Spondyloarthropathy: Terminology and Classification
Spondyloarthropathy (SpA) is synonymous with spondyloarthritis—these terms are used interchangeably to describe the same family of chronic inflammatory rheumatic diseases. 1
Core Definition
Spondyloarthropathy/spondyloarthritis encompasses a group of interrelated inflammatory conditions characterized by:
- Inflammation of the spine and sacroiliac joints (axial involvement) 1
- Peripheral joint inflammation in an asymmetric, oligoarticular pattern predominantly affecting lower limbs 2, 3
- Enthesitis (inflammation at tendon/ligament insertion sites) 1
- Absence of rheumatoid factor (seronegative arthropathy) 1, 2
- Strong association with HLA-B27 (present in 74-89% of cases) 1, 4
Disease Subtypes Included Under This Umbrella
The spondyloarthropathy family includes several distinct but related conditions 1, 5:
- Axial spondyloarthritis (axSpA), which includes:
- Ankylosing spondylitis (AS) - the radiographic form
- Non-radiographic axial SpA
- Psoriatic arthritis (PsA) 1
- Reactive arthritis (including Reiter's syndrome) 1, 2
- Enteropathic arthritis (arthritis associated with inflammatory bowel disease) 1
- Juvenile spondyloarthritis 1
- Undifferentiated spondyloarthritis 1, 2
Context for Psoriasis Patients
In a patient with psoriasis, spondyloarthropathy specifically refers to psoriatic arthritis (PsA), which is an inflammatory seronegative spondyloarthropathy associated with psoriasis. 1
Key features distinguishing PsA within the SpA family 1:
- Occurs in 6-42% of patients with psoriasis (prevalence estimates vary widely) 1
- Cutaneous psoriasis precedes arthritis in 84% of cases, typically by an average of 12 years 1
- Nail involvement (pitting, onycholysis) occurs in 80-90% of PsA patients 1
- Dactylitis ("sausage digit") is particularly characteristic 1
- DIP joint involvement is more common in PsA than other SpA subtypes 1
Clinical Recognition Points
The shared features across all spondyloarthropathies include 1, 2, 3:
- Inflammatory back pain with characteristic features: onset before age 40-45, morning stiffness >30 minutes, improvement with exercise but not rest, night pain 1, 4
- Sacroiliitis (may be bilateral in AS or unilateral/bilateral in PsA) 1
- Extra-articular manifestations: anterior uveitis (40% of AS patients), psoriasis, inflammatory bowel disease 1, 4
- Familial aggregation and genetic predisposition 2, 3
Important Terminology Note
The terms "spondyloarthropathy" and "spondyloarthritis" are completely interchangeable—the shift toward "spondyloarthritis" in recent literature reflects evolving nomenclature preferences rather than any clinical distinction. 1, 5 Both terms describe the identical disease spectrum and should be understood as synonymous in all clinical contexts.