Differential Diagnosis: Demystifying SI Joint Pain
Insight into a clinicians mind when identifying SIJ as the source of your pain.
At some point in time, chronic back pain sufferers will probably come across the idea of sacroiliac joint pain and it's potential role as a cause of back pain.
For some, this will come from the suggestion of a PT that this may be the cause of your pain. For others, it may the result of you conducting your own online research and stumbling across a post about SIJ that sounds very similar to your experience.
Regardless, most who begin to investigate the idea of SIJ related pain will quickly be overwhelmed with the myriad of opinions on the topic.
Some people will tell you SIJ pain is so rare you probably shouldn't even worry about it. Others may suggest there is no way for you to know if SIJ is even causing your pain. And then there are those that believe SIJ dysfunction is a common cause of back pain and their brand of treatment, whether it be exercise, massage, manipulation or something else, will be the cure to your problems.
You will likely begin to wonder things like: Is SIJ pain even a real thing? How do I found out if SIJ is the cause of my pain? Is it one of many things causing my pain? What do I even do about it? Is it treatable? Should I see a PT, Chiro, Neurologist or someone else? Is there a simple exercise to help with this?
This article aims to demystify the confusion around SIJ related pain. I want to help you understand what we know (and what we don't know) about SIJ pain, so that you can decide if it is worth your time to even think about it any further. I want to help you make informed decisions about your back pain so you can get on the right journey for you, back to comfort and pain free living.
What are our SI joints?
Our sacroiliac joints (SIJ for short) are the joints that connect between the spine and pelvis.
"Sacro" refers to sacrum = the bottom section of our spine, below our lumbar section.
"Iliac" refers to ilium = is the largest uppermost portion of our pelvis. It's the large, flaring 'wing-like' portion that you can feel when you place your hands on your hips.
You can identify these joints on many people from the back. They are the dimples on either side of the base of the spine.
These are very strong joints designed to transmit forces between our legs and spine. As a result, there is very little movement at these joints. However, a very small amount of gliding and rotation can occur.
How do our SI joints cause pain?
This isn't a straightforward answer, unfortunately. It is generally accepted that SI joints can be a source of pain, but why pain occurs in them is less clear.
One potential reason is the presence of an inflammatory condition within the joint itself, causing pain.
Another potential cause may be related to joint instability. This instability may be caused by an injury such as a tear in the joint capsule or laxity in the ligaments that surround and support the joint.
Another possibility that has been discussed in the literature is that perhaps pain in this region can be a musculature issue. This belief comes from the fact that the origin of many muscle attachments are in this region.
How do I know if SIJ is the cause of my pain?
Firstly, I want you to understand that it is very difficult to ever be 100% certain that SIJ is the cause of your pain.
I do however, want to lay out some common patterns and observations that we usually see with SIJ pain. Hopefully this will give you some quick insight whether it is worth your time to bother pursuing the possibility that SIJ is the cause of your pain.
Identifying SIJ pain
The following are some general observations we usually see associated with SIJ related pain:
Pain can be present in back, buttock, groin and legs
The location of the pain can be experienced in the same locations as many other more common lumbo-sacral pain sources. Making it difficult to distinguish based on the presence of pain alone.
Symptoms are rarely felt above the L5 level of the spine
If you are experiencing pain above this level of your spine it is unlikely to be cause by your SIJ.
Symptoms are rarely experienced bilaterally
Most of the time SIJ pain is only experienced on one side. If you have pain in the region SIJ pain is commonly experienced, but it is on both sides of your back, the pain is less likely to actually be coming from your SI joints.
Symptoms rarely experience along the spine's midline
SIJ pain is rarely felt in the middle of your spine. It is usually a few centimetres lateral (to the side) of your spine.
Pain when walking a specific distance
If pain is initially tolerable but soon becomes painful AND you are a younger person, this can indicate towards a joint (such as the SIJ) being the cause of your pain. Remember, this is only one consideration of many, and you would also need to rule out that the pain is not caused by a different joint other than the SIJ.
Pain exacerbated when standing up and when performing lunges
Therapists can perform a number of assessments that 'stress' the SI joints to see if provoking them replicates your symptoms. Standing up and split lunges are two common movements of daily life that people with painful SI joints often notice aggravate their symptoms.
May be related to a history of trauma
Meaning a traumatic physical injury seems to be related to the onset of SIJ pain in some people.
Excluding other causes
Firstly, if the patterns detailed above do not seem to fit your pain experience, I encourage you to check out my other articles to see if I have described another pathology that is more fitting of your pain mechanism.
