Amanda, a thirty four year old Australian triathlete, came into the office last week. “G’Day Dr. Metzl”, she squawked. “I love to run, but here’s the problem. The front of my knee is hurting so badly that I can barely move. You’ve got to fix me, I want to be a fast Australian, but right now, I’m so slow that the dingos are going to catch me.”
“Amanda, have you ever hurt your knees before?” I asked. “And tell me, how does this pain come about?” I added.
“Yeah, I had a similar type of pain last year, though this has become much worse since I have started training for a marathon this fall.” And about the pain, she said “It seems to hurt mostly after I have run for more than an hour. It is especially bad when I am done. I look like an old lady going up and down the stairs.”
“And where specifically does it hurt?” I inquired.
“Doc, It’s just here in the front of my knee, just under the knee cap. And if you fix it, I’ll buy you a can of Fosters or a Violet Crumble candy bar!”
From this dialogue with Amanda, I already had a pretty clear idea of her problem, and a good idea of how we could fix her.
Patellofemoral knee pain, pain beneath the knee cap, is the most common type of knee pain that we see in the Sports Medicine office. The patella (knee cap) is a sesamoid bone, a bone which sits inside a muscle-tendon unit. In the case of the knee, the patella is located inside the patellar tendon, and connects to the quadriceps muscle group (quads), the most powerful group in the body. The forces distributed around the patella are tremendous, and the direction which the patella moves is related to the forces which come from the quads. For example, if an athlete has a strong lateral quad, the patella can pull outward. The patella also has a thin layer of cartilage lining underneath known as articular cartilage. This lining layer helps the patella track up and down along the front of the femur (thigh) bone.
So what about Amanda? How does her story fit into this picture?
Patellofemoral knee pain, irritation of the undersurface of the patella, is characterized by pain beneath the patella which hurts most after activity, is especially sore going up and down stairs, tends not to swell, and hurts most after an hour of running when the quad starts to tire. Patellofemal pain is also much more common in women, due to the Q angle, the “knock kneed” angle which tends to be more common in women than men due to their wider hips. This is in comparison to ITB syndrome (April 2005 Drs. Orders Column) which hurts on the outside part of the knee within the first 15 minutes of exercise, and has not been proven to be gender specific.
A sports med doc will diagnose patellofemoral knee pain through a combination of patient history, physical examination, and xrays. The physical examination will often show weak, inflexible quad muscles and pain when the undersurface of the patella is palpated. Xrays are usually done when there is any swelling or if the pain has lasted for more than a few months (or if the patient is older than 50). In these cases, the xray can be very helpful to diagnose osteoarthritis, the most common form of arthritis. An MRI is used to evaluate the cartilage in the knee joint, and is often done when the pain doesn’t go away after several months of treatment or when a cartilage injury is suspected.
No two cases of patellofemoral pain are the same. In some athletes, the quad muscles need strengthening, in some cases there is an injury to the cartilage surface under the patella, and in some cases, there is a problem with the mechanics of how an athlete is running or biking. Foot type has also been implicated in patellofemoral knee pain, the most common being a pronated, rolling foot type which can cause patellofemoral pain.
Effective treatment of patellofemoral pain often involves referral to a physical therapist to work on body mechanics, including strength, flexibility, and sometimes running or biking style. Equipment can also play a role, motion control shoes and orthotics are quite useful for athletes who have foot problems as a cause of their knee pain. Once the reasons for patellofemoral pain are defined, treatment is usually successful.
With Amanda, I diagnosed her with patellofemoral knee pain and sent her to a sports physical therapist. Since she pronated, I sent her for some motion control running shoes. While in physical therapy, Amanda worked on hip and knee strength, and also improved her flexibility. Amanda kept her fitness with a good course of water running and biking, and when I saw her back in five weeks she was all better.
As long as she keeps up with her strengthening and stretching exercises, she should be running for many years to come.
Jordan D. Metzl, MD, is a nationally recognized sports medicine specialist at Hospital for Special Surgery in New York City. In addition to his medical practice, Dr. Metzl is a 30 time marathon runner and 11 time Ironman finisher.
Please to read an article on Dr. Metzl in Runners World.