Two wedge-shaped pieces of cartilage act as “shock absorbers” between your thighbone and shinbone. These are called meniscus. They are tough and rubbery to help cushion the joint and keep it stable.
Menisci tear in different ways. Tears are noted by how they look, as well as where the tear occurs in the meniscus. Common tears include bucket handle, flap, and radial.
(Left) Bucket handle tear. (Right) Flap tear.
COURTESY OF AAOS.ORG
Meniscus tears are common in contact sports like football as well as noncontact sports requiring jumping and cutting such as volleyball and soccer. They can happen when a person changes direction suddenly while running, and often occur at the same time as other knee injuries, like an anterior cruciate ligament (ACL) injury. Meniscus tears are a special risk for older athletes since the meniscus weakens with age. More than 40% of people 65 or older have them.
You might feel a “pop” when you tear a meniscus. Most people can still walk on their injured knee. Many athletes keep playing with a tear. Over 2 to 3 days, your knee will gradually become more stiff and swollen.
The most common symptoms of meniscus tear are:
- Stiffness and swelling
- Catching or locking of your knee
- The sensation of your knee “giving way”
- You are not able to move your knee through its full range of motion
Without treatment, a piece of meniscus may come loose and drift into the joint. This can cause your knee to slip, pop, or lock.
Arthritis of the Knee
Osteoarthritis is the most common form of arthritis in the knee. It is a degenerative,”wear-and-tear” type of arthritis that occurs most often in people 50 years of age and older, but may occur in younger people, too. In osteoarthritis, the cartilage in the knee joint gradually wears away.
The major types of arthritis that affect the knee are osteoarthritis, rheumatoid arthritis, and posttraumatic arthritis.
In osteoarthritis, the cartilage in the knee joint gradually wears away. As the cartilage wears away, it becomes frayed and rough, and the protective space between the bones decreases. This can result in bone rubbing on bone, and produce painful bone spurs.
Osteoarthritis develops slowly and the pain it causes worsens over time.
COURTESY OF AAOS.ORG(Left) Normal joint space between the femur and the tibia. (Right) Decreased joint space due to damaged cartilage and bone spurs.
A knee joint affected by arthritis may be painful and inflamed. Generally, the pain develops gradually over time, although sudden onset is also possible. There are other symptoms, as well:
- The joint may become stiff and swollen, making it difficult to bend and straighten the knee.
- Pain and swelling may be worse in the morning, or after sitting or resting.
- Vigorous activity may cause pain to flare up.
- Loose fragments of cartilage and other tissue can interfere with the smooth motion of joints. The knee may “lock” or “stick” during movement. It may creak, click, snap or make a grinding noise (crepitus).
- Pain may cause a feeling of weakness or buckling in the knee.
- Many people with arthritis note increased joint pain with rainy weather.
The cruciate ligaments are found inside the knee. They cross each other to form an “X” with the anterior cruciate ligament in front and the posterior cruciate ligament in back. The cruciate ligaments control the back and forth motion of your knee.
One of the most common knee injuries is an anterior cruciate ligament (ACL) sprain or tear.
Athletes who participate in high demand sports like soccer, football, and basketball are more likely to injure their anterior cruciate ligaments.
The anterior cruciate ligament (ACL) can be injured in several ways:
- Changing direction rapidly
- Stopping suddenly
- Slowing down while running
- Landing from a jump incorrectly
- Direct contact or collision, such as a football tackle
Several studies have shown that female athletes have a higher incidence of ACL injury than male athletes in certain sports. It has been proposed that this is due to differences in physical conditioning, muscular strength, and neuromuscular control. Other suggested causes include differences in pelvis and lower extremity (leg) alignment, increased looseness in ligaments, and the effects of estrogen on ligament properties.
When you injure your anterior cruciate ligament, you might hear a “popping” noise and you may feel your knee give out from under you. Other typical symptoms include:
- Pain with swelling. Within 24 hours, your knee will swell. If ignored, the swelling and pain may resolve on its own. However, if you attempt to return to sports, your knee will probably be unstable and you risk causing further damage to the cushioning cartilage (meniscus) of your knee.
- Loss of full range of motion
- Tenderness along the joint line
- Discomfort while walking
The collateral ligaments are found on the sides of your knee. The medial or “inside” collateral ligament (MCL) connects the femur to the tibia. The lateral or “outside” collateral ligament (LCL)connects the femur to the smaller bone in the lower leg (fibula), and together they control the sideways motion of your knee and brace it against unusual movement.
The medial collateral ligament (MCL) is a broad, thick band that runs down the inner part of the knee, from the femur (thighbone) to about four to six inches from the top of the tibia (shinbone).The MCL’s primary function is to prevent the leg from over-extending inward, but it also is part of the mechanism that stabilizes the knee and allows it to rotate.
Injured ligaments are considered “sprains” and are graded on a severity scale.Complete tears of the MCL (left) and LCL (right).
The MCL is injured more often than the LCL. Due to the more complex anatomy of the outside of the knee, if you injure your LCL, you usually injure other structures in the joint, as well.
Injuries to the MCL commonly occur as a result of a strong force hitting the outside of the knee that causes the MCL — and, possibly, other ligaments on the inside of the knee, such as the anterior cruciate ligament (ACL) — to stretch or tear.
Blows to the inside of the knee that push the knee outwards may injure the lateral collateral ligament (LCL).
Like with most knee injuries, a torn MCL is associated with pain and swelling around the knee joint. An LCL injury may cause pain on the outside of the knee. The knee may also feel like it is catching or locking when moving. In more severe injuries, patients may experience knee instability or buckling during activity.
Patellofemoral Joint Pain
Patellofemoral pain syndrome is pain in the front of the knee. It frequently occurs in teenagers, manual laborers, and athletes. It sometimes is caused by wearing down, roughening, or softening of the cartilage under the kneecap.
Patellofemoral pain syndrome may be caused by overuse, injury, excess weight, a kneecap that is not properly aligned (patellar tracking disorder), or changes under the kneecap.
The main symptom of patellofemoral pain syndrome is knee pain, especially when you are sitting with bent knees, squatting, jumping, or using the stairs (especially going down stairs). You may also experience occasional knee buckling, in which the knee suddenly and unexpectedly gives way and does not support your body weight. It is also common to have a catching, popping, or grinding sensation when you are walking or when you are moving your knee.