A knee sprain is stretching or tearing of the ligaments that support the knee. Ligaments are strong bands of tissue that connect bones to each other.
Knee sprains may be caused by:
- Forced twisting of the knee
- Stopping suddenly while running
- Shifting your weight while running or skiing
- Landing awkwardly after jumping
- A blow to the outer or inner side of the knee
- A blow to the front of the knee while the knee is bent and the foot is firmly planted on the ground
A risk factor is something that increases your chance of getting a disease, condition, or injury. Risk factors for knee sprain include:
- Playing sports
- Poor coordination
- Poor balance
- Inadequate flexibility and strength in muscles and ligaments
- Loose joints
- Pain in the knee
- Swelling, redness, warmth, or bruising around the knee.
- Decreased range of motion in the knee
- Inability to stand on the affected leg
- Tenderness where the injured ligament attaches to a bone in the knee
- Swelling within the knee
The doctor will ask about your symptoms and how you injured your knee. The doctor will examine your knee to assess the stability of the joint and the severity of the injury.
Tests may include:
- X-rays–to make sure that no bones are broken
- MRI scan–to see if a ligament has torn completely (less common)
Knee sprains are graded according to their severity. In addition, the more ligaments involved the more severe the injury.
- Stretching and microtearing of ligament tissue
- Partial tearing of ligament tissue
- Mild instability of the joint when tested
- Severe or complete tearing of ligament tissue
- Significant instability of the joint
Rest–Avoid putting any pressure on your knee by not walking on that leg.
Ice–Apply ice or a cold pack to the knee for 15-20 minutes, 4 times a day for 2 days. This helps reduce pain and swelling. Wrap the ice or cold pack in a towel. Do not apply the ice directly to your skin.
Compression–Wrap your knee in an elastic compression bandage (eg, Ace bandage). This will limit swelling and provide some support for your knee. Be careful not to wrap the bandage too tight.
Elevation–Keep the injured knee raised above the level of your heart as much as possible for 24 hours or so. This will help drain fluid and reduce swelling. A couple of days of elevation may be recommended for severe sprains.
Medication–Ask your doctor if you have any questions about using medications. Drugs that are commonly used to reduce pain and inflammation include:
- Ibuprofen (Motrin, Advil)
- Naproxen (Aleve, Naprosyn)
- Acetaminophen (Tylenol)
Brace–You may need to wear a brace to immobilize your knee during recovery. You may also need to wear one after you return to sports play with your doctor’s permission.
Leg Cast–If you have a severe sprain, your doctor may recommend a short leg cast for 2-3 weeks.
Rehabilitation Exercises–Begin exercises to restore flexibility, range of motion, and strength in your knee as recommended by your healthcare professional.
Surgery–Surgery may be recommended if a ligament is torn completely.
To reduce your risk of spraining a knee:
- Warm up and stretch before exercise. Cool down and stretch after exercise.
- Take a break from both sports and exercise when you feel tired.
- Do exercises that strengthen the leg muscles. Exercises that improve proprioception (typically those involving balance) have been shown to reduce the risk of knee sprains in athletes.
- Do regular stretching exercises of the muscles of the legs.
- Learn the proper technique for exercise and sporting activities. This will decrease stress on all your muscles, ligaments and tendons, including those around your knee.
- Consult with a coach or athletic trainer about whether you (or your child) should use a knee brace designed to prevent ligament tears. There is some evidence that such braces can be useful, but not all experts agree on when they should be used, and the American Academy of Pediatrics recommends that they not be prescribed for children based on data available in 2001.