Piriformis Syndrome – a real pain in the butt?
Piriformis Syndrome – a real pain in the butt?
Before we even discuss what this syndrome is, we should first consider the basic anatomy and function of the piriformis muscle.
The piriformis is a small muscle located in the buttocks. This picture shows a view from behind, with the left buttock dissected back. It shows how the left piriformis (highlighted orange) runs from the inside of the pelvis to the outside of the femur deep across the buttock. It externally rotates and abducts the femur, which means it turns the thigh bone outwards and moves it away from the midline. To help you clearly visualize it you can look at the video below. As you can see in the picture, it is not a large muscle. To be honest, based on my experience dissecting it, the pictures make it seem bigger than it is!
For such a small muscle, you would be surprised how often it is blamed for problems in the buttock or the back of the thigh! Piriformis syndrome (PS) is often suspected or diagnosed when patients are suffering with pain deep in the buttock and/or running down the leg; pain may occur with walking or after long periods of sitting. However, to date, the medical community has not agreed on a clear definition of PS, or a consistent way of diagnosing it. Research has suggested PS is responsible for 5-6% of cases of sciatica, occurs at a mean age of 38, and happens in a ratio of 6:1 females to males1. However, these statistics are a little questionable if we do not have a true definition of the syndrome!
So, is it truly the piriformis that is often at fault, or are there other possibilities?
PS is currently a theory based on anatomy and a set of symptoms that are not universally agreed on. In all honesty, it is often a diagnosis given after others, such as sciatica or facet pain2, have been ruled out using imaging, EMG, and physical testing. However, diagnosing sciatica or facet pain is also not always an exact science, and pain from these structures can refer to the piriformis area, making conclusive diagnosis very difficult. For this reason, a US study of 75 physiatrists found only 72% agreed PS existed, 55% felt it was over-diagnosed, whereas 38% felt it was under-diagnosed3! So, a diagnosis or theory of a client having PS is an inexact science.
When a clinician describes or diagnoses piriformis syndrome (PS), they are talking about a compression of the sciatic nerve caused by the piriformis. They are using this description to differentiate it from the traditional description of sciatica where there is some sort of neural restriction or irritation at the spinal level. For that reason, you will also hear PS described as a pseudo sciatica. The next picture is a close-up of the piriformis and surrounding nerves, and helps us see why this theory has come about.
In this picture, the large yellow line that is shown running beneath the piriformis is the sciatic nerve. Actually, studies have shown that in up to 34% of people the sciatic nerve passes through the piriformis muscle rather than under it4. Some suggest this varied anatomy may lead some people to have a greater risk of PS.
So, are we hearing so much about this small muscle because it is over-diagnosed, or is it truly problematic?We are not going to know until more research is done to delineate a clear diagnostic pathway.5
OK! So we’ve seen what research says about PS, but how do we treat the pain?
The first consideration, and at the forefront of my patients’ attention, is the question of symptom relief. Your butt, or your butt and leg hurts so you want relief! Quite honestly, anything that gives relief is great! Treatments that may be recommended include stretching (really you cannot hit it specifically, you are stretching out the hip rotators), foam rollers or lacrosse balls to “release” the muscle, ice to reduce pain and inflammation, heat to reduce pain and tension, or dry needling to release trigger-points. Although there are many treatment options, sadly there is no specific research to say what works best. This is mostly due to the difficulty defining PS in the first place. A patient who is truly suffering from PS might benefit from one set of stretches and exercises, whereas a patient with sciatica pain referred to the piriformis area might benefit from a slightly different set of stretches. Without a clear test to definitively show the true cause of the patients’ pain, the best approach for the therapist is to recommend a set of exercises and monitor the patient’s response; in effect, the response to the treatment guides the therapist to the correct diagnosis and continued care.
