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Anterior cruciate ligament injury

Dr Roger Henderson
Reviewed by Roger HendersonReviewed on 29.04.2024 | 4 minutes read

Anterior cruciate ligament (ACL) injuries tend to occur in sporty people. Injury can happen if you suddenly change direction or land badly. It’s more common in sports involving lots of contact, changes of direction and speed, or jumping and landing.

Your knee has two cruciate ligaments – the anterior and posterior – to keep it secure and stable during movement. They cross over to form an X, attaching your shin bone (tibia) to your thigh bone (femur). Hence an ACL injury can feel like the knee is giving way, and you get a popping sound on movement.

Pain and swelling occur worst around the line of the joint. It can be hard to fully straighten or fully bend your knee – and even walking can be very painful.

There are three categories depending on the severity of the ACL injury:

Grade 1 is when the ligament is slightly stretched or just a few of the fibres of the ligament are damaged but the knee is still stable and supported by it.

Grade 2 is when a few more of the fibres are damaged so it is partially torn or the ligament is stretched to the point that it is loose and the knee is no longer stable or supported by the ligament.

Grade 3 is a complete tear of the ligament where the ligament has actually been torn in half and can no longer support the knee.

Doctor’s advice

Next steps

You should put ice on as soon as possible after any knee injury and elevate the knee, to reduce swelling. In the first few days, you should avoid playing sports and simply rest it to avoid further injury, while seeking specialist input.

You can take over-the-counter pain relief to help with any pain. Avoid pressing or testing the knee and also avoid using heat on it (such as a hot compress) in the early stages.

In the longer term, you want to get the muscles around the knee moving and staying strong to support it, but this will need specialist advice on your road to recovery.

Healthwords pharmacists' top tips

For pain relief relating to an ACL injury, a sensible stepwise approach is to take one or two paracetamol tablets up to four times daily (ideally leaving a 4 to 6 hour interval between doses). Paracetamol is generally well-tolerated and safe for most (unless for example, you have a severe liver problem).

The addition of an anti-inflammatory such as ibuprofen will bring down swelling and provide additional pain relief. Take 200mg to 400mg regularly three times a day for a few days, which will allow reduce inflammation to relieve swelling and pain.

Ibuprofen is known to cause irritation to the stomach lining, so it's best to take ibuprofen with food. You should speak to your doctor or pharmacist before taking ibuprofen if you are taking any other medicines, particularly blood pressure or stroke prevention medicines, if you have kidney disease, if you are pregnant, or if you have previously had a gastric ulcer.

Additional pain relievers are available over-the-counter which are codeine-containing combinations with either paracetamol (co-codamol), or ibuprofen – these may relieve more severe pain.

Knee supports with braces can help to provide stability around the knee joint, as well as mild compression and warmth to the joint. These may be helpful to prevent further injury caused by unstable rotation or weight-bearing movement of the knee joint.

If in doubt about any medicines or appliances, or the suitability for you specifically, please speak to your local pharmacist, sports therapist, or doctor.

When should I see my doctor?

You should get an urgent doctor's appointment, call NHS 111 or go to an urgent care centre if you think you have injured your ACL.

The doctor will ask about what happened and your symptoms and will examine your knee. They may send you for an X-ray or MRI (or both). Anterior cruciate ligament injuries can often occur alongside other damage to your knee, so this is why an X-ray or MRI can be useful.

Treatment for an ACL injury can be divided into two categories of either non-surgical treatments or surgery. Which is recommended depends on the severity of the injury and an individual's activity levels prior to injury.

Non-surgical options include wearing a knee brace and off-loading the knee by using crutches to allow healing. This will entail directed physio to help strengthen the supporting structures of the knee. This is appropriate in very mild (Grade 1) ligament injuries or in people not needing to be very active.

Surgery involves reconstructing the ligament. This ultimately provides the most support for the knee, so is appropriate if someone wants to get back to a high level of exercise or sport, even with Grade 2. It is usually required in a complete tear of the ACL (Grade 3).

Am I fit for work?

Your doctor will assess whether you are fit for work depending on the nature of your job. You may be able to return to work with altered duties.

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Dr Roger Henderson
Reviewed by Roger Henderson
Reviewed on 29.04.2024
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