If you've ever suffered a knee injury, you know that you
need healthy knees for many activities and sports, and that getting
hurt can mean some time sitting on the sidelines. Fortunately,
there are ways you can prevent knee injuries.
What's in a Knee?
To understand knee injuries, first you have to understand the
knee. The knee is a
, which means it sits between the area where
connect. It's actually the largest joint in the body. Your
knees provide stability and flexibility for your body and allow
your legs to bend, swivel, and straighten.
The knee is made up of several body parts like bones,
, all working as one. So when we talk about a knee injury, it could
be stress or damage to any of these parts.
Bones and Cartilage
The knee sits in the middle of three bones: the
(your shin bone), the
(your thigh bone), and the
(the knee cap). The patella is a flat, triangular bone that
protects the knee joint.
The ends of the femur and the patella are covered in
. Articular cartilage acts like a cushion and to keep the femur,
patella, and tibia from grinding against each other. On the top of
the tibia, extra pads of cartilage called
help absorb the body's weight (if you're talking about one,
it's called a
). Each knee has two menisci - the inside (
) meniscus and the outside (
The muscles in the knee include the
, a large muscle at the front of the thigh, and the
, which is located at the back of the thigh. The quadriceps muscle
helps you straighten and extend your leg, and the hamstring helps
you bend your knee.
Tendons and Ligaments
work together to help the knee move naturally.
Tendons are like cables of strong tissue that connect muscles to
bones. The tendons in the knee are the
. The quadriceps tendon connects to the top of the patella
(kneecap) and allows you to extend your leg. The patellar tendon
connects to the bottom of your kneecap and attaches to the top of
the tibia (shinbone).
Ligaments are like cables of strong tissue that connect bones to
bones or cartilage to bones. There are four ligaments in the knee
that help connect the femur to the tibia and keep your legs
medial collateral ligament (MCL):
The MCL connects your femur to your tibia along the inside of
your knee. It keeps the inner part of your knee stable and helps
control the sideways motion of your knee, like keeping it from
lateral collateral ligament (LCL):
The LCL connects your femur to your tibia along the outside of
your knee. It keeps the outer part of your knee stable and helps
control the sideways motion of your knee, like keeping it from
anterior cruciate ligament (ACL):
The ACL connects your femur to your tibia at the center of the
knee. It helps control forward motion and rotation, like keeping
your shinbone from sliding out in front of your thighbone.
posterior cruciate ligament (PCL)
- The PCL connects your femur to your tibia at the back of the
knee. It helps control the knee's backward motion, like
keeping the shinbone from sliding out under the thighbone.
Types of Knee Injuries
Now that you know all about its working parts, you probably
realize that there are a bunch of ways to injure a knee. Common
causes for injuries are overuse (from repetitive motions, like in
many sports), sudden stops or twists, or direct blows to the knee.
Here are some of the more common injuries:
A sprain means you've stretched or torn a ligament. Common
knee sprains usually involve damage to the ACL and/or MCL. The most
serious sprains involve complete tears of one or more of the knee
ligaments. Symptoms of knee sprains include:
- a popping or snapping sound in the knee at the time of
- pain that seems to come from within the knee, especially with
- not being able to put any weight on that leg
- fluid behind the kneecap
- the knee feels loose or unstable
A strain means you've partially or completely torn a muscle
or tendon. With knee strains, you may feel symptoms similar to a
sprain and may see bruises around the injured area.
Tendinitis happens when a tendon gets irritated or inflamed. It
is often caused by overuse. A person with tendinitis might have
pain or tenderness when walking, or when bending, extending, or
lifting a leg.
Damage to the menisci is a really common sports injury,
especially in sports where sudden changes in speed or side-to-side
movements can cause them to tear. Meniscal injuries often occur
together with severe sprains, especially those involving the
Meniscal injuries can cause tenderness, tightness, and swelling
around the front of the knee. Sometimes fluid collects around the
knee (this is called
Fractures and Dislocations
A fracture is a cracked, broken, or shattered bone. You may have
trouble moving that bone and it's likely there's a lot of
pain. Patellar dislocation happens when the patella (the kneecap)
is knocked off to the side of the knee joint, by twisting or some
kind of impact. Sometimes it will go back to its normal position by
itself, but usually it will need to be put back into place by a
Symptoms include swelling and a lot of pain at the front of your
knee. There will usually be an abnormal bulge on the side of your
knee, and you may be unable to walk.
Sometimes a small piece of bone or cartilage softens or breaks
off from the end of a bone, causing long-term knee pain. This is
. Symptoms of OCD include pain, swelling, an inability to extend
the leg, and stiffness, catching, or popping sensations with knee
movement. Treatment can include resting the knee, wearing a cast
for a couple of months, and sometimes surgery in older teens.
happens when the cartilage in the knee joint softens because of
injury, muscle weakness, or overuse, and the patella and the
thighbone may rub together. This causes pain and aching, especially
when a person walks up stairs or hills. Treatment may involve
Other Conditions of the Knee
is a sac filled with fluid located near a joint. If a bursa in the
knee becomes inflamed and swollen from overuse or constant
friction, it can develop into a condition called bursitis. Symptoms
of bursitis in the knee include warmth, tenderness, swelling, and
pain on the front of the kneecap.
