Iliopsoas muscle- a hip flexor or a stabilizer?

Hello everyone,
I'm a 3rd year physiotherapy student from Latvia who's just registered here and let me just say that the forums look great!

I'm thinking of writing my Bachelor's thesis on a subject of the ilioposas function. As far as I known there has been a controversy lately (and by lately I mean- in the last 10 years) on weather the primary role of the muscle is to flex the hip as most of the textbooks will say or to stabilize the pelvis. I've done a bit of a research myself and i did find a few studies on this subject but that's not enough for a proper "systematic review" type of study I'm planning to do.
So I was wondering if anyone has got some materials, evidence based studies or anything along the lines of it. That would be much appreciated.

Thanks in advance

Dear Spekis

Do you have a supervisor or tutor? if you do, that person is perhaps the best person to put you through...
what is the title of your topic? from your description, it is unlikely that the focus of your dissertation will generate any papers sufficient for a systematic review.. i say this because it doesnt sound like a clinical question is being asked here...
every muscle in the body has a primary and secondary role depending on the activity it is being subjected to...the iliopsoas muscle group will flex the hip as well as stabilize the pelvis/lumbar spine...
maybe what you should be thinking about doing is a literature review...with this you would find several materials, papers, textbooks etc that would mention the role of the iliopsoas muscle group, however you will not be able to systematically review this papers you find because many of them would be asking clinical questions that will not be aimed at explaining the role of the iliopsoas muscle...

On the other hand you may want to review your topic with a clinical question attached to it...for instance you could say you want to review papers that have looked at the effect of low back pain on iliopsaos function? or the effect of hip arthritis on iliopsoas function..? or what is the effective management of iliopsoas tendinopathy? these kind of topics will generate more clinically based studies which you can now review systematically...

If one of these topics is what you choose...your literature review can be now explain the controversies in the assumed role of the iliopsoas muscle in lumbar/pelvic stabilization? how poor stability in the lumbar spine/pelvis can contribute to lowback pain/hip arthritis/iliopsoas tendinopathy? what the general concensus of the function of these muscle is preventing or causing these problems? what groups of people are more susceptible to these problems etc...

the other option is to generally carry out an experimental study...wherein you measure the EMG values of the iliopsoas muscle in low back and non low back pain patients and find out if there is any difference when lets say carrying out a onle leg stance for instance...this can give you an idea of the role the iliopsoas muscle plays in certain musculoskeletal dysfunction, and perhaps at the end of this study...give you an insight to what the therapist needs to do or involve the iliopsoas muscle in when rehabing such patients...

i hope i have been able to give you several options that should make your dissertation more meaningful...

Cheers

It's a good question and it probably has even more roles. So I would suggest you discuss/examine all the possibilities where it might be involved - prime mover, stabilizer, synergistic accessory muscle etc.

Consider synergistic rolls with the sartorious & rectus femoris (which may be different in the later depending on what the knee is also doing at the time e.g. extending), the roll played both concentrically & eccentrically from a flexed position e.g. a sit up/roll down to the floor from long sitting. Also it's action from a lengthened position such as hip extension vs's it's action at 90 degrees hip flexion. now that may be different if the pelvis is 'fixed' or supported as in sitting on a chair vs. a state of unsupported movement e.g a pike position in diving. The discussions are so varied and the cases for examination are therefore such that you cannot generalise the data from a single action that has been examined in a piece of research to all actions of the iliopsoas and for that matter the iliacus affect as well. It does make for a nice forum discussion though.

Final paper has always been a headache regarding choosing a good topic. I have found that dissertation topics should be simple and educational towards you actual work that you could use often. Hence i suggest you let that topic to side for now and choose an easy one. As you can see Dr Damien gave out quite few perspectives to look into the ilipsoas function and could further elaborate on it. Choose one varialble to look at such as ROM or strenth in specific population etc. or review basic rehabilitation approach that could be easier and more educational to you.