The piriformis muscle is a small muscle deep in the buttock area. It attaches at one end to the sacrum or the tailbone, and at the other to the femur - the long thigh bone.
Despite being small the muscle has an important role. Its main job is to turn the hip joint outward, but it only does this when the hip joint is in a neutral position (which means not bent up). If the hip joint is bent up then piriformis also moves the leg outwards or away from your midline. The technical term for this is abduction. You use this muscle:
Piriformis Muscle showing the sciatic nerve
The muscle is also very important for stabilising the hip joint and the pelvis so it is also in action:
You can feel the muscle by feeling along the edge of the sacrum or the tailbone where it is attached. It's worth noting though that this muscle is deep in there and has close relationships with other pelvic muscles - look at the diagram above to see what I mean. This means it is very hard to feel it unless you know exactly what you are looking for.
Piriformis syndrome is caused by irritation and tightness of the piriformis muscle which in turn irritates the sciatic nerve..
It is a surprisingly common problem and is 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.
When the piriformis muscle gets tight two things can happen:
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
The muscle can tighten for a variety of reasons:
This last one is by far the most common one I see in my clinic. I have met many 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.
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.
It is difficult to diagnose this problem yourself so you need to be examined by a health care professional to make sure that you have the right diagnosis and can get the correct treatment..
This can be done by an experienced health care professional using the straight leg raise test as shown below:
This test lets your physio work out if its the sciatic nerve that is the problem or not. Your physical therapist will lift your leg up and may push your ankle toward your nose or turn your hip inwards.
If the ankle movement changes your pain you may have sciatica.
If the test is positive it does not mean that you definitely do have sciatica. However, if it is negative it’s likely that you don’t have a sciatic nerve problem.
After taking a full history your doctor will:
1. Feel the muscle (palpate) and often small tender trigger points can be felt that reproduce the symptoms, usually in the middle of the muscle or grouped toward the tailbone.
2. Put the piriformis muscle onto a stretch. Providing the hip has enough movement in it, lengthening the muscle often reproduces the same painful feelings.
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Treatment for this syndrome involves accurate diagnosis of the cause of the problem.
You're physical therapist will need to find out if the muscle is short and tight or simply overactive because of core stability and hip muscle weakness.
If the problem is more hip and core muscle patterning problems you need to look for a strengthening programme for the abdomen and pelvis. Your physio can help with that.
The best start is always to examine your posture, in particular the way you sit. As this problem is so commonly caused by driving positions I would have a really good look at the position your leg is in when you are sitting in the car.
if the answer is yes then you may need to try adjusting the seat position.
If you can't change anything then avoiding the postural stresses and strains that caused it initially may be a good idea. This can mean avoiding sitting or standing for long periods with your foot turned out for a while.
If you have a short, tight muscle then stretching it out is usually very helpful. Combining postural changes with stretches of the muscle usually does the trick.
Try warming the muscle first with heat therapy - it will make it much easier to stretch out and be less uncomfortable. 20 minutes should do the trick.
Make sure you don't cause a burn, properly wrap up whatever you are using for warmth and don't lie or sit on the heat source pressing it against your skin.Wander into any physiotherapy department and mention piriformis stretches and you will provoke a debate about the best way to do it. The problem is the action of piriformis - it does different things depending on the position of the hip.
Some of my colleagues use a different stretch but this is the one I particularly like. I have found this to be a very successful stretch for many of my patients with this problem.
This video shows the foot being turned inwards, If it doesn't work it is worth trying a variation on it by turning the foot outwards.
Sometimes the tight muscle needs to be released with deep soft tissue work, similar to acupressure, called trigger point release.
It is possible to self treat this muscle using the back knobber - one of my favourite tools for managing trigger points.
Sometimes this syndrome is caused by the muscle tightening in response to a problem with your hip joint, or more commonly as a result of sacroiliac joint dysfunction.
If this is the case diagnosis of the exact cause is needed otherwise the treatment suggested above will only give you short term symptom relief - your physiotherapist can advise.
This shows the relationship of the piriformis muscle to the other deep muscles of the hip and the sciatic foramen. The video starts with a 3D overview and then switches to a static image before shifting back to 3D at about 4.15 secs. Worth sticking with it if you want to visualise the muscle.
Cassidy, L. et al., 2012. Piriformis syndrome: implications of anatomical variations, diagnostic techniques, and treatment options. Surgical and radiologic anatomy: 34(6), pp.479–486.
Hopayian, K. et al., 2010. The clinical features of the piriformis syndrome: a systematic review. European spine journal 19(12), pp.2095–2109.