When trying to identify SIJ pain, it is common for disc injuries to provide false positive results. This means it is important to rule out that a disc injury is not causing your symptoms as it commonly presents with a similar pain experience (this even confuses therapists who are physically assessing people's SI joints, as attempting to provoke the SI joints often causes symptoms in those who actually have disc injuries).
One commonly utilised way of identifying if a disc is the cause of your pain is whether there is "centralisation" or "peripheralisation" of your symptoms.
These two terms describe changes in someone's pain experience.
Centralisation refers to the phenomenon where pain that was initially felt over a wide area or at various distant parts of the body starts to recede towards the spine or becomes localised to a more central area. Imagine you have pain that starts in your lower back and extends down your leg. If the pain starts to move up your leg and gets closer to your lower back, it's considered to be centralising.
Peripheralisation is when the pain moves away from the midline or central part of the spine outwards to the more distant areas of the body.
You have probably noticed in your own research that the field of back pain is a hotly contested topic, full of many mixed opinions. If you look further into the concepts of centralisation and peripheralisation, you find them to be no different.
While the usefulness of these pain experiences as a diagnostic indicator is contested, I want to point them out to you regardless as one additional data point for your own self-investigation.
If your pain tends to "centralise" or "peripheralise" in response to different movements and postures, it becomes *more likely* that your pain is caused by a disc rather than SI joints.
If you would like to confirm whether a disc bulge is the cause of your pain, check out my Differential Diagnosis article on disc bulges here.
Another indication that your pain is not caused by SIJ is the presence of signs relating to nerve root compression. If you notice things like a loss in strength and motor function, or a loss of sensation like a numb toe or foot, those are not symptoms that are caused by SI joints.
Physical assessments for SIJ pain
There are a number of physical assessments therapists can use to try and provoke your SI joints and assess if this provocation replications your pain experiences. Even in the case of true SIJ pain, not all SIJ provocation tests will cause pain. So the commonly accepted wisdom is that if at least 3 SIJ provocations replicate your familiar pain symptoms, a positive SIJ pain source is indicated.
These tests require a skilled therapist to perform them. I think describing them here is probably beyond the scope of this article. Let me know if you are interested in understanding the physical assessments that can be involved in assessing SIJ pain and I might do a follow-up on the topic!
I hope atleast you can use this information to consider the assessments you may have had thus far. Or it may equip you with the knowledge to ask more specific questions of your therapists when trying to understand what is going on with your pain.
What to do about it
If you have been paying attention thus far, you are probably wondering how in the hell I could give you a clear answer to solving SIJ pain.
You are right to be sceptical. While plenty of clinicians out there have successfully treated people with SIJ pain, in the broader scheme of things we don't particularly have any definitively confirmed treatments for SIJ pain.
As I have already discussed, we often are not even particularly sure what causes SIJ pain, so how could we be confident in the correct treatment?
Don't lose hope, however. There are options out there and suggestions in literature about the direction treatment should take.
From a physical therapy point of you, the treatment with perhaps the strongest evidence and likelihood of success is stabilisation based exercises.
A few other existing treatment that are outside my wheelhouse include corticosteroid, phenol and prolotherapy injections. Or in more extreme cases, fusion surgery. I'll let you research these on your own and find experts more qualified on these treatments to learn from.
What if there are multiple things wrong with me
There exists the very real possibility you have SIJ pain as well a spine pathology. While less common, it is the case for some with back pain to also have a comorbid hip or SI pain source. If this is the case for you, a physical assessment with a skilled therapist may be helpful to tease out those pain mechanisms and provide appropriate treatment advice.
How confident can we be
So if the experience of your pain tends to line up with the patterns I described above + other possible causes have been excluded as best as possible + 3 or more SIJ provocations tests were positive for you pain = we can be fairly confident (likely 80+%) that the SIJ is the source of your pain.
This may not seem like a great result. And this probably contributes to why many find it difficult to recover with an SIJ pain diagnosis. However, if you have found yourself at this level of confidence, it probably becomes worth your time (and money) to follow through on some SIJ focused treatment.
To be any more confident than this requires a diagnostic injection. This can involve different products being used, but often involves injecting your SIJ with an anaesthetic solution to gauge your response. If the act of injecting the solution into your SIJ produces a familiar pain, that is one indication to help confirm SIJ as the pain source. If in addition after receiving the injection a significant reduction in your symptoms occurs, this tends to confirm SIJ as the pain source. However, sometimes multiple injections are used in this diagnostic process.
Stabilisation exercises for SIJ
I considered dicussing some options for stabilisation based exercises that I like to use personally. I think this article may be getting a bit long however. Let me know if this would be a valuable to you and I will aim to do a follow up detailing some of these exercises.