Acute Knee injury – meniscal and ligament

The term acute knee injury can incorporate a variety of soft tissue structures within the knee joint. Acute means a problem that has started very recently (within the last few weeks).

The most common acute knee injuries are:

  • A sprain when a ligament stretches too much as a result of an injury, usually from twisting
  • A tear – when a ligament overstretches so much it tears either partially or fully
  • An acute meniscus tear – the “shock absorber” pad within the knee that can tear from a twisting injury

Here we give you a little bit more information on each of the structures that could be involved in an acute knee injury.

  • Ligaments work in combination alongside muscles to give you a stable and supported knee. One of the more common ligament injuries is the Anterior Cruciate Ligament (ACL), a strong ligament in your knee that prevents the forward movement of the knee when slowing down; there is also the Posterior Cruciate Ligament (PCL) that prevents backwards movement in your knee.
  • The two ligaments on either side of your knee are the medial collateral ligament (MCL) and lateral collateral ligament (LCL). These prevent sideways motion of your knee.
  • The meniscus is a cartilaginous pad, of which there are two in the knee. They act as a shock absorber within the knee joint and can be injured alongside a ligament injury, or as a standalone injury.

The initial symptoms vary slightly between a ligament and meniscus injury and can help give you an idea of which type of injury you have.


The most common causes of meniscal and ligament injuries are:

  • Rapid change of direction when running or walking
  • Direct contact e.g. sports tackle
  • Stopping suddenly when running
  • Landing from a jump incorrectly
  • Twisting with your foot fixed on the floor

Common symptoms:

  • Swelling – ligament injuries generally swell quicker than a meniscus injury but in both cases swelling will appear within 24 hours of the injury
  • Reduced movement of the knee for both ligament and meniscal injuries
  • Giving way of the knee is common in ACL injuries
  • A feeling of you knee not being stable or sideways movement in the knee is more common in MCL and LCL injuries
  • Meniscal injuries can cause your knee to ”catch”, “click” or “lock”

When to seek help:

If you have any of the following symptoms it is important to get an early review by a healthcare practitioner:

  • If you heard a snap or pop at the time of the injury
  • If a large amount of swelling appears very quickly (within an hour) of the injury
  • You are unable to weight bear immediately after the injury
  • If you are unable to fully straighten your knee, this could indicate a large meniscal tear causing your knee movement to be blocked


After this kind of injury your knee will likely become very swollen and painful with reduced movement.

  • It is important to keep your knee gently moving as much as possible to prevent stiffness (unless otherwise directed by a healthcare professional).
  • Ice is recommended, particularly within the first 24 – 48 hours as a way of reducing swelling.
  • Taking regular pain relief will enable you to move your knee as much as possible and help prevent stiffness caused by lack of movement. A pharmacist or your GP can help advise you what to take if needed. You can find further information here on what medications you could take here:

How and when to take paracetamol for adults – NHS (

Ibuprofen for adults: painkiller which also treats inflammation – NHS (

  • You may require the support of crutches and a brace to support walking in the early stage of your injury.


Try the exercises below to start to improve the movement and strength in the knee:

Bending your knee

Use a ball or a carrier bag to slide your foot back underneath a chair, increasing the bend in your knee as you do this.

acute knee injury ball slide

Straightening your knee

Place a rolled up towel underneath the heel and allow your knee to straighten in this position.

acute knee injury towel

Muscle activity

Lying flat or sitting up with your leg straight in front of you, squash the back of the knee down into the floor or sofa. Hold 5 seconds.

patellar tendinopathy static quad

Strengthing your thigh muscle (quadriceps)

Lying flat or sitting with your leg straight in front of you. Squeeze your thigh muscle to lift the leg off the floor, keeping it straight as you do this
patellar tendinopathy straight leg raise

What if my symptoms don’t improve

If your symptoms continue after trying the advice above, you should seek further advice from a healthcare practitioner. A Physiotherapist will be able to help you manage your symptoms better by creating a tailored treatment programme. 

In some cases conservative management is not effective and you may need further treatment such as surgery to reconstruct or repair the injured structure. If this is the case your healthcare practitioner will talk you through the process involved.