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Knee snapping, popping, or grinding

A knee that snaps or pops when you walk, exercise, twist, or turn may be annoying but usually is not a cause for concern if you don't have any pain and your knee feels stable.

A knee that snaps or pops at the time of a painful injury may be caused by:

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As the name suggests, runner's knee is a common ailment among runners. But it can also strike any athlete who does activities that require a lot of knee bending -- like walking, biking, and jumping. It usually causes aching pain around the kneecap. Runner's knee isn't really a condition itself. It's a loose term for several specific disorders with different causes. Runner's knee can result from: Overuse. Repeated bending of the knee can irritate the nerves of the kneecap. Overstretched...

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  • Sprains, strains, or other injuries to the ligaments and tendons that support the kneecap.
  • A torn ligament, such as the torn anterior cruciate ligament (ACL) or the medial collateral ligament (MCL).
  • A tear in the rubbery cushions of the knee joint (menisci).
  • Breaks (fractures) of the kneecap, lower portion of the femur, or upper part of the tibia or fibula. (See an illustration of the structures of the knee .) Knee fractures most commonly are caused by abnormal force, such as a falling on the knee, a severe twisting motion, severe force that bends the knee, or when the knee forcefully hits an object.
  • Kneecap dislocation. Pieces of bone or tissue (loose bodies) from a fracture or dislocation may get caught in the joint and interfere with movement.

Grinding may occur with joint movement because of other conditions, such as:

  • Degenerative joint disease (osteoarthritis).
  • Wear and tear on the material that absorbs shock and provides a gliding surface (articular cartilage) on the underside of the kneecap (chondromalacia patellae).

Prompt treatment is important to promote healing and prevent complications.

Author Sydney Youngerman-Cole, RN, BSN, RNC
Editor Susan Van Houten, RN, BSN, MBA
Associate Editor Tracy Landauer
Primary Medical Reviewer William M. Green, MD - Emergency Medicine
Specialist Medical Reviewer Patrick J. McMahon, MD - Orthopedics
Last Updated September 18, 2009

WebMD Medical Reference from Healthwise

Last Updated: September 18, 2009
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.

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