In more than a decade of practice, I have seen what I would consider true cases of PS; however, I believe it is also sometimes over-diagnosed. I believe that any of the symptom relief treatments listed above are reasonable, but in my experience the most consistent relief comes from stretching. However, there is no research to define why this is, other than an anatomical theory that a tight/shortened piriformis will pressure the sciatic nerve.
Is there a way to move beyond providing pain relief to eliminating the pain and preventing it from returning?
Again, sadly there is not much research on this matter. As described earlier, some people’s anatomy may predispose them to PS. However, in my experience there are other options that we can consider that might stop PS from returning! I have found that a thorough physical examination indicates treatments of stretching, and lumbar stabilization/motor control exercises. Using this approach appears to get the client to the point where they can stop stretching without the feeling that the piriformis is tightening back up and pain recurring.
A recent study6 that is still in-press may lend evidence to this. In this Australian study, a group of professional Aussie Rules Footballers were examined through a season at three intervals. Those with no back pain had an increase in cross-sectional area (CSA) and therefore strength of their piriformis muscle at each interval. Those who started with low back pain underwent motor control exercises and their piriformis muscle followed with the same increases. However, those who started pain free but developed LBP and were then started on motor control exercises found a different relationship. Their piriformis CSA reduced with pain, but increased when the the motor control exercises were added. So, the study certainly shows motor control exercises affect the piriformis. It is outside the scope of their results, but it may be possible that in people with piriformis syndrome there is a lack in motor control of the lumbar spine which leads to the weakness and tightness. By stretching we are hitting the tight component, but if we do not perform lumbar motor control exercises we are missing half the picture.
This is particularly interesting when looked at with the earlier statistic that PS affects 6:1 females to males. This is a similar ratio to how many females have knee injuries, and one of the key features that may lead to that statistic is females falling into internal rotation and adduction (thigh bone falls and turns inward, as is seen in the earlier video). You will note from our video that internal rotation and adduction are the opposite motions to external rotation and abduction. For these knee problems, many studies have shown the gluteus maximus and medius to be underactive. When gluteus maximum and medius are strengthened, they counteract the tendency toward internal rotation and adduction. Interestingly, a 2012 study shows that the piriformis muscle also acts to counteract these tendencies7. Therefore, a strengthening program that addresses all three of these important muscles may help to not only reduce knee injuries, but also PS!
(The same paper7 also describes the top three exercises for activating the piriformis which you can see in the playlist below:)
However, this is my clinical theory based off of anatomy, biomechanics, available evidence and experience. At this point there is no research that clearly directs us, and it is in these times that it is important to see a clinician with experience. That clinician should be able to use their experience and knowledge of anatomy and function and research to rule in/out diagnoses and issues, and appropriately treat you.
- Jankovic D, Peng P, Van zundert A. Brief review: piriformis syndrome: etiology, diagnosis, and management. Can J Anaesth. 2013;60(10):1003-12.
- Huang JT, Chen HY, Hong CZ, et al. Lumbar facet injection for the treatment of chronic piriformis myofascial pain syndrome: 52 case studies. Patient Prefer Adherence. 2014;8:1105-11.
- Silver JK, Leadbetter WB. Piriformis syndrome: assessment of current practice and literature review. Orthopedics. 1998;21(10): 1133-5
- Adibatti M, V S. Study on variant anatomy of sciatic nerve. J Clin Diagn Res. 2014;8(8):AC07-9.
- Miller TA, White KP, Ross DC. The diagnosis and management of Piriformis Syndrome: myths and facts. Can J Neurol Sci. 2012;39(5):577-83.
- Leung FT, Mendis MD, Stanton WR, Hides JA. The relationship between the piriformis muscle, low back pain, lower limb injuries and motor control training among elite football players. J Sci Med Sport. 2014; In-Press.
- Giphart JE, Stull JD, Laprade RF, Wahoff MS, Philippon MJ. Recruitment and activity of the pectineus and piriformis muscles during hip rehabilitation exercises: an electromyography study. Am J Sports Med. 2012;40(7):1654-63.