Knee injury facts

• The knee is one of the most common body parts to be injured.
• Types of knee injuries include sprains, strains, bursitis, dislocations, fractures, meniscus tears, and overuse injuries.
• Knee injuries are generally caused by twisting or bending force applied to the knee, or a direct blow, such as from sports, falls, or accidents.
• Risk factors for knee injury include overuse, improper training, having osteoporosis, and playing high-impact sports that involve sudden changes in direction.
• The main signs and symptoms of knee injury are pain and swelling.
• Knee injuries are diagnosed by a history and physical. Sometimes an X-ray or MRI may be done.
• Treatment of knee injuries depends on the type and severity of the injury and can involve RICE therapy (rest, ice, compression, elevation), physical therapy, immobilization, or surgery.
• Prognosis for knee injury depends on the type and severity of the injury and the need for physical therapy or surgery.
• Knee injuries can be prevented by proper training, proper equipment, and maintaining a safe playing field or home environment to avoid falls.

What are the different types of knee injuries?

The knee is one of the most common parts of the body to be injured. Sports, falls, and motor vehicle accidents account for the vast majority of injuries to the knee.

The different types of injuries to the knee are defined by the affected anatomy of the knee and the mechanism by which it's injured.

Knee sprains are injuries to the ligaments that hold the knee together. There are multiple ligaments that stabilize the knee and keep it in alignment. The anterior cruciate ligament (ACL) and the posterior cruciate ligament (PCL) stabilize the knee in movement from front to back and cross each other in the middle of the knee joint. The medial collateral ligament (MCL) and lateral collateral ligament (LCL) stabilize the knee so that the bones do not slide from side to side.

Ligament sprains are graded by the amount of stretching or tearing of the ligament fibers and how much instability it causes as follows:

Knee sprains:

• Grade 1 knee sprain: The ligament is stretched and painful, but fibers are not torn and no instability is present.
• Grade 2 knee sprain: The ligament fibers are torn partially, mild instability may be evident.
• Grade 3 knee sprain: The ligament fibers are completely torn and the knee is unstable.

Knee strains occur when tendons or muscles surrounding the knee are stretched, usually due to hyperflexion or hyperextension of the knee. These strains can lead to pain outside of the knee joint but can cause dysfunction of the normal range of motion of the knee. The patellar tendon stretches from the lower kneecap to the front of the tibia bone at the front of the leg.

Knee bursitis occurs when a fluid-filled pouch (called a bursa) in the knee is irritated, inflamed, or infected. Bursas are fluid-filled sacs located around joints that act as shock absorbers that minimize the friction between various tissues, such as the muscles and tendons around the joints. In the knee, there are two main bursas, one above the kneecap (patella), and one below the knee joint near the front of the tibia bone.

Tears of the meniscus can occur from damage to the inside of the knee. The medial and lateral menisci (plural of meniscus) are semi-round pieces of cartilage that act as shock absorbers and smooth cushions for the thighbone (femur). These menisci can be injured acutely or can become dysfunctional gradually due to overuse and/or aging.

Knee joint dislocation can occur due to high-impact, large-force injuries to the knee (sports, motor vehicle accidents). This is a rare injury but causes severe damage to all the anatomical components of the knee and can include damage to the blood vessels and nerves about the knee. This requires emergency treatment or surgery.

The kneecap (patella) can dislocate to the side of the knee. The patella dislocation can be very painful but is generally not life-threatening and can be treated by popping it back into place (reduction of the patella), splinting, and physical therapy.

Knee fractures occur from direct blows to the bones. Patella, or kneecap, fractures occur when a person falls directly down onto the knees and the kneecap cracks due to the force. Collapse of the top of the tibia bone in the knee (tibia plateau fracture) can occur from sudden compression injury to the knee, especially in people with osteoporosis. Other fractures of the long bones (fibula, tibia, and femur) are rare with isolated injures to the knee.

Other overuse injuries of the knee include patellofemoral pain syndrome (often referred to as "runner's knee") and weakness and degeneration of the cartilage under the kneecap (chondromalacia patella). These injuries are due to an accumulation of repetitive damage to the knee structures. This may be cause by either congenital problems or improper mechanics of the knee movement.

Call your doctor if you:

• Can't bear weight on your knee or feel as if your knee is unstable or gives out
• Have marked knee swelling
• Are unable to fully extend or flex your knee
• See an obvious deformity in your leg or knee
• Have a fever, in addition to redness, Pain and Swelling in your knee
• Have severe Knee Pain that is associated with an injury

Knee pain can be caused by injuries, mechanical problems, types of arthritis and other problems

Injuries

A knee injury can affect any of the ligaments, tendons or fluid-filled sacs (bursae) that surround your knee joint as well as the bones, cartilage and ligaments that form the joint itself. Some of the more common knee injuries include:

