Snappy Hips, What The Psoas?

The iliopsoas has gained the reputation over the years as one of those mystical biological structures that can store spiritual and emotional energy. Although I don’t shy away from the ‘woo woo’ stuff (who doesn’t like a bit of ‘woo woo’?), as a health professional I’m a big advocate for enforcing things that we can measure and ‘prove’. One of the ways we demonstrate the appropriate duty of care and integrity to our clients as movements enthusiasts is to be informed by research. 

So let’s look at some of the research with regards to everyone’s favourite mystical tissue, the iliopsoas!

For this blog, I’ll be talking about the psoas major and the iliacus when referring to the iliopsoas muscle. The psoas minor is present in 40-50% of the population (Stecco et al 2015) and has it’s own unique functions that can be spoken about in a future blog. 

Because of how deep the psoas major is within the body, collecting meaningful and reliable data on the nature of this myofascial tissue is tricky. The psoas major ‘attaches’ to the spine via the transverse processes of the lumbar spine, vertebral bodies and intervertebral discs (as well as the vertebral body of T12). It descends down the spine, over the superior pubic rami, ‘inserting’ onto the minor trochanter of the femur. The iliacus spans most of the surface area of the iliac fossa where it also moves superiorly over the pelvis. From here, certain muscle fibers unite with the distal tendon of the psoas major whereas the more lateral muscle fibers of the iliacus directly ‘attach’ onto the anterior cortex of the proximal femoral shaft (Polster et al 2007). 

Although it is generally thought that the psoas major and iliacus share a common tendon, research has shown that this is only the case for 28.3% of 53 frozen pelvic girdle cadavers that were examined. 64.2% presented with two tendons and 7.5% presented with three tendons! The additional tendons originated from the iliacus (Philippon et al 2014). 

The anatomical variance at the iliopsoas tendon(s) will most likely influence the osteokinematics of the femoral head, pelvic posture and potentially how predisposed an individual is to certain hip pathologies. It’s not a huge surprise that the pelvic girdle will manifest differently in the population as it’s even been demonstrated that the right and left ilia in the same pelvis can present with different bony prominence size and height (Preece et al 2008). 

The function of the iliopsoas is still a hotly debated topic with convincing arguments on all sides. It’s generally accepted that it’s the primary hip flexor, especially the iliacus. Other functions such as modulating lumbar stiffness (stability) and hip rotation have also been demonstrated (Bordoni et al 2021). The iliopsoas has also been shown to play an important role during certain phases of walking (Michaud et al 2011).

So, allot of functions (and I’m sure there are more) related to this large myofascial tissue. Because there are so many jobs, it’s reasonable for people to be concerned with the functionality of this muscle/fascial unit. Unfortunately our ability to be specific and reliable with our iliopsoas and pelvic assessments are very limited (at best!). 

The orientation of the pelvis has been a measurement method to assess the length of the iliopsoas muscle (anterior pelvis = ‘short’ iliopsoas and posterior pelvis = ‘long’ iliopsoas). The fallacy with this theory is that the orientation of the pelvis doesn’t seem to correlate strongly with health issues such as back pain which the psoas major is commonly blamed for (Herrington 2011). 

But what about the orientation of the pelvic girdle in relation to the curvature of the lumbar spine? Well, they don’t correlate highly either (Heino et al 1990), which calls into question our ability to reliably assess the ‘length’ of the iliopsoas. 

This doesn’t mean that we shouldn’t be mindful of the iliopsoas just because we can’t reliably assess it. Certain hip issues such as snapping hip syndrome can sometimes be produced by the iliopsoas. ‘Internal’ snapping hip syndrome is thought to be produced by the iliopsoas whereas ‘external’ snapping hip syndrome can be produced by the iliotibial band, gluteus maximus or proximal hamstrings (Musick et al 2021). 

Although external snapping hip syndrome is thought to be more common, those who participate in sports like ballet have shown to present with the iliopsoas related snapping hip. Out of the 87 professional ballet dancers in one study, 91% complained of a snapping hip while 80% complained of bilateral snapping hip. 51% experienced pain when their hip snapped (Winston et al 2007). 

It’s important to acknowledge that snapping hip isn’t always a problem or a predictor to something worse down the line. That being the case, for some it can be an issue and the remedy completely depends on the individual. The intervention to resolve snapping hip may be clinical, therapeutic or exercise based. In my opinion, if exercise can resolve an issue that is favourable over clinical interventions like surgery (if it can be avoided). Teaming up with clinicians is important if you’re an exercise professional working with someone who has a clinical issue. This is so the best duty of care possible is delivered. 

So, what am I getting at with this blog? Well, the iliopsoas is an important structure. It’s useful to be aware of it’s functions as health professionals and although our ability to actually assess the thing with our hands is poor, knowing how to condition the iliopsoas for optimal strength, elasticity and flexibility (what ever optimal is for the person) is prudent. As one of my great mentors Eric Franklin says, “exercise alone is no guarantee for improving function.”

Having a practical understanding of the iliopsoas complex is for sure going to be incredibly useful when prescribing exercises. If that’s something you’re interested in, I’ll be teaching a 3 hour Franklin Method® webinar on the iliopsoas: Tone Your Psoas, Free Your Hips next weekend.

This will be a 3 hour webinar where we will explore the functional fascial anatomy of the iliopsoas as well as Franklin Method embodiments and exercises to move and condition the iliopsoas. If you’re interested in approaches to the body that are evidence based, practical, in-depth and fun then you will love this webinar! 

There are two dates to choose from, Saturday 18th or Sunday 19th September 2021.

Click here to book your space now, spaces are limited!

Movement is medicine

Tom