The IT band is a common irritant in runners, and its various pain presentations each convey a litany of information. Photo courtesy Beginnertriathlete.com.

The Asics Los Angeles Marathon is now five weeks away, and this is the time that most overuse injuries begin to appear. Lateral knee pain is one of the most common complaints from marathon runners as they build up the mileage in training to above 12-15 miles in preparation for the race on March 9th. 

In most cases, the pain is in one knee and not the other, and this begs the question: why would only one knee hurt if both legs ran the same mileage? The answer, as in all asymmetric overuse injuries, is a mechanical deviation in one or more of the joints of the lower extremity or pelvis on one side or the other.

Joint mechanics can be corrupted by an old injury such as an ankle sprain or hamstring strain, or by a pelvic mal-alignment causing a leg-length discrepancy. When the pelvis, which is comprised of two independent large bones call the ilium, is out of line, the joints of the "short" or "long" leg will make adjustments to compensate. The most common compensation is that the foot on the long side will over-pronate as a strategy to flatten the arch and functionally shorten that leg, while the foot on the short side will typically supinate in an attempt to hold that arch up and functionally elongate that leg. These subtle but significant compensations alter joint mechanics and cause aberrant forces to bear down on vulnerable tissues including tendons, ligaments, fascia, and bursa. An effective rehabilitation program must not only treat the painful area but also address the cause of injury by exposing and correcting the mechanical imbalance creating the excessive forces to bear down on the inured structure.

Anatomy and Function

The illiotibial band is a thick band of fascia that extends from the pelvis down along the outside of the thigh to attach below the knee on the outside of the lower leg bone called the tibia. The IT band functions to stabilize the thigh bone and knee during the weight bearing "stance" phase of the running gait, and helps guide the lower leg as it swings forward through the air in the swing phase. Just before foot strike, the illiotibial band slides over a bony prominence on the outside of the knee called the lateral epicondyle. A structure called a bursa (a fluid filled sac much like an internal blister that is suppose to be there) prevents friction between the bony prominence and the illiotibial band.

Pain Presentation

Illiotibial band problems may present at one end or the other of this broad band of fascia running along the outside of the thigh: either at the top, where it originates on the lateral aspect of the pelvis, or much more commonly at the lower end at the site of the bursa on the outside of the knee. This lower IT band pain tends to appear suddenly on a run, and it often becomes so severe that you have to limp or stop the workout and walk home. While it does not represent a high degree of damage to the bursa, or to the IT band, it can be one of the most painful conditions runners suffer and it will stop you in your tracks. If you ignore the pain and continue to run, the pain will progress to daily activities including stairs, squatting, and pivoting.

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Additionally, look for Forster's soon to be released book, Healthy Running, Step by Step, due out this Fall.