This document discusses spondyloarthropathies (SpA), a group of inflammatory musculoskeletal disorders. It defines the diagnostic criteria for SpA and describes five main subgroups: ankylosing spondylitis, psoriatic arthritis, reactive arthritis, enteropathic arthritis, and undifferentiated spondyloarthritis. For each subgroup, it provides details on epidemiology, clinical features, pathogenesis, and imaging findings.

1. Dr Nihal Ahmed
Apollo Cancer Centre
Teynampet, Chennai

2.  Spondyloarthropathies (SpA), are a group of
musculoskeletal syndromes linked by common clinical
features and immunopathologic mechanisms.
 Diagnostic criteria:
1) Absence of RF
2) Sacroiliitis with/without AS
3) Peripheral arthropathy
4) Clinical overlap including 2 or more of following:-
 Psoriatic skin or nail lesion
 Conjuctivitis/GUT infection
 Ulceration of mouth, intestine or genitals
 Eryhtema nodosum

3.  Five subgroups of spondyloarthritis are
distinguished:
 Ankylosing spondylitis: ~90% HLAB27 positive
 Psoriatic arthritis: ~60%
 Reactive arthritis: ~85%
 Enteropathic arthritis (i.e. extraintestinal
manifestation of IBD)
 Undifferentiated spondyloarthritis

4.  A chronic, progressive inflammatory disease resulting in fusion
(ankylosis) of the spine and sacroiliac (SI) joints.
 Mostly affects young adults(3rd decade), Male predilection of
3:1.
 The axial skeleton is predominantly affected, although in
~20% of cases the peripheral joints are also involved.
 Associations
 Anterior uveitis (25-40%)
 Cardiovascular disease, Aortic valve disease
 Apical/upper lobe predominant interstitial lung disease with small
cystic spaces (in ~1% of patients)
 Arachnoiditis

6. SACRUM
Sacroiliitis is usually the first manifestation
– Bilateral, symmetrical
 Subchondral demineralization - equivalent of
subchondral bone marrow hyperintensity seen on MRI.
 Subchondral erosions, sclerosis (>5mm) on the iliac side
of the SI joints.
 At end-stage, total ankylosis/complete obliteration of joint
space.

8. SPINE
 Begins in the thoracolumbar spine and progresses cranially.
 Small erosions at the corners of vertebral bodies with reactive
sclerosis: Romanus lesions (shiny corner sign)
 Vertebral body squaring
 Noninfectious spondylodiscitis: Andersson lesion
 Diffuse syndesmophytic ankylosis -Bamboo spine (Lat)
 Interspinous ligament ossification - Dagger spine (AP)
 Ossification of facet joint – Tram track sign
 Enthesophyte
 Complications – carrot stick fractures

11. Hips
 Bilateral and symmetric, uniform joint space narrowing, axial
migration of the femoral head, protrusio acetabuli, and a collar
of osteophytes at the femoral head-neck junction.
Pelvis
 Whiskering of the pelvic bones primarily affects the ischial
tuberosities/iliac crest.
 Bridging or fusion of the pubic symphysis.
Knees
 Knees demonstrate uniform joint space narrowing with bony
proliferation.
Shoulders
 Large erosion of the anterolateral aspect of the humeral head
- 'hatchet' deformity, glenohumeral joint involvement is not
uncommon

14.  Inflammatory arthritis seen in ~30% of patients with
psoriasis.
 In contrast to many other arthropathies, there is no
gender predilection, mean age: 20-40 years.
 Dermatological features of psoriasis precede arthritis in
70-75% of cases.
 Strong association with nail involvement, particularly for
distal interphalangeal joint arthritis.
 Pathogenesis – Chronic synovitis – joint destruction

15. Five subtypes :
Symmetric polyarthritis (similar in
appearance to RA)
Asymmetric mono- or oligoarthritis
Spinal column involvement (spondylitis)
Distal interphalangeal arthritis of the hands
and feet
Arthritis mutilans

16.  The hallmark of psoriatic arthritis is the combination of bone erosions
with bone proliferation and predominantly distal distribution.
(e.g. interphalangeal more than metacarpophalangeal joints).
 Enthesitic and marginal bone erosions; “Pencil in cup” deformities
are common, but not pathognomonic for PsA.
 Joint subluxation, joint space - preserved.
 Periostitis
 Dactylitis: Soft tissue swelling of a whole digit- “Sausage digit”;
underlying synovitis and tenosynovitis
 Acro-osteolysis
 Arthritis mutilans: osteolysis and articular collapse-"telescoping
fingers"
 Ivory phalanx: Classically involving the distal phalanx of the great toe

19.  Sacroiliitis: often
asymmetrical
 Spondylitis:
 Osteophytes – coarse,
asymmetric, non marginal
 Parasyndesmophytes

20.  Sterile inflammatory monoarticular or
oligoarticular arthritis that follows an infection
at a different site, commonly enteric or
urogenital.
 Reiter syndrome -Urethritis, arthritis and
conjunctivitis.
 Similar appearance to psoriatic arthritis -
ill-defined erosions, enthesopathy, bone
proliferation and fusiform soft tissue
swelling.

21.  Lower extremity involvement - MTP joint, DIP
rarely involved*
 Enthesitis -Calcaneus at the sites of Achilles
tendon and plantar fascia attachment.
 Large bulky paravertebral ossification
"floating osteophyte"
 Sacroiliitis -usually unilateral,asymmetric
 Knee > Ankle > Sacroiliac joint) is more
prevalent than upper extremity.

23. Enteropathic arthritis (EA) is a form of
chronic, inflammatory arthritis associated
with IBD(Crohns,UC), Whipples disease.
Location – 3 patterns
1) Peripheral joint arthritis
2) Sacroiliitis
3) Spondylitis identical to AS – can precede
bowel disease*

25. Non-specific mono or polyarthropathy.
Early presentation of a more well-known
form of arthritis.
A specific diagnosis is usually reached
within three months – commonly RA
(30%), AS
HLA B-27 positive in ~75% cases