Popping, creaking, or clicking that is heard or felt in the joints are fairly normal and common. Joint popping is medically termed “crepitus.” The bones of a synovial joint are enveloped by a joint capsule that seals the joint and is filled with synovial fluid.
The fluid provides lubrication and nourishment on the joint, acts as a shock absorber, and contains dissolved gases [oxygen, nitrogen, and carbon dioxide].
Passively moving a joint, such as cracking the knuckles, will stretch the joint capsule, leading to the release of natural gases, including nitrogen gas, causing the popping or cracking sound.
Joint crepitus is usually not painful and is not a concern among individuals. However, if it is associated with pain and swelling, it might indicate a problem in the joint.
Another cause for joint popping or cracking is a tendon rubbing against a bone. When a joint is actively moved, the tendons that run across it may rub against a bony structure, moves out of place, and returns to its original position resulting in the popping or cracking sound. This usually occurs in the ankles, shoulders, and knees.
Popping or cracking in the ankles may be caused by tendon subluxation or dislocation. Tendons are responsible for connecting the muscles to their bone attachments and act as stabilizers of the joint.
The ankle has three peroneal muscles that originate from the small bone of the lower leg (called fibula) and insert into the long bones of the foot (called metatarsals).
Before attaching to the metatarsals, the tendons of the two peroneal muscles run on a groove behind a bony structure on the outer side of the ankle.
When these tendons are moved out of their position, which happens during subluxation or dislocation, it may rub against the bony bump creating the popping or cracking sound.
Ankle popping is usually not a concern if it is not painful or the area is not swollen. As long as it does not hinder normal daily function, treatment is not usually warranted.