Torn outer ligament of the knee


English: rupture /injury of collateral ligament

  • Injury of the Ligamentum collaterale laterale
  • Rupture of the outer ligament

Definition outer band

The outer ligament of the knee joint runs along the outside of the knee joint from the thigh bone to the calf bone. It is not fused with the joint capsule of the knee joint and is also narrower than the inner ligament of the same joint. The outer ligament is taut when the knee joint is stretched and rotated outwards.

When the knee is stretched, together with the inner ligament it serves to stabilize the knee joint. When the knee joint is bent, the two ligaments limit the outer rotation. The outer ligament of the knee joint belongs to the so-called collateral ligaments and runs – as the name suggests – along the outside of the knee joint.

It is used for lateral stabilization. If it is torn, pain and instability are the main consequences. The cause is usually a trauma (rotation, dislocation).

The physician (usually an orthopaedic surgeon and/or sports physician) has a simple manual way of testing the stability of the knee joint by checking the folding mechanism. However, more precise statements can only be made by means of an MRI examination of the knee. Depending on the extent of the injury (rupture of the outer ligament), the therapy depends on the extent of the injury, which can range from immobilization for a few days to surgery. The prognosis is usually good.


The outer ligament usually only tears as a result of trauma (medical term for accident). This can be a kink, a rotational trauma or a dislocation of the knee joint, such as occurs when skiing or playing football.


The general symptoms of a torn external ligament include pain and some instability of the knee joint. Further symptoms are:

  • Painful restriction of movement
  • Pressure pain on the band
  • Possible joint effusion, also bruising in the joint
  • Feeling of instability ̈hl

If a tear occurs in the outer ligament of the knee joint, this is immediately associated with severe pain. In addition, there is usually a pressure pain at the torn outer ligament and the knee joint can no longer be loaded due to pain, swelling and lateral instability.

In order to reduce the pain of a torn outer ligament at the knee joint as quickly as possible, the so-called PECH scheme should be used as an immediate measure. Here, the P stands for pause and means that all physical activity should be stopped for the time being and the affected leg should be kept still. The E stands for ice, the injured knee joint should be cooled immediately with an ice pack, ice gel or ice spray.

This can significantly reduce the swelling and pain. The C stands for compression and means that an additional pressure bandage or similar is applied to further reduce the swelling. The H stands for high support.

The injured leg should be elevated in order to promote venous reflux and thus reduce the swelling of the knee joint. In addition, painkillers such as ibuprofen can be used to treat the pain caused by the rupture of the outer ligament. If this scheme is not followed and the injury to the knee joint is ignored, the injury can become chronic and instability and pain in the knee joint can persist.

In general, it can be said that the examination of the injured knee can be quite difficult due to pain. A rupture of the external ligament must also be distinguished from an extension of the external ligament. The lateral stability test serves to examine the intactness of the collateral ligaments.

The knee joint is tried to “open up” to the side in full extension but also in 20 degrees of flexion. If the inner collateral ligament is torn, the knee joint can be opened outwards and vice versa. If the outer ligament is injured, i.e. torn, the knee joint can be “unfolded” from the outside.

To do this, the examiner presses laterally against the lower leg from the outside while the thigh is fixed. One can feel that the joint gap opens slightly. For a more precise diagnosis, MRI images are taken in the case of ruptures of the external ligaments of the knee joint.

X-rays only allow an assessment of the bony involvement, but cannot directly detect the ligament injury. Theoretically, a knee endoscopy, the so-called arthroscopy, is also possible, but this has given way to the MRI examination of the knee. In addition, it is more likely to be used for torn cruciate ligaments, as arthroscopic surgery is also possible in this case.

By means of a knee MRI, further diagnoses, such as a torn meniscus, torn cruciate ligament, etc. can be displayed in parallel. Especially in the case of larger injuries, an MRI of the knee is now almost always necessary.

To diagnose a torn outer ligament of the knee joint, an MRI examination of the knee joint may be necessary. An MRI examination (magnetic resonance imaging) is a non-invasive imaging procedure. This means that no instruments need to be inserted into the body for this examination.

With the help of a strong magnetic field, organs, tissues and joints can be displayed as sectional images during an MRI examination and finally assessed for pathological changes. The MRI examination is characterized by good soft tissue contrast and high resolution and is therefore very well suited for imaging ligament structures and cartilage parts of the knee joint. With the help of an MRI examination, injuries to the knee joint, such as torn ligaments, can also be diagnosed.

