One of the most common knee injuries is the injury or rupture of the anterior cruciate ligament. Athletes involved in high-demand sports such as football and basketball are very likely to injure the anterior cruciate ligament. If the anterior cruciate ligament is injured, there may be a need for surgical treatment to recover the full range of motion of the patient’s knee. This will depend on factors such as the severity of the injury and the level of sports activity of the patient.



Three bones are involved to form the knee joint; the femur, the tibia and the patella. The latter is located at the anterior part of the joint, and with the patellar tendon it participates in the extensor knee mechanism. These bones are joined together by ligaments. There are 4 main ligaments on the human knee. They act as strong straps (ropes) that keep the bones in contact with each other and the knee firm.


Collateral Ligaments

They are located on the lateral surfaces of the knee. The medial collateral ligament is located on the inner side of the knee and the lateral collateral ligament on the outer side of the knee. They control the lateral movements of the joint and protect it against movement of the knee in varus–valgus directions


Cruciate Ligaments

They are located within the knee joint. They intersect with each other in the form of an X with the anterior cruciate ligament at the front and the posterior cruciate ligament at the rear. The cruciate ligaments control the anterior-posterior movement of the knee. The anterior cruciate ligament is extended diagonally into the knee joint and prevents the tibia from sliding forward on the femur. In addition, it provides rotational stability to the knee.



In about half the cases, the anterior cruciate ligament injury is accompanied by injuries to other knee joint structures, such as articular cartilage, meniscus and other ligaments.


Ligament injuries are considered “sprains” and are classified based on their severity. Grade 1: The ligament is slightly injured. It may be partially extended, but it still maintains its ability to keep the knee joint stable.

2nd Grade: In this type of sprain the ligaments is extended to the point where it becomes looser. This is often referred to as partial rupture of the ligament.

Grade 3: This type of sprain is referred to as a complete rupture of the ligament. The ligament is torn and the knee joint becomes unstable. Partial ruptures of the anterior cruciate ligament are rare. Most ruptures are complete.



The anterior cruciate ligament is injured in several ways:

  • During an abrupt change of direction
  • When we stop abruptly
  • During an abrupt slowdown as we run
  • When we land in the wrong way after a jump
  • After a sharp mechanical crash or impact, such as in football with a single tackling

Several studies have shown that women athletes are more likely to injure the anterior cruciate ligament than male athletes in specific sports.

This is mainly due to different muscular endurance, different physical condition and neuromuscular control. Other reasons include differences in pelvis and lower extremity alignment, increased flexibility-looseness of ligaments and the effect of estrogens on the mechanical properties of ligaments.




When the anterior cruciate ligament is injured, a characteristic sound may be heard and the patient may feel that he has lost control of movements below the knee. Other typical symptoms are:



  • Pain with edema. Within 24 hours the knee gets swollen. If it is ignored for days, the edema may recede on its own. However, a return to sports activities will reveal an apparent knee instability with the risk of injury of other joint structures as well (e.g. meniscus)
  • Loss of full range of motion
  • Pain-Sensitivity along the knee joint
  • Walking pain



During the first visit, the orthopedist focuses on the patient’s symptoms and medical history. During the physical-clinical examination the orthopedist examines all the structures of the patient’s knee and compares them with the corresponding structures of the healthy leg. Most injuries can be diagnosed with a careful clinical examination.



Other tests that will help confirm the diagnosis are:

  • Simple X-rays: Although they cannot depict the anterior cruciate ligament rupture, simple X-rays are able to correlate the rupture with some bone injury.
  • Magnetic resonance imaging: Provides detailed imaging of soft tissues, such as the anterior cruciate ligament. However, magnetic resonance imaging is not always necessary for the diagnosis of the anterior cruciate ligament rupture.



The treatment of ruptured anterior cruciate ligament depends on the individual needs of each patient. For example, a young athlete involved in high-demand sports will often require surgery to return safely to his or her sporting activities. Less active, older patients may return to less demanding daily living without surgery.



The ruptured anterior cruciate ligament will not be healed without surgical treatment. However, conservative treatment may be the best option for older patients or patients with low activity levels. If the overall stability of the knee is not disturbed, then the orthopedist can recommend simple, non-surgical treatment options.

Splint Use: The orthopedist may suggest using a splint to protect the patient’s knee from instability. For further protection of the knee it may be necessary to walk with crutches so that the affected leg is not loaded.

Physiotherapy: As the edema recedes, a carefully planned recovery program can be initiated. Specific exercises will restore functionality to the patient’s knee and strengthen the muscles that support it.



In the vast majority of cases, the anterior cruciate ligament cannot be repaired by simple sutures. The surgeon uses autologous tissue grafts to surgically restore the ligament and the knee’s stability. These grafts act as a scaffold, so that the anterior cruciate ligament can be rebuilt.

These grafts can be recovered from various sources. Often, a portion of the patellar tendon, located between the femur and patella, is isolated. Sometimes, hamstring grafts are used. The quadriceps tendon is rarely used. Finally, allografts from cadaveric donors may also be used.

There are advantages and disadvantages in each different graft. This should be discussed with the Orthopedic Surgeon, who will suggest the most appropriate solution for each patient. Complete rehabilitation is time-consuming and may take up to 6 months for an athlete to return to his or her sporting activities.


Surgical Procedure

The surgery to repair the anterior cruciate ligament is performed arthroscopically using very small incisions, so it is considered a minimally invasive procedure. The advantages of this method are shorter hospitalization period, less pain and faster recovery.

Surgery to repair the anterior cruciate ligament is not performed in the acute post-traumatic phase (immediately after injury) unless its rupture is part of a more complex injury. This delay enables the swelling to recede and allows the range of motion to be restored before surgery. In addition, immediate restoration of the anterior cruciate ligament increases the risk of arthrofibrosis or scar formation in the joint, leading to loss of knee movement.



Rehabilitation plays an important role in returning to daily activities, whether the treatment is surgical or conservative. A physiotherapy program will help regain strength and range of motion.

In patients undergoing surgery, physiotherapy initially aims to regain the range of motion of the joint and the surrounding muscles. This is followed by a stretching program specifically designed to protect the new joint. The stretching program gradually increases the load on the joint. The final stage of rehabilitation aims at the functional recovery of the athlete and is personalized to his/her needs.