Cruciate ligament rupture

Accidents in ball sports or skiing are usually the reason for a cruciate ligament rupture. Women are more often affected by them than men. Whether surgery has to be done on a cruciate ligament rupture depends on the extent of the injury, stability of the knee and the age of the particular person affected, among other things.

At a glance

  • The anterior cruciate ligament is one of 4 large ligaments that keep the knee stable – it ruptures the most frequently.
  • This is usually caused by sports injuries that are for instance the result of a fall when skiing or a twisted knee when playing soccer.
  • Cruciate ligament ruptures are more common in women than men.
  • Whether surgery has to be done depends on the extent of the injury, stability of the knee and the age of the particular person affected, among other things.

Note: The information in this article cannot and should not replace a medical consultation and must not be used for self-diagnosis or treatment.

Torn cruciate ligament: footballer lying grimacing in pain on the ground clutching his head with one hand and his leg with the other. Another player is standing next to him and supporting the injured man’s foot.

What is a cruciate ligament rupture?

The anterior cruciate ligament is one of 4 large ligaments that keep the knee stable – it ruptures the most frequently. A cruciate ligament rupture is usually caused by sports injuries that are for instance the result of a fall when skiing or a twisted knee when playing soccer.

A rupture of the anterior cruciate ligament does not always require surgery. Whether an operation is required depends on the extent of the injury, stability of the knee and the age of the particular person affected, among other things. The affected person’s personal situation also plays an important role in treatment. For example, the occupation or sports that should still be carried out have an influence.

Ruptures of the posterior cruciate ligament are far rarer. But this case is not being considered here.

What are the symptoms of a cruciate ligament rupture?

When the anterior cruciate ligament ruptures, a snapping or popping sound can often be heard. The knee normally swells up immediately thereafter. It is especially painful during movement.

Many of those affected can appear normal after a cruciate ligament rupture. But the knee feels unstable, as though the upper and lower leg were shifting slightly. This feeling occurs for example when the knees are being bent and during sideways and rotary movements. But also when the affected leg has the body’s full weight put on it during stair climbing.

In around 90% of all cruciate ligament ruptures, other knee ligaments or cartilage apart from the anterior cruciate ligament are also injured:

  • for 50 to 75%, one or both menisci
  • for about 50%, the articular cartilage
  • for about 15%, the medial collateral or lateral ligament of the knee

Furthermore, the bones are usually bruised. This injury most commonly involves severe pain and other discomfort.

What are the causes of a cruciate ligament rupture?

The anterior and posterior cruciate ligament, along with the lateral and medial collateral ligament, connect the upper and lower leg bones. What is more, the anterior cruciate ligament has the following tasks:

  • It stabilizes the knee and ensures that the tibia does not shift forward.
  • Along with the posterior cruciate ligament, it prevents the knee from twisting. For that reason, the cruciate ligaments wrap themselves around each other and stabilize the knee.

The anterior cruciate ligament moreover has special sensory cells (receptors) that control muscle reflexes in order to stabilize the knee.

If severely strained, the anterior cruciate ligament can rupture, for example if:

  • the knee twists with force – such as when slowing down quickly from a run, a rapid change in the direction of movement or if the leg with weight on it gives way inwardly.
  • an unfortunate landing with stretched leg after a jump.

What are the risk factors for a cruciate ligament rupture?

Cruciate ligament ruptures occur in particular with sports like soccer, handball, volleyball, basketball and skiing.

Women playing ball sports have a higher risk for cruciate ligament ruptures than men. Among other things, doctors debate whether this could be due to women’s often weaker hamstrings.

How often does a cruciate ligament rupture occur?

The number of anterior cruciate ligament injuries in men playing ball sports is 2% and 3-4% in women playing ball sports.

Most cruciate ligament ruptures occur in ball sports. Sportspeople aged 15 to 45 years are especially affected. The risk of a cruciate ligament rupture increases with a sport’s duration. A summary of more than 50 studies with people who play ball sports has revealed that:

  • 3 to 4% of women and
  • 2% of men

injure their anterior cruciate ligament at one time or another.

How does a cruciate ligament rupture progress?

If a cruciate ligament rupture is successfully treated, the knee functions again normally or almost normally in about 80 to 90% of those affected. If the injuries have healed, most of them engage in sports again. However, about 20 to 30% of them subsequently decide, out of fear of another injury, to play another sport or to engage in less intensive sports – even though this is completely unnecessary in many instances. 

A cruciate ligament rupture increases the long-term risk of developing arthritis of the knee earlier – especially if the menisci were also injured. 

Important: A summary of studies over a period of more than 10 years has shown that after a cruciate ligament rupture, an X-ray showed clearly visible osteoarthritis that had developed in the knee in about 20% of cases. Without a cruciate ligament rupture, this amount is only about 5%. However, the risk for arthritis of the knee does not depend on how the injury is treated.

But visible changes in an X-ray do not mean that there will also be discomfort. It is known from other studies that X-rays do not often say much about symptoms. Anyone who has a cruciate ligament rupture can moreover ensure a well-functioning knee with training.

How can a cruciate ligament rupture be prevented?

