Cruciate Ligament Rupture: Symptoms and Treatment of Knee Injury

The anterior cruciate ligament tear (cruciate ligament rupture) is the most common knee injury. Due to its increasing frequency has become one of the most well-known sports injuries in recent decades. In Germany alone, the cruciate ligament tears about 50,000 times a year. The anterior cruciate ligament is affected almost ten times more often than the posterior. Since a cruciate ligament tear can have long-term consequences if left untreated, you should always have the injury treated. Please learn more about the causes and symptoms, when an operation can make sense, and how long it takes to heal.

What ligaments are there in the knee?

Several ligaments in the knee form a strong ligament apparatus to stabilize the knee joint and simultaneously enable the most significant possible movement for sports and other activities. A side ligament on both the inside and outside of the knee, also called the collateral ligament, secures the knee against shearing movements from the outside when the knee is extended but still allows movement when it is flexed.

The cruciate ligaments are two other ligaments that, strictly speaking, are not in the knee joint itself but in the joint capsule surrounding it. There is the anterior cruciate ligament and the posterior cruciate ligament, which intersect as their name suggests. They connect the thigh and lower leg bones and prevent the thigh bone from slipping backwards and forwards. The cruciate ligaments are, therefore, important for stability in the knee.

The cruciate ligaments themselves consist of several bundles. However, the anterior cruciate ligament is significantly thinner than the posterior, so it tears more often. The posterior cruciate ligament is also the strongest in the knee. The cruciate ligaments are supplied with nutrients and oxygen via small arteries.

 

Causes: When do the cruciate ligaments tear?

The typical course of injury that leads to a tear in the anterior cruciate ligament is usually a knee that is turned outwards or inwards and, at the same time, bent while the lower leg remains standing. This can happen with sudden changes in direction while running, twisting or traffic accidents, but also with some sports. There is a significant risk of this in football and skiing.

The cruciate ligament alone is rarely torn. The joint capsule, cartilage, other ligaments and the menisci can also be injured. The two menisci (inner and outer meniscus) are two discs of cartilage that act as shock absorbers and protect the cartilage of the knee joint. Simultaneous injury to the medial collateral ligament, medial meniscus, and anterior cruciate ligament are the most common. This combination of injury as a particular form is called the “unhappy triad” in medicine.

The posterior cruciate ligament usually tears when falling on a bent knee and is a typical sports injury for goalkeepers in football games. However, dislocations of the knee joint or a direct impact on the tibial plateau in high-speed accidents can also tear the rear cruciate ligament. The posterior cruciate ligament tears less often, but unfortunately, not alone; other ligaments are also affected. In addition, the posterior cruciate ligament tear is often “overlooked” in the diagnosis.

What are the symptoms of a cruciate ligament tear?

The following symptoms often indicate a cruciate ligament tear:

• sudden, instead of stabbing pain
• Buckling, unsteady gait up to complete restriction of movement
• joint swelling
• joint effusion (fluid accumulation from blood in the joint)
• bruising (hematoma)

These are possible signs of a tear in the posterior cruciate ligament:

• Pain on the pressure in the hollow of the knee
• The knee cannot bend well

But be careful; the symptoms are only sometimes apparent after the injury. Some of those affected did not feel any problems at first. Complaints only become noticeable much later – mainly in the form of instability or pain due to the cartilage or meniscus damage caused by the changed knee mechanics.

 

Diagnosis of cruciate ligament rupture

After questioning the exact course of the injury and the symptoms, the doctor treating you will try to find out which ligaments are damaged with a series of function tests. Attention is paid to increased knee mobility when pulling or pushing against the lower leg, which is bent by 90°. If the lower leg can be pulled forward like a drawer, this can indicate an injury to the anterior cruciate ligament. If the leg shows instability when pressed against the tibia, it is more likely to be a posterior cruciate ligament injury. These tests are called “anterior and posterior drawer tests”.

Other functional tests support the suspected diagnosis. However, this examination cannot always be carried out on fresh cruciate ligament tears because of the severe pain and increased muscle tension.

Older cruciate ligament tears show up primarily through a recognizable instability in the knee. A swollen knee (effusion) may also be present. Most of the time, cruciate ligament tears that occurred long ago are painless, so the tests are more accessible, and the injury is more straightforward to diagnose.

After the clinical examination, the location of the injury should be precisely determined using an MRI (magnetic resonance imaging). Injuries to the cruciate ligament can be reliably assessed here. MRI provides essential information, especially when cartilage damage and involvement of the menisci can be assumed.

The leg should also be x-rayed to rule out additional fractures. The leg is X-rayed from the front, side, and kneecap.

In addition to the cruciate ligaments, the condition of the collateral ligaments, menisci, cartilage surface and joint capsule can also be assessed as part of an arthroscopy. For this purpose, a camera is inserted into the joint via smaller incisions. The cruciate ligaments can also be operated on using this technique.

First aid and treatment: What do you do if you tear a cruciate ligament?

The affected person can relieve pain and swelling immediately after the injury by elevating the leg, cooling it and resting it. However, a cruciate ligament tear does not heal well and should be treated medically.

