Case 4: Ann Green

Osteoarthritis (OA): Description

Joint degeneration (articular cartilage, subchondral bone (under cartilage), synovium)

Affects knee > hip > hand

OA: Epidemiology

Risk factors…

• Increasing age

• Obesity

• Joint stress

• Female

OA: Etiology

Primary: Idiopathic

Secondary:

• Hemochromatosis: Excess Fe deposition

• Wilson disease: Excess CU deposition

• Ehlers-Danlos syndrome: Defective collagen synthesis

• DM

• Osteonecrosis (avascular necrosis): Decreased blood supply = Bone necrosis

• Alkaptonuria: Defective tyrosine metabolism

• Congenital joint disorders

• Joint trauma

OA Etiology: Osteonecrosis

Clinical Presentation:

• Early: Asymptomatic

• Advanced: Limited movement, joint pain + swelling

• Local tenderness

Investigations: US

• Jagged non-rounded bone head

OA: Pathophysiology

1. Chronic mechanical stress on joints + decreased proteoglycans (age-related) = Decreased articular cartilage elasticity

• Increased friability

2. Cartilage degeneration + inflammation + swelling = Joint space narrow and thicken + subchondral bone sclerosis

• Chondrocyte hypertrophy = Fibroblast-like collagen production = Decreased elasticity + thicken joint articular cartilage

3. Bone tissue attempt to repair damage = Osteophyte formation (bone outgrowth)

OA: Clinical Presentation

Pain with movement

• Relief at rest

Joint stiffness + decreased ROM

• Early: In morning

• Advanced: Throughout the day

Asymmetric joint involvement

Crepitus

Knee:

• Locking/crepitus

• Bowed legs

• Joint swelling with activity

Hip: Pain in groin

Hands:

• Heberden’s Nodes: Pain + nodes on dorsal DIP

• Bouchard Nodes: Pain + nodes on dorsal PIP

• Rhizarthrosis: 1st CMC joint

OA: Investigations

Suspect in ≥ 45 years + clinical presentation

Imaging

Labs

OA Investigations: Imaging

XR: First-line

4 cardinal signs (LOSS)

1. Loss of joint space

• Irregular

2. Osteophytes

• Spurs/densification on joint edge

3. Subchondral cysts

• Fluid-filled cyst on joint surface (from joint stress)

4. Subchondral sclerosis

• Increased bone density below joint cartilage

OA Investigations: Lab Tests

Blood test: Normal inflammatory markers

• Erythrocyte sedimentation rate (ESR)

• C-reactive protein (CRP)

Athrocentesis: Synovial fluid analysis

• WBC < 2000/mm³ (no inflammation)

OA: Treatments

Non-pharmacological

Pharmacological

Surgery

OA Treatment: Non-Pharmacological

Exercise + physical therapy

Weight loss

Supportive devices (cane, knee brace)

OA Treatment: Pharmacological

NSAIDs

Acetaminophen

Opioids

Intraarticular glucocorticoid injections

OA Pharmacological: NSAIDs

First-line

Topical: Knee

Oral: Inadequate with topical or hip OA

OA Pharmacological: Acetaminophen

Second-line

Less effective than NSAIDs

OA Pharmacological: Opioids

Short-term use

Not recommended

OA Pharmacological: Intraarticular Glucocorticoid Injections

Local short-term relief in hip + knee

OA Pharmacologic: Adverse Effects

From long-term use

NSAIDs:

• Increase GI bleeds

• Increase MI risk

• Worsen HTN + edema

• Renal toxicity

Acetaminophen: Liver injury

Opioids:

• Constipation

• CNS effects

Intraarticular Glucocorticoid Injections:

• Pain + swelling

• Hyperglycemia

• HTN

OA Treatment: Surgery

Arthroplasty: Partial/complete joint replacement with endoprosthesis (artificial joint)

Arthrodesis: Fuse bones in joint position

OA: Complications

Limiting function (walking, sleeping)

Pain

Osteonecrosis (less common)

OA: Prognosis

Highly variable

Remain stable with treatment

Slow evolution → Joint replacement

OA vs Inflammatory Arthritis (IA): Pathophysiology

OA: Mechanical + age-related joint degradation

IA: Autoimmune disorder = Immune cells (T cells) attack/damage synovial joints

OA vs IA: Clinical Presentation

Morning stiffness

• OA: < 30 mins

• IA: > 1 hour

Joint swelling

• OA: Cool + hard

• IA: Warm + soft

Joint pain

• OA: Relieved by rest

  • Tender + deep → From bones

• IA: Persistant

  • Soft + boggy

OA vs IA: Investigations

Blood test

• OA: No inflammatory markers

• IA: Increased…

  • ESR

    • Normal Men: 0-15 mm/hr

    • Normal Women: 0-20 mm/hr

  • CRP

    • Normal: < 10 mg/L

Synovial fluid analysis

• OA: < 2000/mm³

  • More fluid, less viscous

• IA: > 2000/mm³

Analgesics: Tylenol

Acetaminophen

Tylenol: Indications

Fever

Pain

Preferred in pregnancy

Tylenol: MOA

Reversible COX inhibition

Mainly in CNS

Tylenol: Efficacy

Preferred for mild symptoms

Antipyretic + analgesic

Tylenol: Toxicity

Gastric symptoms (minimal)

Liver toxicity + failure

Analgesics: NSAIDs

Ibuprofen

Diclofenac

Naproxen

Aspirin

NSAIDs: Indications

Acute + chronic pain

• RA

• IA

• Acute gout attack

• Headache/migraine

Fever

Indomethacin: Close patent ductus arteriosus

NSAIDs: MOA

Reversible COX inhibition = Decrease prostaglandin synthesis

Aspirin: Irreversible COX inhibition

NSAIDs: Efficacy

Preferred for moderate/severe symptoms

Antipyretic + analgesic + anti-inflammatory

NSAIDs: Toxicity

Gastric ulcers

Heart attack

Stroke

Renal impairment