Etiology — what causes it

Multifactorial — age-related cartilage changes, prior joint injury (especially ACL, meniscectomy), obesity (mechanical and inflammatory), genetics, and altered mechanics. The 'wear and tear' framing has been largely replaced by a metabolic, mechanical, and inflammatory model.

Epidemiology — who gets it

Most common form of arthritis; lifetime risk is around 45% (Murphy et al., Arthritis Rheum). Prevalence rises sharply after age 50. Higher rates with female sex, obesity, and prior knee injury.

Clinical signs

Reduced range, crepitus, bony enlargement, mild effusion in flares, varus or valgus alignment in advanced cases. Joint line tenderness. Functional limitations on sit-to-stand, stair descent, and timed up-and-go testing.

Symptoms

Activity-related knee pain, often worse late in the day and with prolonged loading. Morning stiffness less than 30 minutes (distinguishes from inflammatory arthritis). Reduced walking tolerance. Sleep disturbance in advanced cases.

Best evidence for chiropractic treatment

OARSI 2019 guidelines (Bannuru et al., Osteoarthritis Cartilage) place land-based exercise, education, and weight management as first-line core treatments — superior to passive modalities and pharmacological options alone in long-term outcomes. The GLA:D program (Skou et al., BMC Musculoskelet Disord) demonstrates large effects on pain and function. Manual therapy is a useful adjunct. Total knee replacement is reserved for advanced disease with significant functional limitation despite structured conservative care.

Subtypes

  • Medial compartment. Most common; often with varus alignment.
  • Lateral compartment. Less common; often with valgus alignment.
  • Patellofemoral compartment. Anterior pain with stairs and squatting.
  • Multi-compartment. Combined involvement; often the picture in advanced OA.

When to seek emergency care

Some symptoms need urgent medical attention — not a chiropractic visit. Call 911 or go to the nearest emergency department for: progressive limb weakness, loss of bowel or bladder control, saddle anesthesia (numbness in the groin/inner thighs), severe unrelenting pain unrelieved by position, signs of fracture after significant trauma, chest pain, stroke-like symptoms (face drooping, arm weakness, speech changes), or any rapidly worsening or unusual symptom.

Bottom line

Knee osteoarthritis responds substantially to exercise and weight management. Surgery is for late-stage disease, not first-line care.