Brief overview
- Course and prognosis: With early therapy and careful follow-up, the course and prognosis are usually good. It takes several weeks or months until complete healing.
- Treatment: Acute therapy according to the PECH rule (rest, ice, compression, elevation), conservative therapy through splints (orthoses), bandages and physiotherapy, surgery, painkillers.
- Examinations and diagnosis: inspection with palpation, imaging (MRI, CT), knee function tests, X-ray examination to clarify concomitant injuries.
- Causes and risk factors: Mostly sports injuries in the course of a sudden change of direction during a movement or in a fixed stance (sudden twisting and bending movements), as well as traffic accidents (falls, impact).
- Prevention: warm-up before sports, build-up and regular exercises, special muscle training (especially of the thigh).
What is a cruciate ligament tear?
In the case of a cruciate ligament tear (cruciate ligament rupture), one of the two cruciate ligaments in the knee joint is usually either completely or partially torn. The anterior cruciate ligament is most frequently injured, the posterior ligament is less frequently affected.
Both cruciate ligaments have the task of stabilizing the knee, limiting its movements and protecting it from dislocation. They run crosswise inside the joint from the thigh bone (femur) to the shin bone (tibia).
In addition to the two cruciate ligaments, the inner and outer ligaments also stabilize the complex knee joint.
Anterior cruciate ligament
The anterior cruciate ligament, which is about four centimeters long and ten millimeters wide, rotates like a screw, especially when the knee is bent, preventing the tibia from advancing relative to the femur. It consists of two parts. The anterior portion originates anteriorly at the center of the tibia, while the posterior portion originates at the outer portion of the posterior articular surface of the tibia. Both parts unite for joint anchorage in the posterior, inner portion of the external articular process of the femur.
An injury to the anterior cruciate ligament (such as a cruciate ligament tear) is the most common knee ligament injury, accounting for 20 percent of all knee injuries, followed by isolated injury to the medial ligament. Those affected are usually between 20 and 30 years old, active in sports and male in over two-thirds of cases. Only in rare cases (ten percent) does an anterior cruciate ligament tear occur in isolation. In about half of the cases, one or even both menisci are also damaged.
In about a quarter of cases, the anterior cruciate ligament is merely torn and not completely ruptured.
Posterior cruciate ligament
The posterior cruciate ligament is considered the most stable of the four knee ligaments. It consists of two strands: One originates at the anterior, outer femoral joint surface, while the second strand originates posteriorly at the center of the femur. Together, both strands pull toward the posterior aspect of the tibia bone. The posterior cruciate ligament prevents posterior thrust of the tibia.
A posterior cruciate ligament tear is rarer than an anterior cruciate ligament rupture and often happens during sports. Then it is often an isolated injury (no concomitant injuries). If, on the other hand, a traffic accident is the cause of a posterior cruciate ligament tear, other parts of the knee are usually injured.
Cruciate ligament rupture: symptoms
You can read everything important about the typical signs of a cruciate ligament tear in the article Cruciate Ligament Rupture: Symptoms.
How long does a cruciate ligament tear take to heal?
After a cruciate ligament tear, complications such as bleeding, joint infections, thrombosis, nerve and vascular injuries rarely occur. The long-term results after a cruciate ligament tear are good in most cases – both with surgical and conservative treatment. Consistent physiotherapeutic therapy is very important in both cases to prevent the joint from wearing out too early (arthrosis).
The risk of osteoarthritis is also increased if the full range of motion in the knee joint is not achieved through therapy. For a good late result, it is important to train the muscles regularly in the long run (especially the thigh muscles).
It is not possible to say exactly how long it takes for a cruciate ligament tear to heal completely. It depends mainly on the severity of the injury, the quality of the therapeutic measures, and the age and general condition of the affected person. Several weeks to a few months can be expected. This entails a corresponding downtime depending on the activity or activity.
Often, because of the greater blood flow, the chances of recovery from a tear of the posterior cruciate ligament without surgery are better than for an anterior cruciate ligament tear, for which surgery again shows the better prognosis.
In most cases, after a successfully treated cruciate ligament tear, even sports that put a strain on the knee, such as soccer or skiing, are possible again. However, it must be remembered that the knee is no longer as stable after a cruciate ligament tear as it was before.
Typical late effects, which sometimes occur with inconsistent therapy or very severe injuries, are instability in the knee joint, pain on exertion and an increased susceptibility to a renewed cruciate ligament tear.
How is a cruciate ligament tear treated?
Doctors recommend that acute measures be taken according to the PECH rule (rest, ice, compression, elevation) if an ACL tear is suspected. Interrupt your sporting activity, elevate the leg, cool the knee joint (ice, cryospray et cetera) and apply a pressure bandage. Common painkillers help against severe pain.
