Encyclopedia / K / Knee Injury

Knee Injury


An injury to either or both knees causing pain and/or disability.


The legs, especially the knees, are the most injury-prone parts of the body. Knee injuries are the leading cause of long-term disability among athletes.

Although most commonly due to sport, anyone can hurt their knees if they make an awkward movement or give the knee a hard blow. Some women may be especially susceptible because their wider pelvis tends to make them knock-kneed. Besides the knock-kneed, those prone to knee problems are the flat-footed, whose feet pronate or turn inward too much, those with unstable or loose kneecaps (patella), and those who have imbalanced thigh muscles.


Diagnosing knee injuries can be tricky, but any sudden knee swelling signals trouble. Knee pain should never be ignored or masked with medication. If symptoms persist, consult a physician. Accurate diagnosis, preferably soon after a knee injury, is essential for correct treatment. Any details noticed at the time - a pop or snap, and how soon swelling and disability appeared - can help the physician determine the cause and guide treatment.

Your physician will take a medical history and perform a physical examination with special focus on your knee(s). In some cases, an MRI (magnetic resonance imaging) may improve the diagnosis of certain knee injuries. It may be done for individuals with severe pain or for those who cannot relax sufficiently to allow adequate physical examination.

Two of the most common knee problems are:

Tendonitis: Where a tendon itself, or the sheath around a tendon becomes inflamed and painful.

Swelling: Excessive fluid accumulates in the synovium (membrane in the knee capsule) and this may be a sign of an underlying condition. Such fluid buildup can be blood or increased secretion form the synovium as a reaction to some type of inflammation or overuse.


For mild knee discomfort, ice, pain medications, and modified movement may be enough, but persistent swelling or pain requires medical care. Your physician may suggest elevation of the knee joint, application of a compression dressing or brace, and occasional ice.

Crutches may be recommended to minimize weight-bearing on the affected knee, at least initially. He or she may prescribe pain medications as well. Physical therapy can often be helpful after the acute injury has been treated. More serious injury may require referral to a surgeon for evaluation.

Total knee replacements have improved with the development of new designs and materials.

Knee Braces

A knee brace can help reduce stress on the knee. Some knee braces are designed for the recovery phase after an injury or surgery. The post-surgical brace, which is usually bulky and restricts mobility, is normally made of rigid carbon fiber or other polymers. Lightweight metal or plastic hinges allow limited flexion. Most braces fasten around the knee with a fabric wrap.

Apart from sophisticated knee braces, a variety of other braces are available in a drugstore. These knee braces include neoprene sleeves, lace-up canvas, metal-supported, and ace bandages. Even the elastic pull-on bandages can be useful, because they help the body to know where the knee is in space at any given moment. This can help protect a potentially vulnerable knee while avoiding compromising or hazardous positions.

Arthroscopic Knee Surgery

Knee injuries can now often be diagnosed and surgically corrected at the same time with arthroscopy, reserving the older, open-knee operations for ligament and reconstructive problems. Occasionally, surgeons now replace entire damaged knees with arthroplasty (knee transplants) or with metal replacements. Arthroscopic surgery greatly reduces recovery time.

The arthroscope is a fiberoptic device useful for removing torn cartilage and for ligament repairs. It contains a light and magnifying lenses that relay a clear view of the knee's interior spaces through a monitor and eyepiece. Tiny incisions are made in the knee to insert the arthroscope and inject saline (salt) solution. An accurate diagnosis and surgical correction are undertaken at the same time, under local or general anesthetic. An arthroscope allows a thorough analysis of knee problems, and can be used to diagnose ligament tears, see toughened surfaces, and plan open-knee surgery.

After arthroscopic surgery, the small incisions are taped or stitched, the knee bandaged, and a few hours after surgery, the person can usually go home - preferably accompanied by a relative or friend who stands by until the side-effects of the anesthetic wears off.

Crutches may be needed to keep weight off the knee for a few days. Physiotherapy has become an indispensable part of post-surgical treatment to strengthen the knee and promote recovery.

Following arthroscopy, the knee may feel slightly uncomfortable and a gurgling noise may be heard for a time when walking. After about four weeks or less of mild exercise, regular sports may often be resumed.


What diagnostic tests are available for the knee?

What is the extent of the injury to the knee?

What is the current treatment for the injury?

Will heat or ice packs be beneficial?

Will any special exercises need to be done?

Will I need to wear a knee brace for activities?

How long will it take to fully recover?

Avoiding sudden jolting movements and rough running surfaces can help prevent knee injuries. Obesity adds pressure to the vulnerable knee joint, so weight reduction may help.

Exercises considered better for the knees include small (not deep) knee bends and straightening motions - done while in supination with most weight on the outside of the foot.

Sports that are easier on the knees include walking, swimming (flutter kicks, knees straight), skating, baseball, cross-country skiing, and, depending on the state of the knee, cycling (seat high, low gear, avoiding hills).

Choose activities to suit your own knee strength and capacity, and remember that sports especially "hard on the knees" include football, sprinting, soccer, rugby, hockey, squash, volleyball, basketball, downhill skiing, tennis and jogging - anything that pounds, jolts, or twists the knees.