What Is Crepitus?

Crepitus is the abnormal popping or crackling sound in either a joint, like a knuckle, or in the lungs. It may be faint or loud enough for people to hear. It often comes with a popping or crunching sensation, which can sometimes be uncomfortable or painful.

The term crepitus is derived from the Latin for "rattling" or "creaking." Crepitus is not a condition, but rather a descriptive quality. Healthcare providers use it to help pinpoint the source of a problem.

This article explains crepitus and some of its causes in the joints or the lungs. It also discusses how crepitus can be a part of diagnosing and then treating a condition.

Crepitus of the Joints

Crepitus of the joints is typically related to joint damage. It may occur in tandem with a joint disorder or entirely on its own.

As a symptom, it is not necessarily a problem in and of itself. Cracking your knuckles, for example, reveals a form of crepitus caused by tiny nitrogen gas bubbles in a joint. They suddenly pop with the strenuous movement.

Crepitus of the joints is generally only a problem when the popping is progressive, meaning it continues or grows worse over time, or if you have other symptoms of joint damage, injury, or infection.

Joint Damage

Crepitus can occur when the rough surfaces of two joints rub together. This causes the cartilage and/or bone to physically grate against each other.

When there is pain, it is typically related to advanced joint damage. Pain also may be due to the compression, or squeezing, of nerves between the narrowed joint spaces. It is at this stage that the joint may begin to show signs of injury, including:

• Swelling
• Redness
• Limited range of motion
• Joint malformation

Osteoarthritis ("wear-and-tear arthritis") is a common cause of this type of joint injury. Crepitus can occur with other forms of arthritis, though. These include:

• Rheumatoid arthritis
• Psoriatic arthritis
• Gout
• Juvenile idiopathic arthritis

While any joint of the body can be affected, the symptoms are most common in the knees, hands, feet, lower back, hips, and shoulders.

Joint Inflammation or Injury

Crepitus can also occur with certain other conditions involving inflammation of or injury to the structures around a joint. These types of disorders are usually accompanied by pain and restricted movement.

• Bursitis: This is inflammation of the fluid-filled sacs near the joint called bursa. It may be caused by an infection, autoimmune disorder, trauma, or a repetitive use injury. Crepitus can occur when the inner surfaces of an inflamed bursa rub against each other.
• Tenosynovitis: With this, inflammation builds up in the lining of the tendon sheath called the tenoysnovium, which surrounds a joint tendon. Crepitus can occur when a tendon slides through an inflamed sheath.
• Patellofemoral pain syndrome (PFPS): Also known as runner's knee, this is caused when the cartilage under the kneecap (patella) is damaged. This roughened cartilage can cause crepitus during knee movement.
• Temporomandibular joint disorders (TMJ), which are characterized by pain and other symptoms related to problems in the TMJ, the joints between the jaw and the base of the skull. People with TMJ arthritis can sometimes hear crepitus with jaw movement. TMJ disorders can also result in both a clicking sound and popping sensation as you open your mouth.

Almost any injury of the joint cartilage can cause clicking or popping sounds as the uneven surfaces rub together. Rotator cuff tears and triangular fibrocartilage complex (TFCC) of the wrist are two such examples. Even abnormally-shaped cartilage, such as with discoid lateral meniscus (misshapen disc in the knee), can cause crepitus.

Scleroderma, a rare disorder characterized by the hardening and tightening of the skin and connective tissues, is a less common cause. It can cause coarse creaking sounds and sensations as the muscles and tendons rub against inflamed or hardened tissues.

Crepitus of the Lungs

Most people think of the joints when they think of crepitus, but the term can also be used to describe audible crackling sounds in the lungs. Crepitus in the lungs is caused when collapsed or fluid-filled air sacs abruptly open when you breathe.

Also referred to as crackles or rales, the sounds are related to abnormalities in the lungs. Most often, the sounds signal that there may be lung scarring or a buildup of excess fluid.

Among some of the conditions for which rales are common:

• Pulmonary edema, or fluid on the lungs typically associated with congestive heart failure (CHF)
• Pneumonia, infection that inflames the lungs and may cause them to fill with fluid
• Bronchitis, inflammation of the tubes that allow air to flow in and out of your lungs (either caused by infection or associated with chronic obstructive pulmonary disease (COPD)
• Interstitial lung diseases affecting the interstitium (the tissue surrounding the alveoli sacs in the lung)

Diagnosis

The diagnostic process for determining the cause of crepitus can vary depending on the part of the body where the sounds are coming from, the severity, and any accompanying symptoms.

Identifying Joint Disorders

In some cases, the popping of a joint may be more irritating than anything else. It may not warrant extensive investigation or any treatment.

