Classification of Arthritis

Classification	Characteristic features
Seropositive rheumatic diseases
1. Connective tissue diseases Rheumatoid arthritis (RA) Systemic lupus erythematosus (SLE) Antiphospholipid antibody syndrome (APS) Scleroderma/progressive systemic sclerosis (PSS) Polymyositis/dematomyositis (PMY/DMY) Mixed connective tissue disease Sjogren’s syndrome	Skin: Nodules, ulceration, rash, mucosal ulcers Raynaud’s phenomenon Sicca syndrome Neurological involvement Renal involvement Vascular involvement Positive serology Constitutionally unwell
2. Vasculitides Polyarteritis nodosa (PAN) Wegener’s granulomatosis Predominantly cutaneous vasculitis Giant cell arteritis
Seronegative rheumatic diseases
Ankylosing spondylitis (SA) Reactive arthritis Psoriatic arthritis Inflammatory bowel disease	Involvement of axial skeletal Anterior uveitis, conjunctivitis Enthesitis, sacroiliitis, dactylitis, urethritis Psoriasis Family history HLA-B27 association
Crystal induced
Gout (monosodium urate) Pseudogout (calcium pyrophosphate dihydrate) Hydroxyapatite deposition disease	Remitting, recurring pain Mono or oligoarthritis Tophi Renal involvement
Septic/infectious	Acute monoarthritis or migratory polyarthritis Constitutional symptoms
Degenerative	Insidious onset
Non-articular rheumatism	Generalised non-articular pain Trigger points Strong association with psychiatric illness

Approach to Diagnosis

HISTORY

Onset/duration

Acute (hours) – gout, infectious, palindromic rheumatism

Subacute (days) – pseudogout, infectious

Insidious (onset) – degenerative, inflammatory

Trauma and prodromes – e.g. diarrhoea, infection

Course

Intermittent with periods of complete remission – gout

Gradual progression over time with acute exacerbations – pseudogout

Wax and wane with slow progression over time – RA

Characteristics of joint involvement

Pain, swelling, loss of function

Inflammatory characteristics

Morning stiffness >30min

Aggravated by rest, better with activity

Signs of acute inflammation – red, swollen, warm, painful

Non-inflammatory/degenerative characteristics

No or minimal morning stiffness

Aggravated by use, improved by activity

Pattern of joint involvement

Symmetric vs. asymmetrical

Small vs. large

Mono-, oligo- vs. polyarticular

Axial vs. peripheral

Monoarticular

Polyarticular (more than 4 joints)

Oligo-arthritis (2-4 joints)

(Mnemonic: SINGL JOINT)

Septic Arthritis (most important to rule-out)

1. 1. Bacterial / Fungal / Parasitic Arthritis
  2. Gonococcal Arthritis (esp. young sexually active adults)
  3. Mycobacteria

Internal derangement or Trauma

1. 1. Meniscus Injury
  2. Ligament tears
  3. Overuse syndromes

Inflammatory Arthritis – Aseptic (Reactive Arthritis)
Neuropathy (Charcot’s Joint)
Gout, Pseudogout
Trauma

1. Overuse injury
2. Fractures
3. Hemarthrosis
Juvenile or adult Rheumatoid Arthritis
Osteoarthritis
Osteomyelitis
Ischemic bone (avascular necrosis)
Neoplasms
1. Osteoid Osteoma
2. Pigmented Villonodular synovitis
3. Bony metastases

Large joints

Ankylosing Spondylitis

Small joints

Parvovirus B19

Systemic Lupus Erythematosus

Large and small joints

Osteoarthritis

Rheumatoid Arthritis

Psoriatic Arthritis

Viral Infection

Parvovirus B19, EBV, VZV, Enterovirus, Adenovirus or Coxsackievirus, Hepatitis, HIV, Mumps, Rubella

Bacterial Infection

Gonococcal Arthritis
Bacterial Endocarditis
Rheumatic Fever
Salmonella, Shigella or Yersinia
Staphylococcus aureus
Tuberculosis
Lyme Disease
Syphilis

Inflammatory disease

Sjogren’s Syndrome
Ankylosing Spondylitis
Reiter’s Syndrome
Psoriatic Arthritis
Inflammatory Bowel Disease
Rheumatoid Arthritis
Systemic Lupus Erythematosus

Systemic conditions

Polymyositis
Polymyalgia Rheumatica
Sarcoidosis/Scleroderma
Henoch-Schonlein Purpura
Polyarteritis Nodosa
Wegener’s Granulomatosis
Hyper/Hypothyroidism
Hyperparathyroidism

Miscellaneous

Fibromyalgia
Osteoarthritis
Cancer (Multiple Myeloma, Metastatic Cancer)
Crystal-induced (e.g. Gout, Pseudogout)

Oligoarticular JIA
Reactive arthritis
Psoriatic Arthritis

NB: Monoarticular arthritis is infectious until proven otherwise (need synovial fluid analysis, with cell counts, Gram stain and C&S)

Extraarticular features

ADLs and limitations
- Gross motor – walking, stairs, toileting
- Fine motor – dressing, grooming, eating, grip
General health
- Infections, constitutional symptoms, sexual history, past medical history
Treatments
- Medications & dosages, physiotherapy, alternative therapies, surgical (how effective?)

Investigations:

Blood and urine – FBC, BUN, creatinine, ESR, complement (C3/4), fibrinogen, serum proteins, CRP, albumin
Urinalysis to detect disease complications
Serology – autoantibodies

Radiology:

Modality	Advantages	Disadvantages	Clinical utility
Plain film	High resolution, inexpensive	Inadequate soft tissue images, radiation exposure	Bone pathology
CT	Better in complex joints	Radiation, suboptimal for detecting soft tissue pathology, cost	Sacroiliac joints, ankle joints, spinal canal, chest
MRI	No radiation, best for soft tissue pathology, effusions, abscesses, avascular necrosis	Cost, potential for patient injury from metallic objects, contrast allergy	Evaluation of tendons, bursae, effusions, ligament, muscle, spinal canal
U/S	No radiation, cheap	Resolution decreases with deeper structures, dependent on operator	Evaluation of rotator cuff injury, tendons, bursae, effusions
Bone densitometry	Relatively low radiation		Osteoporosis
Angiography	Ideal for vascular pathology	Radiation exposure, contrast allergy, emboli risk	Inflammatory disorders with vascular components
Scintillography (bone scan)	Sensitive for metabolic processes	Low resolution, non-specific	Septic joints, fractures, cancer

Classification of Arthritis

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