• ACL injury. An ACL injury is a tear of the anterior cruciate ligament (ACL) — one of four ligaments that connect your shinbone to your thighbone. An ACL injury is particularly common in people who play basketball, soccer or other sports that require sudden changes in direction.
• Fractures. The bones of the knee, including the kneecap (patella), can be broken during falls or auto accidents. Also, people whose bones have been weakened by osteoporosis can sometimes sustain a knee fracture simply by stepping wrong.
• Torn meniscus. The meniscus is the tough, rubbery cartilage that acts as a shock absorber between your shinbone and thighbone. It can be torn if you suddenly twist your knee while bearing weight on it.
• Knee bursitis. Some knee injuries cause inflammation in the bursae, the small sacs of fluid that cushion the outside of your knee joint so that tendons and ligaments glide smoothly over the joint.
• Patellar tendinitis. Tendinitis causes irritation and inflammation of one or more tendons — the thick, fibrous tissues that attach muscles to bones. This inflammation can happen when there's an injury to the patellar tendon, which runs from the kneecap (patella) to the shinbone and allows you to kick, run and jump. Runners, skiers, cyclists, and those involved in jumping sports and activities may develop patellar tendinitis.

Mechanical problems

Some examples of mechanical problems that can cause knee pain include:

• Loose body. Sometimes injury or degeneration of bone or cartilage can cause a piece of bone or cartilage to break off and float in the joint space. This may not create any problems unless the loose body interferes with knee joint movement, in which case the effect is something like a pencil caught in a door hinge.
• Iliotibial band syndrome. This occurs when the tough band of tissue that extends from the outside of your hip to the outside of your knee (iliotibial band) becomes so tight that it rubs against the outer portion of your thighbone. Distance runners and cyclists are especially susceptible to iliotibial band syndrome.
• Dislocated kneecap. This occurs when the triangular bone that covers the front of your knee (patella) slips out of place, usually to the outside of your knee. In some cases, the kneecap may stay displaced and you'll be able to see the dislocation.
• Hip or foot pain. If you have hip or foot pain, you may change the way you walk to spare your painful joint. But this altered gait can place more stress on your knee joint and cause knee pain.

Types of arthritis

More than 100 different types of arthritis exist. The varieties most likely to affect the knee include:

• Osteoarthritis. Sometimes called degenerative arthritis, osteoarthritis is the most common type of arthritis. It's a wear-and-tear condition that occurs when the cartilage in your knee deteriorates with use and age.
• Rheumatoid arthritis. The most debilitating form of arthritis, rheumatoid arthritis is an autoimmune condition that can affect almost any joint in your body, including your knees. Although rheumatoid arthritis is a chronic disease, it tends to vary in severity and may even come and go.
• Gout. This type of arthritis occurs when uric acid crystals build up in the joint. While gout most commonly affects the big toe, it can also occur in the knee.
• Pseudogout. Often mistaken for gout, pseudogout is caused by calcium-containing crystals that develop in the joint fluid. Knees are the most common joint affected by pseudogout.
• Septic arthritis. Sometimes your knee joint can become infected, leading to swelling, pain and redness. Septic arthritis often occurs with a fever, and there's usually no trauma before the onset of pain. Septic arthritis can quickly cause extensive damage to the knee cartilage. If you have knee pain with any of the symptoms of septic arthritis, see your doctor right away.

Other problems

Patellofemoral pain syndrome is a general term that refers to pain arising between the kneecap and the underlying thighbone. It's common in athletes; in young adults, especially those whose kneecap doesn't track properly in its groove; and in older adults, who usually develop the condition as a result of arthritis of the kneecap.

Treatment for a knee injury depends on the part of the knee that is damaged and the extent of the damage.

Some injuries such as simple strains or sprains are treated with RICE therapy (rest, ice, compression, and elevation). Taking time off from sports and exercise may be enough for minor injuries to heal. Over-the-counter anti-inflammatories such as ibuprofen (Advil, Motrin) or naproxen (Aleve) may help treat the pain and inflammation from these minor injuries.

Knee immobilization or splinting keeps the knee from moving and decreases the chance of further injury. It can help stabilize an injured knee that may not be stable due to torn ligaments. It also keeps the knee from moving to assist in resting the knee.

Chronic knee injuries involving inflammation and bursitis may be treated with anti-inflammatories. Injections of cortisone (a steroid with powerful anti-inflammatory effects) may be helpful in these situations.

More extensive injuries involving torn ligaments, instability of the knee joint, swelling, decreased range of motion, or fractures will require an orthopedic surgeon consultation. In the initial stages of these more extensive injuries, RICE therapy can still be used. Staying off the leg by using crutches or a wheelchair may be advised.

Surgery may be indicated for tears of the ligaments or extensive damage to the menisci. Surgery may also be needed for fractures or dislocations of the knee. Some acute injuries such as those with high-force impact, or multiple parts of the knee damaged, may require emergency surgery.

Most knee surgery can be done arthroscopically, a procedure in which a camera is used and small punctures are made in the knee to insert instruments. Repairs can be done inside the knee without having the open the knee with a large incision. Most arthroscopic surgeries do not need to be done immediately after an acute injury. Some are delayed to allow for decreased inflammation.

