Knee Pain: Causes

What causes knee pain?

There are many diseases and conditions that can cause knee pain, but the leading causes are typically related to physical activity, such as overuse, injury, and age-related wear and tear on the muscles, cartilage, tendons and ligaments of the knee.

Trauma- and injury-related causes of knee pain

Knee pain may be caused by injuries and trauma-related problems including:

• Bone fracture (broken bone) or knee dislocation, especially of the patella (kneecap)

• Bursitis (also described as “housemaid’s knee,” which is caused by kneeling on hard surfaces, leading to inflammation of the sacs cushioning the knee)

• Laceration, abrasion or contusion of the knee

• Ligament sprains and tears, especially of the anterior cruciate ligament (ACL) and medial collateral ligament (MCL) of the knee, which ensure leg and knee stability

• Meniscus tear (tear in the shock-absorbing cartilage of the knee)

• Osgood-Schlatter disease (painful swelling of the anterior tibial tubercle, the bump on the front, upper part of the lower leg bone, that occurs in growing adolescents due to overuse)

• Runner’s knee (kneecap pain usually due to overuse or injury)

• Tendinitis (inflammation or irritation of tendons due to overuse or injury), such as patellar tendinitis

• Tendon avulsion or fracture (tendon rupture or pulling away from the bone), such as that of the biceps femoris tendon or quadriceps tendon

Infectious causes of knee pain

Knee pain can be caused by various infections including:

• Cellulitis (invasive infection of the skin and surrounding tissues)

• Infection of a knee wound or sore

• Infection of the knee joint (septic arthritis)

• Osteomyelitis (bone infection)

Neurological causes of knee pain

Knee pain can be caused by neurological conditions that cause inflammation, entrapment, compression, or damage to the nerves including:

• Peripheral neuropathy (disorder that causes damage and dysfunction of nerves that lie outside the brain and spinal cord) and diabetic neuropathy (neuropathy caused by long-term diabetes)

• Piriformis syndrome (buttock muscle compressing or irritating the sciatic nerve, causing pain, tingling or numbness down the leg)

• Sciatica (compression, injury or inflammation of the sciatic nerve, which causes burning or shooting pain running from the buttocks down the back of the leg)

Other causes of knee pain

Other causes of knee pain include:

• Arthritis including osteoarthritis, rheumatoid arthritis, and gout

• Baker’s cyst (fluid-filled cyst behind the knee)

• Certain connective tissue disorders, such as lupus

• Deep vein thrombosis (blood clot in the leg that can break loose from the leg, causing a pulmonary embolism in the lung, heart attack, or stroke)

• Fibromyalgia (chronic condition causing widespread muscular pain, stiffness, and tenderness)

Questions for diagnosing the cause of knee pain

To diagnose your condition, your doctor or licensed health care provider will ask you several questions related to your symptoms including:

• In what part of the knee do you feel pain?

• When did the pain start?

• How long does the pain last?

• Are there any activities that cause the pain?

• Are you experiencing any other symptoms?

What are the potential complications of knee pain?

Complications of knee pain can vary depending on the underlying cause. Pain due to a minor condition, such as a mild muscle strain or bruise, usually responds to rest, ice, and over-the-counter anti-inflammatory medications. However, some underlying causes of knee pain, such as a joint infection or deep vein thrombosis, can lead to serious and possibly life-threatening complications including:

• Chronic pain

• Difficulty walking

• Disability

• Loss of hip or knee joint mobility

• Permanent nerve damage

• Poor quality of life

• Pulmonary embolism associated with deep vein thrombosis

• Spread of infection and serious infections, such as gangrene, which can lead to amputation

• Weakness or paralysis

It is important to contact your health care provider when you have persistent pain or other unusual symptoms. Once the underlying cause is diagnosed, following the treatment plan outlined by your health care provider can lower your risk of complications.