Certain exercises prior to playing sports can prevent ruptures of the anterior cruciate ligament. Among other things, special programs that include warm-up exercises and exercises for strengthening the core and leg muscles are suitable, as are workout elements to improve balance, coordination and elasticity.

For example, professional medical associations recommend the “FIFA 11+” program available from the German Football Association (DFB) and the "Stop-X” program developed by the German Knee Society (Deutsche Kniegesellschaft).

These kinds of programs were developed for sports like soccer or handball, which are associated with an increased risk of a cruciate ligament rupture. They are especially worthwhile for active sportspeople. That is because the injury risk in ball sports depends on the extent of the training and number of competitions.

How is a cruciate ligament rupture diagnosed?

To diagnose a cruciate ligament rupture, the doctor initially asks about the circumstances of the accident and symptoms. The knee is then palpated and examined further. To check the stability of the knee, the upper and lower leg are moved.

When necessary, magnetic resonance imaging (MRI) provides accurate pictures of the knee with the ligaments and menisci. An X-ray can reveal whether bones are broken – but not whether ligaments are ruptured or damaged.

How is a cruciate ligament rupture treated?

First of all, the knee needs rest after a cruciate ligament rupture. It should therefore be elevated and cooled immediately after the accident until the acute pain and swelling subside.

A pressure bandage can also be useful. The same is true of non-steroidal anti-inflammatory drugs such as ibuprofen. Later on, a walking aid can help relieve stress on the knee – especially if it is very unstable.

A number of methods can be used to treat torn cruciate ligaments: rest, elevation and cooling, a walking aid, physiotherapy, surgery, non-steroidal anti-inflammatory drugs (NSAIDs).

There are 2 options for treating a ruptured cruciate ligament:

  • With a conservative treatment, the knee muscles should be strengthened so that they compensate for the function of the ruptured cruciate ligament. Whether this treatment is considered depends on whether and which other knee structures are injured.
  • With an operation, the ruptured cruciate ligament is replaced. The surgery is carried out with an arthroscopy, during which small surgical instruments are inserted around the knee through several incisions.

If the knee is to be operated on, there is normally a wait of 2 to 4 weeks after the accident before the surgery is performed. In this period, the swelling may subside and the knee settle down.

If the knee is still stiff, swollen or inflamed during the operation, the tissue in the knee may harden and later restrict movement. The flexibility of the knee muscles must therefore be improved before the operation with suitable exercises.

Physiotherapist pressing one hand on the shinbone of a man lying on a massage table. The therapist is pressing the other hand on the area below the knee where the cruciate ligaments are located.

After the operation, a 4 to 12 month healing and training phase is required, depending on the sport.

So far only one major study exists that has compared conservative treatments with surgical ones. The result: a conservative treatment was also successful in the long term for more than 50% of those affected. For an operation however, it is 80 to 90%.

According to current knowledge, there are no disadvantages for the knee function if the knee is initially treated conservatively and only later operated on if necessary. However, there is a somewhat higher risk of further injuries – to the menisci for instance – after a conservative treatment.

How does rehabilitation proceed after a cruciate ligament rupture?

After an operation, it takes months for a cruciate ligament replacement to fully heal and be up to its tasks again. Strong thigh muscles are important for easing strain on the cruciate ligament replacement and stabilizing the knee. The aim of rehabilitation is to strengthen the muscles and get the knee used to the new cruciate ligament. Some time may pass until feeling returns to the knee and it can be moved as naturally as before the accident.

If there is no operation on the cruciate ligament, rehab helps build up the muscles with targeted training to the extent that the knee remains stable. Physiotherapy is therefore useful for all treatments.

Important: If surgery was performed on the knee, those affected can usually start playing gentle sports again after 4 to 6 months. More intense ball or combat sports can normally be played again after 9 to 12 months. If the knee is treated conservatively, the period of convalescence is reduced by about 2 to 3 months.

For many of those affected, it is difficult to accept that it takes a long time for the former performance capability to return and that a lot of effort is required for this. So along with consistent training, patience is an important requirement for a successful rehabilitation.

You can read more detailed information, for instance about rehabilitation after a cruciate ligament rupture, at

What information about a cruciate ligament rupture is still important?

It is helpful to resort to certain measures for the rehabilitation period even before the operation. These can include:

  • Practice moving with walking supports even before the operation.
  • Get rid of potential obstacles or tripping hazards in the residence early on. So for example, it can be sensible to sleep in another room during the period of convalescence to thereby avoid stairs.
  • Adjust the way to work, school or university. Depending on on which leg is affected and how severe the injury is, it can take weeks until those affected can drive by themselves again.
  • Organize help for the daily routine – for instance shopping or other transactions.
  • Buy a small shower stool in order to shower while sitting.

Those affected who have to walk a lot on walking supports can sometimes develop other symptoms such as muscle soreness or tension in the back, neck or shoulders. Such symptoms can also be prevented by working out before the operation.

In cooperation with the Institute for Quality and Efficiency in Health Care (Institut für Qualität und Wirtschaftlichkeit im Gesundheitswesen) (IQWiG).

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