After surgery, or if surgery is not an option, physical therapy can be used to strengthen and stretch the muscles surrounding the knee. Physical therapy can also allow for better movement mechanics of the leg and the knee to help prevent future injury.

What exercises are recommended, and what exercises should be avoided during rehabilitation for a knee injury?

During physical therapy for rehabilitation of a knee injury, the patient will be given specific exercises by the physical therapist in order to strengthen and stabilize the knee joint. These exercises include strengthening the front of the thigh (quadriceps), back of the thigh (hamstrings), calf, and hip. Consult your doctor and your physical therapist before starting any exercise program. Your physical therapist should insure that you are doing the exercises properly before doing them on your own.

If you have any pain or discomfort while doing prescribed exercises, see your doctor or physical therapist.

Some exercises that your physical therapist may recommend include the following:

• Quad sets
• Straight leg raises
• Straight-leg raise to the front
• Straight-leg raise to the back
• Hamstring curls
• Heel raises
• Heel dig bridging
• Shallow standing knee bends

The American Academy of Orthopedic Surgeons (AAOS) has an exercise guide that includes directions and pictures. Consult your doctor or physical therapist before trying any of these exercises on your own.

Some exercises to avoid following knee injury include the following:

• Full-arc knee extensions
• Lunges
• Deep squats
• Hurdler's stretches

These exercises can further stress already damaged knee joints.

What is the recovery time for a knee injury?

The recovery time for a knee injury depends on the type and severity of the injury. If the injury is significant enough to require surgery and/or physical therapy, the recovery time will be longer.

Simple strains or sprains can last for one to two weeks. More extensive injuries requiring arthroscopic surgery may take one to three months to heal.

Major traumatic injuries to the knee may take up to a year to heal.

Following the doctor's instructions for rest, immobilization, staying off your feet, and avoiding exercise that aggravates the injuries will help speed recovery.

Physical therapy can also speed recovery time. It is important to follow directions of your physical therapist to insure you are doing the exercises correctly and attaining the best results.

Chronic knee injuries that do not require surgery may flare up from time to time. Physical therapy, anti-inflammatory medications, and cortisone injections are used to provide temporary relief.

A number of factors can increase your risk of having knee problems, including:

• Excess weight. Being overweight or obese increases stress on your knee joints, even during ordinary activities such as walking or going up and down stairs. It also puts you at increased risk of osteoarthritis by accelerating the breakdown of joint cartilage.
• Lack of muscle flexibility or strength. A lack of strength and flexibility can increase the risk of knee injuries. Strong muscles help stabilize and protect your joints, and muscle flexibility can help you achieve full range of motion.
• Certain sports or occupations. Some sports put greater stress on your knees than do others. Alpine skiing with its rigid ski boots and potential for falls, basketball's jumps and pivots, and the repeated pounding your knees take when you run or jog all increase your risk of knee injury. Jobs that require repetitive stress on the knees such as construction or farming also can increase your risk.
• Previous injury. Having a previous knee injury makes it more likely that you'll injure your knee again.

There's no cure for a knee injury, but there are many things you can do to help manage your symptoms, including:

1. Rest and Ice

The first line of defense for any knee injury is to rest the joint, and reduce inflammation. Use ice packs or a bag of frozen peas wrapped in a towel to reduce swelling and ease the pain.

2. Stretch It Out

A lot of people don't realize that stretching can be just as important as icing when it comes to knee injuries. Stretching helps lengthen the tendons and ligaments around your knee, improving flexibility and preventing further injury. Try doing some squats with your feet shoulder-width apart—this will stretch out your quads and hamstrings, which are some of the most likely parts of your body to be injured during sports activities like basketball or soccer.

Other medications include:

1. Ibuprofen: This is a nonsteroidal anti-inflammatory drug that helps to relieve pain and swelling. It has been shown to be effective in reducing the pain of knee injuries, including the pain associated with osteoarthritis and rheumatoid arthritis.

2. Celecoxib: Another nonsteroidal anti-inflammatory drug, celecoxib can help reduce inflammation, as well as decrease pain and swelling. It's often used for conditions like osteoarthritis or rheumatoid arthritis when ibuprofen isn't enough to get the job done.

3. Naproxen sodium: Available over-the-counter as Aleve, naproxen sodium is also a nonsteroidal anti-inflammatory drug that works by blocking COX enzymes in your body that cause pain and inflammation.

4. Cortisone injections: Cortisone injections are a form of treatment for joint inflammation that has been shown to help patients with knee injuries such as arthritis or tendonitis feel better within days of receiving one.

Symptoms
Pain in the knee joint,Pain when walking or running,Swelling around the knee joint,Tenderness when pressed on the outside of the knee
Conditions
Arthritis,Osteoarthritis,Sports injuries,ACL injury,Cartilage tears
Drugs
Painkillers,Non-steroidal anti-inflammatory drugs (NSAIDs),Corticosteroids,Antibiotics,Anti-malarial drugs