Your knees are put under a lot of stress, whether you’re running, playing basketball, dancing, or simply cleaning house. Just climbing stairs can put pressure on each knee equal to four times your body weight. The result is that an estimated 50 million Americans suffer at some point from knee pain or injuries.

At least one out of every four sports injuries involves the knee. In addition, for millions, the knee is affected by chronic, age-associated ailments such as arthritis.

The knee is the largest joint in the body. Functioning simultaneously as a hinge, lever, and shock absorber, the knee is the key to your ability to stand up, walk, climb, and kick. Yet it depends almost entirely on soft tissue—ligaments and tendons—for stability.

Because of its complexity and the great forces to which it is routinely subjected, the knee is susceptible to a host of injuries, which can take weeks, if not months, to heal, even with proper rehabilitation. Here are the most common problems and their causes.

  • Sprain (torn ligament). The knee connects the thigh bone (femur) to the shin bone (tibia), and the only things holding these two large bones together are four ligaments, which are strong but not very flexible. If these are stretched beyond a certain point, one or more of the ligaments can be sprained. The sprains can range in severity from minor tears to complete ruptures, in which the ligament tears away from the bone and snaps (often with an ominous popping sound). Most seriously, the anterior cruciate ligament can rupture when you twist the knee in a fall, typically while downhill skiing. Other ligaments in the knee can be injured by a violent blow to the knee or sudden wrenching or twisting, as in hockey or soccer.
  • Runner’s knee (chondromalacia patella). This overuse injury is due to degeneration of the shock-absorbing cartilage (called the meniscus) under the kneecap and covering the ends of the femur and tibia. It is characterized by dull, aching pain under or around the kneecap and is usually most noticeable when you are descending stairs or hills. Nearly 30 percent of runners eventually develop this disorder. Skiers, cyclists, soccer players, and people who participate in high-impact aerobics classes are also susceptible to it.
  • Tendinitis. The tendons above or below the kneecap (patella) can become inflamed, usually through overuse—for instance, from dancing, hiking, or cycling. One frequent complaint is jumper’s knee, a form of tendinitis that afflicts basketball and volleyball players and weight lifters in particular.
  • Iliotibial band syndrome. If the tendon that runs down the outer side of the knee is tight, repetitive motion (as in running or cycling) can cause the tendon to rub against the bony area at the end of the thigh bone and become irritated.
  • Torn cartilage. This injury to the cartilage in the knee typically occurs when you twist the joint while putting weight on it. Over the years frequent squatting can weaken the knee to the point where something as minor as getting out of the car can tear the cartilage.
  • Arthritis. The knee is a common site for osteoarthritis, which involves the degeneration of cartilage at the joint and subsequent inflammation. It is the result of normal wear and tear over the years.

Symptoms of Knee Injuries

  • Pain, swelling, tenderness, and/or discomfort in your knee
  • Difficulty moving your knee joint; possibly a cracking sound when you bend your knee
  • An inability to straighten your leg
  • Discomfort or pain while walking or running
  • Fluid behind the kneecap
  • Unable to put any weight on the leg
  • Knee feels unstable
  • A snapping or popping sound in the knee at the time of injury
  • Bruises around the injured area

What Causes Knee Injuries?

Most overuse injuries such as runner’s knee and tendinitis (which are the problems most amenable to self-care) are linked to the muscles of the thigh, particularly the quadriceps. This large four-part muscle group on the front of the thigh, along with the hamstrings (located behind the thigh), provides the muscular support system for the knee. In addition to helping power movement, the quadriceps also stabilizes and guides the kneecap in its groove at the end of the thighbone. Weak or inflexible quadriceps may lead to improper tracking of the kneecap and instability of the supportive tendons, contributing to both runner’s knee and jumper’s knee.

What If You Do Nothing?

Any persistent knee pain (beyond mild discomfort) shouldn’t be ignored, since it may lead to chronic pain, stiffness, and swelling. Moreover, the surest way to speed recovery is to treat a recurring ache or pain right away, even if you’re able to continue the exercise or activity associated with it. If you feel pain, at the very least stop and rest.

Bear in mind, though, that rest alone isn’t likely to eliminate the cause of the problem. To avoid reinjury, you should not only actively treat the problem but take preventive measures such as those described below.

Knee Strengtheners

Staying fit through physical conditioning is the best way to avoid the stiffness and muscle weakness that can contribute to an injury to your knees. The three basic exercises shown here will help restore and maintain knee strength.

