Psoriatic Arthritis
Also known as: PsA
Inflammatory arthritis associated with psoriasis. Can affect joints, tendons, and the spine. Diagnosed clinically and with ultrasound. Treated with DMARDs and biologics.
Key Facts
- Develops in about 30% of people with psoriasis
- Joint symptoms can appear before skin symptoms in 15% of cases
- Distinct from rheumatoid arthritis — different joint patterns and treatment considerations
- Dactylitis (sausage digits) and enthesitis are hallmark features
- Early treatment prevents irreversible joint damage
What is psoriatic arthritis?
Psoriatic arthritis (PsA) is a chronic inflammatory arthritis that occurs in some patients with psoriasis — the autoimmune skin condition causing red, scaly plaques. PsA can affect any joint and also involves tendons (enthesitis) and can cause swelling of entire fingers or toes (dactylitis, or “sausage digits”).
Not all psoriasis patients develop PsA, and joint symptoms can appear before skin symptoms in some cases. PsA is a distinct disease from rheumatoid arthritis, with different patterns of joint involvement and different treatment considerations.
Symptoms
- Joint pain and stiffness, often asymmetric (not the same on both sides)
- Swollen, sausage-like fingers or toes (dactylitis)
- Tendon pain at insertion points (enthesitis) — Achilles tendon, plantar fascia, elbow
- Lower back pain or stiffness (axial involvement)
- Nail changes — pitting, ridging, separation from the nail bed
- Skin plaques — red, scaly patches, often on elbows, knees, scalp
- Morning stiffness
- Fatigue
How we diagnose it
- Clinical evaluation — Joint exam, skin and nail assessment, history of psoriasis (including in family members)
- Musculoskeletal ultrasound — Dr. Fellows uses in-office ultrasound to detect enthesitis, synovitis, and dactylitis — findings that confirm PsA and help distinguish it from other types of arthritis
- Blood work — Inflammatory markers (ESR, CRP); PsA is typically RF-negative, which helps differentiate from RA
- Imaging — X-rays to assess for joint damage; ultrasound for early detection of inflammation
How we treat it
- DMARDs — Methotrexate is commonly used, particularly when skin involvement is significant
- Biologic therapies — TNF inhibitors, IL-17 inhibitors (such as Cosentyx, available as an infusion), IL-23 inhibitors, and others targeting specific inflammatory pathways
- JAK inhibitors — Oral targeted therapy option
- Corticosteroid injections — Ultrasound-guided injections for isolated joint or tendon flares
- Coordination with dermatology — For patients with significant skin disease, we coordinate with dermatologists to optimize both skin and joint treatment
At Synergy Rheumatology
Ultrasound is particularly valuable in PsA — it can detect enthesitis and early joint inflammation that may not be apparent on exam alone. When biologics like Cosentyx are administered by infusion, they're given in our on-site infusion center. Patients with active PsA may qualify for clinical trials at our research site.
Have questions about psoriatic arthritis?
Schedule an appointment to discuss your symptoms, diagnosis, or treatment options with Dr. Fellows.