Pain is treated with painkillers such as ibuprofen or diclofenac until further therapy. In the case of severe pain due to severe effusion, the doctor can puncture the knee joint to drain the excess fluid.

Surgery for a cruciate ligament tear

Further therapy takes place individually. Due to possible long-term consequences, a tear in the anterior cruciate ligament is operated on more frequently. Under certain conditions, however, conservative therapy without surgery is also potential.

 

When should an anterior cruciate ligament tear be operated on?

In the case of an anterior cruciate ligament rupture, surgery is recommended for:

• sporty and professionally active people
• high load requirements on the leg
• children and young people
• an additional meniscus tear
• marked instability of the leg

What to do before the operation?

A tear in the anterior cruciate ligament alone is operated on either shortly after the injury or four to six weeks later. If the inner meniscus is also damaged, the operation is only performed after about two months. In the meantime, the knee is treated with an orthosis (splint), which is applied from the outside and immobilizes the knee and thus immobilizes it. Depending on the extent of the symptoms and the person’s fitness, physiotherapeutic treatment can already be carried out during this time in preparation for the operation.

Torn posterior cruciate ligament: when is surgery necessary?

The posterior cruciate ligament can be expected to heal more favourably than the anterior cruciate ligament rupture due to its better blood circulation after a fracture. Therefore, conservative therapy using a splint is usually sufficient.

However, posterior cruciate ligament surgery may be considered in the following circumstances:

• Failure of conservative therapy
• high level of physical activity
• strong instability
• more complicated injuries such as:
  • Avulsion of bony parts
  • dislocation of the knee joint

 

Surgical method for a cruciate ligament tear

During the operation, the entire knee is not opened; only smaller incisions are made through which a camera and the instruments are inserted. This surgical method is called arthroscopic anterior or posterior cruciate ligament surgery.

The broken cruciate ligament is replaced by a tendon from the patient’s body (autologous cruciate ligament plastic). Suturing the damaged tendon alone produces less good results than a complete replacement. Usually, the tendon of the thigh muscles (musculus gracilis or semitendinosus) is removed. Parts of the patellar ligament are used less frequently, which can lead to ligament tears from the removal point in occupational groups that kneel a lot (e.g. tilers).

The removed tendons are often taken in double or quadruple strands to increase tear strength and allow for complex movements in the knee joint. Depending on the number of bundles formed, tunnels are drilled into the bones of the knee for attachment. The tendon implants are then attached to the thigh and lower leg bones with screws.

Cruciate ligament tear: alternatives to surgery

Conservative therapy can be considered after a cruciate ligament tear in the case of:

• little loss of stability
• old age
• little activity and stress on the leg in everyday life
• sole injury of the posterior cruciate ligament

This is how treatment occurs without surgery if the anterior cruciate ligament is affected: In conservative treatment, the leg is fitted with a knee orthosis. This is worn for three months and stabilizes and relieves the knee. In addition, the affected person receives physiotherapy.

The posterior cruciate ligament can also be treated without surgery: injuries to the posterior cruciate ligament are usually treated conservatively, i.e. purely with physiotherapy. The exercises should primarily strengthen the four-headed thigh muscle.

How long does a cruciate ligament rupture take to heal?

The healing time for restoring the knee joint’s load and functionality after an operation is six to nine months. 

After surgical treatment of the anterior cruciate ligament tear, the leg may initially only be loaded with 50 per cent of the body weight and bent up to a maximum of 90° for the next four weeks. For three months, the knee is relieved with the help of a knee orthosis, and physiotherapy is carried out over several weeks.

After an operation of the posterior cruciate ligament, the following applies: First of all, the leg may be partially loaded for six weeks after the operation with a maximum of 20 kg and only bent up to 90° in the prone position, but only passively and not under your power. An orthosis should be worn for the next twelve weeks, which is exchanged for an orthosis without a hinge at night. Focused training to stabilize the knee joint begins six weeks after the operation.

 

Rehabilitation after a cruciate ligament tear

Rehabilitation takes place in several steps:

1. Pain relief, swelling reduction, thrombosis prophylaxis
2. Encourage passive movement
3. Muscle training for active stabilization, regaining performance
4. Freedom from pain and safety in the knee joint

Surgery enables 80 per cent of those affected to return to their previous sport and activity level. In addition to the usual surgical risks (e.g. infections), restricted movement and permanent instability can occur.

How long is no sport after a cruciate ligament rupture surgery?

Depending on the pain and swelling – if mobility allows – swimming and cycling can be started again from the fourth week after the operation and after three months with running training on level ground. Sports that involve rotational strain on the knee should be avoided for at least six months. Anyone in high-risk sports should take a year off to prevent tearing ligaments again.

Prognosis: how bad is a cruciate ligament tear?

A cruciate ligament tear does not always go unnoticed in the body and can lead to long-term consequences. For example, it can increase the risk of meniscus and articular cartilage damage. With unstable ligaments and increased mobility of the lower leg bone compared to the thigh bone, the joint surfaces shift, and there is increased stress on the menisci and articular cartilage. The risk of developing arthrosis in the knee joint later is also greater.