Knee pain can affect people of all ages—from active youngsters to elderly individuals with arthritis. Because the knee supports body weight and allows walking, bending, and climbing, it is highly vulnerable to wear, injury, and inflammation.

Understanding the exact cause of knee pain helps in early treatment and prevents long-term damage.

Why Do Knees Get Hurt So Easily?

The knee is a hinge joint that bears up to 3–4 times body weight during walking and stair climbing. It is supported by:

  • Cartilage

  • Ligaments

  • Meniscus

  • Muscles and tendons

Common reasons knees become painful include:

  • Weak thigh and hip muscles

  • Poor posture and alignment

  • Cartilage degeneration

  • Repetitive stress

  • Inflammation

  • Age-related wear and tear

Why Does My Knee Hurt While Walking?

Knee pain during walking usually means one or more structures are under stress.

Mechanical Causes

Pain increases with activity and improves with rest:

  • Meniscus tear

  • Cartilage thinning

  • Patellofemoral (kneecap) misalignment

Inflammatory Causes

Pain with stiffness and swelling, worse in the morning:

  • Osteoarthritis

  • Rheumatoid arthritis

  • Synovitis

Why Does My Knee Hurt While Bending or Climbing Stairs?

Pain during stair climbing or squatting is commonly caused by:

  • Runner’s knee (patellofemoral pain syndrome)

  • Early cartilage wear under the kneecap

  • Quadriceps muscle weakness

What Causes Popping, Locking, or Instability in the Knee?

These symptoms often indicate:

  • Meniscus tear

  • ACL or MCL ligament injury

  • Loose cartilage fragments

They may follow twisting, sudden stops, or uneven walking surfaces.

What Causes Knee Pain Without Any Injury?

Knee pain can occur even without trauma due to:

1. Bursitis

Inflammation of fluid-filled sacs from prolonged kneeling or squatting.

2. Tendonitis

Overuse of tendons after sudden increase in activity.

3. Gout & Pseudogout

Crystal deposition inside the joint is causing sudden swelling and severe pain.

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4. Early Arthritis

Gradual cartilage thinning causes stiffness and pain without injury.

What Causes Knee Pain in Old Age?

The most common cause is osteoarthritis, due to:

  • Progressive cartilage loss

  • Reduced joint lubrication

  • Increased joint pressure from body weight

  • Muscle weakness

Even small weight gain increases knee load significantly.

When Is Knee Pain Serious?

Seek urgent medical attention if you have:

  • Inability to bear weight

  • Severe swelling and redness

  • Fever with knee pain

  • Deformity after a fall

  • Night pain is not relieved by medication.

  • Recurrent swelling after walking

Serious conditions may include:

  • Ligament rupture

  • Fracture

  • Septic arthritis

  • Advanced arthritis

How Is the Cause of Knee Pain Diagnosed?

  • X-ray: Arthritis, alignment, bone damage

  • MRI: Ligament, meniscus, cartilage, tendon injuries

  • Blood tests: Gout, infection, inflammatory arthritis

Treatment Options Based on Cause

Non-Surgical

  • Physiotherapy for muscle strengthening and alignment

  • PRP injections to reduce inflammation and promote healing

  • Hyaluronic acid injections for joint lubrication

  • Weight management and activity modification

Surgical (for Severe Cases)

  • Arthroscopy for meniscus and ligament injuries

  • Knee replacement for advanced arthritis when conservative treatment fails

Conclusion

Knee pain may start mildly but can progress if ignored. The most common causes include arthritis, ligament injury, cartilage degeneration, inflammation, and muscle weakness. Early diagnosis, strengthening exercises, proper footwear, and timely medical care can prevent long-term disability and surgery.

Persistent or worsening knee pain should always be evaluated by an orthopaedic specialist for accurate diagnosis and personalised treatment.