Years ago, I had a car accident and knocked both knees into the dashboard. My knees never worked the same but I got along okay. Now my doctor tells me I damaged both my posterior cruciate ligaments with that accident. I've been told I should have surgery but I've done fine so far. Is there really any reason to do this?

The knee has two main ligaments that criss-cross and stretch between the femur (thigh bone) and the tibia (lower leg bone). These are the anterior cruciate ligament (ACL) and the posterior cruciate ligament (PCL). 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 keeps the tibia from sliding too far backward. They PCL also controls 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 much like your situation -- in a car accident. The force of the impact slams the passenger's bent knees into the dashboard. This high-velocity injury pushes the tibia back underneath the femur. 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, thus the term hyperextension. Although many people seem to function fine without an intact PCL, there can be long-term problems that develop as a result of the deficient joint. Early arthritic changes are the most common problem. Knee instability is another. Instability is seen as chronic knee pain and episodes of giving way when the knee goes out from under you. Both of these problems tend to develop as people get older and experience weakening of the quadriceps muscle or degenerative changes in the other supporting structures holding the knee together. The decision to have surgery can be complicated with many things to consider. Many surgeons advise their patients to try a more conservative approach first. A program of strengthening and conditioning often goes a long way in protecting the knee and preventing instability. Usually a three- to six-month course of nonoperative care is enough to show you if this approach can be successful. Having a physical therapist evaluate you and set up the program is a good idea. That way the exercises and suggestions can be tailored to your specific needs. You will be able to progress through successively more difficult exercises in order to build strength, improve coordination, and develop endurance. Most of this can be done as a home exercise program. If you are still having problems at the end of that time, then it might be time to reconsider the pros and cons of surgery.

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