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Knee Ligament Injury

Anterior Cruciate Ligament Sprain (ACL) FAQs

Minute Read


Posted 1 year ago


Last updated: 29/11/2022


by James McCormack

What Does a Sprained ACL Feel Like?

An ACL sprain will have symptoms that come on immediately at the time of injury such as a “popping sound”, and pain in the knee. Swelling will rapidly follow within a few hours, this can limit the range of movement of the knee making it difficult to fully straighten or bend the knee. The slowest sign to appear is bruising which can take several days to appear on the skin.

A feeling of instability at the joint, of that the knee might “give way” is often felt from the moment of injury, some people find if they have a lot of swelling this can mask the extent of instability. ACL sprains can be mind to severe, or complete ruptures. The symptoms will reflect this, in particular, the instability felt will be closely liked to the extent of the damage.

How to Tell if ACL is Torn or Sprained?

The specific diagnosis of a tear or a sprain will depend on the examination carried out by a medical professional, and the symptoms reported to them. A tear is a higher-grade injury to a sprain, therefore symptoms will be more severe, specifically greater instability and pain. 

Is Heat or Ice Better for ACL Tear?

In the initial phases of an ACL tear there will be significant pain and inflammation, therefore, ice will be more effective. Ice can help with short-term pain relief, and also reduces inflammation by constricting the local blood vessels. Ice should never be applied directly to the skin as it can cause frostbite, a layer of cloth should be between the ice and your skin. It should be applied for 10-20minutes every 2-3 hours in the initial phase after injury, and throughout the peak of inflammation, this may be for the first 2-3 days or slightly longer.

How Should You Sleep With a Torn ACL?

It can be difficult to find a comfortable position to sleep in with a torn ACL that is not going to aggravate your pain or delay the healing process. The best position is with your knee straight and slightly elevated, on your back with a small pillow under your ankle. If the tear is minor you may be advised that sleeping with a bent knee is ok, in which case lying on your side with a pillow between your knees for support is a good position.

With severe tears such as grade 2-3 ACL tears, you may be advised to wear a knee brace to keep your knee straight for a period of time. In the acute phase, you may need to wear this at night also. This can be done with a pillow under your ankle or calf to keep your leg slightly elevated.

Elevation is the best way to reduce swelling as it helps to drain excess fluid from the knee. Compression is also very effective so wearing a compression bandage or sleeve at night can also be helpful.

Can You Walk on a Sprained ACL?

If the knee feels unstable, or it is unable to be held in a fully straight position then it is not advised to walk without aid. Using crutches  to reduce the weight on the leg to a level that the muscle can cope with, or a knee brace to provide stability, can help to improve the quality of the walk. This can prevent further complications and injury to the knee joint, and prevent the development of a limp, that can be difficult to get rid of.

With an acute ACL injury the surrounding muscles, in particular the quadriceps, become inhibited and unable to activate fully. Therefore the control of the knee will be impaired and it might be difficult to keep the knee straight. In addition to this, if the ACL sprain is severe it will cause instability in the joint, as the ligament is unable to play its role in stability.

Can You Bend Your Knee With ACL Tear?

ACL tears swell up quickly in the initial hours after injury, this swelling can reduce the mobility of the joint, making it harder to bend and straighten the knee. As the swelling reduces the mobility will improve, but some residual stiffness may prevent the full range of movement. Rehabilitation exercises and stretches, directed by your physical therapist will help to regain your full movement.

Can an ACL Tear Heal on its Own?

While the ACL has a good blood supply, meaning it can repair itself if the tear is significant enough it can disrupt this blood supply. If the tear is severe enough to disrupt the blood supply then it will not be able to heal on its own. This is why in most cases of severe tears or full ruptures, surgery will be offered to reconstruct or augment the anterior cruciate ligament.

Does ACL Reconstruction Lead to Knee Replacement?

There is a greater risk of early-onset osteoarthritis and further knee surgery following ACL reconstruction. In this study, they found 1.9% of patients had subsequent ACL reconstruction within 1 year, and 6.5% had subsequent knee surgery within 1 year (Lyman et al, 2009). In another study, they showed the potential reasoning for a greater risk of earlier onset osteoarthritis, which may be linked to the greater knee abduction moment (Butler et al, 2008).

Do All ACL Tears Require Surgery?

Not all ACL tears require surgery. In mild cases where there is only a small degree of injury and if the ligament function is maintained, then surgery is not necessary. Surgery is required if severe damage causes a loss of function of the ligament, and symptoms of instability are felt and do not resolve with rehabilitation. 

Physiotherapy with James McCormack

This is not medical advice. We recommend a consultation with a medical professional such as James McCormack. He offers Online Physiotherapy Appointments for £45.

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