Crepitus

Crepitus (from Latin crepitare — to creak, crunch) is a specific auditory phenomenon and tactile sensation that occurs when rough, hard surfaces physically rub against each other. In traumatology, the term is used to describe the characteristic crunching of bone fragments at a fresh fracture site.

Etiology and pathophysiology

In fractures, the integrity of the smooth cortical layer of the bone is disrupted. Fracture lines almost always have uneven, jagged, and sharp edges. At the slightest displacement of the limb or palpation of the injury site, these edges rub against each other, creating high-frequency mechanical vibrations.

This vibration can be distinctly felt by a physician’s fingertips and, in some cases, heard without a stethoscope. It is important to differentiate bone crepitation from crepitus in subcutaneous emphysema (accumulation of air in tissues). The “snow crunch” in emphysema is softer and does not provoke a sharp pain reaction.

Clinical significance

Crepitus is one of the absolute (reliable) clinical signs of fracture, along with pathological mobility and visible bone deformation. Its detection allows the physician to make a provisional diagnosis even before radiography is conducted.

However, deliberately inducing crepitus to verify a diagnosis is categorically prohibited. This manipulation causes the patient severe pain, aggravates traumatic shock, and the sharp edges of the bone upon displacement may cut nearby large vessels or peripheral nerves. The symptom is only determined inadvertently during careful initial examination.