What happens when your knee collapses?

Answered by Robert Dupre

When your knee collapses or buckles, it can be a frightening and painful experience. This happens when the knee joint gives way due to instability or weakness, often caused by a problem with the ligaments, muscles, or tendons that support the knee. One common cause of knee collapse is an injury to the anterior cruciate ligament (ACL).

The ACL is one of the major ligaments in the knee, located in the center of the joint. Its primary function is to prevent the shin bone (tibia) from sliding forward in relation to the thigh bone (femur) during twisting movements or sudden changes in direction. It provides stability and allows the knee to move smoothly.

When the ACL is injured or torn, the knee loses its stability, making it more susceptible to collapsing or buckling. This can occur during activities that involve pivoting, jumping, or sudden stops and starts. The lack of support from the ACL causes the shin bone to slide forward, which results in the knee giving way.

The sensation of the knee collapsing can be quite alarming. It often feels like the knee is suddenly giving out or unable to support your weight. This can lead to pain, swelling, and difficulty in walking or bearing weight on the affected leg. In some cases, a popping or snapping sound may be heard or felt at the time of the injury.

Apart from ACL injuries, other factors can contribute to knee collapse. These include weakness or imbalances in the surrounding muscles, such as the quadriceps and hamstrings, which provide stability to the knee joint. If these muscles are weak or not functioning properly, they may not be able to support the knee adequately, leading to buckling or collapsing.

Additionally, conditions like osteoarthritis or degenerative joint disease can cause the knee joint to become unstable over time. The gradual breakdown of the joint structures, including the ligaments, can result in the knee giving way during certain movements.

Knee collapse or buckling occurs when the knee joint becomes unstable due to factors like ACL injuries, muscle weakness, or degenerative conditions. The lack of support from the ligaments and muscles causes the shin bone to slide forward, leading to the knee giving way. This can result in pain, swelling, and difficulty in walking. Proper diagnosis and treatment are essential to address the underlying cause and restore stability to the knee joint.