No parent wants to see their sports-loving child sitting on the sidelines, but knee injuries put thousands of young athletes on the bench every year. It's not unusual for kids to fracture, sprain, strain, or dislocate the knee joint while playing on the field or just goofing around with friends.
Most kids just need a few days or weeks of rest to recover from a knee injury. Severe cases can require surgery and a longer recovery before kids are walking again and back on the playing field.
To understand how injuries happen, it helps to know how the knee works. The knee is the largest joint in the body; it provides stability and allows the legs to bend, swivel, and straighten.
The knee joint is at the ends of the femur (thighbone) and the tibia (shinbone); it is protected by the patella (kneecap). The ends of the femur and tibia and the back of the patella are covered in articular cartilage, which acts as a cushion to keep the femur, patella, and tibia from grinding against each other. On the top of the tibia, extra pads of cartilage called menisci help absorb the body's weight. Each knee has two menisci — the inside (medial) meniscus and the outside (lateral) meniscus.
The muscles around the knee include the quadriceps, a large muscle at the front of the thigh, and the hamstring, located at the back of the thigh. The quadriceps help straighten the leg and the hamstring helps bend the knee.
Several tendons — cables of strong tissue that connect muscles to bones — work together to help move the knee. The tendons in the knee are the quadriceps tendon, the patellar tendon, and the hamstring tendons. All work together to allow the leg to extend.
Ligaments are cables of strong tissue that connect bones to bones. The four main ligaments in the knee that help connect the femur to the tibia and keep the knees stable are:
Because the knee is such a complex joint with many moving parts, knee injuries are quite common. Frequent causes of injuries are overuse (from repetitive motions, as in many sports), sudden stops or twists, or direct blows to the knee.
Common injuries among kids include:
A strain happens when a child partially or completely tears a muscle or tendon. With knee strains, kids may have bruising around the knee in addition to the symptoms mentioned above for sprains.
Tendonitis happens when a tendon gets irritated or inflamed. It is often caused by overuse or poor training (such as lack of strength exercises or stretching). A child with tendonitis might have pain or tenderness when walking or at rest, or when bending, extending, or lifting a leg.
Damage to the menisci is a very common sports injury, especially in sports where kids have sudden changes in speed or make side-to-side movements. Meniscal injuries can occur together with severe sprains, especially those involving the ACL. Meniscal injuries can cause tenderness, tightness, and swelling around the front of the knee. Sometimes fluid collects around the knee (known as effusion).
A fracture is a cracked, broken, or shattered bone. Kids may have trouble moving the bone and are likely to have a lot of pain. Patellar dislocation happens when the patella 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 needs to be put back in place by a doctor. Symptoms include swelling and pain in the front of the knee, an abnormal bulge on the side of the knee, and inability to walk on the leg with the affected knee.
Sometimes a small piece of bone or articular cartilage softens and/or breaks off from the end of a bone, causing long-term knee pain. This is called osteochondritis dissecans (OCD). Symptoms include pain; swelling; an inability to move the joint; and stiffness, catching ("locked knee"), or popping sensations with knee movement.
Chondromalacia pattellae happens when the cartilage in the patella 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.
A bursa is a sac filled with fluid located over a bony prominence to prevent friction. 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. Most common in athletes 10 to 15 years old, its symptoms include a bump below the knee joint that's painful to the touch and painful with activity. Pain is relieved with rest.
Most knee exams involve lying down flat on a table while the doctor manipulates the knee to see how stable it is and if any part of the joint hyperextends or dislocates.
Any child with a knee injury should rest the knee as much as possible.
Immediately after the injury, apply ice to the area for 20-minute intervals to reduce swelling and use compression bandages to help stabilize the knee. Do not let the child bear weight on the knee, and elevate the leg (above the heart) on pillows or other soft objects to reduce pain and swelling.
Doctors call this method of treatment RICE:
The doctor might prescribe anti-inflammatory medication if your child has severe inflammation and pain.
After initial treatment, some kids may wear a knee immobilizer (a brace or a sleeve that's wrapped around the leg to keep it from moving too much) or a cast for a few weeks while the knee heals, and might need to use crutches to get around.
More serious knee injuries can require surgery to reconstruct the knee if the child has torn ligaments or tendons or bone fractures.
During arthroscopy (a minimally invasive surgical technique) surgeons make a small opening in the knee and insert an arthroscope, a tiny tube-like tool, into the joint. The arthroscope has a lighted video camera on the end that is wired to a TV screen to give the surgeon a magnified view while operating.
Most of the time, the doctor is able to fix the problem during an arthroscopy. But if the injury is too complex, the surgeon will have to switch to "open" surgery, which requires a larger incision to see the area with the naked eye.
