Symptoms and Causes of Piriformis Syndrome

Piriformis syndrome is a surprisingly common problem. It is also a condition that can trick many people (including some physiotherapists and doctors) into thinking that they have sciatic nerve pain caused by a disc bulge. In fact piriformis syndrome is caused by irritation and tightness of the piriformis muscle.The piriformis muscle runs from your sacrum or tailbone to your hip joint.


piriformis muscle diagrmaIts job is to move the hip joint inwards and outwards (depending on the position of the hip). Piriformis is a particularly interesting muscle because in 30% of us the sciatic nerve runs directly through it. In the rest of us the sciatic nerve passes very close by. When the piriformis muscle gets tight two things can happen:

  • The sciatic nerve can become irritated leading to leg pain and sciatic nerve symptoms.
  • The muscle itself can become a bit short and tight, it can also get tight sore spots in it (called myofascial trigger points)

These trigger points can usually be found in predictable places in the muscle, they are usually grouped toward the tailbone or in the centre of the muscle in the middle of the buttock. These sore spots can be very painful to touch and they can sometimes cause a referral of pain into the leg too. So, sometimes, if you apply pressure to the piriformis muscle you can reproduce a feeling of pain in a true sciatic nerve irritation.

What causes piriformis syndrome?

The muscle can tighten for a variety of reasons:
  • Sometimes in response to a sacroiliac joint problem

  • Sometimes in response to a hip problem

  • Very often in response to sustained postural stresses

This last one is, I think, the most common one I see in my clinic. I have met quite a few people who have developed this after sitting in a car for long periods. This seems to particularly affect the driver where the right foot is often resting for long periods holding the accelerator steady.

In the UK our roads are too busy for cruise control!

I think it is a combination of holding the foot turned slightly outwards and the leg slightly out to the side. This creates tension in the piriformis muscle as it is in a shortened position for a while.

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