrast-enhanced hand MRI was performed on adult (≥18 years) patients with clinically suspect arthralgia and symptom-free (control) individuals. Using the rheumatoid arthritis MRI scoring system, MRIs were evaluated for interosseous tendon inflammation on the radial and ulnar sides of the second to fifth metacarpophalangeal joints, as well as for synovitis, tenosynovitis, and osteitis.
Patients with clinically suspected arthralgia were monitored for the development of clinical arthritis. Using immunohistochemistry for anti-CD55 and anti-CD68, tissue from the palms of three embalmed bodies donated for scientific research was examined for local tenosynovium. MRI evidence of interosseous tendon inflammation was the primary outcome for the cross-sectional portion of the study. In the longitudinal portion of the investigation, the development of clinical arthritis was the primary outcome. About 667 patients with clinically suspect arthralgia (mean age 44 years [SD 13], 504 [76%] women, and 163 [24%] men) underwent contrast-enhanced hand MRI between April 3, 2012, and May 20, 2020. 193 symptom-free controls were recruited between November 1, 2013, and November 30, 2014 (mean age 50 years [SD 16], 136 [70%] women and 57 [30%] males). Two (1%) of 193 symptom-free controls inflamed the interosseous tendon. The absence of tenosynovium encompassing interosseous tendons was revealed by immunohistochemistry of cadaveric hand tissue.
At the time of inclusion, 10% of 667 patients with clinically suspect arthralgia had interosseous tendon inflammation (P < 0.0001 vs. symptom-free controls). Interosseous tendon inflammation occurred more frequently in the presence of metacarpophalangeal synovitis (odds ratio [OR] 24 [95% CI 1·2–4·2]) or tenosynovitis (OR 9·7 [CI 5·5–17·0]). A three-dimensional MRI reconstruction indicated that interosseous tendon inflammation and metacarpophalangeal flexor tenosynovitis were confluent. About 91 (16%) of 558 patients with clinically suspect arthralgia developed clinical arthritis during follow-up (median total follow-up duration: 25·3 months [95% CI: 25·1–25·5]). Patients with clinically suspect arthralgia and interosseous tendon inflammation had an increased risk of developing clinical arthritis (hazard ratio [HR] 4·5 [2·8–7·2]), which was reduced but still significant after adjusting for concurrent synovitis, tenosynovitis, or osteitis (HR 1·7 [1·02–2·8]). In patients with clinically suspect arthralgia, interosseous tendon inflammation correlates with symptoms and is associated with the progression to clinical arthritis. In the pre-arthritis phase of rheumatoid arthritis, the absence of local tenosynovium suggests that interosseous tendon inflammation results from expanding local subclinical inflammation.