Psoriatic Arthritis

Psoriatic arthritis (PsA) is a chronic inflammatory arthritis that occurs in association with psoriasis. It affects approximately 20–30% of people with psoriasis, though joint symptoms can occasionally precede skin disease. PsA belongs to the spondyloarthropathy family of conditions and has a wide spectrum of musculoskeletal involvement that can affect peripheral joints, the spine and sacroiliac joints, tendons, and the areas where tendons and ligaments insert into bone (entheses).

Unlike rheumatoid arthritis, psoriatic arthritis can affect joints asymmetrically and has characteristic patterns such as involvement of the distal joints of the fingers and toes (DIP joints), and the distinctive "sausage digit" or dactylitis — diffuse swelling of an entire finger or toe. Nail changes including pitting, onycholysis and subungual hyperkeratosis are common and are closely associated with DIP joint disease.

PsA can pursue a destructive course if untreated, with some patients developing significant joint damage. However, modern therapeutic options — including biologics and targeted synthetic DMARDs — have considerably improved outcomes. Effective management requires collaboration between rheumatologist and dermatologist to address both joint and skin disease.

Treatment is guided by the pattern and severity of disease. NSAIDs are useful for mild peripheral and axial symptoms. For peripheral joint disease, conventional DMARDs — most commonly methotrexate — are used, though they have limited efficacy for axial disease, enthesitis and skin disease. Local corticosteroid injections can provide targeted relief for individual inflamed joints or entheses.

Biologic therapies have transformed management of moderate-to-severe PsA. TNF inhibitors (adalimumab, etanercept, certolizumab, golimumab) are widely used and effective across multiple disease domains. IL-17 inhibitors (secukinumab, ixekizumab, bimekizumab) are particularly effective for both skin and joint disease. IL-12/23 and IL-23 inhibitors (ustekinumab, guselkumab, risankizumab) offer further options, especially where skin disease is prominent. JAK inhibitors (tofacitinib, upadacitinib) provide additional oral targeted therapy.

The choice of treatment takes into account disease domain, severity, comorbidities, concomitant skin disease, and patient preference. Close coordination with a dermatologist is valuable when skin disease is significant, and some patients benefit from a single agent that effectively treats both joints and skin simultaneously.