MRI can also detect the involvement of other ligament structures or cartilage components of the knee joint, such as the meniscus or cruciate ligament. In the case of ruptures of the external ligament with additional injury to parts of the bone, an X-ray examination may be necessary in addition to the MRI examination, since bony structures can be better delineated here. According to current studies, the MRI examination is an examination procedure without side effects and, unlike X-ray examination, does not require harmful X-rays.

The MRI examination is therefore used nowadays for a large number of injuries of the musculoskeletal system. The therapy of the torn ligament depends on the extent of the injury. If the ligament is only stretched or overstretched, short-term immobilization (a few days) of the joint is sufficient, followed by muscle building training.

In case of a rupture (medical term for tear) of the outer ligament, it depends on whether this injury has complex side effects. If there are no bony involvement (i.e. if the structure of the thigh and the lower leg bone is uninjured) and the knee joint is unstable, conservative treatment in the form of a splint for about 6 weeks is also carried out. Complex ligament ruptures (torn ligament) with bony involvement and/or instability of the knee joint must be treated surgically.

The torn ligament is refixed by means of a suture. In case of torn out bone parts, these are fixed with screws. Depending on the extent of the injury, conservative procedures such as wearing a splint and regular muscle building training and surgical procedures are considered in the case of a torn external ligament on the knee.

Surgical procedures are very rarely used for ruptured outer ligaments. Only complicated ruptures of the external ligament, in which additional bone parts are injured, or which are accompanied by significant instability in the knee joint, are treated surgically. In addition to the extent of the injury, the age of the affected person, as well as other underlying diseases play a major role in the decision whether the torn external ligament should be treated conservatively or surgically.

During the operation, either the torn ligament parts are sewn back together or the torn ligament parts are completely removed and replaced by another healthy tendon, for example the patellar tendon. The procedure is usually performed in a minimally invasive manner as a joint endoscopy (arthroscopy of the knee joint) and the duration of the procedure is up to two hours, depending on the extent of the injury. As a rule, surgical procedures on the outer ligament are performed under general or spinal anaesthesia.

In principle, operations on the outer ligament are low-risk procedures, but complications such as knee joint infections, bleeding or cartilage damage can occur. After the operation, the leg should first be protected, cooled and elevated. As soon as possible, physiotherapy with muscle building training should also be carried out.

For the prophylaxis of collateral ligament ruptures in general, it should be said that only the sports causing the rupture (skiing, playing football) should be exercised with caution. Strong thigh and lower leg muscles also counteract ligament injuries, as they stabilize the knee joint. If the collateral ligaments are injured (torn outer ligament / torn inner ligament), there is usually a good chance that the joint can be used without restrictions after an appropriate recovery phase.

How long this takes depends on the type and severity of the previous injury. The worse the injury was (only distension vs. complex tear with bone involvement), the longer the complete rehabilitation takes. The duration of the healing process of a torn external ligament at the knee joint is several weeks, depending on the extent of the injury.

Immediate measures according to the PECH-scheme (pause-ice high storage compression) can reduce consequential damage and shorten the duration of the healing process. As a rule, the injured leg should initially be immobilised for at least six weeks using forearm supports or a splint (so-called orthosis). At the same time, regular physiotherapy should be started as soon as possible and muscle-building exercises should be performed to regain the stability of the injured knee joint.

Afterwards, the knee can be gradually subjected to greater stress in consultation with the treating physician. The time until the injured knee can be fully loaded again can be up to one year. If the outer ligament of the knee joint is torn during sports activities, further strain on the knee joint should be avoided at all costs and a break from sports should be taken.

The injured leg should first be treated according to the PECH scheme (Pause-Ice High Compression). The leg should then be immobilised for at least six weeks using forearm supports or a splint. Over the course of the treatment, the injured leg can gradually be subjected to greater loads.

This should only be done in consultation with the treating doctor and under regular physiotherapeutic supervision. Through targeted muscle build-up as part of physiotherapy, the stability of the injured knee joint can be restored and full fitness for sport can be achieved. Depending on the severity of the injury, a break from sport of up to one year may be necessary after a rupture of the external ligament of the knee joint. If the sports activity is not paused, the injury can become chronic and instability and pain in the knee joint can persist permanently.