Knee Pain

General Information

The most common complaint among athletes who visit our office is knee pain, and this is reported to be the most common reason for missed practice among high school athletes. Fortunately, for most athletes it is also the easiest to manage.

The knee joint is where the thigh bone, called the femur, and the shin bone, known as the tibia, meet. The knee cap, or patella, is a small bone in the front of the knee. The back surface of the patella presses against the front surface of the femur in a special groove called the trochlea. It is this area that causes most of the trouble.

The mechanics of the knee are fairly straightforward since it only moves one way – it bends (flexes) and straightens (extends). The muscles that bend the knee are the hamstrings, and the muscles that straighten the knee are the quadriceps. Because we are upright, the quadriceps must be a strong muscle. Not only is it large, but the patella gives it added power by improving the angle of pull across the knee joint. The quadriceps muscle is connected to the patella, which is connected to the tibia, or shin bone, by the patellar tendon. When the quadriceps pulls on the patella and straightens the knee, the improved angle of pull increases its strength by 30%. This puts a lot of force on the patella as it is pushed against the trochlea, and this force is meant to be spread over these surfaces evenly. If the patella rides unequally on one side or the other in the groove, this results in overuse of that side and the patient experiences pain.

In adolescents, it is common for the patella to not stay perfectly centered in its groove. At times, there are mechanical problems – for example, someone with severe knock knees will tend to have a patella that rides on the outside of the trochlea, and in severe bow legs the patella will track on the inside of the trochlea. This misalignment can also be caused by imbalanced muscle forces, which can occur very easily in overuse injuries or after minor injury to the knee.

In general, the treatment for most sports related injury is simple. Rest, Activity Modification, Local Care, Anti-Inflammatory Medications and Physical Therapy. After an injury, you should rest for two weeks, or until you are completely better, whichever comes first. Activity modification means that when you resume the activity, make sure you don’t overdo it, even if “the team needs you.” Local care consists of ice if sore or elevation and ace bandage if swollen. Anti-Inflammatory medications such as Ibuprofen or Naproxen are helpful in improving symptoms of pain and swelling, and do not usually mask symptoms enough to be a problem. Physical therapy helps correct any underlying imbalance by balancing and strengthening muscles.

The final, and possibly most important concept is moderation. Sports are important for our kids and the community. Being active is good for physical and emotional development, self image and helps teach kids team building skills. But, as with all things, we need to be careful about overzealous participation. If your child feels well and has no complaints, they should continue to play. If pain occurs, they will need to stop or slow down and get the right treatment until they are ready to restart their activity. 

Treatment

The exercises to strengthen the quads begins with “isometric quadriceps setting” or quad sets. While lying down, tighten the quadriceps muscle and squeeze it, then lift the foot off the bed or floor about 6 inches. Then put your foot down but don’t stop squeezing, and finally relax. This should take about 10 seconds. It should be repeated 10 times slowly, each time making sure you are squeezing your quad muscle. By the end you should begin to feel your quad burn or ache.

Next is “limited arc quads.” Although strengthening the quads by leg presses or extending the knee with ankle weights on will work, if the knee goes through a full range of motion, from completely bent to straight, it may cause too much pressure on the patella and hurt the cartilage further. Our job is to balance the muscles, not make you Arnold Schwarzenegger. Many athletes do not feel isometric quads give enough of a work out, but one can do limited arc quads by extending the knee through about a 30 degree range, even with some ankle weights, and feel the burn.

Lie with your foot off the end of the bed or couch and put a folded pillow or some folded towels underneath your knee. Make about a 30 degree angle with your knee. Put some weights on your ankle such as a strap on ankle weight, or use a purse with some weights or soup cans in it and hang it on your ankle. Then raise your ankle and hold it. Then flex to 30 degrees and straighten, flex and straighten. Hold it for 10 seconds when straight and do this 10 times. This works your quads and with enough repetitions you can help strengthen the muscle. Do not over do it or you will be sore. If that happens, do not worry, but wait until it feels better, then use fewer weights or do less reps. 

Frequently Asked Questions

Will my child need to wear a brace or have surgery?
The majority of patients we see with this condition do not have anatomic abnormalities such as knock knees, bow legs, in-toeing, out-toeing, flat feet or muscle weakness and imbalance. Most children with knee pain have relatively minor degrees of muscle imbalance resulting from either a minor injury that never completely got better or normal growth. All we need to do to solve the problem is strengthen and rebalance the muscles of the thigh to equalize the pressure distribution in the joint between the patella and the femur.

What is the goal of physical therapy?
The physical therapy is quite simple and involves strengthening the quadriceps muscle and stretching any tight structures, such as the large tendon on the outside of the thigh, the iliotibial band. In most kids, we want to strengthen the inside quadriceps muscle, the vastus medialis, to help pull the patella into the right position during sports.

What kinds of physical therapy will they need to do?
The most common exercises used in physical therapy for anterior knee pain are isometric quadriceps setting, or quad sets, and limited arc quads. The point of both of these exercises is to strengthen the quads and balance the muscles that pull on the patella.

How do we prevent this problem from occurring?
Knee pain is essentially an overuse injury, and most overuse injury are the result of not having any down time. Avoid multiple practices without adequate rest time, be careful during long weekend tournaments, as in soccer an volleyball, and be very careful if your child participates in multiple sports in consecutive seasons, such as soccer in the fall, basketball in winter and baseball in spring. All of these things put kids at high risk for injury or overuse.

How long should my child stay out?
Once knee pain occurs your child will need to make the hard decision to slow down or even stop for a while. Encourage them to sit out, heal, and go back at 100%. Remember, their body doesn’t care if the team needs them, it only knows that it needs to rest. Your team and coaches should care that they are healthy and at your best.