The anterior cruciate ligament is the most commonly injured ligament of the knee, and it is most frequently injured during an athletic activity. Sports are becoming an increasingly important part of day-to-day life in the United Kingdom, increasing the number of ACL injuries. This injury has received a great deal of attention from orthopaedic surgeons over the past 15 years, and very successful operations have been developed to reconstruct the torn anterior cruciate ligament.
Anterior cruciate ligament injury Anatomy
The Anterior cruciate ligament controls how far forward the tibia (shin bone) moves in relation to the femur (thigh bone). If the tibia moves too far, the anterior cruciate ligament can rupture. The anterior cruciate is also the first ligament that becomes tight when the knee is straight. If the knee is forced past this point, or hyper extended, the anterior cruciate ligament injury can occur. In severe cases the cruciate ligament injury can develop into a full blown tear or rupture.
This tearing of the anterior cruciate ligament results in a loud pop and a feeling of instability in the knee. The cruciate ligament may not be the only ligament injured in the knee is twisted violently, such as in a clipping injury in football. It is not uncommon to see both the medial collateral ligament (MCL) and anterior cruciate ligament injury to occur at the same time
The major cause of anterior cruciate ligament injury is sports related. Numerous types of sports-related activities have been associated with anterior cruciate injury. Those sports requiring the foot to be planted and the body to change direction rapidly (such as football) carry a high incidence of injury.
Football is frequently the source of an anterior cruciate injury because it combines the activity of planting the foot and rapidly changing direction with the threat of bodily contact. Downhill skiing is another frequent source of anterior cruciate ligament injury, especially since the introduction of ski boots that extend higher up the calf.
These boots move the forces caused by a fall to the knee rather than the ankle or lower leg. Cruciate ligament injury usually occurs when the knee is forcefully twisted or hyper extended Many patients recall hearing a loud pop when the ligament tears and feeling the knee give out.
There has been a dramatic increase in the number of females who suffer anterior cruciate ligament tears. This is in part due to the rise in women’s athletics, but studies have shown that female athletes are more likely to suffer this cruciate ligament injury, injury then their male counterparts. It is uncertain why this is the case. Initially, it was thought that females were at higher risk because of differences in training intensity. However latest research suggests that there may be a difference in the anatomy of the female knee, or the female ligament may not be as strong due to the effects of the female hormone oestrogen. These factors may lead to a higher risk of anterior cruciate ligament injury for the female athlete.
The symptoms following cruciate ligament injury vary in different people. Usually, swelling of the knee occurs within a short time following the injury. This is due to bleeding into the knee joint from torn blood vessels in the damaged ligament.
If the anterior cruciate ligament ruptures, instability caused by the torn ligament leads to a feeling of insecurity and weakness of the knee, especially when attempting to change direction. The knee may feel like it wants to bend too far backwards.
The pain and swelling from the initial injury will usually be gone after two to four weeks, but the instability remains. The symptom of instability and the inability for the patient to trust the knee is usually the reason for treatment.
!!!The following advice pertains to ligament strain only! If the anterior cruciate ligament has been injured and rupture is suspected, medical help should be sought.!!!
Remember that virtually all anterior cruciate ligament injury happens at the contact phase of gait (when the foot hits the ground) due to increased biomechanical stress at this point.
Golden rule- Don’t ignore the problem, it won’t go away!
The way we function biomechanically is predominantly controlled by genetics, its hereditary (runs in the family). The way you function is set and cannot be cured. What you can do however is control lower limb biomechanics by altering foot position during the contact phase of gait. This can be achieved by wearing a good shoe (see our shoe guide) with orthotics (foot beds), knee strengthening and knee support.
1. Check your footwear
Are your running shoes worn and in need of replacing? If so change them. The chances of anterior cruciate ligament injury is greatly increased with higher impact forces so a good shock absorbing shoe is a must. For more advice on running trainers our running shoe advice page is worth reading. Read more->
Below are a selection of trainers that are ideal for athletes.
Trainers for a neutral or under pronating foot type
Trainers for over pronators
2. rectify Poor biomechanics with orthotics
The way your foot strikes the ground and the forces that are placed on it can have a direct effect on biomechanics causing anterior cruciate ligament injury and can also delaying healing times. Check our biomechanics page for detailed information. Read more->
3. Knee strengthening
The single best exercise to improve the strength of the muscles around the knee is eccentric loading. This is usually done none weight bearing, however the use of a wobbleboard is an excellent way to strengthen muscles around the knee, foot and ankle in a controlled gentle manner. Whilst our clinicians have found it a brilliant way to strengthen muscles around the knee, traditionally a wobbleboard was used to help balance (proprioception). Proprioception is the nerve connection from the brain to the foot. This is often damaged/ disrupted after injury and can increase the chances of injury from recurring. It can also significantly delay recovery.
Use of a wobbleboard therefore has a dual benefit in the treatment of anterior cruciate ligament injury.
4. Knee support
One of the most vital considerations after suffering cruciate ligament injury. This device provides extra stability to the knee when playing sports. The material also causes localised vasodilation (opening of the blood vessels) increasing circulation to the area. Ligaments have a notoriously poor blood supply. Increasing circulation to the ligaments can reduce the chance of injury. A knee brace will help supports the knee whilst the cruciate ligament recovers and will also provide support post injury.
Anterior cruciate ligament injury prevention checklist summary
- Rectify Biomechanics if necessary
- Check Running shoes
- Knee strengthening
- Knee support
Returning to Activity
The goal of rehabilitation is to return you to your sport or activity as soon as is safely possible. If you return too soon you may worsen your cruciate ligament injury which could lead to permanent damage. Everyone recovers from anterior cruciate ligament injury at a different rate.
Returning to your activity is determined by how soon your cruciate ligament recovers, not by how many days or weeks it has been since your anterior cruciate ligament injury occurred.
You may safely return to your sport or activity when, starting from the top of the list and progressing to the end, each of the following is true:
You have full range of motion in the injured leg compared to the uninjured leg.
You have full strength of the injured leg compared to the uninjured leg.
You can jog straight ahead without cruciate ligament injury pain.
You can sprint straight ahead without anterior cruciate injury pain.
You can do 45-degree cuts, first at half-speed, then at full-speed.
You can do 20-yard figures-of-eight, first at half-speed, then at full-speed.
You can do 90-degree cuts, first at half-speed, then at full-speed.
You can do 10-yard figures-of-eight, first at half-speed, then at full-speed.
You can jump on both legs without pain and you can jump on the injured leg without pain.
Anterior cruciate ligament surgical intervention
Often if a complete tear has occurred, the only option is surgery to repair the ligament.
Below is a video showing surgery for anterior cruciate tear.