- History of the Obers test
- Muscle insertions into the ITB
- Assessing hip extension during the Obers test
- What is the traditional concept behind a positive Obers?
- What does the Willette article suggest about a limited Obers test finding?
- How lack of hip extension and adduction can relate to lower back pain in standing
Check out the video below for your viewing pleasure, or if you would rather read check out the text blog post below.
History of the Obers test
The year was 1935, and in the Journal of the American Medical Association May edition Frank Ober wrote an article describing the pattern he observed about a contracted TFL and ITB correlating to sciatica and low back pain. At that time he did not mention avoiding hip flexion or hip IR when testing the length of the TFL/ ITB.
Henry Kendall saw this article and connected with Ober in person in 1936. In 1937 Frank Ober wrote an article reviewing the TFL/ ITB length test again discussing the need to control hip flexion/ hip IR to get a better measurement of structural length.
There was confusion due to some people not having read the 2nd article published by Ober, and it was not clear what plane of motion Ober was trying to control while testing in the 2nd article.
Muscle attachments to the ITB
There are many attachments along the entire length of the ITB, so it would behoove us to consider some of these other structures when assessing hip extension and adduction length.
The connection of the anterior thigh and hip muscles to the ITB is also why testing is done with a flexed knee, due to the late propulsion of gait requiring knee flexion we want to see if the client can even represent this shape on the table passively.
Assessing hip extension during Obers test
If the hip can not due to move into 0 degrees of hip extension (without compensatory lumbar lordosis) then we can assume the client will not have any hip adduction available.
The lack of hip extension can be caused by a number of different variables, but the most notable ones are the fact that they lack the ability to expand in the anterior pelvis/ hip. To name a few muscle structures on the anterior pelvis:
- Anterior gluteus medius
- Rectus abdominus
- Adductor longus
- Adductor brevis
- Rectus femoris
- Anterior triangle of the pelvic floor
Anterior hip/ pelvis expansion is a perquisite for hip adduction. Usually once hip extension is cleared up, hip adduction measures will usually improve as well.
What we traditionally interpreted aa a positive Obers test
The initial idea behind the Obers test was that the TFL and ITB itself was “too tight.” After studying that concepts for the last couple of decades we can safely say that probably isn’t what we are viewing when someone is lacking hip extension and adduction.
But this idea leads us to a bigger concept that should probably be improved upon.
“Muscles are too tight.”
I don’t think this is a very accurate statement. There are a lot of things going on under the hood we can’t see when someone is lacking ROM like a nervous system firing, fluids moving within a joint, and guts that need to be reoriented within the thorax (especially when moving the hip).
Are there times when tissues shorten under extreme circumstances like trauma or surgery…. sure. But more often than not lack of motion is due to many variables, not structures being too short (thats why we can make a big change in 1 session). We are not pizza dough.
What does the Willette et al. study suggest about the Obers test?
This was a simple yet fascinating study. The methods could be explained in very quickly.
- Hip adduction was measured on a cadaver with everything intact
- Hip adduction was measured with half the cadavers having the ITB transected
- Hip adduction was measured in 1/4 of the cadavers having the glute med transected
- Hip adduction was measured in 1/4 of the cadavers having the lateral hip capsule transected
The ITB transection resulted in the least amount of hip adduction ROM increase, while the glute med and hip capsule transection created the largest increases in ROM
What does this mean? The ITB probably isn’t too tight, but other structures limiting its ability to expand, don’t blame the ITB.
How lack of hip extension and hip adduction correlate with back pain
If someone is lacking hip extension in standing, this will force the issue of maintaining balance else where, and usually force will follow the path of least resistance (low back). Typically the deeper posterior hip musculature and/ or lower back will pick up the slack so you don’t fall forward on your face (important thing to prevent).
This constant compressive strategy in the lower back and hip can is usually fine, until it isn’t anymore (like charging a credit card and only paying the minimum payment, until at some point that card is maxed out, oops).
- Confusion about the Ober test has been present since the inception of the test (so if you’re confused about it, don’t worry a lot of people are in the same boat 🙂
- If hip extension is lacking, then so is hip adduction.
- Lacking hip adduction is most likely not from an ITB that is too short, but rather other structures that don’t know (yet) how to expand and eccentrically orient.
- Lacking hip extension causes extra work and compression in the posterior hip and lower back.