Knee buckling can be a sign of injury or damage to the knee. It can increase the risk of falling and can prolong recovery from knee problems.

Knee buckling is relatively common among adults. In one study, 11.8 percent of adults aged 36-94 reported at least one episode of knee buckling in the past 3 months. It can affect people of all ages and levels of fitness.

In this article, we look at the causes of knee buckling, exercises that can help, treatment, and when to see a doctor.


Knee buckling is a complicated condition with many different potential causes.

Many people associate knee buckling with osteoarthritis. However, one study found that more than half of the participants who reported episodes of knee buckling did not show any signs of arthritis in X-rays.

The complex structure of the knee joint can make it difficult to determine what is causing knee buckling.

The knee consists of two joints, which allow it to move in different directions. The knee has support from:

  • tendons, which connect the leg muscles to the knee bones
  • ligaments, which connect the knee bones together
  • cartilage, which allows smooth movement of the joints and acts as a shock absorber

It is possible to damage any of these different parts, sometimes in combination with other injuries to the knee. This can lead to instability in the knee and knee buckling.

Certain factors may be related to knee buckling. These include knee pain, which can occur for a variety of reasons, and weak muscles at the front of the leg.

The following may also contribute to the likelihood of knee buckling:

  • Arthritis, which can cause severe pain in the knees and create joint instability. Disease, injury, and worn cartilage can all lead to arthritis.
  • A torn meniscus, which interferes with the normal motion of the knee.
  • A fragment of bone or cartilage becoming trapped between the bones.
  • Tearing of any of the ligaments, which can occur as a result of a blow to the knees or a sudden twisting motion.
  • Partial or complete dislocation of the kneecap.
  • An inflammation of the synovial folds of the knee, or plicae, which can be painful and cause the knee to pop, crack, or buckle.
  • Multiple sclerosis is an autoimmune condition that attacks the central nervous system. It can cause muscle weakness and tightness, in addition to balance and sensory problems, which may all contribute to knee buckling.
  • Damage to the femoral nerve, which controls the muscles that straighten the leg, can lead to a sensation of the knee giving way.


Certain exercises can strengthen the leg muscles and improve knee stability, which may help to prevent or reduce knee buckling.

A doctor or physical therapist can design an exercise program to address the needs of a person worried about knee buckling. This will usually focus on:

  • strengthening the muscles that support the knee and keep the kneecap in proper alignment
  • Increasing the range of motion in the upper and lower legs
  • Reducing stiffness
  • Promoting flexibility

Specific exercises will stretch and strengthen:

  • the quadriceps the muscles in the front of the legs
  • the hamstrings the muscles in the back of the legs
  • the calves the muscles in the back of the lower legs
  • the gluteal muscles the muscles in the buttocks

Following a knee rehabilitation program will help a person by:

  • improving their ability to bend and straighten their legs
  • increasing the weight their legs can support
  • building strength in their inner and outer thighs, and expanding their range of motion

It is important to start these exercises very slowly and gently. People need to gradually build up strength and flexibility in their legs and knees before moving on to tougher exercises.

However, to make progress, it is important for people to challenge themselves a little, both at home and in Physical Therapy sessions. It can be hard to achieve the right balance, but a trained therapist can help to ensure that the level of exertion is suitable.

People who experience knee buckling may also need to adapt their exercise habits. For example, a person with arthritis may need to switch from high-impact activities, such as running or tennis, to lower-impact activities, such as swimming or cycling.

Cycling can also help to build strength in the upper legs, which will contribute to improved stability in the knee.

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