Anterior Cruciate Ligament (ACL) Reconstruction

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Anterior Cruciate Ligament (ACL) Reconstruction

The function of the knee joint

The function of the knee is to enable movement but also to transfer body weight to the feet during walking. The articular bodies in the knee area are a combination of convex articular surfaces of the femur and almost flat articular surfaces of the tibia. In this way, the mobility of the knee is increased, but also its stability is significantly reduced. In order to increase the stability of the knee, the correct function of the knee stabilizers is of great importance.

Stabilizers are divided into active and passive. Active stabilizers are muscles that are among the strongest in the human body and also move the joint. Passive stabilizers are: ligaments, joint capsule and meniscus. The most important ligaments of the knee are: the inner and outer lateral ligament and the anterior and posterior cruciate ligaments.

Anterior cruciate ligament (ACL)

The anterior cruciate ligament (ACL) is one of the four key ligaments responsible for knee stability. ACL is primarily responsible for preventing excessive anterior displacement of the lower leg relative to the upper leg, i.e. movement of the tibia (shinbone) relative to the femur (upper leg bone), and is also important for preventing excessive rotation of the lower leg. The anterior and posterior cruciate ligaments within the knee form an X-shaped structure, hence their name. Cruciate ligament injury, especially ACL, is a common injury in athletes and especially in football, basketball, and skiing, i.e., sports with sudden changes in direction of movement that result in rotations in the knee. About 30 ACL injuries per 100,000 population are expected annually.

Knee anatomy

  • Femur
  • Patel - kneecap
  • Tibia - shinbone (larger bone of the lower leg)
  • Fibula - a smaller bone of the lower leg
  • Collateral ligaments - firm, elastic connective tissue that surrounds the joint to ensure its stability
  • Cruciate ligaments - the anterior and posterior cruciate ligaments in the knee form an X shape, they ensure rotational stability and also prevent excessive displacement of the lower leg relative to the upper leg.
  • Meniscus - curved cartilaginous parts in the joint that serve as shock absorbers that absorb the load, increase the contact of the joint surfaces, etc.
  • Muscles - serve the dynamic stability of the joint

Mechanism of ACL injury

Acute ACL injuries are often the result of excessive rotation or excessive extension (hyperextension) of the knee. The activities that lead to an ACL injury, which are common in many sports, are:

  • sudden changes in direction
  • turning with feet firmly attached to the ground
  • improper landing
  • abrupt stop after sprint
  • collision or direct blow to the knee area

Such actions can lead to a ligament injury, which can result in complete rupture, partial rupture or minor injury (stretching) that does not result in a ligament tear.


PHOTO: Mechanism of anterior cruciate ligament injury (ACL) – rotation

Symptoms of ACL injury

Early signs:

  • "Shooting sound" at the time of injury
  • the knee “escaped” at the time of the injury
  • severe pain and inability to resume activity after the injury
  • rapid swelling of the knee

Later signs:

  • a feeling of knee instability
  • pain
  • reduced range of motion
  • inability to perform physical activity or work

Do you recognize any symptoms? Arrange an examination and check it out!

What to do immediately after the injury?

Immediately after the injury, it is necessary to reduce pain and swelling in the knee using the R.I.C.E. model that can be performed in your own home:

  • Rest - it is necessary to reduce the load on the knee
  • Ice - it is necessary to cool the knee with ice packs every 2 hours for 20 minutes to reduce swelling
  • Compression - it is necessary to wrap the knee with  elastic or other bandage
  • Elevation - in the supine position, it is necessary to place pillows under the injured leg

When to see a doctor?

In the event of an injury that has caused symptoms of an ACL injury, contact your doctor as soon as possible. ACL is an extremely important structure in the knee, with many functions, and especially in people who want to do sports. It is important to ensure timely diagnosis and adequate therapy for each patient.

Contact us with confidence and arrange an examination.

Risk factors for ACL injury

  • female gender - hormonal differences and differences in anatomy and muscle strength are important factors in the higher incidence of ACL injury in females
  • certain sports such as football, basketball, skiing and other sports in which sudden changes of direction are frequent
  • poor physical condition
  • inadequate sports footwear and equipment
  • terrain changes (parquet, artificial grass, concrete, etc.)

Complications of ACL injury

ACL integrity is crucial in maintaining knee stability. An unstable knee is one of the key risk factors in the development of osteoarthritis in later life. That is why it is important to ensure adequate treatment for every individual with an ACL injury, whether conservative or operative.

In addition to an ACL injury, other associated injuries such as meniscus rupture are common, which are also one of the factors in the later development of knee osteoarthritis.


Preparing for an examination

Before examining by an orthopaedic surgeon it is important that the patient prepares answers to the following questions:

  • When did the injury happen?
  • What were you doing when the injury happened?
  • Did you hear a “shooting sound” at the time of the injury?
  • Did your knees swell after the injury?
  • Have you ever injured your knee before?
  • Are your symptoms constant or do they appear occasionally?
  • Does your knee ever block?
  • Do you feel instability in your injured knee?

