IT Band Syndrome- What is it?
In this post we're going to be talking about one of the most common running injuries out there- the Iliotibial Band or ITB.
The ITB is a thick fibrous band that runs from the outside of the hip, all the way down the outside of the thigh to insert just below the knee joint on the tibia. More specifically, as you can see in the picture above, it starts from fibers of the gluteus medius (GM) + Tensor Fascia Latae (TFL) and inserts onto the Tibia (larger lower leg bone, the smaller is the fibula). As the IT Band inserts below the knee, it splays out some sending fibers to the knee cap, as well as, the hamstring muscles (these are represented by the blue lines in the picture above).
What does it do?
The outside of the hip/knee is unique in that it provides stability when standing on one leg. For example, when you step onto your left foot, the glute med + ITB pull down on your left hip to keep both hips level with each other during single leg stance. If there is injury or weakness, the right side will drop and gait will be compromised as the body then needs to compensate for leg clearance and propulsion. Since the ITB also crosses the knee joint it also works to assist with knee movement thanks to those little blue expansions pictured above. As the leg bends and straightens, the band works to assist those movements. The thing to keep in mind with this is that ITB is NOT a muscle. It works at the knee based on how the knee is moving in relation to it's attachments. If the knee bends more than 30 degrees, it helps bend the knee more. If the knee is less than 20 degrees bent, it helps to straighten it.
How does it get hurt?
IT Band injuries are not like muscle injuries where you get sprains & strains. The band is a large tendon, which instead means tendonitis and friction syndromes. Typically, the band is injured when it becomes tight and those little blue expansion attachments pull the tendon out of it's normal place. This results in the band a) being pulled tight over the femur (big upper leg bone), and b) repeatedly dragged back and forth over the bone as it helps bend and straighten the knee. Once this happens, the band is wide open to injury, especially in the presence of repetitive activities such as running or biking.
So why does the band tighten in the first place? This can happen in two ways:
1) On a muscular level, tension is increased on the outside of the hip/knee any time that the knee is pulled in towards the mid-line of the body. This can happen with chronic tightness (or contracture) of the adductors and internal rotators. When this occurs, the gluteus medius and minimus muscles are held in a lengthened position and subsequently weakened. Over time, the ITB can be injured as it works increasingly harder to try and keep the hips level during running/walking.
2) On a structural level (meaning bones and joints), the knee joint can be pulled in towards the mid-line when there is over-pronation at the foot and ankle (this is where those side of the road issues can come in to play- they make the leg over/under pronate because the foot cannot land flat due to the slanted road surface). Indirectly, the outside of the hip can also be affected by the presence of an anterior pelvic tilt (when the front of the pelvis rotates down towards the ground). This results in tight hip flexors and weak hamstrings/glutes which alters normal propulsion during gait. The result is commonly that the inner hamstrings and adductors work harder to extend the hip and over time shorten due to the repetitive stress; the knee is pulled in towards the mid-line due to the resulting muscle contracture and the lateral hip muscles overloaded.
Sound confusing?? The key take away is this: the ITB will become prone to injury any time the knee is a) pulled in towards the middle of the body or b) away from it. Here are some pictures to show you what I mean.
When running or walking, the knee should be over the middle of the foot as it lands and moves through stance.
Likewise, the achilles or heel cord should be straight at push off (pictured above).
One of the prime culprits behind ITB injury is the foot/ankle. If the foot comes in on that inside arch (the lower purple arrow), the result is that it pulls the knee in towards the midline of the body (upper purple arrow). This places the ITB in a stretched position which pulls it down closer to the bone. With time and repetition that friction syndrome can start.
From behind, you can see how this twists the whole lower leg.
Likewise, if the foot stays on the outside of the foot, this pulls the knee out away from the midline of the body. This will put the ITB into a shortened position which over time can result in a contracture (where the muscle/tendon becomes stuck in this tightened position and unable to stretch out under use).
From the back, you can see that the heel goes out while the knee comes in.
How do I know if this is what I have??? (Differential diagnosis)
Normal symptoms: typical symptoms with ITB syndrome include pain or tightness on the outside of the knee at or just above the level of the knee cap and can move all the way up the outside of the leg to the hip. Symptoms are typically worse with activity and better with rest, and swelling can occur at the lower tendon if the inflammation is severe enough. (note: laying on your side with ITB problems can be difficult as the knees are usually pulled in
What else could it be??
1) Patellofemoral Syndrome (PFS).
One of the easiest ways to differentiate PFS from ITB is to look at where it is. The ITB runs down the outside of the knee and inserts onto the outer tibia (lower leg bone). If your symptoms are at the level of the knee cap but are behind it looking from the side, it is more likely that your problem is ITB related versus PFS.
PFS symptoms are typically on the inner knee cap + just above the outer part of the knee cap along the quad muscle (the two purple circles above). One of the classic symptoms of PFS is being unable to sit for long periods of time.
#2) Trochanteric (Hip) Bursitis-
At the top part of the IT Band where it originates from the glute med muscle + TFL is a small fluid sac known as a bursa. It's job is to provide cushioning over the bone underneath it (the greater trochanter) so that the IT Band doesn't get torn sliding back and forth over it as you walk. If the ITB tightens up, it's common for this little bursa to get pinched and irritated. Symptoms are typically very spot specific and tender to the touch. You may also get some swelling if the inflammation is severe enough.
To find the greater trochanter, start with your thumb on the top of hip bone and lay your hand down over the outside of your hip. The greater troch will be in the area of where your middle two fingers land (you should be able to feel the bony bump there). The bursa is there as well.
#3 Lateral meniscus tear-
There are two meniscus in the knee joint itself (one on the inside and one on the outside). Both work to act as shock absorbers between the two large leg bones. It is possible that sharp pain along the outside of the knee joint could be coming from a tear in the outer meniscus. The big clues that this could be happening would include: 1) buckling/giving way of the leg and 2) locking of the knee joint itself. If you should ever experience these types of symptoms, it's time for a trip to the orthopedic.
Stay tuned: in the next post, we're going to discuss how to treat IT Band syndrome.