Sports Medicine: Locking, Popping, Stiffness
Locking is an inability to fully bend or straighten a joint. This is due to either pain limitations or mechanical block. A mechanical block is often caused by damage to the cartilage or bone that makes up the joint; pain limitations are limits to movement due to increased amounts of pain. A physical exam can determine if the locking sensation is due to pain or a mechanical block.
An audible popping of a joint can be caused by sudden trauma, the shifting of air, or the snapping of a tendon. In some cases when an athlete injures a joint, they will hear or feel a pop. A pop can be a sign of damage to a ligament or cartilage. This is generally the case in injuries resulting from sudden trauma. Other popping in a joint may result from tendons snapping over boney structures (i.e. snapping hip syndrome) or from the movement of air in the joint (i.e. popping ones knuckles).
Joint stiffness is discomfort in a joint after a period of inactivity. Joint stiffness is usually at its worst in the morning or at the end of the day. Inflammation is usually the cause of stiffness. Surgery, arthritis, tendonitis, and injuries may all contribute to stiffness.
The grinding sensation felt in a joint is most likely a result of tissue friction caused by inflammation and/or irregularities in the joint surface.
Giving way, looseness or “not trusting” a joint
Joints that feel like they are loose and/or giving way are usually the result of ligament damage. In some cases pain and inflammation in a joint will make the sensory nerves perceive that the joint is unstable.