Peritenon extensor tendon inflammation, not metacarpophalangeal joint synovitis, is associated with active enthesis in patients with psoriatic arthritis (PsA), according to research published in the Journal of Rheumatology.

Researchers conducted a post hoc study to examine the connection between peritenon extensor tendon inflammation and enthesitis and metacarpophalangeal joint synovitis and enthesitis in patients with PsA. In total, 27 patients with PsA (63% men, mean age 56 ± 11 years) were included in the analysis. Investigators evaluated a total of 16 metacarpophalangeal joints using clinical assessment and ultrasound.

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Researchers noted power Doppler-identified peritenon extensor tendon inflammation in 66.7% of patients and 17.6% of joints and noted grayscale-identified peritenon extensor tendon inflammation in 70.3% of patients and 18.9% of joints. In addition, investigators found synovitis in 66.7% of patients and 18.9% of joints as identified by power Doppler. Investigators found synovitis as identified by grayscale in 85.1% of patients and 29.2% of joints.

Researchers scanned a total of 324 entheses using ultrasound. Mean Madrid Sonographic Enthesis Index (MASEI) score was 30.62 ± 13.89. In addition to ultrasound, power Doppler activity was evaluated using both the MASEI and Outcome Measures in Rheumatology (OMERACT) definitions: MASEI was found in 18.2% of entheses and OMERACT in 10.2%. Although peritenon extensor tendon inflammation was associated with both the MASEI and OMERACT definitions, only power Doppler OMERACT showed a positive correlation with peritenon extensor tendon inflammation.

Study limitations included the small sample size, lack of clinical enthesis data, and reliability of the exercise based on videos instead of real scanning.

The researchers of the study concluded that “[peritenon extensor tendon inflammation is] associated with active enthesitis as opposed to [metacarpophalangeal joint] synovitis, which may support a functional association between [peritenon extensor tendon inflammation] and enthesitis, and reinforces the role of [peritenon extensor tendon inflammation] in PsA as an enthesis-related lesion”.

Reference

Macía-Villa C, Falcao S, Gutierrez M, Medina J, Berner Hammer H, De Miguel E. Peritenon extensor tendon inflammation in psoriatic arthritis is an enthesis-related lesion [published online February 1, 2019]. J Rheumatol. doi:10.3899/jrheum.180856