Osteoarthritis is a chronic, progressive degenerative disorder of synovial joints characterized by articular cartilage degradation, subchondral bone changes, osteophyte formation, and varying degrees of synovial inflammation, leading to pain, stiffness, and reduced joint function.
2. Causes / Risk Factors
A. Primary OA
Occurs without a specific underlying disease.
- Increasing age
- Genetic/hereditary factors
- Female sex, particularly after
menopause
- Obesity
- Repetitive joint use
B. Secondary OA
Occurs due to an identifiable cause:
- Previous joint injury/trauma
- Joint deformity
- Congenital abnormalities
- Rheumatoid arthritis or other
inflammatory arthritis
- Gout
- Joint infection
- Metabolic diseases
- Previous surgery
Major risk factors
Age + obesity + previous joint injury + genetic predisposition +
excessive mechanical stress
3. Clinical Manifestations
Major symptoms
- Joint pain – usually worsens with
activity/use and improves with rest.
- Morning stiffness <30 minutes is typical.
- Stiffness after prolonged
inactivity ("gelling phenomenon").
- Reduced range of motion.
- Difficulty walking or performing
daily activities.
- Joint instability in advanced
disease.
Signs
- Bony enlargement of joints
- Crepitus on movement
- Joint-line tenderness
- Reduced joint movement
- Osteophyte formation
- Usually little or no obvious
warmth or swelling
Characteristic hand findings
- Heberden's nodes → DIP joints
- Bouchard's nodes → PIP joints
- 1st CMC joint may also be
affected.
Commonly affected joints
- Knee
- Hip
- Hands
- Spine
- First MTP joint
4. Diagnosis
Diagnosis is mainly based on clinical findings + imaging.
A. Clinical examination
Look for:
- Activity-related joint pain
- Morning stiffness <30 min
- Crepitus
- Restricted movement
- Bony enlargement
B. X-ray
Typical findings:
Joint-space narrowing + osteophytes + subchondral sclerosis + subchondral
cysts
C. Laboratory tests
There is no specific blood test for OA.
Usually:
- ESR → usually normal
- CRP → usually normal
- Rheumatoid factor → generally
negative
Blood tests are mainly used to exclude other diseases such as
rheumatoid arthritis or gout.
D. Synovial fluid
If joint aspiration is performed, OA typically shows non-inflammatory
synovial fluid.
5. Pharmacotherapy
Treatment approach
6. Drugs: Indications,
Contraindications & Adverse Effects
A. Paracetamol
Indication
- Mild OA pain
- When NSAIDs are contraindicated
or not tolerated
Contraindication/caution
- Severe hepatic impairment
- Chronic heavy alcohol use
Adverse effects
- Usually well tolerated at
therapeutic doses
- Hepatotoxicity in overdose or excessive chronic
use
B. Topical NSAIDs
Examples: Diclofenac gel, ibuprofen gel
Indication
- Mild–moderate localized OA,
particularly knee and hand OA
- Preferred when systemic NSAID
risk is high
Contraindication/caution
- NSAID hypersensitivity
- Application over damaged/infected
skin
- Caution in patients with
significant NSAID allergy
Adverse effects
- Local skin irritation
- Rash
- Itching
- Systemic NSAID effects are less
common than with oral NSAIDs
C. Oral NSAIDs
Examples: Ibuprofen, naproxen, diclofenac
Indication
- Moderate–severe OA pain
- When topical treatment is
inadequate
Contraindications/cautions
- Active peptic ulcer/GI bleeding
- Severe renal impairment
- Severe heart failure
- Significant cardiovascular
disease
- NSAID hypersensitivity
- Avoid in the third trimester
of pregnancy
Adverse effects
- Gastritis
- Peptic ulcer
- GI bleeding
- Renal impairment
- Fluid retention/edema
- Increased blood pressure
- Cardiovascular events
Key point: Use the lowest effective dose for the shortest duration.
D. COX-2 selective NSAID
Example: Celecoxib
Indication
- OA pain when an oral NSAID is
required
- May be preferred in some patients
with increased GI risk
Contraindications/cautions
- Sulfonamide/celecoxib
hypersensitivity
- Significant cardiovascular
disease
- Severe renal impairment
- Pregnancy, particularly late
pregnancy
Adverse effects
- Dyspepsia
- Edema
- Hypertension
- Renal impairment
- Increased cardiovascular risk
E. Duloxetine
Indication
- Chronic OA pain, particularly when pain persists
despite conventional therapy.
- Useful when NSAIDs are unsuitable
or inadequate.
Contraindications/cautions
- MAOI use
- Severe hepatic impairment
- Severe renal impairment
- Caution with other serotonergic
drugs
Adverse effects
- Nausea
- Dry mouth
- Dizziness
- Constipation
- Insomnia
- Increased sweating
- Sexual dysfunction
- Possible withdrawal symptoms if
stopped abruptly
F. Intra-articular corticosteroid
Examples: Triamcinolone, methylprednisolone
Indication
- Short-term relief of moderate–severe
knee OA pain
- Acute painful flare
- When oral/topical medicines are
inadequate
Contraindications
- Joint infection
- Infection at injection site
- Uncontrolled systemic infection
- Avoid inappropriate/repeated
frequent injections
Adverse effects
- Temporary increase in blood
glucose
- Post-injection pain
- Infection, rarely
- Skin atrophy/depigmentation
- Repeated injections may have
adverse effects on joint structures
G. Topical Capsaicin
Indication
- Localized OA pain, especially
knee/hand OA
- Alternative or adjunct to other
analgesics
Contraindication/caution
- Broken or irritated skin
- Hypersensitivity
Adverse effects
- Burning sensation
- Stinging
- Redness
- Skin irritation