1. Fractures
Any of the bones in or around the knee can be fractured. The most commonly broken bone in the joint is the patella or kneecap.
High impact trauma, such as a fall or car accident, causes most knee fractures. People with underlying osteoporosis may fracture their knees just by stepping the wrong way or tripping.
2. Anterior cruciate ligament injuries
ACL injuries can range from grade 1 to 3 in severity.
The anterior cruciate ligament (ACL) runs diagonally down the front of the knee, providing critical stability to the joint. Injuries to the ACL can be serious and require surgery.
ACL injuries are graded on a scale from one to three. A grade 1 sprain is a mild injury to the ACL, while a grade 3 refers to a complete tear.
Athletes who participate in contact sports such as football or soccer often injure their ACLs. However, contact sports are not the only cause of this injury.
Improperly landing from a jump or quickly changing the direction of motion can lead to a tear in the ACL. Most people who pursue an active lifestyle will benefit from arthroscopic ACL surgery.
3. Posterior cruciate ligament injuries
The posterior cruciate ligament is located at the back of the knee. It is one of the many ligaments that connect the thighbone to the shinbone. This ligament keeps the shinbone from moving too far backward.
An injury to the posterior cruciate requires powerful force while the knee is in a bent position. This level of force typically happens when someone falls hard onto a bent knee or is in an accident that impacts the knee while it is bent. Injuries to the PCL can be treated conservatively or surgically depending on the severity of injury and associated injuires to the knee.
4. Dislocation
Dislocating the knee happens when the bones of the knee are out of their proper placement and alignment.
In a knee dislocation, one or more of the bones may slip out of place. Structural abnormalities or traumas, including car accidents, falls, and contact sports, can cause a knee dislocation.
5. Bursitis
Bursae are small fluid-filled sacs that cushion the knee joints and allow the tendons and ligaments to slide easily over the joint.
These sacs can swell and become inflamed with overuse or repeated pressure from kneeling. This is known as bursitis.
Most cases of bursitis are not serious and can be treated by self-care. However, some instances may require antibiotic treatment or aspiration, which is a procedure that uses a needle to withdraw excess fluid.
6. Meniscal tears
When people refer to torn cartilage in the knee, they are probably talking about a meniscal tear.
The menisci are two rubbery wedges of cartilage between the thighbone and shinbone. These pieces of cartilage can tear suddenly during sporting activities. They may also tear slowly due to aging.
When the meniscus tears due to the natural aging process, it is referred to as a degenerative meniscus tear.
With a sudden meniscus tear, a pop may be heard or felt in the knee. After the initial injury, pain, swelling, and tightness may increase over the next few days.
7. Collateral ligament injuries
Collateral ligaments connect the thighbone to the shinbone. Injury to these ligaments is a common problem for athletes, particularly those involved in contact sports.
Collateral ligament tears often occur due to a direct impact or collision with another person or object.
8. Tendonitis
Tendonitis can affect physically active people.
Tendonitis or inflammation of the knee cap tendon is known as patellar tendinitis. This is an injury to the tendon that connects the kneecap to the shinbone.
The patellar tendon works with the front of the thigh to extend the knee so a person can run, jump, and perform other physical activities.
Often referred to as jumper’s knee, tendonitis is common among athletes who frequently jump. However, any physically active person can be at risk of developing tendonitis.
9. Tendon tears
Tendons are soft tissues that connect the muscles to the bones. In the knee, a common tendon to be injured is the patellar tendon
It is not uncommon for an athlete or middle-aged person involved in physical activities to tear or overstretch the tendons. Direct impact from a fall or hit may also cause a tear in the tendon.
Most people who tear their quadriceps and/or patellar tendon and have subsequent difficulty in lifting the leg straight will require surgery.
10. Iliotibial band syndrome
Iliotibial band syndrome is common among long-distance runners. It is caused when the iliotibial band, which is located on the outside of the knee, rubs against the outside of the knee joint.
Typically, the pain starts off as a minor irritation. It can gradually build to the point where a runner must stop running for a period to let the iliotibial band heal.
11. Cartilage Injuries
Injuries to the cartilage can be either due to direct severe trauma or due to repetitive microtrauma. The Human cartilage does not heal back to its native state once injured but heals into a stiff fibrocartilage which lacks the desired native cartilage properties. Neglected and poorly treated cartilage injuries eventually lead to Osteoarthritis of the knee.
