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I've heard of anterior cruciate ligament tears. But what's a posterior cruciate? My favorite hockey player is out because of this kind of injury. How can they tell what kind of cruciate injury has occurred?
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Much has been written about the evaluation and treatment of anterior cruciate ligament (ACL) tears. That's because they are the most common knee injuries among athletes. Though less common, injuries to the posterior cruciate ligament are just as important.
To better understand how PCL knee injuries occur, it is important to understand some of the anatomy of the knee joint. Knowing how the ACL and PCL work together to maintain stability and normal function is a large part of determining the optimal treatment for each patient.
The ACL and PCL are the two main ligaments that criss-cross and stretch between the femur (thigh bone) and the tibia (lower leg bone). These two bones join together to form the knee joint. Working together, the two cruciate ligaments control the back-and-forth motion of the knee.
The ACL keeps the tibia from sliding too far forward in relation to the femur. The PCL is made up of two separate but adjoining bundles of fibers. Each bundle has its own specific function. These bundles work together to keep the tibia from sliding too far backward in relation to the femur. They also control how much the tibia rotates externally (outward direction). Besides the ACL and PCL, there are other ligaments, cartilage, and soft tissues that surround the knee to help give it strength and stability.
There are two ways the PCL gets injured most often. The first is in a car accident when the passenger slams his or her bent knees into the dashboard on impact. The force and speed of the knee against a solid object pushes the tibia back underneath the femur. In a high-velocity injury of this type, the shear force is enough to rupture the PCL holding the tibia in place.
A second mechanism of injury (more common with athletes) occurs when the foot is planted on the ground and the knee hyperextends. Hyperextension means the joint is as straight as it can be and then a force pushes it into even more extension or overextension, thus the term hyperextension.
When the patient gives either one of these histories, the physician directs his or her examination to test the PCL. Several tests are commonly used such as the posterior drawer test, posterior sag, and the reverse pivot shift. The examiner will also check knee motion, quadriceps muscle function, and compare external rotation of the legs (the Dial test).
Besides looking at the integrity of the posterior cruciate ligament, it's important to evaluate if there's been any damage to the blood vessels or nerves in the knee. Sensation, pulses, reflexes, and muscle strength will all be carefully reviewed.
Next, X-rays may be ordered. Any fractures or avulsion injuries can be seen on X-ray. An avulsion describes damage strong enough to pull a piece of bone away from the femur or tibia. The flat upper part of the tibia called the tibial plateau could also be fractured or damaged. Tibial plateau fractures are also visible on X-rays. Sometimes it can be difficult to tell if the PCL is partially or fully ruptured. Additional X-rays called stress radiographs and/or MRIs may be ordered for further clarification of the extent of damage.
Once the diagnosis has been made, then a plan of care must be determined. The severity of the injury usually guides who has surgery and how soon. For example, patients with avulsion injuries usually have surgery right away. The loose fragment of bone is screwed or stitched back in place with sutures.
Many players are actually able to participate in their sport with PCL-deficient knees. And they do so until the end of the season before considering surgery to reconstruct the knee and restore full stability. This is more likely to work when there is a partial tear, rather than a complete rupture. Undamaged supporting structures make it possible to continue functioning without a completely intact PCL. But when severe damage has been done to the ligament and its support system, then surgery (even mid-season surgery) is often advised.
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*Disclaimer:*The information contained herein is compiled from a variety of sources. It may not be complete or timely. It does not cover all diseases, physical conditions, ailments or treatments. The information should NOT be used in place of visit with your healthcare provider, nor should you disregard the advice of your health care provider because of any information you read in this topic. |
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