The posterior cruciate ligament lies at the back of the knee. It is one of the ligaments that hold the knee joint stable. In particular, it prevents the tibia from over-sliding relatively to the femur. The rupture of the posterior cruciate implies an injury of high force (serious injury). The most common cause is a knee stroke on the dashboard of a car in traffic accidents or a fall of an athlete on his already bent knee.
The knee joint consists of three bones: the femur, the tibia and the patella. The last one lies in front of the knee and provides, among other things, protection.
These bones are joined together by ligaments. There are 4 main knee ligaments that act as strong straps that hold the bones in place and stabilize the knee.
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
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 and part of the rotational movement of the knee. In particular, the posterior cruciate ligament prevents the tibia from sliding relatively to the femur (thigh). It is stronger than the anterior cruciate ligament and is rarely injured.
It consists of two parts that form a structure in the size of a human’s toe.
Injuries to the posterior cruciate ligament are not as common as other knee injuries. They are more difficult to diagnose and are often accompanied by injuries to other knee structures.
These injuries are called sprains and are classified according to 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.
Ruptures of the posterior cruciate ligament are usually incomplete and are characterized by satisfactory healing potential. Patients with ruptured posterior cruciate ligament often return to their sports activities without knee stability problems.
Injury to the posterior cruciate ligament is caused by strong forces and consequently they constitute high-force injuries.
- A direct impact on the front of the knee (such as when a bent knee forcefully hits the car dashboard or during a fall on the athlete’s bent knee)
- Extension of the ligament when turning or extending the joint
- Simple stumbling
Typical symptoms after rupture of the posterior cruciate ligament are:
- Pain and swelling that occurs immediately after an injury
- Swelling that leads to inability to bend and stretch the knee
- Instability (the knee feels “out of place”)
During the first examination the Orthopedist receives a detailed medical history. Then, he/she checks all the ligament elements of the injured knee during clinical examination by comparing them with that of a healthy knee. Often the knee feels like it is sinking backwards due to the tibia sliding relatively to the femur.
Radiographs and MRI can help in the diagnosis.
Radiographs: Although they cannot depict the posterior cruciate, they exclude the possibility of a tibial fracture, while being able to depict small detachable fractures, due to the tension of the ligament during injury.
Magnetic Resonance Imaging: It is a useful tool for detailing the posterior cruciate ligament.
If the injury is limited only to the posterior cruciate ligament, conservative treatment can offer very good results. Immediately after the injury, the patient is relieved with ice therapy, elastic knee bandaging and leg lifting.
Immobilization: It is recommended to use a splint to immobilize the joint. In addition, crutches help to move the patient without charging the leg.
Physiotherapy: After the initial edema of the first few days, the patient should start a recovery program with exercises. With these special strengthening and stretching exercises, the knee regains its functionality and strength.
In the event of a combined injury, the Orthopedist may recommend surgery. In the case of knee dislocation and/or multiple ligament injuries, surgery is required.
Reconstruction of the ligament: Since suturing is not sufficient to heal the ligament, a tissue graft is used. This graft is obtained from another part of the patient’s body or from another human donor.
Surgery: It is performed arthroscopically through small incisions and is less invasive. The benefits of the arthroscopic method include less post-traumatic pain, shorter hospitalization time and faster recovery.
The surgical repair of the posterior cruciate ligament is constantly being improved with new techniques that reduce the recovery time.
Rehabilitation, whether after surgery or not, plays a vital role in returning to daily activities. The physiotherapy program helps to recover the movement and strength of the knee. Usually, physiotherapy begins 1-4 weeks after surgery.
The time of recovery after rupture of the posterior cruciate ligament depends on the severity of the injury and the accompanying injuries.
In case the injury requires surgery, it will take several weeks to get back to work. It may take 6 to 12 months for the joint to fully recover.