POSTERIOR CRUCIATE LIGAMENT RUPTURE

The posterior cruciate ligament (PCL) is one of the less commonly injured ligaments and located in the back of the knee. It is one of several ligaments that connect the femur (thighbone) to the tibia (shinbone).

Up to 95% of the function of the ligament is to restrain posterior tibial displacement (posterior drawer).  Additionally functions as a restrain to excessive lateral and medial opening of the knee joint in extension.

ANATOMY

Two bones meet to form your knee joint: your thighbone (femur) and shinbone (tibia). Your kneecap sits in front of the joint to provide some protection.

Bones are connected to other bones by ligaments. There are four primary ligaments in your knee. They act like strong ropes to hold the bones together and keep your knee stable.

The PCL origin is a comma-shaped area on the medial femoral condyle. Its insertion is located in an oval midline shallow sulcus below the articular surface of the tibia.

Two components (bundles) of the PCL are commonly recognized: a thicker, stronger anterolateral portion that is tight in flexion and smaller posteromedial portion that is tight in extension.

Τhe posterior Cruciate ligament.


Knee MRI: The posterior cruciate ligament is intact (arrow)


Knee MRI, posterior view, intact posterior cruciate ligament (arrow)

MECHANISM OF INJURY

The mechanism of injury is most commonly a posteriorly directed force to the anterior of a flexed knee, the so-called dashboard injury. In athletics, such injuries can be caused by a fall on a flexed knee with a plantarflexed foot.

More rarely, PCL injuries can result from hyperextension or hyperflexion and are often associated with multiple ligament injuries.  Unlike ACL injuries, the patient with a PCL injury does not usually feel a pop and the athlete may not be able to describe exactly how or when the injury occurred.

 

Posterior cruciate ligament rupture due to trauma.

SYMPTOMS

The typical symptoms of a posterior cruciate ligament injury are:

• Pain with swelling that occurs steadily and quickly after the injury
• Swelling that makes the knee stiff and may cause a limp
• Difficulty walking
• The knee feels unstable, like it may "give out"

DIAGNOSIS

The history and physical examination is probably the most important tool in diagnosing a ruptured or deficient PCL.  During the physical examination, the doctor will check to see if the tibia moves too far back on the femur.

Tests are also done to see if other knee ligaments or joint cartilage have been injured. The doctor may order X-rays of the knee to rule out a fracture.  Ligaments and tendons do not show up on X-rays.


Clinical examination, posterior draw test for the knee instability due to posterior cruciate ligament rupture.

Examination of the posterior stability of the knee.

X-ray:  Posterior stress test of the tibia is normal.

X-ray:  The posterior translation of the tibia is not normal due to posterior cruciate ligament rupture.

The magnetic resonance imaging (MRI) scan is the most accurate test without actually looking into the knee. The MRI machine uses magnetic waves rather than X-rays to show the soft tissues of the body.

This machine creates pictures that look like slices of the knee. The pictures show the anatomy, and any injuries, very clearly.

MRI demonstrating a disrupted PCL (red arrow) with posterior sag.

CONSERVATIVE TREATMENT
THERAPY: 

Conservative Treatment

Isolated partial rupture of Posterior Cruciate Ligament (PCL), usually do not require surgery. The relatively benign course of these injuries is most likely due to the integrity of the secondary restraints and various portion of the PCL remaining intact.

Treatment of acute partial rupture of PCL focuses on decreasing pain and swelling in the knee. Rest and mild pain medications, such as acetaminophen, can help decrease these symptoms. Newer braces that attempt to prevent posterior tibial translation are available, but their clinical efficacy has not been proved.

   

Functional knee brace for PCL injuries.

The mainstay of postinjury rehabilitation treat swelling and pain with the use of ice, electrical stimulation, and rest periods with your leg supported in elevation. Quadriceps strengthening exercises, which have been shown to counteract posterior tibial translation, quadriceps sets, straight leg raises, and partial weightbearing with crutches are initiated.

Studies have suggested that prolonged nonoperative management of PCL injuries may lead to early osteoarthritis of the medial femoral condyle and patella as a result of altered contact pressures.

OPERATIVE TREATMENT
THERAPY: 

Surgical treatment
 

Operative indications for PCL reconstruction include patients found to have “isolated” tears associated with functional disability, as well as patients with other ligamentous injuries combined with complete PCL injury. Ultimately, the decision for surgical reconstruction of the PCL is based on the activity level of the patient and whether the injury is isolated or in combination with other ligament injuries.

The variety techniques developed for PCL reconstruction and the main aid of these is the restoration of normal anatomy of the ligament.

Graft options for PCL reconstruction include autografts such as bone-patellar-bone, hamstring, and quadriceps. Limitations of these grafts include but are not limited to donor site morbidity and increased operative duration.

The gracilis and semitendinosus tendons can be taken out without really affecting the strength of the leg because bigger and stronger hamstring muscles will take over the function of the two tendons that are removed.

Allograft options such as Achilles tendon, patella, posterior tibialis, and anterior tibialis tendon are often used for the multiple ligament reconstructions;
In a typical surgical reconstruction, the torn ends of the PCL must first be removed.

Surgery to rebuild a posterior cruciate ligament is done with an arthroscope using small incisions. Arthroscopic surgery is less invasive. The benefits of less invasive techniques include less pain from surgery, less time spent in the hospital, and quicker recovery times.

Hamstrings graft harvesting

Semitendinosous and gracilis musce after harvesting.

The graft is ready.

Achilles tendon allograft preperation.

The allograft is ready.

ARTHROSCOPIC SURGERY

 

If the symptoms of instability are not controlled by a brace and rehabilitation program, then surgery may be suggested. The main goal of surgery is to keep the tibia from moving too far backwards under the femur and to get the knee functioning normally again. New studies also suggest the need to restore medial-lateral (side-to-side) and rotational stability, too.

The Posterior Cruciate Ligament is absent due to chonic rupture (red arrow).
 

IndicatIions

Combined posterior cruciate ligament (PCL) and posterolateral corner (PLC) injury
Symptomatic chronic grade II or III injury that failed rehabilitation
Physiologically young active patient
Symptomatic instability/“something not right” with knee
Unwilling to change lifestyle
Committed to rehabilitation

 


To recostruct the posterior cruciate ligament the posterior medial portal is necessary.

Shaving the area of PCL remnants from medial femoral condyle. 

Bone prepare to create the tunnel.

X-ray during artroscopy.  Placement control of  the guide wire.  This step is very critical for the right bone tunner creation. 

The autograft is inserted to the femoral bone tunnel

Stability graft testing.

The right bundle is the posterior cruciate ligament autograft. 
The left bundle is the anterior cruciate ligament.

REHABILITATION: 

A physical therapy program will help to regain the knee strength and motion. Postoperatively the knee is placed in a hinged brace that is initially locked in full extension. The tibia is supported posteriorly to prevent posterior sagging. The patients ambulates with partial weightbearing crutch assistance and emphasis is placed on avoiding posterior tibial translation during the early rehabilitation phase. Formal physical therapy can begin as early as 2–3 days postoperatively. Early therapy involves effusion control and progression of motion and weight bearing.

Quadriceps exercises are encouraged and hamstring exercises are discouraged in the early postoperative period. Isometric exercise including straight leg raising and quadriceps sets are begun immediately postoperatinely. Range of motion is started between the second and fourth week, depending on the extent of ligamentous injury that is involved.