A knee sprain is an injury of the ligaments; tough bands of fibrous tissue that connect the bones of the upper and lower leg at the knee joint. One of the main forms of knee sprain is in the anterior cruciate ligament (ACL). The ACL and the posterior cruciate ligament (PCL) bridge the inside of the knee joint, forming an, “X” pattern that stabilises the knee against front-to-back and back-to-front forces. There are certain movements in the knee that causes a sprain in the ACL such as: a sudden stop; a twist, pivot, or change in direction at the joint; extreme over-straightening (hyperextension); or a direct impact to the outside of the knee or lower leg. These injuries are quiet common among athletes in sports such as: football, basketball, soccer, rugby, wrestling, gymnastics, and skiing.
It is suggested that when one knee ligament suffers a sprain, there is a good chance that the other parts of the knee may also be injured, most commonly the ACL. Knee sprains are very common. ACL sprains tend to cause more significant symptoms compared to MCL injuries. The most frequent signs of an ACL sprain are:
- A pop heard or felt inside your knee at the time of injury
- Significant knee swelling within a few hours after injury
- Severe knee pain that prevents you from continued participation in your sport
- Black-and-blue discoloration around the knee
- Knee instability- the feeling that your knee will buckle or give out
After injury, a physiotherapist will examine both knees, comparing the injured knee to the uninjured one. During this exam, the physiotherapist will check your injured knee for signs of swelling, deformity, tenderness, fluid inside the knee joint and discoloration. If the patient does not have too much pain and swelling, a physiotherapist will then evaluate the knee’s range of motion and will pull against the ligaments to check their strength. During the exam, the patient will have to bend their knee and the physiotherapist will gently pull forward or push backward on their lower leg where it meets the knee.
Based on the results of the patients’ exam, diagnostic tests may need to be performed to further evaluate the condition of the patients’ knee. These tests may include standard X-Ray’s to check for ligament separation from bone or fracture. Tests may also include a MRI scan or a camera –guided knee surgery (arthroscopy). The expected duration of the injury depends on the severity of the patients’ knee sprain, their rehabilitation program, and what type of sports the patients play. In general, milder sprains heal within 2-4 weeks, whereas other types may take 4-12 months. There are many ways of preventing ACL knee sprain, to help sports related injuries you can:
- Warm up and stretch before participating in athletic activities
- Do exercises which strengthen the leg muscles around the knee, especially the quadriceps.
- Avoid sudden increases in the intensity of a training program. Do not push too hard or too fast. Gradually increase intensity.
- Wear comfortable, supportive shoes that fit your feet and fit your sport
About 90% of people with ACL injuries can expect a full recovery after proper treatment and a good physical therapy program. As a long-term complication, some patients who suffered from an ACL sprain eventually develop pain from osteoarthritis in the joint where the knee has been injured. This symptom may not become present until 15 to 20 years after the initial knee injury.
Call a professional when:
- Knee becomes very painful or swollen
- Cannot bear weight
- Feels as if it will buckle or give out.