Anterior cruciate ligament

One of the most common knee injuries is damage or rupture of the anterior cruciate ligament.

Specializing in orthopedics, traumatology and sports-related medical diagnostics

Polyclinic Ribnjak is a specialized institution for the treatment of orthopedic and traumatic injuries of the locomotor system.

One of the most common knee injuries is damage or rupture of the anterior cruciate ligament.

In our institution, we perform several different methods of anterior cruciate ligament treatment, including ligament transplantation, as well as subsequent recovery and extended physicaland functional rehabilitation that ensure adequate recovery after treatment.

Read all the details about the anterior cruciate ligament and its injury below.

The human body is a fascinating whole capable of adapting to all kinds of conditions, from extreme environmental conditions to adapting to extensive traumatic conditions.

Rupture of the anterior cruciate ligament is one of the most common knee injuries of the physically active population, both in recreational activity and in professional sports, and is still accompanied by a dose of mystification when it comes to treatment, recovery and return to everyday life.

The frequency of this injury is, according to some authors, 30 to 78 cases per 100,000.00 people per year!

Therefore, carefully planned treatment, adapted to each individual with regard to his own characteristics, but also the characteristics of the injury itself, is a necessity!

KNEE ANATOMY – what is the role of the anterior cruciate ligament?

The knee is the most complex built joint in the human body. It is characterized by numerous features that make it unique. The structures that are most important in terms of knee stabilization and its mechanical movement are fibrocartilage structures, menisci, and lateral (medial and lateral collateral ligament) and cross (anterior and posterior cruciate ligament) ligament ligaments. (figure 1.)

Figure 1. The structures that make up the knee joint

Strong ligaments in the joint are necessary for its proper functioning. Based on the structure and strength of these ligaments, the type and limits of the maximum range of motion in the knee are determined.

The anterior and posterior cruciate ligaments are collagen structures whose main task is to constantly maintain contact between the articular bodies (femur and tibia). Since the topic of this text is the anterior cruciate ligament, we will focus exclusively on it. The anterior cruciate ligament starts from the medial (inner, rounded red, Figure. 2) surface of the lateral (outer) part of the femur, and is diagonally attached to the anterior part of the tibia (rounded yellow, hence the name “cruciate ligament”, since its course starts with one side of the joint and grips the other side, Figure 2).

Figure 2. Representation of the anterior cruciate ligament continuity in context with other structures in the knee. The starting point of the anterior cruciate ligament is rounded in red, while its grip on the tibia is rounded in yellow.

At all times and with all possible types of movement, at least one part of the ligament is tense. In close cooperation with the menisci and collateral ligaments, the cruciate ligaments ensure synchronized movement in the joint, while preventing any kind of movement between the articular bodies. With its stabilizing effect, the anterior cruciate ligament prevents hyperextension in the knee (excessive stretching of the leg), movement of the tibia forward in relation to the femur, and rotational movements of the tibia in relation to the femur.

The anterior cruciate ligament consists of two large bundles with respect to their grip on the tibia – the anteromedial (anterior inner) and posterolateral (posterior outer) bundle. (figure 3)

Figure 3. View of the anatomical structure of the anterior cruciate ligament

The forces acting through a particular beam differ with respect to the movement that is performed in the knee at that moment. One study showed that the forces acting in the anteromedial bundle are strongest between 60 ° and 90 ° flexion (knee flexion movement), while the forces acting in the posterolateral bundle are strongest at full knee extension (extension).

The blood supply to the anterior cruciate ligament is provided by the artery media genus (a. Poplitea), while the nerve fibers innervating the ligament come from the nervus articularis posterior (n. Tibialis). This information is important in the context of treatment and reconstruction of the ruptured anterior cruciate ligament, since these same nerve fibers are used for sensory joint proprioception (a sensation that allows us to instinctively adjust the position of the joint according to the situation). graft, ie the original structure of the tissue is lost, a certain amount of time is needed for the re-development of proprioceptive nerve fibers, which makes people feel as if the knee is “not theirs” after the operation.


Risk factors for anterior cruciate ligament rupture include modifiable and non-modifiable factors. Modifying factors include:

  • Body mass index
  • Hormonal status
  • Muscle fatigue
  • Various neuromuscular and biomechanical deficits
  • Shoes
  • The surface on which the sports activity takes place
  • Weather conditions
  • The level of sports competition in which you participate
  • The type of sport you play

Non-modifying factors are risk factors that cannot be influenced by lifestyle changes. These include:

  • Female gender
  • The size of the area from which the anterior cruciate ligament originates (narrowed in some people)
  • The size (volume) of the anterior cruciate ligament
  • Ligament looseness
  • Previous anterior cruciate ligament injuries
  • Genetic predisposition


Injuries of the anterior cruciate ligament in as many as 70-80% of cases occur without direct contact with, for example, a player of the opposing team in team sports. They most often occur after a jump, during a sudden change of direction or during a violent slowdown after a sprint. One of the most commonly described injury mechanisms involves landing on a leg that is extended at the hip and knee, with the knee “escaping” to the valgus position (leaning inward), the tibia rotating outward, and the foot in pronation. In this position, it is about the so-called. “Points of no return.”

