Spondyloarthritis and psoriatic arthropathy
Exam Tips
- Inflammatory back pain pattern (young onset, >3 months, morning stiffness, improves with exercise, night pain) is a high-yield discriminator from mechanical causes.
- Normal ESR/CRP or negative HLA-B27 does not exclude spondyloarthritis; diagnosis is clinical plus imaging context.
- In psoriasis patients, ask specifically about dactylitis, heel pain, and nail changes (pitting/onycholysis), which strongly support psoriatic arthritis.
- Distal interphalangeal involvement with nail disease is classic for psoriatic arthropathy in OSCE stations.
- Urgent same-day ophthalmology referral is required for possible acute anterior uveitis (painful red photophobic eye).
- Before biologics/JAK inhibitors, mention mandatory infection screening (TB, hepatitis, HIV) and vaccination review for prescribing safety questions.
- Image memory aid: See figure of dactylitis and nail pitting in a standard rheumatology atlas and MRI sacroiliitis examples in axial SpA teaching sets.
Definition
Spondyloarthritis is a family of chronic inflammatory rheumatological diseases that primarily involve the axial skeleton (sacroiliac joints and spine) and/or peripheral joints, with overlapping extra-articular features. Psoriatic arthropathy (psoriatic arthritis) is a predominantly peripheral subtype linked to psoriasis, characterized by arthritis, enthesitis, dactylitis, and nail disease, and can also include axial inflammation even when plain radiographs are initially normal.
Pathophysiology
Disease arises from interaction between genetic susceptibility and environmental triggers. Key genetic associations include HLA-B27 (especially axial disease) and multiple immune-related loci in psoriatic disease; family history markedly increases risk. Immunologically, innate and adaptive pathways (notably TNF-alpha and the IL-23/IL-17 axis) drive inflammation at entheses, synovium, and adjacent bone marrow, producing pain and stiffness; chronic inflammation can cause both erosive joint damage and paradoxical new bone formation (syndesmophytes/ankylosis). Barrier and microbiome factors (skin and gut), plus post-infectious immune activation in reactive arthritis (e. g, Chlamydia, Salmonella, Shigella, Campylobacter, Yersinia), contribute to phenotype expression.
Risk Factors
- Current or previous psoriasis
- Inflammatory bowel disease (Crohn disease or ulcerative colitis)
- History of acute anterior uveitis
- Family history of spondyloarthritis, psoriasis, or psoriatic arthritis
- Age at onset 16-45 years for axial symptoms
- First-degree relative with psoriatic arthritis
- Recent gastrointestinal or genitourinary infection (reactive pattern)
- HLA-B27 positivity
- Possible trigger from joint/tendon trauma in susceptible individuals
- Smoking (clear association with psoriasis)
Clinical Features
Symptoms
- Chronic back pain (>3 months) with inflammatory pattern: morning stiffness >30 minutes, improves with movement, recurs with rest
- Nocturnal back pain, often in second half of night
- Alternating buttock pain
- Peripheral joint pain/swelling (often asymmetric oligoarthritis), especially lower limbs
- Dactylitis ('sausage digit')
- Heel pain or first-step foot pain suggesting enthesitis
- Fatigue and reduced function
- Eye pain/redness/photophobia suggesting anterior uveitis
- History of psoriasis, nail symptoms, or bowel inflammation
- Rapid symptomatic response to NSAID trial within 48 hours (supportive, not diagnostic)
Signs
- Restricted spinal movement and reduced chest expansion in axial disease
- Sacroiliac tenderness
- Peripheral synovitis including distal interphalangeal joint involvement in psoriatic arthritis
- Dactylitis on inspection
- Enthesitis at Achilles insertion, plantar fascia, or epicondyles
- Psoriatic plaques (including scalp, trunk, extensor surfaces)
- Nail pitting, onycholysis, subungual hyperkeratosis
- Reduced range of motion and functional limitation
Investigations
Management
Lifestyle Modifications
- Early rheumatology referral for diagnostic confirmation and treat-to-target planning
- Structured physiotherapy and regular exercise to maintain spinal mobility, posture, and function
- Smoking cessation and cardiovascular risk reduction (BP, lipids, weight, diabetes prevention)
- Weight management to improve joint load and reduce systemic inflammation
- Patient education on flare recognition, adherence, and red-flag symptoms (acute painful red eye, neurological deficit after trauma)
- Psychological support and fatigue/sleep management; assess impact on work and daily activities
Pharmacological Treatment
NSAIDs (first-line symptomatic control)
- Naproxen 500 mg twice daily orally
- Ibuprofen 400 mg three times daily orally
- Celecoxib 200 mg once daily (or 100 mg twice daily)
Use lowest effective dose for shortest duration; co-prescribe gastroprotection (e. g, omeprazole 20 mg once daily) if GI risk. Avoid/caution in peptic ulcer disease, CKD, heart failure, uncontrolled hypertension, anticoagulant use, and late pregnancy; monitor renal function and blood pressure.