Regardless of whether a child has arthroscopy or a traditional open surgical procedure for a knee injury, the recovery period will be several weeks to a couple of months.
Most kids who recover from a knee injury will need some sort of rehabilitation ("rehab") therapy to help heal the knee and to:
Most kids undergo rehab at a center three times a week, with daily exercises they practice at home. Accelerated rehab programs require more frequent therapy and speed up recovery to 4 to 6 months.
While most sports are off limits — especially the one that caused the injury in the first place — kids can do some low-impact activities that may be fun and even therapeutic, like swimming, bike riding, or protected running. Talk to your doctor about which of these might benefit your child and when normal activities can be resumed.
Preventing knee injuries is a lot less painful and a lot less hassle than undergoing surgery.
If your kids play sports, be sure they always wear appropriate protective equipment during practices and competitions. Kneepads and shin guards (as well as helmets and other protective gear) will help prevent injury. Also be sure that they wear supportive shoes that are in good condition and appropriate for the sport.
More tips for avoiding sports injuries:
Reviewed by: Alfred Atanda Jr., MD
Date reviewed: October 2012
|American Academy of Orthopaedic Surgeons (AAOS) The AAOS provides information for the public on sports safety, and bone, joint, muscle, ligament and tendon injuries or conditions.|
|American College of Sports Medicine This site has tips on staying safe while playing sports and exercising.|
|National Athletic Trainers' Association This site contains information on certified athletic trainers and tips on preventing and healing sports injuries.|
|Bursitis Bursitis, an irritation of the small fluid sacs that provide cushioning in some joints, is often caused by sports-related injuries or repeated use of a particular joint.|
|Runner's Knee Runner's knee is the most common overuse injury among runners, but it can also happen to other athletes who do activities that require a lot of knee bending.|
|Jumper's Knee Jumper's knee is an inflammation or injury of the patellar tendon. Although it can seem minor, it's actually a serious condition that can get worse over time and ultimately require surgery if not treated.|
|Jumper's Knee (Patellar Tendonitis) Jumper's knee is an inflammation or injury of the patellar tendon. Although it can seem minor, it's actually a serious condition that can get worse over time and ultimately require surgery if not treated.|
|Medial Collateral Ligament (MCL) Injuries MCL injuries - which are common in active and athletic kids - happen when excessive pressure is put on the knee joint, resulting in a torn ligament.|
|Strains and Sprains Are a Pain What's a sprain? What's a strain? Find out in this article for kids.|
|Osgood-Schlatter Disease Osgood-Schlatter disease isn't serious, but it causes knee pain in athletes. Find out more in this article for kids.|
|Osgood-Schlatter Disease Osgood-Schlatter disease (OSD) is an overuse injury that can cause knee pain in teens, especially during growth spurts. Learn more.|
|Knee Injuries Healthy knees are needed for many activities and sports and getting hurt can mean some time sitting on the sidelines.|
|Bones, Muscles, and Joints Without bones, muscles, and joints, we couldn't stand, walk, run, or even sit. The musculoskeletal system supports our bodies, protects our organs from injury, and enables movement.|
|Anterior Cruciate Ligament (ACL) Injuries ACL injuries - which are common in active and athletic kids - happen when excessive pressure is put on the knee joint, resulting in a torn ligament.|
|Knee Injury: Caroline's Story Caroline loved sports. But when an ongoing knee injury kept her from playing the sports she loved, she discovered new interests. Read her story.|
|Your Bones Where would you be without your bones? Learn more about the skeletal system in this article for kids.|
|Anterior Cruciate Ligament (ACL) Injuries ACL injuries - which are common in active and athletic people - happen when excessive pressure is put on the knee joint, resulting in a torn ligament.|
|Medial Collateral Ligament (MCL) Injuries MCL injuries - which are common in active and athletic teens - happen when excessive pressure is put on the knee joint, causing a torn ligament.|
|Repetitive Stress Injuries Repetitive stress injuries happen when too much stress is placed on a part of the body, causing problems like swelling, pain, muscle strain, and tissue damage.|
|Sports and Exercise Safety Playing hard doesn't have to mean getting hurt. The best way to ensure a long and injury-free athletic career is to play it safe from the start. Find out how.|
|Meniscus Tears The key to healing meniscus tears is not to get back into play too quickly. Find out what meniscus tears are and how to treat them.|
|Preventing Children's Sports Injuries Participation in sports can teach kids sportsmanship and discipline. But sports also carry the potential for injury. Here's how to protect your kids.|
|Osgood-Schlatter Disease Osgood-Schlatter disease (OSD) is one of the most common causes of knee pain in adolescents. It's really not a disease, but an overuse injury.|
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