Knee

PCL (Posterior Cruciate Ligament) Injuries and Reconstruction

Anatomy

The knee is the largest joint in your body and one of the most complex. Three bones meet to form the knee joint: the thighbone (femur), shinbone (tibia), and kneecap (patella). The kneecap sits in front of the joint to provide some protection. Knee ligaments connect the thighbone to the lower leg. The four primary ligaments in the knee act like strong ropes, holding the bones together and keeping the knee stable.

• Collateral ligaments—Found on the inside (the medial collateral ligament or MCL) and on the outside (lateral collateral ligament or LCL) of the knee, these ligaments control the sideways motion of the knee and brace it against unusual movement.
• Cruciate ligaments—Found inside your knee joint, these ligaments cross each other to form an "X" with the anterior cruciate ligament in front and the posterior cruciate ligament in back. The cruciate ligaments control the knee's back and forth and rotational/twisting motion.
• Posterior cruciate ligaments—Located in the back of the knee, this ligament keeps the tibia from moving backwards too far. Stronger than the anterior cruciate ligament and injured less often, the posterior cruciate ligament has two parts that blend into one structure that is about the size of your little finger.

Description

Injuries to the posterior cruciate ligament are not as common as other knee ligament injuriesACL Injuries and ReconstructionCollateral Ligament InjuriesCombined Ligament Injury. They are often subtle and more difficult to evaluate than other ligament injuries in the knee. Many times a posterior cruciate ligament injury occurs along with injuries to other structures in the knee, such as cartilage, other ligaments, and bone. Posterior cruciate ligament tears tend to be partial tears with the potential to heal on their own. When only the posterior cruciate ligaments are injured, patients can usually return to sports without knee stability problems.

An injured ligament is considered a sprain, and is graded on following severity scale:

• Grade 1 sprain—The ligament is mildly damaged. It has been slightly stretched but is still able to help keep the knee joint stable.
• Grade 2 sprain—The ligament is stretched to the point where it becomes loose. This is often referred to as a partial tear of the ligament.
• Grade 3 sprain—The ligament has been split into two pieces and the knee joint is unstable. This is commonly referred to as a complete tear of the ligament.

Symptoms

Common symptoms of a posterior cruciate ligament injury include: pain with swelling that occurs steadily and quickly after the injury; swelling that makes the knee stiff, possibly causing a limp; difficulty walking; or a feeling of instability, as if the knee may give out from under you.

Causes

An injury to the posterior cruciate ligament typically requires a powerful force, such as a bent knee hitting a dashboard in a car accident or a fall onto a bent knee during sports.

Diagnosis

Your physician will examine all the structures of your injured knee and compare them to your uninjured knee. The injured knee may appear to sag backwards when bent, or it may slide backwards too far, particularly when bent beyond a 90° angle. Other tests which may help confirm your diagnosis include magnetic resonance imaging (MRI), and X-rays, which can reveal any injury to the bone. It is possible, however, for these images to appear normal, especially if the injury occurred more than three months prior to testing.

Nonsurgical Treatment

If only the posterior cruciate ligament is injured, it may heal quite well with nonsurgical treatment recommended by your physician.

• RICE (rest, ice, compression, elevation)—Used immediately following your injury, this method can help relieve discomfort and speed your recovery.
• Immobilization—Your doctor may apply a brace to keep your injured knee from moving. Crutches may also be recommended to prevent you from putting weight on your leg.
• Physical therapy—As the swelling goes down, a careful rehabilitation program will be started. Specific exercises will restore function to your knee and strengthen supporting leg muscles, especially the front thigh muscles (quadriceps), which are a key factor in successful recovery.

Surgery

If you have combined injuries (for example, a dislocated knee and multiple torn ligaments), surgery is almost always necessary. Because sewing the ligament ends back together does not usually heal, a torn posterior cruciate ligament must be rebuilt using a tissue graft taken from another part of your body, or from another human donor (cadaver). It can take many months for the graft to heal into your bone. This is typically an arthroscopic surgery. Knee arthroscopy is performed using small incisions. The benefits of this less invasive technique include less post-surgery pain, less time in the hospital, and quicker recovery times.

Recovery

Whether your treatment involves surgery or not, rehabilitation plays a vital role in helping you regain knee strength and motion, and getting you back to normal activities. How long it takes you to recover from a posterior cruciate ligament injury will depend on the severity of your injury. Combined injuries often have slower recovery, but most patients do well over time.

If you undergo surgery, your physical therapy will begin from one to four weeks after the procedure. You may be able to return to a desk job after several weeks, but if your job requires a great deal of activity, it may require many months. Full recovery typically requires six to 12 months. Although recovery is a slow process, your commitment to therapy and proper conditioning exercises is the most important factor in returning to all the activities you enjoy.

VIDEO:Knee Injuries with Kirk Cousins & Dr. Bruce Stewart, Holland Hospital Sports Medicine

VIDEO:Dr. Bruce Stewart Knee Injuries in Athletes, Holland Hospital Physician Lecture Series, May 2015