|Posterior Cruciate Ligament Injury
Posterior cruciate ligament injury happens far less often than does injury to the knee's better known counterpart, the anterior cruciate ligament (ACL). But just because it's less common doesn't mean that your posterior cruciate ligament injury isn't painful.
The posterior cruciate ligament and ACL help hold your knee together, giving it stability. If either ligament is torn, you may experience pain, swelling and loss of mobility. Posterior cruciate ligament injury generally causes less pain, disability and knee instability than ACL tears do, but it can still sideline you for several weeks or longer.
Ligaments are strong bands of tissue that attach one bone to another. The cruciate (KROO-she-ate) ligaments connect the thighbone (femur) to the shinbone (tibia). The anterior and posterior cruciate ligaments form a cross in the center of the knee.
If you injure your posterior cruciate ligament, you may experience pain and swelling at the back of your knee. Occasionally, this injury can cause a feeling of instability or looseness in the knee. Treatment depends on how severe the injury is and how long you've had it.
The PCL can tear if your shinbone is hit hard just below the knee, or if you fall on a bent knee. These injuries are most common during :
- Motor vehicle accidents. A so-called dashboard injury occurs when the driver's or passenger's bent knee slams against the dashboard, pushing in the shinbone just below the knee and causing the PCL to tear.
- Contact sports. Athletes in sports such as football or soccer may tear their PCL when they fall on a bent knee with their foot pointed down. The shinbone hits the ground first and it moves backward. Being tackled when your knee is bent also can cause this injury.
|Other causes include bending or extending your knee past its normal position and getting hit on the side of the knee while your leg is twisted.
When to seek medical advice :
Call your doctor if you experience signs and symptoms of a PCL injury or if your knee feels unstable. If you're already being treated for a PCL injury, see your doctor if :
- Your knee feels more unstable than it was
- The pain and swelling return after subsiding
- Your injury doesn't seem to be healing over time
Signs and symptoms of a posterior cruciate ligament (PCL) injury may include :
- Mild to moderate pain at the back of the knee
- Sudden knee swelling and tenderness (within three hours of the injury)
- Pain with kneeling or squatting
- A slight limp or difficulty walking
- Feeling of instability or looseness in the knee, or the knee gives way during activities
- Pain with running, slowing down, or walking up or down stairs or ramps
Most people with a torn PCL don't feel a "pop" — the classic sign of an ACL tear — at the time of the injury. Signs and symptoms may be mild or vague, and you might not even notice anything wrong. Over time, the pain may worsen and your knee may feel more unstable. If other parts of the knee are affected, your signs and symptoms will likely be more severe.
To diagnose a PCL injury and assess its severity, your doctor will do a physical exam. He or she may also do some tests and procedures to learn the full extent of your injury. The exam may consist of the following :
- Medical history. Your doctor will ask about the accident or injury, the problems you're having with your knee, how long you've had symptoms and whether you have a history of knee injuries.
- Physical examination of the knee. Your doctor may press on your knee to feel for injury, looseness or fluid in the joint from bleeding. He or she may move your knee, leg or foot in different directions and ask you to stand and walk to see if your knee stays in proper position. Your doctor will compare your injured leg with the healthy one to look for any sagging or abnormal movement in the knee or shinbone.
- Posterior drawer test. In this test, you lie on your back with your knee bent. Your doctor gently moves your lower leg backward at the knee. If the leg moves back too far, your PCL is torn.
- X-ray. An X-ray picture of the bones and tissues in your knee joint won't show a PCL injury, but it can show damage to bones and cartilage, a sagging shinbone or an avulsion fracture.
- Magnetic resonance imaging (MRI). This painless procedure uses magnetic fields to create computer images of the soft tissues of your body. An MRI scan can clearly show a PCL tear and determine if other knee ligaments also are injured.
- Arthroscopy. If it's unclear how extensive your knee injury is, your doctor may use a surgical technique called arthroscopy to look inside your knee joint. A small, lighted optic tube is inserted into your knee joint through a small incision. The doctor views images of the inside of the joint on a computer monitor or TV screen.
- Joint aspiration. This procedure uses a syringe to remove fluid from the joint. Aspiration may be performed if you have significant swelling of the knee that interferes with the joint's range of motion and your ability to use your knee or leg muscles.
If you have a PCL injury, in the short term you may have to limit your physical activity until the swelling goes down, your knee and leg movement is normal, and the pain is gone.
The more extensive your PCL injury, the more likely it is that your knee will feel unstable. It may give out during physical activities, such as running, slowing down, or walking up or down stairs.
If your injury causes episodes of knee instability, the cartilage in your knee can become torn and you may develop arthritis in the joint.
What treatment is best depends on the extent of your injury and whether it just happened (acute) or you've had it for a while (chronic). For an isolated PCL tear, with no damage to other parts of the knee joint or shinbone, you probably won't need surgery. Many people with a minor PCL injury can return to their previous level of activity after completing a rehabilitation program, which may take from one to four months.
If you have a bad PCL tear combined with other torn ligaments, cartilage damage or a broken bone, you may need surgery to reconstruct the joint. Surgery may also help if your knee remains unstable after a rehabilitation program. If your doctor recommends surgery, it's best to have it within two to three weeks of your injury. After surgery you'll go through a rehabilitation program. Full recovery may take several months.
To treat the acute injury :
- Apply ice packs to your knee for 20 to 30 minutes every three to four hours for two to three days or until the pain goes away
- Elevate your knee by placing a pillow underneath it
- Take pain relievers such as ibuprofen (Advil, Motrin, others) as needed
- Wrap an elastic bandage around your knee
- Use a splint or walk with crutches if needed
Knee brace or other devices
You may need to avoid putting weight on your injured knee for several weeks. You may wear a knee brace to protect the knee during activity and keep it stable. Using crutches also can decrease strain on your knee.
After the swelling in your knee goes down, you'll begin a program of exercises to strengthen your front thigh muscles (quadriceps) and restore your knee's normal range of motion. These exercises may include straight leg raises and isometrics. Gradually you'll add more weight-bearing exercises, such as squats and leg presses, and you'll progress with isolated quadriceps strengthening.
PCL reconstruction surgery uses arthroscopic techniques to rebuild the ligament. The surgeon inserts a narrow, flexible instrument (arthroscope) with a light and a small camera at the tip into one or two small incisions. This allows the surgeon to see the inside of the knee joint and make the repairs. The surgeon rebuilds the ligament by using a piece (graft) of tendon, usually from a cadaver, or from a tendon in your leg. If some of the shinbone has been pulled off with the torn ligament, the surgeon places screws in the joint.
Unfortunately, most PCL injuries happen during accidents that usually aren't preventable. But these suggestions may help you avoid an injury :
- Do strengthening exercises for your upper leg muscles (quadriceps and hamstrings), which protect your knee.
- Maintain a good leg-stretching routine.
- Use proper techniques when playing sports or exercising.