Patello-femoral joint dysfunction syndrome, also known as "runner's knee", refers to tracking problems between the knee cap (patella) and the upper leg bone (femur). The underside of the patella is shaped like the bow of a ship, and rides in a groove created by the femur (upper leg bone). The contact between the patella and the groove (femur) is called the patello- femoral joint. The knee cap slides up the groove when we straighten our knee and down the groove when we bend it. A normal functioning patella runs down the center of this groove. If the patella begins to run too much to the inside or outside of the groove, it increases pressure along the underside of that portion of the knee cap. This eventually leads to roughening of the cartilage overlying the bone, clinically known as chondromalacia patella.

Chondromalacia pain usually begins as a diffuse "pressure" under and around the patella, often accompanied by a grinding noise present when going up or down stairs after your longer runs. It progresses to a constant dull ache with sharp pain on the stairs.

There are three factors which determine if the knee cap runs along the center of the groove. These are the "Q" angle, the degree of "pronation", and tightness or uncoordination of the quadriceps muscle group.

Both increased "Q" angle (see figures I & II) and overpronation cause someone to be "knock kneed". This changes the direction of pull by the quadriceps, causing the patella to be pulled more to the outside of the groove and grind. Increased "Q" angle is more prevalent in women due to their wider hips, particularly if their gluteal (butt) muscles are weak or inhibited. Stretching out the groin muscles will help the gluteal muscles work more efficiently. Overpronation can be helped by choosing running shoes with extra medial support such as a stability or motion control shoe. Check out your local specialty running store for recommendations.

Tightness and uncoordinated function of the quadriceps muscle group can be present for some time before surfacing with training errors or different stresses placed on it by other activities like cycling. Imbalance typically presents as weakness in the part of the quadriceps muscle group on the inner (medial) aspect and over activity of the outer (lateral) aspect of the knee. This imbalance can lead to pain on the lateral aspect under the knee cap from the rubbing, or on the medial aspect from the knee cap slamming into the inner side of the groove as the knee straightens. Tightness causes increased downward pressure on the patella, forcing it deeper into the groove and grinding results.

During growth spurts the bones lengthen before the muscles, which lead to increased muscle tightness and relative weakness as they lag behind bone growth. The result is a decreased threshold for injury in middle and high school athletes during periods of accelerated growth, and can be helped by a proper stretching program.

WHAT TO DO?

Start with stretching the quadriceps muscle groups. All stretches should be held for 20-30 seconds and performed 5-6 times throughout the day.

1. While standing, bend one knee and grasp the ankle, keeping your knees together. Pull back until you feel a comfortable stretch on the front of your thigh. Now contract the gluteal (butt) muscle on the side with the knee bent to accentuate the stretch (figure III).

2. Kneel down on your right knee, move left foot out in front. Reach back with your right hand, grasp and lift your right ankle off the floor. Lean forward in a lunge position towards your left foot.

You can do a self massage of the outer aspect of your quadriceps by rolling it along a foam roll (see figure IV). These rolls are becoming more widely available, and we recommend medium stiffness instead of firm, the most widely available. If you have a foam roll and it is too painful to perform this maneuver, fold up a towel and place it overtop the roll for added padding. Roll your leg up and down the roll for 1-3 minutes as tolerable. This will be painful the first 2-3 times you perform it, but it will get easier.

Myofascial release and exercises to coordinate the quadriceps muscles are all part of a well-rounded treatment plan, and unfortunately, beyond the scope of this article. If these measures do not provide relief after 2-3 weeks, consult your local sports medicine specialist.

Dr. Ken Sheridan is a local road and trail runner who enjoys competing in a variety of events, from marathons to duathlons. He practices at ActiveCare Chiropractic & Rehab in Golden, a clinic specializing in sports injuries. To ask him your injury questions, call 303-279-0320.