Crepitus is "a grating sound or sensation produced by friction between

bone A bone is a rigid organ that constitutes part of the skeleton in most vertebrate animals. Bones protect the various other organs of the body, produce red and white blood cells, store minerals, provide structure and support for the body, ...

and

cartilage Cartilage is a resilient and smooth type of connective tissue. Semi-transparent and non-porous, it is usually covered by a tough and fibrous membrane called perichondrium. In tetrapods, it covers and protects the ends of long bones at the joints ...

or the fractured parts of a bone". Various types of crepitus that can be heard in joint pathologies are: *Bone crepitus: This can be heard when two fragments of a fracture are moved against each other. *Joint crepitus: This can be obtained when the affected

joint A joint or articulation (or articular surface) is the connection made between bones, ossicles, or other hard structures in the body which link an animal's skeletal system into a functional whole.Saladin, Ken. Anatomy & Physiology. 7th ed. McGraw- ...

is passively moved with one hand, while the other hand is placed on the joint to feel the crepitus. *Crepitus of

bursitis Bursitis is the inflammation of one or more bursae (synovial sacs) of synovial fluid in the body. They are lined with a synovial membrane that secretes a lubricating synovial fluid. There are more than 150 bursae in the human body. The bursae (bu ...

: This is heard when the fluid in the

bursa Bursa () is a city in northwestern Turkey and the administrative center of Bursa Province. The fourth-most populous city in Turkey and second-most populous in the Marmara Region, Bursa is one of the industrial centers of the country. Most of ...

contains small, loose fibrinous particles. *Crepitus of

tenosynovitis Tenosynovitis is the inflammation of the fluid-filled sheath (called the synovium) that surrounds a tendon, typically leading to joint pain, swelling, and stiffness. Tenosynovitis can be either infectious or noninfectious. Common clinical mani ...

: From

inflammation Inflammation (from ) is part of the biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. The five cardinal signs are heat, pain, redness, swelling, and loss of function (Latin ''calor'', '' ...

of the fluid-filled sheath ( synovium) that surrounds a

tendon A tendon or sinew is a tough band of fibrous connective tissue, dense fibrous connective tissue that connects skeletal muscle, muscle to bone. It sends the mechanical forces of muscle contraction to the skeletal system, while withstanding tensi ...

Causes

The sound can be created when two rough surfaces in an organism's body come into contact—for example, in

osteoarthritis Osteoarthritis is a type of degenerative joint disease that results from breakdown of articular cartilage, joint cartilage and underlying bone. A form of arthritis, it is believed to be the fourth leading cause of disability in the world, affect ...

rheumatoid arthritis Rheumatoid arthritis (RA) is a long-term autoimmune disorder that primarily affects synovial joint, joints. It typically results in warm, swollen, and painful joints. Pain and stiffness often worsen following rest. Most commonly, the wrist and h ...

when the

around joints erodes and the surfaces in the joint grind against one another, or when the two fractured surfaces of the broken

s rub together. Crepitus is a common sign of

bone fracture A bone fracture (abbreviated FRX or Fx, Fx, or #) is a medical condition in which there is a partial or complete break in the continuity of any bone in the body. In more severe cases, the bone may be broken into several fragments, known as a ''c ...

. 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 Nitrogen is a chemical element; it has Symbol (chemistry), symbol N and atomic number 7. Nitrogen is a Nonmetal (chemistry), nonmetal and the lightest member of pnictogen, group 15 of the periodic table, often called the Pnictogen, pnictogens. ...

forming in the

synovial fluid Synovial fluid, also called synovia, elp 1/sup> is a viscous, non-Newtonian fluid found in the cavities of synovial joints. With its egg white–like consistency, the principal role of synovial fluid is to reduce friction between the articul ...

bursting. Almost every joint in the body can be 'cracked' in this way, but the joints which require the least amount of force to produce this effect include the

hallux Toes are the digits of the foot of a tetrapod. Animal species such as cats that walk on their toes are described as being ''digitigrade''. Humans, and other animals that walk on the soles of their feet, are described as being ''plantigrade''; ...

(big toes), the

knuckle The knuckles are the joints of the fingers. The word is cognate to similar words in other Germanic languages, such as the Dutch "knokkel" (knuckle) or German "Knöchel" (ankle), i.e., ''Knöchlein'', the diminutive of the German word for bone ( ...

s and the neck joints. This phenomenon is caused when the movement of the joint lowers the pressure of its synovial fluid, causing the bubbles to form and burst. A refractory period of about 20 minutes exists where the joint cannot be stimulated to produce crepitus after being cracked until the nitrogen gas dissolves back into the synovial fluid. In soft tissues, crepitus can be produced when gas is introduced into an area where it is normally not present. The term can also be used when describing the sounds produced by

lung The lungs are the primary Organ (biology), organs of the respiratory system in many animals, including humans. In mammals and most other tetrapods, two lungs are located near the Vertebral column, backbone on either side of the heart. Their ...

conditions such as

interstitial lung disease Interstitial lung disease (ILD), or diffuse parenchymal lung disease (DPLD), is a group of respiratory diseases affecting the interstitium (the tissue) and space around the alveoli (air sacs) of the lungs. It concerns alveolar epithelium, pulm ...

; these are also referred to as " rales". Crepitus is often loud enough to be heard by the human ear, although a

stethoscope The stethoscope is a medicine, medical device for auscultation, or listening to internal sounds of an animal or human body. It typically has a small disc-shaped resonator that is placed against the skin, with either one or two tubes connected t ...

may be needed to detect instances caused by

respiratory The respiratory system (also respiratory apparatus, ventilatory system) is a biological system consisting of specific organs and structures used for gas exchange in animals and plants. The anatomy and physiology that make this happen varies gr ...

diseases. In times of poor surgical practice, post-surgical complications involved

anaerobic Anaerobic means "living, active, occurring, or existing in the absence of free oxygen", as opposed to aerobic which means "living, active, or occurring only in the presence of oxygen." Anaerobic may also refer to: *Adhesive#Anaerobic, Anaerobic ad ...

infection by ''

Clostridium perfringens ''Clostridium perfringens'' (formerly known as ''C. welchii'', or ''Bacillus welchii'') is a Gram-positive, bacillus (rod-shaped), anaerobic, spore-forming pathogenic bacterium of the genus '' Clostridium''. ''C. perfringens'' is ever-present ...

'' strains, which can cause

gas gangrene Gas gangrene (also known as clostridial myonecrosis) is a bacterial infection that produces tissue gas in gangrene. This deadly form of gangrene usually is caused by '' Clostridium perfringens'' bacteria. About 1,000 cases of gas gangrene are r ...

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 tissue The subcutaneous tissue (), also called the hypodermis, hypoderm (), subcutis, or superficial fascia, is the lowermost layer of the integumentary system in vertebrates. The types of cells found in the layer are fibroblasts, adipose cells, and ma ...

References

External links

* {{Congenital malformations and deformations of musculoskeletal system Medical signs

Causes

Further reading

References

See also

External links