Dactylitis: The Psoriatic "Sausage Digit"
Whole-digit swelling is a hallmark feature distinguishing PsA from rheumatoid arthritis.
- ~40%: Prevalence in PsA (placeholder statistic)
- Toes: Most affected digit (placeholder statistic)
- Asymmetric: Onset pattern (placeholder statistic)
- Flexor tenosynovitis: Imaging finding (placeholder statistic)
What drives sausage digit swelling
Placeholder: combined joint and tendon sheath inflammation causes diffuse digit swelling.
Enthesitis: Inflammation at Tendon Insertions
Entheseal inflammation is a core feature linking PsA to the spondyloarthritis family.
- Achilles: Common site (placeholder statistic)
- ~35%: Prevalence (placeholder statistic)
- Ultrasound: Detection tool (placeholder statistic)
- Insertional: Pain pattern (placeholder statistic)
Why entheses become inflamed
Placeholder: mechanical stress plus immune activation targets tendon-bone junctions.
Axial Spondylitis in Psoriatic Arthritis
Spinal and sacroiliac joint inflammation causes inflammatory back pain in a subset of patients.
- ~25%: Axial PsA prevalence (placeholder statistic)
- Sacroiliac: Key joint (placeholder statistic)
- Syndesmophytes: Imaging sign (placeholder statistic)
- Morning stiffness: Symptom pattern (placeholder statistic)
How axial disease progresses
Placeholder: chronic inflammation drives new bone formation along the spine.
Conventional DMARD Therapy Effects
Conventional synthetic DMARDs reduce peripheral joint inflammation with partial efficacy.
- Methotrexate: Common agent (placeholder statistic)
- ~40-50%: Response rate (placeholder statistic)
- Limited: Axial efficacy (placeholder statistic)
- 6-12 weeks: Onset of effect (placeholder statistic)
What DMARDs do and do not treat
Placeholder: effective for peripheral synovitis, weak for axial and entheseal disease.
Biologic Therapy and Structural Joint Protection
Targeted biologics such as TNF and IL-17 inhibitors slow joint damage progression.
- TNF / IL-17: Target pathway (placeholder statistic)
- ~60-70%: Response rate (placeholder statistic)
- Slows erosion: Radiographic effect (placeholder statistic)
- Strong: Axial efficacy (placeholder statistic)
Why biologics protect joint structure
Placeholder: blocking key cytokines reduces inflammation and limits bone/cartilage damage.
Placeholder: early biologic treatment improves long-term joint outcomes.