Local corticosteroid therapy
- Intra-articular methylprednisolone acetate 20-80 mg depending on joint size
- Intra-lesional/enthesis corticosteroid injection by experienced clinician
Useful for peripheral flares and enthesitis. Exclude sepsis before injection; repeated injections may risk tendon damage/skin atrophy. Systemic oral steroids are generally not preferred long-term in psoriatic arthritis and may trigger psoriasis rebound on withdrawal.
Conventional synthetic DMARDs (peripheral psoriatic arthritis, limited role in pure axial disease)
- Methotrexate 7.5-25 mg once weekly orally or subcutaneously + folic acid 5 mg once weekly (different day)
- Sulfasalazine up to 1 g twice daily (titrated)
- Leflunomide 20 mg once daily
Check baseline and ongoing FBC, LFT, U&E per monitoring protocols. Methotrexate and leflunomide are teratogenic (effective contraception needed); avoid methotrexate in significant liver disease/alcohol excess and severe renal impairment. Counsel about infection risk, mucositis, cytopenias, hepatotoxicity; stop and seek urgent review for systemic infection.
Biologic/targeted therapy for active disease after specialist assessment
- Adalimumab 40 mg subcutaneously every 2 weeks (TNF inhibitor)
- Etanercept 50 mg subcutaneously weekly (TNF inhibitor)
- Secukinumab 150 mg subcutaneously weekly for 5 doses then monthly (IL-17A inhibitor)
- Ustekinumab 45 mg subcutaneously at weeks 0 and 4 then every 12 weeks (IL-12/23 inhibitor)
- Upadacitinib 15 mg once daily orally (JAK inhibitor)
Choice depends on axial/peripheral pattern, skin disease, comorbidity, and local pathway. Screen for latent TB/hepatitis/HIV before treatment; avoid live vaccines during significant immunosuppression. Major warnings: serious infection risk, potential malignancy signal, and VTE/MACE caution with JAK inhibitors in high-risk patients.
Analgesic adjuncts
- Paracetamol 1 g up to four times daily as needed
Adjunct only; does not modify disease progression.
Surgical / Interventional
- Total hip replacement for end-stage hip involvement
- Other joint arthroplasty or synovectomy in refractory structural peripheral damage
- Spinal fracture stabilization in ankylosed/fragile spine when indicated
Complications
- Progressive irreversible joint damage and disability
- Reduced quality of life, sleep disturbance, fatigue, and reduced work/education participation
- Depression and anxiety
- Acute anterior uveitis
- Inflammatory bowel disease association
- Cardiovascular disease risk increase
- Drug-related harms: NSAID gastropathy/renal injury, steroid osteoporosis/fracture risk, biologic-associated serious infection
- Osteoporosis in axial disease
- Ankylosis/spinal fusion
- Spinal fractures (with possible spinal cord injury) in rigid spine
- Large joint destruction requiring replacement
Prognosis
Course is variable and often relapsing-remitting. Axial disease may show persistent MRI inflammation and progressive structural change; psoriatic arthritis can cause early irreversible damage (including within 2 years) if undertreated, but outcomes are improved by early recognition, rapid specialist referral, and timely use of targeted therapy. Reactive-pattern disease is commonly self-limiting over months, though a minority develop chronic inflammatory arthritis.