Inflammatory Conditions

Seropositive

  • RA (in 85%)

Seronegative – HLA B27 association

  • Ankylosing Spondylitis
  • Psoriatic arthritis
  • Reiter’s syndrome
  • DISH

Rheumatoid Arthritis

  • 60% RA patients develop C-Spine disease
  • RA affects C-spine invariably

Risk factors

  • Multiple Joint Disease
  • Long Standing Disease
  • Males
  • Positive rheumatoid factor
  • Steroid use

Pathophysiology

  • RA affects synovial joints – in spine: C1/2; facet & Uncovertebral joints
  • RF is immunoglobulin directed toward synovial cell antigens
  • This antibody-antigen complex causes an autoimmune response:
    • Proteolytic enzymes released
    • These destroy the joint

Patterns of RA C-Spine Disease

  1. Atlanto-Axial Instability (C1/2) (60%)
  2. Basilar Invagination of C2 (40%)
  3. Sub-axial instability (20%)
  4. Mixed (50%)

Clinical Presentation

  • Usually slowly progressing Symptoms of weakness
  • Axial neck pain
  • Cord compression & myelopathy
  • Brainstem compression with basilar invagination can occur
  • Often missed due to slow progress
  • All RA patients should have pre-op C-spine XRs and liaison with anesthetist prior to consideration of GA

Classification (Ranawat)

  • Provides prognostic value to surgery
  • Ranawat 3b do poorly with treatment
  • Therefore goal is to identify and operate early
Stage Features
1 No neurologic findings – pain only
2 Subjective neurology
3a Objective neurology & UMN signs – patient ambulatory
3b Objective neurology & UMN signs – patient not ambulatory

Atlanto-Axial Instability

  • C1/2 is a diarthrodial synovial lined joint – allows large ROM
  • Therefore susceptible to RA
  • Synovitis destroys transverse, apical & alar ligaments
  • This allows subluxation
  • Bone erosion of odontoid and C1 ring slowly occurs
  • Pannus behind odontoid compresses cord
  • Natural history is to slowly progress
  • Not all develop neurology though

Assessment is by XR

  • PADI (posterior atlanto dens interval) (same as SAC)
    • Most prognostic value for the development of neurologic dysfunction
    • <14mm is poor prognostic sign
    • Warrants surgery to prevent progression
  • ADI (Atlanto Dens Interval)

    • 4 abnormal

    • 10mm warrants treatment (not as good prognostic value as PADI)

  • Flexion Extension Views

    • 3.5mm instability is poor prognostic sign for developing neurology

Management

  • C1/2 Fusion with transarticular screws (Magrl)
    • Negates need for HALO
    • Pre-op CT needed
    • May not be possible if Vertebral artery position too risky
    • Pannus resolves with fusion & doesn’t need excision
  • Occiput-C2 Fusion
    • If not able to place transarticular screws
    • Proximity of vertebral artery on pre-op CT
    • If concurrent basilar invagination exists
  • Odontoidectomy & C1 arch excision
    • If subluxation is irreversible or if brainstem severely threatened
    • Revision surgery
    • Not 1st choice option

Basilar Invagination (Cranial Settling)

  • Cranial migration of Dens
  • Due to C1 and Occipital condyle erosion
  • Associated with Atlanto-Axial subluxation – often irreducible
  • Not all patients symptomatic

Assessed by XR MRI or CT (hard to clearly evaluate on XR)

  • McRae’s line easiest
    • Clivus to posterior aspect foramen magnum
    • Does Dens cross into foramen magnum
  • Ranawat measurement
    • Vertical distance between C1 ring and C2 pedicle
    • <14mm = basilar invagination

Indications for surgery

  • Neurologic symptoms
  • Progression of invagination by >5mm

Surgery

  • Occiput to C2 Fusion – high rate of union
  • Add odontoidectomy if brainstem threatened & C1/2 is irreducible

Sub-Axial Instability

  • Less common
  • Due to destruction of Facet and Uncovertebral joints
  • More common in lower C spine
  • Causes subluxation & listhesis
  • Occurs in association with axial instability – rarely alone

Indications for surgery

  • Intractable pain
  • Neurologic symptoms/signs

  • 4mm or >40% translation

  • Vertebral body/width ratio <2

Surgery

  • Posterior fusion with lateral mass screws

Ankylosing Spondylitis

Epidemiology

  • Males 3:1
  • 3rd decade
  • Caucasians more common
  • 95% are HLA B27 +ve
  • HLA B27 (Human Leucocyte Antigen) is a surface antigen

Aetiology

  • Seronegative inflammatory arthropathy
  • Strong genetic link but unknown inheritance pattern
  • HLA B27 strongly implicated but mechanism unknown

Clinical Characteristics

  • Affects entheses rather than synovium
  • Affects whole spine symmetrically
  • Hallmark is symmetric sacroiliitis
  • Enthesiopathy causes bony erosion
  • Reactive bone forms in response and causes osteophytes
  • In spine these are bridging & called syndesmophytes
  • Eventual ankylosis

Management

  • Physio: Maintain motion and strength
  • Drugs: NSAIDs, Anti-TNF alpha drugs
  • Surgery: High complication rate, osteotomies for deformity
  • Fractures: Posterior instrumented fusion

Psoriatic Spondylitis

  • HLA B27 +ve in 70%
  • 10% with psoriatic arthritis develop spinal disease
  • Features: Asymetric, non-contiguous, marginal and non-marginal syndesmophytes
  • Management: Medical Rx as for RA, surgery as per deformity

Reiter’s Disease

  • Post-infective arthritis
  • Onset within 1 month of urethritis or enteritis
  • Asymmetric sacroiliitis
  • Management: Symptomatic – rarely surgical

Osteophytes in DDD; AS (marginal) & DISH (non-marginal)

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