Posterior Cruciate Ligament Injury

Original Editors - Sigrid Bortels as part of the Vrije Universiteit Brussel's Evidence-based Practice project

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Definition/Description 

A posterior cruciate ligament injury (PCL) can appear in different forms. The severity of the injury determines the treatment protocol. It can range from a slightly stretch of the ligament, stretched to the point where the ligament becomes loose, or a total tear of the ligament in the transverse direction.

Clinically Relevant Anatomy

The posterior cruciate ligament (PCL) is found in the knee joint, and runs from the medial femoral condyle of the femur to the tibia plateau. It crosses the anterior cruciate ligament to form an 'X'.
The PCL is twice as thick as the anterior cruciate ligament (ACL). This means that it is much stronger, which results in less injuries than the ACL.
A posterior cruciate ligament consists of 2 inseparable bundles: the anterolateral bundle (AL) and the smaller posteromedial (PM) bundle.
The AL bundle is tighter in knee flexion and inward rotation, while the PM bundle is tighter in knee extension.
The orientation of the fibers varies between bundles. The AL bundle is more horizontally orientated in extension and becomes more vertical as the knee is flexed beyond 30°. The PM bundle is vertically orientated in knee extension and becomes more horizontal through a similar range of motion.
The PCL is the major stabilizing ligament of the knee, and prevents the tibia from moving backwards too far.

Epidemiology /Etiology

- Motor vehicle accidents or 'dashboard injuries' (MRI is a good option in this situation)
- Sports: football, soccer, skiing
- A simple misstep
- Bad landing from a jump
- Fast changes of direction

Characteristics/Clinical Presentation

Characteristics 

- Grade 1 Sprains. The ligament is slightly stretched. (AL and/or PM bundle)
- Grade 2 Sprains. The ligament is stretched to the point were it becomes loose. (AL and/or PM bundle)
This is called a partial tear.
- Grade 3 Sprains. This is a complete tear of the ligament.
The ligament has been split into two pieces, and the knee joint is unstable. 

Clinical Presentation

- Movement restrictions and pain
- A weak feeling in the knee
- Swelling
- Knee joint instability
- Difficulty walking
 

Differential Treatments

Grade 1 sprains. Conservative treatment : it is a non-operative treatment. An example of a conservative treatment is physical therapy. This is the most important treatment for physiotherapists and is explained further bellow.

Grade 2 sprains. The treatment options are somewhat controversial, but the following guidelines can be considered as general guidelines:
- An isolated acute PCL tear with less than 10 mm of posterior laxity at 90 degrees of flexion will probably be treated with physical therapy.
- An acute PCL tear that causes more than 10 to 15 mm posterior laxity or more than one ligament injury, will be treated with surgery in order to repair or reconstruct the PCL.
- Sometimes, a portion of bone is pulled off with the torn ligament. If the fragment is large enough, the bone is usually reattached. If the fragment is too small, it is discarded and the PCL is repaired or reconstructed.
- All chronic PCL injuries are initially treated with an aggressive quadriceps rehabilitation program. But if the aggressive rehabilitation program fails, if there is more than 10 to 15 mm posterior laxity in the knee, or if degenerative changes in the knee joint can be seen on x-rays, surgery may be required. An operation to treat a long-term PCL injury does not make the knee normal, but it may decrease its laxity. 

-> These are the general guidelines, but after reading some articles about the conservative treatment of grade 2 sprains, it is clear that the results are controversial.
Some experiments are rather positive about conservative treatment, and conclude that almost all patients can resume their normal sport activities after treatment, without further problems.
But there are also other studies that are rather negative. One study concluded that significant symptoms and degenerative changes increase with increasing interval from injury. But can early reconstruction prevent degenerative changes? According to another article, this still remains uncertain.
Another study concludes that the posterior instability of the PCL injured patients showed little improvement when compared with the initial status before the treatment and that residual laxity still remained.
It is probably necessary to realize more studies in order to know what treatment is best for grade 2 injuries.

Grade 3 sprains. Use of an operative treatment. This means repairing the ligament by reattaching the torn fibres to each other.
If not enough fibres remain to repair the PCL or if the tissue has degenerated beyond repair, the PCL can be reconstructed. The ligament will be replaced with tissue from another part of the body or from a donor. Part of the patellar tendon (tissue that connects the muscle to the patella) or hamstrings can be used in the reconstruction. 
 

Diagnostic Procedures

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Outcome Measures

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Examination

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Medical Management

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Physical Therapy Management

1. RICE- method: Rest, Ice, Compression, Elevation → helps to speed the recovery.

2. Physical therapy: it is a careful rehabilitation program, with specific exercises to stretch and strengthen the leg muscles and to restore function in the knee. Strengthening the quadriceps is the key factor in a successful recovery, because the quadriceps can take the place of the PCL to a certain extent, helping to prevent the femur from moving too far forward over the tibia.
Some therapists recommend the use of a knee brace to support the knee during movement or when the patient is engaged in athletic activity. The use of a brace has not yet been shown effective during exercises.

These are some typically exercises for a PCL injury.
- "Closed chain" exercises (minisquats, gentle stretching, leg press, bicycling, stair-stepper exercises).                                                                                                                                                                                  - Proprioceptive exercises such as balance-board therapy, mini-trampoline balancing.
- Full range of motion should be achieved 4-6 weeks after injury
- Functional training (for sporters), beginning with forward and backward running and progressing to lateral movements, and sport-specific activities 
 

Key Research

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Resources

1. http://www.wheelessonline.com/ortho/anatomy_of_the_posterior_cruciate_ligament
2. http://www.arthroscopy.com/sp05001.htm
3.Gerard B. Rondhuis (1196). Knierevalidatie, Elsevier/De Tijdstroom
4.http://orthoinfo.aaos.org/topic.cfm?topic=a00420
5. http://www.hughston.com/hha/a.pcl.htm
6. R. Timothy, M.D. Stapleton (1996). The posterior cruciate ligament, Hughston Health Alert, 8, nr. 1, 2-3.
7. E. Brown David, D. Neumann randall (2004). Orthopedic secrets, 3, Philadelphia, Pennsylvania 
8. http://www.healthcentral.com/encyclopedia/408/264.html

Clinical Bottom Line

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Recent Related Research (from Pubmed)

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