There are common situations in which there is hyperextension (extension) of the knee, which is another mechanism of non-contact injury, and it occurs, for example, in football players after they break the ball. In addition, of the non-contact mechanisms of injury, the one in alpine skiers has been described, in which there is an internal rotation of the tibia in relation to the femur with a fully extended (extended) knee or a knee flexed (bent) over 90 °.

Contact or traumatic mechanisms of injury are most often associated with the action of strong forces on the femur along the fixed tibia or on the outside of the knee (various blows, levers), which creates stress-valgus position of the knee (knee moved “inward”). Traumatic injuries of the cruciate ligaments are most often accompanied by injuries of the medial meniscus and medial collateral ligament, which in medicine we call the “ominous triassic”, and often the symptoms of these two injuries hide the injury of the anterior cruciate ligament, which can pose a risk of chronic instability in the knee.

Anterior cruciate ligament injuries, similar to ligament injuries globally, are divided into three stages.

  • Anterior cruciate ligament distension
    • A condition after a traumatic event in which there is movement that usually leads to ligament rupture, but with insufficient force. The ligament stretches, and since it is an inextensible tissue, it remains stretched (distended) and it takes some time for it to return to its original state. In the distended state, we can find local microtraumas and edema in parts of the ligament, but it mostly still performs its function and the knee is mostly stable.
  • Partial rupture of the anterior cruciate ligament
    • In case of partial rupture, the continuity of a part of the fibers of the anterior cruciate ligament is interrupted. Depending on the extent of the injury, this degree of anterior cruciate ligament injury may be accompanied by a normal level of knee stability or various forms of knee instability.
  • Total rupture of the anterior cruciate ligament
    • Complete rupture of the anterior cruciate ligament fibers. Injury can occur at the origin of the ligament (lateral condyle of the femur), the grip of the ligament (the area on the tibia called the eminentia intercondylaris tibiae) or both of these localizations at the same time while maintaining the continuity of the anterior cruciate ligament fibers but not its insertion sites. on the femur and tibia. These injuries are often accompanied by avulsion (a type of injury in which a strong and sudden force on the ligament causes damage to the part of the bone from which the ligament originates or the part of the bone to which it is attached), so it is often advisable to take an X-ray to rule out this diagnosis. knees.


The most common symptom is a strong, sudden pain in the knee during physical activity, often accompanied by the sound of a dry twig cracking. Patients often report a feeling of instability in the knee, a feeling of lack of confidence and confidence in the knee, and very often there is an inability to perform terminal movements in the knee (full flexion and full extension).

In the clinical picture we often find swelling in the knee, hemarthrosis (bleeding in the joint space) and spasm of the surrounding muscle, which occurs as a protective mechanism of the body to the injury.


An experienced clinician can establish the diagnosis already on the basis of anamnesis and clinical examination, while the final diagnosis is confirmed by magnetic resonance imaging. Several tests are specific to confirm the diagnosis of rupture or distension of the anterior cruciate ligament, the most applicable being the Lachman test (Figure 4) and the “front drawer” test (Figure 5). A positive “front drawer” test raises the suspicion of an anterior cruciate ligament injury, and its high positivity also suggests a rupture of the medial collateral ligament in the “ominous Triassic” syndrome (along with the anterior cruciate and medial collateral ligament ruptures the medial meniscus). The Lachman test is an extremely reliable method of proving a fresh anterior cruciate ligament injury. However, the diagnosis of anterior cruciate ligament rupture is by no means an easy task, so a large number of such injuries are overlooked in favor of other disorders with more pronounced symptomatology, which often often results in chronic knee instability.

Figure 4. Lachman test. The leg is bent at the knee at approximately 20-30 °. The doctor fixes the femur with one hand, while with the other hand he pulls the tibia towards himself. Due to the rupture of the anterior cruciate ligament, the tibia is not stable in relation to the femur and, depending on the extent of the injury, it moves forward, ie in the direction of traction. Excessive mobility of the tibia may also indicate a combined injury of the anterior cruciate and medial collateral ligament.

Figure 5. Front drawer test. This test is similar to the Lachman test, but differs in the angle of flexion of the knee when performing the test (the knee is bent at 90 ° as opposed to 20-30 ° in the Lachman test) and the foot is fixed to the ground so that the test taker sits on it. . The tibia is pulled forward and it is seen if there is a shift relative to the femur.

In case of suspicion of the aforementioned avulsion, it is important to perform radiological processing in the form of X-ray findings of the knee, in order to identify any bone fragments left behind after the trauma itself.

