When your knee’s catch – a meniscal tear
If you feel your knees locking and when you are unable to straighten your leg, there is a possibility that you may have a meniscus tear. But what is a meniscus and how does it tear?
Redistributing Weight and Shock
You have two meniscus at each knee. These menisci are C-shaped are placed at each side of the knee facing each other to form a circle of sorts. The meniscus on the outer part of your knee is called the lateral meniscus and the inner one, the medial meniscus.
The meniscus simply functions to distribute the weight or forces at the knee, between your thigh (femur) and shin (tibia) bones more evenly. The meniscus is also very smooth and helps reduce friction during movement. Without the menisci, your thigh and shin bones were be rubbing against each other on their ends. This would be extremely painful and your leg movements will not be smooth.
The meniscus is a fibrocartilaginous band that is quite tough and is designed to bear the brunt of forces acting on it daily. But it can be damaged or torn by twisting the knee or applying direct force in direct contact sports. Because the meniscus has relatively poor blood supply, the tears do not heal on their own and may require surgery.
A meniscal tear that catches, locks the knee, or produces swelling on a frequent or chronic basis should be removed or repaired before it damages the articular (gliding) cartilage in the knee.
There are many different ways the meniscus can tear and some types have fanciful names like the Parrot-Beak tear and Bucket-Handle Tear. you can learn more about them here.
Here’s a video showing a type of meniscus tear (Bucket Handle Tear) that causes knee locking.