Anatomical Structure of the Knee and How They are Injured

What Anatomical Structures Are Located In A Person's Knee?

In your knee, there are several anatomical structures: the cruciate ligaments, the collateral ligaments, menisci, and the articular (joint) cartilages. When someone injures their knee, there can be simultaneous insult to more than one of these structures.

What Are The Cruciate Ligaments?

There are two separate cruciate ligaments in a person's knee: the anterior cruciate ligament (located in the front) and the posterior cruciate ligament (located at the back). These two ligaments can be referred to as the ACL & PCL respectively. It is important to note that the cruciate ligaments help to secure the stability in the knee, which is assisted also by other ligaments, the menisci and the muscles.

How do injuries to the cruciate ligaments occur?

Injuries to the anterior cruciate ligament (ACL) are more common than injuries to the posterior cruciate ligament (PCL). The posterior cruciate ligament (PCL) is more commonly damaged in an accident on the road. When the person is sitting down and their knees hit the dashboard, driving the lower leg backward in an unnatural manner. When the posterior cruciate ligament is torn across, your shin bone will move be able to move backwards on the thigh bone.

What are Collateral Ligaments?

Collateral ligaments are located both on the inside and on the outside of the knee joint. The two collateral ligaments are known as the medial collateral ligament (MCL- located on the inside of your knee), and the lateral collateral ligament (LCL- found on the outside of the knee.) Ligaments, primarily, are tough bands of tissue that serve to connect ends of bones together. You can see a clear illustration of this from the photo.

The collateral ligaments aid the stability of your knee in limiting side to side motion. A collateral ligament is not a single stranded, thin ligament, but is made of many minor ligaments which come together to form a single ligament that is strong. The reason why this is important for you to know is that if you have a partial tear of your collateral ligament, the knee may still remain fairly stable.

How do collateral ligament injuries occur?

A collateral ligament injury will be caused usually by a force from the inside or outside of your knee. To help you understand, we will first discuss the MCL's function. The MCL is made to help stop your knee from "widening". If someone's knee receives a blow from the outside, the MCL will be strained or even torn because the ligament is over powered. (Just imagine a force that makes the knee excessively move toward your other knee, to the point of injury.)

On the other hand, an LCL injury occurs when there is a blow to the inside of the knee. This could happen when there is a quick change of direction. The LCL may also be injured when someone falls to the side, while there foot is planted firmly, causing your knee to bow outward.

Tears of the collateral ligaments are graded on a scale of 1-3:

Grade 1: A minor stretch, this is otherwise known as a "sprain" of the ligament.
Grade 2: Involves a partial tear of the ligament.
Grade 3: Is more severe, and results in a complete tear of the ligament.
A ligament injury can also be accompanied by major or minor swelling of the knee joint

 

What is a meniscus? and What Does It Do?

The menisci (plural for meniscus) are two C-shaped pads of cartilaginous tissue which serve to disperse friction in the knee joint. When the meniscus is damaged, treatment can involve the use of surgery, the use of a well designed knee brace, and the use of physical therapy. The function of the meniscus : The menisci functions to help distribute your body weight across the knee joint by helping with shock absorption. This is very important because without the meniscus present, the weight of your body would be unevenly applied to the bones in your legs (the femur and tibia). This unevendistribution of weight would cause excessive and unequal forces leading to early arthritis of knee joint. The meniscus also helps to provide stability, lubrication and nutrition for the knee joint.

One interesting point is that the majority of the meniscus has no blood supply. This is important to note because unlike the rest of the body, the meniscus is unable to undergo the normal healing process of a tissue, with a normal blood supply. In addition to compromised healing, with age the meniscuscan deteriorate, leading to degenerative tears.

What happens when the meniscus tears?

When the meniscus is damaged, the torn piece can begin to move in an abnormal fashion inside the joint. When part of your meniscus begins to move abnormally, the knee can become painful, swollen, and difficultfor an individual to move the joint.

What can I expect if surgery is needed?

The exact surgical routine may differ among surgeons, but surgery is usually done on an outpatient(meaning you are not going to be staying overnight in the hospital). On the average, most patients are able to walk (ambulate) without crutches within 48 hours. An active rehabilitation program begins after surgery in an effort to rebuild the muscle strength in the muscles around the knee. In most patient cases, an exercise program is startedby the seventh day after surgery, while restrictions on activity levels can last for 6 weeks.