  • Knee extensions. Sit on a desk or counter and hold onto the edge. Slowly straighten one leg, extending the knee completely. Hold for five seconds, then lower it slowly. Repeat 10 times, then switch legs. You can also do this with a light weight.
  • Straight leg lifts. Lie on your back and bend one knee, keeping your foot on the floor. Slowly lift the straight leg about 12 inches off the floor; keep hips and lower back on the floor. Hold for five seconds, then lower it slowly. Repeat 10 times, then switch legs. You can also do this with a light weight around your ankle. Avoid this exercise if you have back problems.
  • Wall sit. Lean your back against a wall and squat until your upper legs are at a 45-degree angle to the wall. Hold for one minute, while tightening your buttocks. This exercise strengthens your quadriceps and gluteal muscles. Be sure to keep your knees aligned with your feet.

Home Remedies for Knee Injuries

For knee pain stemming from overuse injuries like runner’s knee or tendinitis, you can reduce aches and pains and speed recovery with the following measures.

  • RICE the injury site. Stopping any activity and resting is the first step in RICE, an acronym for rest, ice, compression, and elevation. Apply ice as soon as possible. Use an elastic wrap for compression, and then keep your leg elevated to reduce pain and swelling.
  • Take over-the-counter pain relievers. Nonprescription NSAIDs (aspirin, ibuprofen, and naproxen) will help reduce pain and swelling, though they won’t speed healing; acetaminophen will help with pain.


You can reduce the likelihood of a knee injury with the following precautions and conditioning exercises.

  • Beware of suddenly intensifying or lengthening your workouts. This can create additional friction in the joint and increase the risk of an overuse injury.
  • Wear protective gears. If playing sports, protective gears such as kneepads, shin guards and helmets can help to protect from injury.
  • Run on the right surface. Avoid running on very hard, very soft, or hilly terrain, all of which put added stress on knee joints.
  • Check your exercise shoes. If they are worn or don’t fit well, they may put your knees at risk.
  • Check your feet. The knee sometimes pays the price for foot abnormalities (such as flat feet), overpronation (the feet roll inward too much), or poor leg alignment (such as knock-knees), which can put greater stress on the joint. An orthotic device—a custom-made arch support—may help correct some foot or alignment problems. Make sure your knee is always aligned with your foot while exercising.
  • Minimize knee stress when cycling. To accomplish this, set your seat to the proper height and don’t pedal in high gears.
  • To gauge seat height, check your knee position at the bottom of the stroke: your knee should be only slightly bent.
  • Cycling in high gear—which increases tension on the pedals—also increases the pressure on your knees. Stay in low gears, which means faster, easier revolutions on the pedals. You’ll get more aerobic exercise with less stress on your knees.
  • Stretch your leg muscles before and after exercise. Maintaining flexibility allows you to attain maximum range of motion for your knees.
  • Strengthen your leg muscles. It’s especially important to condition the quadriceps. If you are a runner or walker, your quadriceps are probably much weaker than your hamstrings, so it’s a good idea to alternate cycling (an excellent way to strengthen the quadriceps) with running. Walking up stairs or hills also helps strengthen these muscles.
  • Be kind to your knees. If you have knee problems, hills and stairs can put too much stress on your knees, so you need to take it easy on these inclines or avoid them if they cause you pain. Also don’t kneel or do full squats, which can greatly increase stress on the knee. And avoid “knee-unfriendly” sports such as football, running on concrete, soccer, squash, tennis, and skiing.

Beyond Home Remedies: When To Call Your Doctor

Call your doctor immediately if you hear a popping sound when you injure your knee. Also call if your knee is swollen, stiff, and painful, or if you have any knee discomfort that interferes with your everyday activities.

What Your Doctor Will Do

After a careful physical examination to determine the cause of the knee pain, discomfort and/or instability, your doctor may recommend magnetic resonance imaging (MRI) to help make a more definitive diagnosis. For chronic or severe overuse injuries, physical therapy may be advised. For acute injuries such as a torn ligament, damage to the meniscus, or loose bodies floating in the knee cavity (which cause the knee to “lock”), surgery may be recommended. Much knee surgery is done by arthroscopy, in which tiny optical and surgical instruments are inserted through small incisions. Because it avoids opening up the knee, arthroscopic surgery substantially reduces the time a patient needs to stay in the hospital and can also speed up recovery time


The Complete Home Wellness Handbook

John Edward Swartzberg, M.D., F.A.C.P., Sheldon Margen, M.D., and the editors of the UC Berkeley Wellness Letter

Updated by Remedy Health Media

Publication Review By: the Editorial Staff at

Published: 07 Nov 2011

Last Modified: 26 Jan 2015