The doctor treats a cruciate ligament tear either conservatively or surgically. This depends, for example, on the type and severity of the injury (cruciate ligament tear or complete tear, isolated injury or with concomitant injuries et cetera).
Individual factors are also taken into account when planning treatment, for example the age of the injured person, his or her sports ambitions and the extent of activities that put a strain on the knee (such as at work). In younger people who are very active in sports, a doctor is more likely to operate on a cruciate ligament tear than in older people who are less active and are hardly exposed to major knee loads.
Conservative treatment
In the first step of conservative treatment for a cruciate ligament tear, the doctor usually immobilizes the knee and stabilizes it in a splint (knee orthosis). The duration of immobilization is usually several weeks. This is followed by intensive physiotherapy. It is important to strengthen the thigh muscles in order to stabilize the knee joint. The aim is to gradually move the injured knee more and more and to put more weight on it.
The quality of physiotherapy is crucial for the stability and function of the knee joint after a cruciate ligament tear. Knee instabilities are the result of inadequate treatment otherwise.
Cruciate ligament surgery
You can find out everything you need to know about surgical treatment in the article Cruciate Ligament Surgery.
How do you diagnose a cruciate ligament tear?
The specialists for a cruciate ligament tear are orthopedists, trauma surgeons and sports physicians. To clarify the cause of the injury, the doctor first asks the following questions, among others:
- How did you hurt yourself?
- When did the accident happen?
- Did you hear a noise during the accident?
- Were you still able to walk after that?
- During which movements do you have particular pain?
- Have you ever injured your knee before?
The description of the accident may already give the doctor reason to suspect a cruciate ligament tear, especially if the knee joint is swollen. If the anterior cruciate ligament is torn, those affected usually report a cracking sound during the accident. Afterwards, it was usually no longer possible for them to walk. Tearing of the posterior cruciate ligament, on the other hand, is less often accompanied by a noise.
Physical examination and tests
Then the doctor examines the injured knee by palpating it (palpation) and performs stability tests, gait and balance tests. Important tests for detecting an ACL injury (such as cruciate ligament rupture) are the drawer test, the Lachman test, and the pivot shift test.
Thus, in the drawer test, the affected person lies on his back with the injured leg at 45 degrees of hip flexion and 90 degrees of knee flexion. If the doctor is now able to push the lower leg forward in the knee joint like a drawer in relation to the upper leg (anterior drawer test), there is an injury to the anterior cruciate ligament (like an anterior cruciate ligament tear).
If it is possible to move the lower leg excessively backwards in relation to the upper leg (posterior drawer test), this indicates damage to the posterior cruciate ligament.
The doctor also checks blood flow, motor function and sensitivity in the affected area (DMS test) and the range of motion of the injured knee compared to the healthy opposite side. For example, in the case of a posterior cruciate ligament tear, flexion in the knee is reduced by up to 20 degrees due to the altered biomechanics. Shortly after the accident, flexion cannot always be tested because the knee is usually painful and swollen due to the bruise. Then corresponding tests are only possible a few days later.
Imaging
The X-ray examination can be used to determine whether there is also a bony injury in the knee area or a bony ligament tear. The cruciate ligament tear itself cannot be detected on the X-ray. This requires another imaging procedure such as magnetic resonance imaging (MRI) or, in some cases, computed tomography (CT). Ideally, both procedures show whether the cruciate ligament in question is completely torn or only torn.
What leads to a cruciate ligament tear?
Sports and traffic accidents are the most common reasons for a cruciate ligament tear, especially a tear of the anterior external ligament. In sports, the injury often happens when the athlete hits the ground with sudden braking with the knee extended, as in a jump. Such a fall causes the knee to brake involuntarily, bend and rotate outward (external rotation trauma).
An anterior cruciate ligament tear thus classically occurs as a result of an abrupt braking movement with simultaneous rotation in the knee. The risk of this is particularly prevalent in soccer and skiing. In the case of an inward rotation, the cruciate ligament tear is based on a so-called internal rotation trauma.
Complex injuries often occur with an anterior cruciate ligament rupture: The rupture is then accompanied by an injury to the medial meniscus and/or the medial ligament. If all three structures are injured, this is referred to as an unhappy triad.
A posterior cruciate ligament tear is usually the result of external force, such as in sports or car accidents. By forcibly pushing against it while the knee is bent, the posterior cruciate ligament overstretches and tears. In some cases, the posterior cruciate ligament also tears when there are strong twisting movements and a lateral upward pressure on the knee joint. In most cases, other parts of the knee are also damaged.
Can a cruciate ligament tear be prevented?
To prevent a cruciate ligament tear, you should warm up your muscles well before any sporting activity. If you improve your coordination skills by jumping and running, you also reduce the risk of injury. Targeted muscle training, especially that of the thigh muscles, also prevents cruciate ligament injury.
