Why Do My Knees Crack?

By Andrew Heideman PT/ATC

Why Do My Knees Crack?

By Drew Heideman, MPT, ATC, PES

Cracking of the knees with motions such as squatting or stair climbing can be very common though is usually harmless. Why do your knees crack then? Through the normal aging process the cartilage that covers the joint surfaces of bones can develop uneven or rough areas that can create a sound when gliding across each other. Soft tissues such as the joint capsule, muscles and fascia can also create a popping or cracking noise as they glide and stretch across other tissue layers as a result of joint movement. Other times, an audible popping noise can be heard when the pressure quickly changes in the joint capsule as the space between the two joint surfaces expands. Occurring most commonly in the knuckles of the hand, this rapid expansion of the joint space releases a gas as the pressure changes within the joint and an audible pop or crack is heard. Though much more rare, popping that is painful should be evaluated by an orthopaedic professional. Your doctor or physical therapist, can determine whether the painful popping is a result of a meniscus tear, severe cartilage wear, or even ligamentous instability.

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