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.