Osgood-Schlatter disease is a painful disorder caused by
repetitive stress on the front end of the tibia where the patellar
tendon connects to the bone. It happens most frequently in young
athletes between the ages of 10 to 15 years. Symptoms include a
bump below the knee joint that's painful to the touch and is
also painful with activity. Pain is relieved with rest.
What Do Doctors Do?
There are different things a doctor may do to figure out whether
you have a knee injury. Treatment for a knee injury usually depends
on the type of injury you have.
First, your doctor will ask you questions about your symptoms,
including what your usual activities are, especially any sports you
play. The doctor will also want to know about other health
conditions that lead to knee pain.
The doctor will then examine the different parts of your knee,
checking the bones, ligaments, and tendons for any signs of injury.
The doctor will probably bend, twist, and turn your knee to look
for any signs of an unstable knee joint. Don't be surprised if
you're asked to get off the exam table and walk, bend over, or
squat so your doctor can get a better look at your knee.
of your knee is needed to get a good picture of your bones. A
may also be recommended so doctors can get a better
For injuries like mild sprains, strains, and overuse, resting
your knee may be one of the first treatments your doctor
If your doctor recommends RICE, you should rest your knee as
much as possible, use ice packs for a couple of days to bring down
swelling, use compression (ACE) bandages, and elevate the leg on
pillows or other soft objects. For inflammation and pain, your
doctor may prescribe anti-inflammatory medications like
Other treatment for knee injuries may involve using a knee
immobilizer (kind of like a brace or a sleeve that you wrap around
your leg to keep it from moving too much), or having to wear a cast
for a few weeks or months. You may also have to use crutches to get
around for awhile.
For more serious knee injuries, your doctor might recommend you
, a doctor specially trained in the care of bone and joint diseases
(also called an
). Orthopedists take care of many kinds of knee injuries,
especially those involving sports and different types of accidents.
He or she will know how to treat the injury and follow your
progress as it heals.
If necessary, an orthopedist will perform
, a type of surgery that takes a direct look at the inside of your
During arthroscopy, the orthopedist first makes a small opening
in the knee and inserts an arthroscope, a tiny tube-like tool, into
the joint capsule. The arthroscope contains a lighted video camera
on the end, and is wired to a television screen that the surgeon
watches while moving the scope to pinpoint the exact knee problem.
Most of the time, the doctor is able to fix the problem during the
procedure, like repairing a torn ACL ligament.
Arthroscopy is often used to treat knee injuries such as
ligament and meniscal tears, as well as other types of serious knee
injuries. An orthopedist can also perform open surgery on the knee,
which allows him or her to see the injury without the aid of a
Depending on the type of knee injury you have, your doctor may
recommend rehabilitative physical therapy. Working with a physical
therapist, you'll do specific exercises designed to take your
knee joint through its range of motion to prevent stiffness and
scarring as your knee heals. You may also need to do regular
exercises to strengthen the muscles surrounding the knee. Physical
therapy is commonly used to help a person recover after
You may be anxious for your knee to heal so you can get back to
your sport and your normal life. But trying to rush your recovery
after an injury or surgery can put you at risk for future injury
and may further extend the healing process. Take your doctor or
physical therapist's instructions seriously, and don't put
your health in jeopardy by returning to your normal activities
before you get the go-ahead from a health pro.
Preventing Knee Injuries
Preventing knee injuries from the start is a lot less painful
and a lot less hassle than undergoing surgery. If you play sports,
always wear appropriate protective equipment during practices and
competitions. Kneepads and shin guards (as well as helmets and
other protective gear) will help to protect you from injury.
You'll also want to make sure you wear supportive shoes that
are in good condition and are appropriate for your sport.
When it comes to your workouts, always warm up and cool down,
and remember to work up to your training program slowly. Suddenly
increasing the intensity or duration of your workouts can lead to
overuse injuries. Try weightlifting to strengthen your muscles and
stretching and yoga to improve your flexibility because strong,
flexible muscles help support and protect joints.
If you play only one sport, try conditioning and training
year-round - even if it's at a lower intensity than during your
competitive season - to maintain coordination and balance. That way
you'll be less likely to injure yourself during your
In growing kids and teens, imbalances in muscle flexibility and
strength can lead to injuries and inflammation from overuse.
Regular stretching can help. After an injury or surgery has healed,
it is also important to continue a regular stretching or
conditioning program to prevent another injury.
The way you move can also help you prevent knee injuries. If
your sport involves a lot of jumping, make sure to bend your knees
when you land, which takes pressure off of the ACL. Do you have to
cut laterally or pivot frequently in your sport? Use your joints to
crouch and bend at the knees and hips, reducing your chance of a
Remember, if you experience any symptoms of knee injuries or
knee pain, don't hesitate to tell your coach, parent, or
doctor. Limit your activities until you can get treatment or a
Barbara P. Homeier, MD
Date reviewed: January 2006
Originally reviewed by:
Suken A. Shah, MD
Note: All information is for educational purposes only. For specific medical advice,
diagnoses, and treatment, consult your doctor.
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