· chronic systemic inflammatory disease
· mainly affects the cartilaginous joints of the axial skeleton
· SI joints (hallmark) and spine
· is a seronegative spondyloarthropathy along with
· Reiter’s syndrome
· psoriatic arthritis
· arthritis associated with inflammatory bowel disease
· positive x-rays of sacroiliitis PLUS
· one or more criteria:
· history of pain in lumbar spine
· decreased lumbar spine movement
· limitation of chest expansion to 1” at 4th intercostal space
· incidence is 0.1% in Caucasians
· geographic variation
· varies with prevalence of HLA-B27
· genetic predisposition
· more common in family members
· male preponderance M:F = 3:1
· women have
· less progressive spinal disease
· more peripheral disease
· average age of onset is 25 yrs
· associated with HLA-B27 in 95% of cases
· considerable geographic variation in prevalence of B27 in general population
· 50% of Canadian Indians and absent in Black Africans
· thought that HLA-B27 is disease susceptibility factor
· trigger may be infection with GIT or GU organism
· much greater tendancy than rheumatoid arthritis to affect cartilagenous joints
· two basic lesions
· enthesitis
· synovitis of diathrodial synovial joints
Enthesitis
· enthesis is site of insertion of tendon, ligament or capsular attachment into bone
· affects
1. ligamentous structures of cartilagenous joints
· intervertebral discs
· manubriosternal joints
· symphysis pubis
2. capsular attachments of synovial joints
· hip
· shoulder
3. ligamentous attachments
· spinous processes of vertebrae
· iliac crests
· trochanters
· initial inflammatory erosive process of enthesis
· followed by healing with new bone formation
· bone forms in fibrous tissue and fills defect
· forms new enthesis above original level of cortical surface
· result is irregular bony prominence with sclerosis of adjacent cancellous bone
Synovitis
· similar changes to rheumatoid arthritis
· villous proliferation of synovial tissue with pannus formation
· articular cartilage destroyed by pannus
· joint surfaces ankylosed by bone and/or fibrous tissue
· areas of articular cartilage may be preserved
Intervertebral discs
· initial feature is erosive lesions of ligamentous insertions into bone
· of anterolateral part of outer annulus just below annular flange
· spondylodiscitis (Anderson lesion)
· lesions heal by formation of new bone
· Romanos lesion
· new bone on outer annulus forms syndesmophyte
· thin, vertical projections from end-plate
· syndesmophytes fuse to form osseous casing for disc (bamboo spine)
· later in disease see destructive end-plate changes
· due to replacement of bone by granulation tissue
Manubriosternal and pubic symphysis
· initial inflammation
· followed by destruction of cartilage
· then replacement of joint by fibrous tissue
· finally ossification and obliteration of joint
Sacro-iliac joints, apophyseal joints and costovertebral joints
· typical changes with
· erosive synovitis
· capsular enthesopathy and ossification
· synovitis with pannus formation and ankylosis
· may be inflammatory enthesopathy of capsular insertion with resulting ossification of joint capsule
· especially involves hip and shoulder
Symptoms
· back complaints are first features in 75%
· insidious onset of low back pain
· usually dull and poorly localised
· back stiffness
· worse in morning and after inactivity
· improved by warming up
· chest pain and decreased expansion
· neck pain and stiffness
· inflammatory pain suggested by
· age < 40
· gradual onset
· persistence > 3 months
· morning stiffness
· improvement with exercise
Signs
· altered posture
· loss of lumbar lordosis, increased thoracic kyphosis and decrease in cervical lordosis
· inability to perform occiput-to-wall test (occiput, shoulders, buttocks and heels to wall)
· tenderness
· over spinous processes from enthesitis
· decreased lumbar spine movement
· decreased forward flexion (Schober’s test < 4cm over 10 cm)
· decreased lateral flexion
· decreased hyperextension
· pain and tenderness in SI joint
· tenderness to direct palpation of SI joint
· pain on pressure on ASIS
· pain on forced flexion of one hip and hyperextension of contralateral hip
· pain on downward pressure on flexed knee with hip flexed, abducted and externally rotated (figure 4 position)
· decreased respiratory excursion
· diaphragmatic breathing
· limited chest expansion (normal is 2” at 4th intercostal space)
Complications
· spinal fracture
· with trauma
· difficult to diagnose radiologically because of ossified spinal ligaments (CT scan useful)
· may result in neurological deficit
· craniocervical instability
· mechanism similar to RA with erosive synovitis
· most common basilar invagination
· pseudarthrosis
· syn. spondylodiscitis
· unclear whether due to pathological fracture or erosive process of disease
· cauda equina syndrome
· due to spinal stenosis
· involvement of hips and shoulders
· insidious onset of pain and stiffness
· pain and tenderness at sites of enthesopathy
· pelvis (iliac crests, greater trochanters, ischial tuberosities, iliac spines, pubic symphsis)
· thorax (costosternal joints, manubriosternal joint)
· heels (Achilles tendon, plantar fascia)
· acute anterior uveitis
· aortitis and aortic valve incompetence
· pulmonary fibrosis
SI joint
· initial blurring of subchondral bone
· followed by bone erosion and sclerosis
· like postage stamp
· seen more on iliac side
· may lead to pseudowidening of joint
· followed by interosseous bridging and bony ankylosis
Pelvis
· erosions and whiskerinig at sites of attachment of tendons and ligaments
· esp. ischial tuberosities and iliac crests
Spine
· initial erosions on corners of vertebral bodies
· followed by formation of osteophytes and then syndesmophytes
· eventual complete fusion with bamboo spine
· associated osteoporosis and crush fractures
Hip and shoulder
· concentric joint space narrowing
· subchondral sclerosis
· osteophyte formation
· ultimate bony ankylosis
· ESR elevated in 75%
· CRP more accurate marker of disease activity
· HLA-B27 usually positive
· rheumatoid factor negative
· seronegative seroarthropathies
· often indistinguishable
· diffuse idiopathic skeletal hyperostosis
· non-inflammatory with no SI joint involvement
· other causes of back pain
· mechanical
· infectious
· neoplastic
· simple analgesia
· NSAIDs
· problems with associated GIT disease
· physiotherapy
· to maintain ROM and posture
· observed to improve pain and decrease progression
· risk of inducing malignancy decreased use
· may have isolated indications in peripheral involvement where NSAIDs contraindicated
Corrective osteotomy
· indicated for
· severe deformity leading to difficulty in looking forward
· respiratory compromise
· contraindicated in
· elderly patients
· aortic calfication
· poor general health
· closing wedge osteotomy of posterior elements
· single stage posterior procedure
· osteotomies in spinous processes above and below central vertebrae
· may use posterior instrumentation
· good correction can be achieved
· major risk is to aorta
Fracture and pseudarthrosis
· if stable lesion with no neurological deficit, external bracing may suffice
· halothoracic brace should be used for cervical lesions
· surgery indicated for
· unstable lesion
· neurological deficit
· failure of bracing
Total hip replacement
· good functional outcome and durability
· majority of patients have good or excellent pain relief and improvement in mobility
· no increased loosening seen
· main problem is heterotopic ossification
· 10-20% develop Brooker III or IV ossification
· more common with previous surgery or complete ankylosis preoperatively
· may be reduced with indomethacin or XRT