Knee Injury

Medically Reviewed By William C. Lloyd III, MD, FACS
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What is a knee injury?

An injury to the knee typically occurs as a result of trauma, whether sudden and severe or gradual and occurring over a period of time. Sports injuries are one of the most common causes of knee injury.

Injury to the knee can involve any or all of the components of the knee joint: the bones, ligaments, tendons, menisci, bursae, or the muscles that stabilize the knee joint. Four ligaments are important in maintaining the stability and function of the knee joint, the anterior and posterior cruciate ligaments and the medial and lateral collateral ligaments. The menisci (singular meniscus) are two pieces of cartilage that cushion the bones of the knee joint (the femur, or thigh bone, and the tibia, or large bone of the lower leg) permitting them to move smoothly against one another. Bursae are fluid-filled sacs that serve as an extra layer of protection for the joint. In addition to the tibia and the femur, the knee joint contains the patella, the bone commonly known as the kneecap.

Symptoms of a knee injury depend on the exact type and location of the injury. The pain may be dull or sharp and occur all the time or only when participating in certain activities. Swelling, bruising or bleeding can accompany the injury. At the time of injury you may hear or feel a crack or pop. With some knee injuries, the joint may lock or even give way when you try to stand. You may notice weakness in the affected leg.

Fortunately, most knee injuries are treatable conditions. Treatment options can include anti-inflammatory or pain control medications, physical therapy, and, in some cases, surgical repair of the injury.

A knee injury can require emergency care. Seek immediate medical care (call 911) for serious symptoms, such as paralysis, loss of sensation, absent pulses in the feet, the inability to move the knee joint, severe bleeding, or uncontrollable pain.

Seek prompt medical care if you have any pain, soreness, or other problems with you knee, or if you are being treated for a knee injury and symptoms recur or are persistent.

What are the symptoms of a knee injury?

Symptoms of knee injury include pain, limitation of movement, the presence of cracking or popping sounds, instability of the knee joint, and swelling, redness, or warmth of the skin. Symptoms may be mild or severe and depend to a great degree upon both the extent and severity of the injury.

Common symptoms of a knee injury

You may experience knee injury symptoms daily or just once in a while if the injury is minor. At times, any of these knee injury symptoms can be severe:

  • Bleeding or bruising
  • Inability to bear weight on the affected leg
  • Inability to move the knee joint, or restricted mobility of the joint
  • Inability to straighten the leg completely (locking)
  • Muscle weakness or spasm
  • Pain, whether at rest or during specific movements, that may be described as dull, sharp, burning, stabbing or aching
  • Popping, snapping or cracking sounds when the joint is moved
  • Swelling
  • Warmth and redness of the skin

Symptoms that might indicate a serious condition

In some cases, knee injury can be a serious condition that should be immediately evaluated in an emergency setting. Seek immediate medical care if you, or someone you are with, have any of these serious symptoms including:

  • Coldness of the feet, with weak or absent pulses
  • Loss of sensation in the lower leg
  • Obvious breakage or deformity of the bones
  • Paralysis
  • Severe bleeding
  • Uncontrollable pain

What causes a knee injury?

Knee injury can be a result of a direct fall or blow to the knee, a sudden twisting motion of the joint, or stress placed on the joint from any direction. Injuries may also develop as a result of overuse. Because of the different structures that comprise the knee joint, a number of different types of knee injury can occur, either singly or in combination.

Common causes of a knee injury

  • Bursitis (inflammation of the protective fluid-filled sacs around the joint)

  • Chondromalacia (problem with the structure of the cartilage of the kneecap)

  • Fracture of any of the bones of the knee

  • Iliotibial band syndrome (presence of tissue rubbing over the outer part of the knee bones that may result from overuse)

  • Osgood-Schlatter disease (repetitive stress injury involving the upper part of the shin bone)

  • Osteochondritis dissecans (problem with blood supply to the joint)

  • Sprains and strains

  • Tearing or damage to the menisci (protective cartilage inside the joint)

  • Tearing or stretching of the ligaments

  • Tendinitis

  • Tendon rupture

What are the risk factors for a knee injury?

A number of factors increase the risk of developing knee injury. Not all people with risk factors will get knee injury. Risk factors for knee injury include:

  • Muscle weakness or imbalance

  • Occupational activities that expose the knee to injury (slips, fall, blunt trauma)

  • Overweight or obesity (due to excess stress on the joint)

  • Participation in certain sports, particularly sports that involve stress or twisting of the knee joint such as downhill skiing

  • Previous knee injury

Reducing your risk of a knee injury

You may be able to lower your risk of knee injury by:

  • Exercising regularly to maintain muscle strength and flexibility

  • Maintaining a healthy weight

  • Wearing proper and well-fitting footwear for sports activities

How is a knee injury treated?

The first treatment for any knee injury involves typically rest, ice (ice or cold pack application), compression (soft compression with an elastic bandage), and elevation (keeping the affected knee elevated). These steps are commonly known by the acronym RICE. This combination of measures should bring immediate relief until medical care can be accessed and may be sufficient to treat minor injuries.

Knee injury may be treated by medications to control pain and inflammation, injections into the joint, physical therapy and exercise, bracing or the use of orthotic devices, or, in some cases, surgical repair. In most cases, a combination of these methods will be used by your treatment team. Most knee injuries are treatable, and it is important to precisely follow the treatment plan that your health-care team has designed specifically for your injury.

Medications for a knee injury

Medications to treat knee injury may be given to control pain if necessary. Sometimes medications may be injected into the joint itself. Examples of medications for knee injury include:

  • Anti-inflammatory medications such as ibuprofen (Advil, Motrin) or naproxen (Aleve) to decrease inflammation and control pain

  • Corticosteroid injections into the joint to decrease inflammation

  • Hyaluronic acid injections into the joint for pain relief

Other treatments for a knee injury

The use of orthotic devices such as shoe inserts, bracing of the knee, physical therapy, and surgical procedures are other treatments for knee injury.

Examples of additional treatments for knee injury include:

  • Arthroscopic surgery (the use of a camera and long, narrow tools inserted through a few small incisions) to repair the injury

  • Bracing of the knee joint

  • Partial or total knee replacement surgery

  • Physical therapy to strengthen muscles and stabilize the joint

  • Shoe inserts or orthotics

What are the potential complications of a knee injury?

Complications of untreated knee injury can be serious. You can help minimize your risk of serious complications by following the treatment plan you and your health care professional design specifically for you. Complications of knee injury include:

  • Absenteeism from work or school

  • Adverse effects of treatment

  • Decreased athletic performance

  • Disability

  • Infection

  • Joint deformity and destruction

  • Nerve problems that cause pain, numbness or tingling

  • Permanent or chronic pain

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Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2020 Nov 22
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THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.
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