To better understand what is causing your sudden knee buckling, it helps to learn the basics of the knee joint.
At the knee joint, three bones intersect to form a complex structure that supports your weight and enables movement in the legs. These bones include the femur, also known as the thigh bone; the tibia, or shin bone; and the patella, commonly referred to as the kneecap. The patella is positioned at the front of the knee, acting as a protective shield for the delicate structures within the joint. The patella acts as a fulcrum to assist knee movement and as such can see very high forces.
The bones of the knee joint are held together and supported by a network of ligaments. These ligaments help maintain the knee’s stability. In total, there are four main ligaments in the knee:
- Anterior cruciate ligament (ACL)
- Lateral collateral ligament (LCL)
- Medial collateral ligament (MCL)
- Posterior cruciate ligament (PCL)
The collateral ligaments (the LCL and MCL) are found on the sides of the knee. The LCL is located on the outer side, and the MCL is located on the inner side. The cruciate ligaments (ACL and PCL) form an X on the inside of the knee joint. The ACL is in the front, and the PCL is in the back. All of these ligaments work to provide stability, strength and mobility to the knee joint.
Culprits for knee buckling.
Knee buckling is often attributed to osteoarthritis, a common type of arthritis, but it can also be a symptom of a knee injury. Buckling of the knee often represents a natural response to dysfunction in the knee, acting like a circuit breaker.
Here are some reasons why your knee may be suddenly giving way:
- Ligament injury. A ligament injury, such as an ACL tear, can cause knee instability and sudden knee buckling. An ACL tear is one of the most common knee injuries, according to the American Academy of Orthopaedic Surgeons.
- Meniscus tear. The meniscus is cartilage that sits between the thigh and shin bone and absorbs shock whenever you walk, jump, run, etc. Meniscus tears often happen while playing sports when turning suddenly, but they can also happen from an awkward twist of the knee when bending or standing up. Common symptoms include pain, stiffness and a feeling like your knee is giving way. Your knee may also feel like it is locking up.
- Osteoarthritis. Knee buckling is common in people who have osteoarthritis. Wear of the cartilage of the kneecap, known as chondromalacia patella, is the most frequent cause of buckling.
- Plica syndrome. This a syndrome that represents thickening of the knee’s lining, creating irritation to the cartilage. Common symptoms of plica syndrome are pain, swelling and knee instability, which can lead to knee buckling.
Other causes for knee buckling can include instability, or poor tracking, of the kneecap, and issues with the nerve control of the thigh muscles. Examples of nerve issues include pinching in the spine and progressive neurologic conditions.
Strengthening of the knees to help regain stability.
Straight leg raises: This exercise strengthens leg muscles.
Hamstring curls: This exercise works the hamstrings, the group of muscles in the back of the thigh.
Double leg squats: This exercise helps improve balance and strengthens the muscles around the knee joint.
These are only some as practitioners would give you tailored stretches to your injury or situation.