Examination by orthopedic specialists

The diagnosis of anterior cruciate ligament rupture is based on knowledge and understanding of the biomechanical elements of the injury after a detailed description of the problem and the mechanism of the injury. Data about the strength and direction of the force acting on the knee at the time of the injury, the auditory sensation of cracking, the impossibility of further activities immediately after the injury and the rapid swelling of the knee are important.

Clinical examination includes tests to assess knee stability, tests to detect injuries to other structures such as the meniscus, examining a range of motion, and assessing the functionality of the entire knee. The orthopaedic surgeon will compare the function of the injured and healthy knee and decide on possible additional diagnostic procedures.

In order to confirm the diagnosis of ACL injury in unclear cases, magnetic resonance imaging (MRI) of the knee is performed. MRI of the knee is a non-invasive test to obtain quality data on the condition of all knee joint structures. After determining the type and size of the injury, a decision on further treatment follows.


It should be emphasized that unfortunately the anterior cruciate ligament cannot heal on its own. Treatment must be individualized and tailored to the patient. It is of great importance to establish a dialogue between the doctor and the injured person. The most important factors influencing the decision are the age of the injured person, motivation, level and type of physical activity that the person wants to engage in, the degree of knee instability and the condition of other knee structures. Treatment can be surgical and conservative.

Book your appointment and check out all treatment options.

Conservative treatment

Conservative or non-surgical treatment consists of strengthening the muscles and improving the proprioception (sense of position in the space) of the knee. In this way, an attempt is made to compensate for the lack of an important passive stabilizer such as the anterior cruciate ligament with muscles, by active stabilization of the knee. It should be emphasized that by strengthening the musculature acting on the knee joint the rotational stability of the knee provided by the crossed ligaments cannot be achieved.

Preoperative rehabilitation

The goal of preoperative rehabilitation is to reduce pain and swelling while at the same time strengthening the muscles and restoring range of motion in the injured knee. The results of surgery in a stiff and swollen knee are worse than in patients with full range of motion and no swelling.

In the case of the elderly with an ACL injury or in individuals who do not intend to play sports or whose work does not require physical activity, this form of physical therapy may also be the final treatment. By strengthening the muscles, the knee becomes more stable and it is necessary to maintain the musculature to avoid unwanted complications.

Surgical treatment

People with complete loss of the anterior cruciate ligament develop degenerative joint changes more quickly and are significantly more susceptible to recurrent knee injuries. For this reason, surgery is proposed in:

  • younger and motivated individuals
  • athletes (professional and recreational)
  • for people with associated injuries of the meniscus or other knee structures
  • for people with an unsatisfactory range of motion and a knee that "blocks"

The operation consists of the reconstruction of the anterior cruciate ligament. The entire operation is performed arthroscopically, under spinal anesthesia, where the knee does not open, but the operation can be performed through two to three small incisions of a few millimeters. The course of the operation is monitored on a video screen and, if desired, the patient can watch the operation and communicate with the operator. During the operation, the operator removes the damaged ligament, while a part of the injured person's tissue (graft) is used for reconstruction. The most commonly used tissue for graft preparation are muscle tendons from the posterior part of the thigh (semitendinosus and gracilis muscle tendons), patellar ligament nd quadriceps tendon. Such a graft can be fixed with a completely resorbable material that is slowly resorbed over time, i.e. melts inside the body after the graft heals.


PHOTO: Preparation of graft for anterior cruciate ligament (ACL) reconstruction

At the end of the operation, the patient is transferred to the orthopaedic ward where the physical therapy is immediately started. Along with the physiotherapist, the patient learns to walk with crutches and behave with the operated leg. The patient usually spends one night in the hospital after the procedure and is discharged from the hospital in the morning after bandaging the surgical wounds and performing physical therapy.

Risks of surgery

As with any surgery, there are risks such as bleeding or surgical wound infection with ACL reconstruction. Other risks in ACL reconstruction may be:

  • Knee pain or stiffness
  • Poor graft healing ("new" ligament)
  • Graft rupture after returning to sport

Postoperative rehabilitation

It takes several months for the graft to fully coalesce and heavy knee load is allowed before that time. Proper postoperative rehabilitation is complex and extremely important for complete recovery of knee stability and function and generally lasts 5 to 6 months after the surgery. Before returning to normal physical activity, it is necessary to perform several control exams the current function of the knee joint and the "new" ligament. After the physical therapy, the athlete needs to do proper kinesitherapy to balance the muscles, increase stability and reduce the possibility of re-injury to the ACL.

If you feel any problems, book an appointment with one of our orthopedic experts and prevent further complications.

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