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The challenges of anterior knee pain

By Michael Gordon, MD, Milwaukee Orthopaedic Group, Ltd. Orthopedic Surgery, Sports Medicine Fellowship

A common site of discomfort for runners is pain in the front of the knee. Annoying in nature, this aching can be attributed to several possible sources, some of which are easily correctable.

Generally, "anterior knee pain" refers to symptoms that originate in the knee extensor mechanism. Quite simply, this is the part of the leg that allows you to straighten out your knee. It begins in the thigh with your quadriceps (large muscle bulk), which connects to the kneecap by the quadriceps tendon. The next structure in the chain is the kneecap (patella), and finally, the patellar tendon connects to the shinbone (tibia). An injury to any of these structures can lead to pain that is felt in the front of the knee.

The most common source of pain that I see in runners is called chondromalacia patellae, a softening of the cartilage on the backside of the kneecap. This particular cartilage is the thickest in the body helping the kneecap glide along the front and end of the thighbone. When it softens, it doesn't dissipate the impact of walking/running, which can then lead to pain in the kneecap.

The obvious question (and $64,000 one) is what makes this soften? The answer is fairly complex and something that's not quite understood completely. We do know that the kneecap is exposed to some of the highest "sheer stress" levels in the body – every pound we weigh leads to about 4 pounds of stress across this cartilage. We also know that for articular cartilage to work well, it needs to evenly distribute stress; any mal-alignment or small defect in the cartilage can cause significant pain.

Treatment for chondromalacia patellae focuses on fixing any underlying mal-alignment and then trying to create a more supportive environment for the cartilage. When diagnosing knee problems, I start with the feet to make sure that the ankles and arches are doing what they are supposed to do. Then, it's on to the hips to be sure that there is good strength and balance across these joints. Next, I work on correcting any poor tracking of the kneecap along the front of the knee with either stretching exercises or in rare cases, surgery.

Just as critical for pain reduction are muscle rebalancing between the quadriceps and hamstrings, as well as hamstring stretching. Finally, I encourage my patients to consider glucosamine sulfate and chondroitin sulfate as potential cartilage supporting supplements. There are several studies that have reported encouraging benefits, but more importantly, these supplements have shown minimal side effects. However, before starting any new medical regiment, please discuss it with your doctor to rule out any medicine interactions and contraindications.

Another source of anterior knee pain is patellar or quadriceps tendonitis. This is an inflammation of the main tendons that connect the kneecap to the shinbone and thigh muscle. Oftentimes, these tendons become tender to the touch and are accompanied by local swelling and even a sense of "squeaking" as you rub over them. Treatment is based on stretching, local massage, rest, and anti-inflammatory medications. To help prevent a reoccurrence, it's important to determine what led to the development of this problem (i.e. poor training, "too much, too soon", inappropriate shoe wear, tight muscles, etc.)

Other less common sources of anterior knee pain include hip disease, quadriceps strain and inner knee joint pathology. Surprisingly, in very rare cases, hip arthritis or other problems can imitate knee pain. The discomfort caused by these conditions is referred down the front of the thigh, distributed using one of the major nerves of the leg. In these cases, anterior knee pain can oftentimes be ruled out with simple log rolling of the hip and/or an x-ray of that joint.

Quad, or thigh muscle strains, can also refer pain straight down the front of the knee. Generally, this condition can be fairly easily diagnosed with simple palpation along the muscle.

Finally, there are other issues within the knee that can lead to pain along the front of the joint. These include articular cartilage problems of the trochlea (the groove on the end of the thighbone in which the patella rides), a plica (a shelf of tissue that runs along the front inside portion of the knee), or an anterior tear in one of the menisci. All of these conditions can be nagging problems and oftentimes can benefit from surgery.

Anterior knee pain can be challenging, particularly for runners. It's occurrence is usually due to relatively easily correctable problems "above and below" the knee itself. If you start feeling twinges of pain in the front of your knee or have increasing difficulty with stairs or sitting still for any prolonged period of time, I encourage you to have your knee examined. Early detection and correction of these problems can help to keep a relatively simple condition from becoming much more complex and difficult to treat.

Dr. Michael Gordon, of the Milwaukee Orthopaedic Group, Ltd. is an orthopedic surgeon with a fellowship in sports medicine. For questions, you can reach Dr. Gordon at (414) 276-6000.