TREATMENT OF FRONT CROSS LIGAMENT RUPTURE – is reconstruction surgery necessary?

As with any other type of injury in medicine, the treatment of anterior cruciate ligament injuries can be conservative and invasive (surgical). As with any other type of injury in medicine, the treatment of anterior cruciate ligament injuries can be conservative and invasive (surgical).

In case of a joint injury, surgical treatment of all damaged structures is mandatory. This procedure is called ligament reconstruction. The anterior cruciate ligament today is almost always replaced by a tendon graft m. semitendinosus or muscle gracilis on the inside of the knee.

In isolated anterior cruciate ligament injuries, the approach to treatment depends on several factors

  • patient age – patients up to 40 years of age are candidates for surgical treatment
  • the presence of osteoarthritis
  • level of sports activity and motivation
  • condition of the thigh musculature

Controversies exist when it comes to partial rupture of the anterior cruciate ligament.

If the strength and tone of the thigh muscles is satisfactory for the stability of the knee and the load it can withstand, surgical treatment should not be forced.

In the conservative type of treatment, kinesitherapy methods are used, ie strengthening the thigh muscles, which has a significant role in stabilizing the knee and can take on the role of the primary knee stabilizer in patients with contraindications for anterior cruciate ligament reconstruction.


In general, the prevailing opinion is that even in young patients with fresh anterior cruciate ligament injury, it is advisable to first apply kinesitherapy for a few weeks in order to obtain a full range of motion, and only then proceed to arthroscopic reconstruction of the anterior cruciate ligament.

Of course, there is also an approach to urgent LCA reconstruction, in the case of an associated meniscus injury or simply in individuals in a top professional facility.

After 40 years of age, surgery to reconstruct the cruciate ligaments is not practiced.

Arthroscopic knee toilet, properly indicated, is used regardless of age and it can be used to repair cartilage damage and injuries of the knee meniscus.

Figure 7. Anterior cruciate ligament reconstruction. The procedure begins with arthroscopic exploration of the inside of the joint to assess the condition of structures not available by conservative diagnostic methods, followed by preparation of tissue to replace the anterior cruciate ligament (patellar ligament, semitendinosus, gracilis), drilling small holes in the tibia and femur through which a new, improvised ligament is then passed. The graft is then fixed in its position in the bones.


The main goal of postoperative rehabilitation is to restore muscle trophism to its original state and achieve full range of motion in the knee joint, in order to avoid the creation of contractures that would significantly prolong recovery time.

Rehabilitation begins on the second day of the operation. Exercises are performed to the limit of pain. With a knee orthosis placed, the movement is with the help of crutches for several weeks.

Rehabilitation took place under the control of the operator. There are postoperative rehabilitation protocols to ensure that recovery proceeds smoothly. After 3 to 4 months, running is allowed, without sudden changes of direction. Return to full sports activity is expected after 6-8 months from the procedure.

It should be noted that the application of platelet rich plasma, as a biological method of treatment, can accelerate recovery but also improve the process of knee graft implementation.

After anterior cruciate ligament reconstruction surgery, 61% to 89% of athletes successfully return to sports activities / according to the authors Brophy RH et al., Mai HT et al.


APPLICATION OF PLATELET RICH PLASMA in the postoperative period, as part of rehabilitation after treatment of anterior cruciate ligament rupture and its reconstruction, is a special feature of our institution.

Platelet rich plasma preparation was created by centrifuging your own blood.

It abounds in so-called growth factors, molecules that promote tissue healing, revascularization and return to the state in which the tissue was before damage. Some of these growth factors are FGF (fibroblast growth factor), which stimulates the production of collagen that will provide the new ligament with the necessary strength, VEGF (vascular endothelial growth factor), which promotes the formation of new blood vessels at the site of damage, then PDGF (platelet-derived growth). factor), EGF (epidermal growth factor), TGF-β (transforming growth factor beta) and many others.

The application is painless, it is performed on an outpatient basis on several occasions, with an interval of 7-14 days between individual applications.


Various studies have shown that such a risk exists, as with any other surgical procedure.

However, this primarily depends on the dosed load of the knee as part of the overall sports activity of the postoperative period. Therefore, it is necessary to properly and disciplinedly carry out rehabilitation and dose the load on the knee while adjusting the future training process.

In addition to the operator and physiotherapist, coaches as well as the environment are involved in the process, as needed, in order to provide the best possible recovery outcome with an individual approach.

Your Polyclinic Ribnjak

In short

Polyclinic Ribnjak is a unique institution in the Republic of Croatia. It unites different branches of medicine, all in order to stay true to its slogan “Health and Beauty. Together”. Orthopedics, advanced sports diagnostics, functional and kinesiological rehabilitation, cosmetic surgery and treatments are the services we provide on a daily basis, professionally and in accordance with the latest professional standards.


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