Understanding Knee Osteoarthritis: Symptoms, Causes, and Treatment

Knee Osteoarthritis: An Overview

Osteoarthritis of the knee is an extremely common joint condition, affecting about 30 million adults in the United States. It occurs when protective cartilage on the ends of bones wears down over time, resulting in pain, stiffness, and swelling around the knee joint. Understanding the causes, symptoms, risk factors and both non-invasive and surgical treatments is key to managing this progressive condition.

Knee Anatomy and Cartilage

The knee is the body’s largest joint where the femur bone of the thigh meets the tibia shin bone. Two C-shaped pads of slippery, thick cartilage called menisci act as shock absorbers between these bones. On the joint surfaces, a thin, smooth layer of cartilage provides a cushioning, frictionless surface for motion.

In osteoarthritis, this cartilage thins and wears away. Spurs of new bone called osteophytes often form as the body tries to repair and stabilize the joint. Loss of cartilage cushion causes painful bone-on-bone rubbing. Ligaments and muscles surrounding the joint become thickened as the body tries to stabilize the joint. Fluid may accumulate causing swelling.

Read More: Synovial Sarcoma

Arthritis of the Knee Osteoarthritis
Arthritis of the Knee Osteoarthritis

Main Symptoms of Knee Osteoarthritis:

  • Joint aching, soreness, and stiffness, especially when moving after rest
  • Limited range of motion and loss of flexibility
  • Swelling, warmth, and redness around the joint
  • Tenderness when touching the knee
  • Pain flares after certain activities like climbing stairs
  • Grating or crackling sounds when moving the knee (crepitus)
  • Knee locking or buckling
  • Bony growths around the joint

The pain is often described as a dull, throbbing ache concentrated on the inner knee. Symptoms tend to progressively worsen over time. Severe osteoarthritis can greatly impact mobility and quality of life.

Causes and Risk Factors

While the exact cause is unknown, factors that contribute to developing knee osteoarthritis include:

  • Older age – Most common in people over 50 as cartilage wears down over time.
  • Obesity – Excess weight strains the knee joint, increasing friction and gradual breakdown of cartilage.
  • Joint injury – Sports injuries, fractures, dislocations, and ligament tears can increase risk later in life.
  • Improper joint alignment – Knock-kneed or bowlegged alignment adds abnormal stresses.
  • Repetitive impact – Certain sports or occupations with repetitive kneeling, squatting, or climbing like construction work.
  • Genetics – Congenital joint or cartilage defects, or family history can predispose some people.
  • Female sex – Hormonal changes and differences in cartilage quality are risk factors.

Prevention includes maintaining a healthy weight, proper joint alignment, avoiding excessive repetitive impact to the knees, and preventing injuries.

Diagnosing Knee Osteoarthritis

To diagnose knee osteoarthritis, doctors consider symptoms and perform:

  • Physical exam assessing range of motion, swelling, tenderness, crepitus, and gait.
  • X-rays showing narrowing joint space, osteophytes, cysts, bone deformities, loose bodies.
  • MRI for detailed imaging of cartilage, ligaments, tendons, and soft tissues.
  • Joint fluid analysis evaluating fluid for inflammation and presence of arthritis crystals.
  • Blood tests checking for underlying inflammatory arthritis conditions like rheumatoid arthritis.

Doctors grade osteoarthritis severity from mild to severe based on joint space narrowing, bone changes, pain, and mobility impairment.

Knee Osteoarthritis
Knee Osteoarthritis
Treating Knee Osteoarthritis

Treatment focuses on relieving pain, improving joint mobility and function, slowing progression, and helping return to normal activities. Options include:

Lifestyle Changes

  • Losing weight to reduce knee joint stresses.
  • Low impact exercise like walking, cycling, swimming to improve joint flexibility and muscle strength.
  • Activity modification avoiding high impact activities like running.
  • Assistive devices like canes, walkers, knee braces to improve stability.
  • Physical therapy for stretching, strengthening, range of motion exercises.


  • Acetaminophen or NSAIDs like ibuprofen, naproxen for pain relief.
  • Corticosteroid injections provide temporary pain relief for flares.
  • Hyaluronic acid injections like Synvisc lubricate the knee joint.
  • Durolane, Euflexxa, and Synvisc knee injections add cushioning.


  • Arthroscopic surgery removes torn meniscus fragments, loose bodies, smooths rough cartilage.
  • Osteotomy realigns angled joints to redistribute knee forces.
  • Knee joint replacement surgery implants artificial knee components to restore function.

Alternative therapies like glucosamine chondroitin supplements, acupuncture, massage, and yoga provide relief for some people.

Knee osteoarthritis treatment takes a multifaceted approach combining activity modification, exercise, assistive devices, medications, injections, and sometimes surgery for optimal results. Work closely with your doctor to develop the right plan for your needs and lifestyle.

When to See Your Doctor

See your doctor if you experience persistent knee joint aching, swelling, stiffness, reduced range of motion, or difficulty performing activities. Key times to seek medical care include:

  • Ongoing knee pain lasting more than 2 weeks.
  • Significant knee swelling or tenderness.
  • Sudden inability to fully straighten or bend the knee joint.
  • Buckling, locking, or instability in the knee joint.
  • No improvement in symptoms with rest or over-the-counter medications.
  • Significant disability or limitation of daily activities due to knee symptoms.

Effective osteoarthritis treatments help restore knee joint mobility and improve quality of life. Work with your doctor to maximize function and relief.


Knee osteoarthritis is an extremely common cause of knee pain, swelling, and mobility issues especially in people over 50. While cartilage damage in the knee cannot be reversed, symptoms can be treated and progression slowed with a combination of weight loss, physical therapy, braces, anti-inflammatories, injections, and possibly knee surgery. Addressing knee osteoarthritis early optimizes outcomes. Controlling your weight, avoiding excessive repetitive impact on the knees, and promptly treating injuries can help prevent this progressive joint condition.

Knee Osteoarthritis Pathophysiology Clinical Features
Knee Osteoarthritis Pathophysiology Clinical Features

Read More: Knee Osteoarthritis


What are the first symptoms of knee arthritis?

Early symptoms include knee stiffness after sitting or sleeping, swelling, achiness with use that resolves with rest, and difficulty with stairs or bending. Joint line tenderness and limited range of motion develop later.

What causes cartilage to wear down in the knee?

A combination of aging, excess body weight, joint injury, improper alignment, and repetitive impact lead to cartilage breakdown in the knee over time. Genetics can also play a role.

How is knee arthritis diagnosed?

Diagnosis involves a medical history, physical exam assessing range of motion and swelling, x-rays to evaluate joint space and bone changes, and sometimes MRI if more information is needed.

When should someone consider knee replacement surgery?

If knee arthritis is severe, not well-controlled with other treatments, greatly limiting mobility and quality of life, and less invasive options have failed, knee replacement surgery may be considered.

What are the best exercises for knee osteoarthritis?

Low-impact exercises like walking, swimming, cycling, and strength training to improve leg muscle support without overstressing the knee joint are best. Avoid high-impact activities.

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