High-frequency ultrasonography for the detection of subclinical arthritis in chronic plaque psoriasis patients - A cross-sectional study

Background: Psoriatic arthritis (PsA) is seen in almost 30-40% cases of psoriasis. Psoriasis precedes the onset of PsA in 85% of cases. Delay in the diagnosis of PsA may lead to poor functional outcomes and morbidity. Screening psoriasis patients with high-frequency ultrasound helps to diagnose arthritis at an early stage leading to prompt intervention and possible reduction in the morbidity associated with the disease. Objectives: To determine the role of high frequency ultrasonography (USG) in the detection of subclinical PsA. Methods: A cross-sectional study was conducted in a dermatology and radiology department of Armed Forces Medical College, Pune between July 2021 and December 2022. Patients of chronic plaque psoriasis with no clinical evidence of arthritis were assessed using high-frequency USG. Various parameters such as bony erosions, synovial thickening, tendon thickening, tendon hypo-echogenicity, calcifications and power doppler signals were assessed. Results: A total of 117 patients were included in the study. The distal interphalangeal joint (DIP) and Achilles tendon were the most commonly affected sites. Synovial thickening in DIP was observed in 67 (57%) patients and Achilles tendon thickening was observed in 39 (33%) patients. Limitations of the study: The cross-sectional nature of the study is the major limitation. A longitudinal study will be required to understand the clinical relevance of ultrasonographic changes in these patients. Another limitation of the study is the lack of age and gender-matched controls. Future research should include such controls to ensure more accurate results. Conclusion: Subclinical arthritis is common in patients with chronic plaque psoriasis. High-frequency ultrasound is a useful tool for detecting subclinical synovitis and enthesitis in asymptomatic patients. The DIP joint and Achilles tendon ultrasound can be used for screening for early detection of PsA.