If there is pain, inflammation, or restriction of motion, your healthcare provider may order tests to pinpoint the cause. They may choose among several tests.

Imaging

Imaging tests may be used to detect or help confirm a bone or joint injury. These tests can range from a basic X-ray or ultrasound to a computed tomography (CT) scan, which uses multiple views to create a three-dimensional image of the joint.

A magnetic resonance imaging (MRI) scan may be used to better detect any soft tissue damage.

Blood Tests

Your healthcare provider may order blood tests to check for infection or inflammation. For example, about 80% of people with rheumatoid arthritis (RA) have the presence of a marker called rheumatoid factor (RF) in their bloodstream. A blood test for RF would show this.

Antibodies Tests

Tests for antibodies also are used to confirm RA and other autoimmune disorders. These occur when the immune system mistakenly attacks healthy cells and tissues.

Antibody tests are used to see if your body is making specific proteins, such as antinuclear antibody (ANA), that point to a disorder or its underlying cause.

Arthrocentesis

An arthrocentesis is a procedure done to remove fluid from a joint space with a needle. The fluid is then sent to a lab and analyzed under a microscope for any fluid abnormalities or cells that suggest an infection or inflammation.

Identifying Lung Disorders

Crepitus of the lungs is never considered normal, so the cause needs to be diagnosed. The tests your healthcare provider will order depend on your symptoms and your medical history.

In many cases, these tests will include a chest X-ray or other imaging needed to view the lungs, as well as blood tests meant to find or identify an infection. They also may include pulse oximetry and heart function tests.

Pulse Oximetry

Pulse oximetry is used to measure the level of oxygen in your blood. The test relies on a simple probe, often clipped to your fingertip, to do so.

A low oxygen level can suggest that the rales, or crepitus in the lungs, may be linked to heart failure, pneumonia, or another condition.

Electrocardiogram

An electrocardiogram (EKG) or an echocardiogram may be used to check for heart irregularities.

• The EKG offers your healthcare team information about your heart rhythm and electrical activity.
• The "cardiac echo" is an ultrasound image that shows how well your heart muscle is working.

Treatment

Treatment for any conditions that cause crepitus will depend on the diagnosis. As a result, these treatments may vary widely.

In some cases, such as a mild joint inflammation, basic interventions may help. Others may require complicated surgery to treat a serious heart or lung condition.

Joint Disorders

Treatment for a joint disorder may involve ice application and non-steroidal anti-inflammatory drugs (NSAIDs). These are used to alleviate mild to moderate inflammation and pain.

Severe cases may require splinting support or steroid injections directly into the joint to reduce inflammation.

An infection that causes joint inflammation is usually bacterial. Often, this will be treated with a short course of antibiotics.

Immunosuppressive drugs, those specifically designed to tamp down an overactive immune system, may sometimes be used to treat inflammation caused by an autoimmune disease.

Severe injuries, such as torn tendons, ligaments, or cartilage, may require surgery. This is often done through arthroscopic surgery, a minimally invasive procedure that relies on small keyhole incisions.

If your mobility or quality of life is significantly impaired, joint replacement surgery may be considered. Extensive rehabilitation and physical therapy will follow.

Lung Disorders

Treatment for crepitus related to a lung disorder can vary, depending on the underlying cause and whether it has come on suddenly or is chronic.

Healthcare providers will typically treat bacterial pneumonia or bronchitis with antibiotics. Viral infections may be treated with antiviral drugs but are more often allowed to run their course with bed rest and plenty of fluids.

Chronic conditions usually require lifestyle changes. These may include:

• Smoking cessation
• Exercise
• Avoiding airborne irritants

Conditions like COPD will generally require medication with oral or inhaled corticosteroids and bronchodilators. Pulmonary rehabilitation and oxygen therapy can help prevent disease progression and allow you to maintain a quality of life.

Crepitus related to the fluid buildup of pulmonary edema may require aggressive treatment for heart failure. This may range from long-term medication to bypass surgery.

Surgery also may be an option for people with advanced lung disease when all other treatments fail. A lung transplant is a last resort for those who lungs are no longer functional.

Summary

Crepitus is an abnormal sound that can be found in your joints as well as your lungs. The popping or crackling doesn't always mean there's a medical problem. However, that's often the case when it arises with other symptoms such as pain in a joint or difficulty breathing.

In the joints, crepitus is often associated with inflammation or infection. It also may be a sign of joint injury, such as a torn rotator cuff. Crepitus of the lungs often occurs with heart and lung diseases, such as COPD.

Treatment depends on the underlying cause of the crepitus, the results of any tests, and the level of intervention needed.