Knee & Patellar Instability

What is knee or patellar instability?

Patellar instability occurs when the kneecap shifts out of position from the groove in the thighbone. Unfortunately, untreated patellar instability can lead to the dislocation of the kneecap. Some patients develop chronic patellar instability, which increases the susceptibility of knee arthritis, ACL tears and dislocated knees. Usually, when bending or straightening the knee, the kneecap travels up and down in a notch referred to as the trochlear groove, a V-shaped space. However, with patellar instability, the kneecap does not shift into the groove entirely.

Patellar instability can lead to the following types of kneecap dislocations when left untreated:

• A partial dislocation occurs when the kneecap does not completely dislodge from the trochlear groove.
• A complete dislocation happens when the ligaments that help secure the kneecap in position move out of position.

What are the signs?

You can expect buckling at the knee when the kneecap dislodges from the trochlear groove. As a result, you may not be able to walk properly because your knee cannot straighten.

Furthermore, additional symptoms include the following:

• Stiffness, pain and swelling in the knee
• Cracking noises emanating from the knee when bending or moving the joint
• The kneecap feels unstable as if it shifts from one side to another or gets caught on tissue.

What are the causes of patellar instability?

Patellar instability may occur as a result of the following:

• Irregular-shaped/shallow trochlear groove
• Lax ligaments or joints that appear to be too flexible
• A sudden impact to the kneecap due to a sports injury, unexpected fall or motor vehicle collision.

How does Dr du Toit treat patellar instability?

There exist different types of non-surgical treatments for patellar instability, such as the following:

• A knee brace helps keep the knee in place, which is why it should be worn over several weeks.
• Non-steroidal anti-inflammatories are recommended to alleviate pain and inflammation in the joint.
• Physical therapy is advised to restore the joint’s range of motion.

Dr du Toit will advise surgical (arthroscopic) treatment for progressive patellar instability to help stabilise the joint. As a result, Dr du Toit creates tiny incisions over the knee and inserts a flexible scope (arthroscope) through one of these openings. Next, he removes bone fragments or loose cartilage in the knee.