crépitus

Crépitus is a medical term describing a crackling, popping, or grating sensation or sound felt or heard with movement or palpation of tissue. It can be detected beneath the skin, in a joint, or within soft tissues and may be audible, palpable, or both. Crépitus is a sign rather than a diagnosis and points to underlying processes affecting soft tissues, bone, or gas presence.

Subcutaneous crepitus refers to air trapped within the tissues beneath the skin, producing a characteristic crackling sensation on touch. It commonly follows trauma, surgery, or pulmonary barotrauma and may indicate pneumothorax, emphysema, or gas in soft tissues. Crepitus at a fracture site describes bone ends rubbing together or movement across irregular surfaces, often associated with fracture healing or displacement. In joints, crepitus arises from roughened cartilage, gas bubbles, or synovial changes during movement, and is common in osteoarthritis or chondromalacia.

Gas-producing infections, such as gas gangrene, can cause marked crepitus due to gas formation by bacteria within tissues; this is a medical emergency requiring prompt antibiotic therapy and surgical intervention.

Diagnosis relies on history, physical examination, and imaging when indicated. X-ray or CT can reveal subcutaneous gas or fracture alignment; ultrasound may detect soft-tissue gas.

Management targets the underlying cause. Subcutaneous crepitus from noncritical causes may be observed; fracture-related crepitus may require immobilization or reduction; joint crepitus is often managed conservatively for osteoarthritis. Gas gangrene or other infections require urgent treatment, including antibiotics and debridement. Prognosis varies with the etiology and timeliness of intervention.