Crepitus

Crepitus is a medical term to describe the grating, crackling, crunching or popping sounds and sensations experienced under the skin and joints. The sound can be created when two rough surfaces in the human body come into contact, for example, in osteoarthritis when the cartilage around joints has eroded away and the joint ends grind against one another, or when the fracture surfaces of two broken bones rub together.

In soft tissues, crepitus can be produced when gas is introduced into an area where it normally isn’t present. For example, subcutaneous emphysema can often be seen as a smooth bulging of the skin. When a health care provider feels (palpates) the skin, it produces an unusual crackling sensation or crepitus as the gas is pushed through the tissue.

Air can also be found in between skin layers on the arms and legs or torso after certain infections, including gas gangrene, and after scuba diving. In times of poor surgical practice, post-surgical complications involved anaerobic infection by Clostridium perfringens strains, which can cause gas gangrene in tissues, also giving rise to crepitus. Scuba divers with asthma are more likely to have this problem than other scuba divers.

Crepitus can also be used when describing the sounds produced by lung conditions such as interstitial lung disease – these are also referred to as “rales”. Crepitus is often loud enough to be heard by the human ear, although a stethoscope may be needed to detect instances caused by respiratory diseases.

Crepitus causes

Crepitus sound can be created when two rough surfaces in an organism’s body come into contact—for example, in osteoarthritis or rheumatoid arthritis when the cartilage around joints erodes and the surfaces in the joint grind against one another, or when the two fractured surfaces of the broken bones rub together. Crepitus is a common sign of bone fracture.

Crepitus can easily be created and observed by exerting a small amount of force on a joint, thus ‘cracking it’. This is caused by bubbles of nitrogen forming in the synovial fluid bursting. Almost every joint in the body can be ‘cracked’ in this way, but the joints which require the least amount of effort include the hallux, knuckles and neck joints.

In soft tissues, crepitus can be produced when gas is introduced into an area where it is normally not present.

Crepitus can also be used when describing the sounds produced by lung conditions such as interstitial lung disease—these are also referred to as “rales”. Crepitus is often loud enough to be heard by the human ear, although a stethoscope may be needed to detect instances caused by respiratory diseases.

In times of poor surgical practice, post-surgical complications involved anaerobic infection by Clostridium perfringens strains, which can cause gas gangrene in tissues, also giving rise to crepitus.

Subcutaneous crepitus or surgical emphysema is a crackling sound resulting from subcutaneous emphysema, or air trapped in the subcutaneous tissues.

Subcutaneous emphysema is a rare condition. When it does occur, possible causes include:

• Collapsed lung (pneumothorax), often occurring with a rib fracture
• Facial bone fracture
• Ruptured bronchial tube
• Ruptured esophagus

Subcutaneous emphysema can happen due to:

• Blunt trauma.
• Blast injuries.
• Breathing in cocaine.
• Corrosives or chemical burns of the esophagus.
• Diving injuries.
• Forceful vomiting (Boerhaave syndrome).
• Gunshot wounds.
• Pertussis (whooping cough).
• Stabbing.
• Certain medical procedures that insert a tube into the body. These include endoscopy (tube into the esophagus and the stomach through the mouth), a central venous line (thin catheter into a vein close to the heart), endotracheal intubation (tube into the throat and trachea through the mouth or nose), and bronchoscopy (tube into the bronchial tubes through the mouth).

Crepitus treatment

Crepitus is a medical term to describe the grating, crackling, crunching sounds and sensations experienced under the skin and joints. Crepitus treatment involves treating the underlying cause.

Crepitus knee treatment

In knee joint crepitus due to osteoarthritis, if you do not have any other symptoms, no specific treatment is necessary for crepitus. If you develop other knee problems, however, you should see a doctor to have your knee evaluated.

Crepitus is caused by the rubbing of cartilage on the joint surface or other soft tissues around the knee during joint movement. When knee snapping or catching is painful, that is usually a result of scar tissue, a meniscus tear or a tendon moving over a bony prominence within the knee joint.

The patellofemoral joint — where your knee cap meets your thigh bone, or femur — is typically the source of knee crepitus. Cartilage, the smooth, elastic tissue that covers the ends of bones, normally allows the bones to glide easily in the joint. But over time, the cartilage surface may start to lose its smoothness. The crunching you hear likely is due to the cartilage in your knee becoming rough, so the bones cannot slide as easily in the joint as they normally do.

Knee crepitus typically happens when the knee is bent, such as when you are squatting, going up or down stairs, or rising from a chair. By itself, crepitus generally is not a cause for concern. Once the cartilage gets rough, though, it may be at risk to begin to wear down, leading to arthritis.

To help prevent additional knee problems, work on strengthening the muscles in the front of your thigh, called the quadriceps. Walking, biking and swimming can all be useful for strengthening the quadriceps muscle. A variety of exercises that directly target the quadriceps, both with and without weights, also may be helpful. If you have questions about specific exercises or if you have other medical conditions, talk to your doctor or a physical therapist before beginning a new exercise program.

Strong quadriceps can take some of the load off your patellofemoral joint. That makes it less likely the cartilage in the joint will wear down. Also, to help prevent further cartilage damage and other knee injuries, avoid overloading the joint when your knee is bent.

If you start to notice additional knee symptoms such as knee pain or fluid in the joint along with crepitus, that could signal the beginning of other problems. For example osteoarthritis, a common cause of knee pain and excess fluid around and in the joint, can develop if the cartilage in your knee wears down.

If other knee symptoms do develop, it is important to have your situation evaluated right away. When left untreated, some knee conditions including osteoarthritis can lead to increasing pain, joint damage and, eventually, disability. But if identified and treated promptly, most knee problems can be successfully managed.