Many narratives about sacroiliac joint pain is more than ten years behind current research. So what is the better narrative and what therapists can do in practice?
A group of researchers and physiotherapists recently challenged the current diagnosis and management of sacroiliac joint pain. Led by Dr. Thorvaldur Palsson from the Department of Science and Technology at Aalborg University in Denmark, the team questioned a few common ideas among clinicians about why the sacroiliac joint is painful among many patients. (1)
Traditional explanations for sacroiliac (SI) joint pain is that there is some sort of movement dysfunction or structural abnormality in the SI joint, such as asymmetry, joint stiffness, weakness, and instability. Physiotherapists would assess the SI joint by using pain provocation tests to see if it is the source of pain sensitivity. Palsson et al. described a few of such tests by applying mechanical stress directly to the pelvic girdle or indirectly through the hip to cause shear stress in the SI joint. (1,2) These tests are used to discriminate SI joint pain from other types of low back pain.
While these tests can help clinicians be informed on whether the SI joint is likely involved or not, pain provocation tests do not tell clinicians why there is pain, Dr. Palsson said in an online interview with Massage & Fitness Magazine. “These tests have been shown to be sensitive and specific for determining whether the source of symptoms lies within the SI joint complex or not. This was done by using CT-guided intra-articular blocking protocols.”
He mentioned that some studies show that anaesthetizing joints outside of the SI joint can provide short-term reduction in SI joint pain. “Peripheral sensitization does not equate to symptoms, and a positive clinical test demonstrating sensitivity of the SI joint complex does not suggest changes in movement of the SI joint,” Dr. Palsson said.
Anatomy, Biomechanics, and Nociception of the Sacroiliac Joint
Like carpals of the wrists and the elbow joints, the SI joint is diarthrodial synovial. Unlike other such joints, its articulations have two types of cartilages: hyaline cartilage on the sacral surface and fibrocartilage on the iliac surface. The sacral surface has a series of depressions while the iliac surface has elevated ridges where the two surfaces form an interlocking joint. This “lock” limits the degree of the SI joint’s movement to no more than 8 millimeters in translation and up to 2 to 8 millimeters in rotation in all planes of motion. (3)
The SI joint’s primary role is to reduce force generated from the lower body—like a shock absorber for the spine—with the help of the thoraclumbar fascia and sacroiliac ligaments. Nerve innervation comes from the ventral rami of L4 and L5, the superior gluteal nerve, and the dorsal rami of the L5 to S2. However, some people have innervation only from the sacral dorsal rami, which can cause different pain patterns from the SI joint. (4)
Such pain usually stems from nociceptors within the anterior capsular ligament and the interosseous ligament of the SI joint. Researchers from the VU University Medical Center in Amsterdam identified neuropeptides within these structures that contribute to pain, including substance P and CGRP (calcitonin gene-related peptide). When a person senses a threatening stimulus, such as from a visual or tactile sensation, these neuropeptides are released from the dorsal horn of the spinal cord. (5)
“Recent findings, showing the immunoreactivity for substance P in the posterior sacroiliac ligaments adjacent to the posterior superior iliac spine, call attention to SI joint ligaments in the generation of pain attributed to the SI joint,” the researchers wrote. “Because the presence of nociceptive structures in both the anterior capsular ligament and the interosseous ligament of SI joint has not yet been reported, the aim of the present study is to determine the distribution of sensory nerves in these ligaments, and by that, possibly provide new insights into the pathogenesis of SI joint pain.” (5)
A Better Narrative About Sacroiliac Joint Pain
Having an “unstable” SI joint as the primary cause of pain is usually the blame, but this idea is not consistent with the current understanding of the SI joint’s anatomy, biomechanics, and neuroscience. With the sacrum wedged between the ilium which are supported by the sacral ligaments and pelvic muscles, it would take a tremendous amount of physical trauma to make the joint “unstable.” Since a majority of patients have such pain without such trauma, the unstable narrative is unlikely. Dr. Palsson mentioned that detection of SI joint movements with palpation is also highly unlikely because the SI joints have a tiny degree of freedom of movement. In his paper, he and his team wrote that the SI joint rotates an average of 0.2 degrees—or about 0.3 millimeters—in a standing hip flexion test. (1)
“Given these challenges in detection of movement, it is not surprising that tests for movement dysfunction are not reliable,” they wrote. “Directly attributing SIJ-related pain to movement dysfunctions causing increased peripheral nociceptive input from SIJ tissues, is a flaw in reasoning, mistaking association for causality. Positive pain provocation tests are likely indicative of increased sensitivity of the tissues, which might to some degree be subsequent to tissue loading.” (1)
“Clinicians’ ability to reliably detect the anatomical landmarks and their excursion when the joint moves (actively or passively) is poor,” Dr. Palsson explained. “Pain itself—in the absence of pathology—can cause changes in the way we move which can affect what is felt during palpation. This has been demonstrated in several experimental pain studies. With these in mind, it appears that the notion of movement dysfunctions of the SI joint and clinicians being able to detect too much or too little motion lacks plausibility. Given that, you have to wonder whether conveying messages, which are based on guessing at best, is helpful for the patients and clinicians.”
“Peripheral sensitization can definitely be a contributing factor in a person’s experience of pain. However, it is only a single factor in the presentation of a person in pain,” Dr. Palsson said. “We should consider physical overload, cognitive processing, and lifestyle factors. Even though we account for such factors and assess our patients within a biopsychosocial framework, such an approach may still have its shortcomings.
What manual therapists can start doing is to avoid fear-provoking messages about patients’ condition, help patients reframe their beliefs about, and explore what they can do. One way is to use the “7 C’s” in narrative medicine as a guideline to help therapists communicate. For example, if a patient was told that their pelvis is “weak and unstable” because of “poor posture,” the therapist could ask, “Well, could there be an alternative reason for the pain?” Or the therapist could help the patient explore other ways to move without less or no pain: “Ok, let’s find out what you can do today. Shall we try this exercise?”
“Messages that focus on weakness or fragility are more likely to maintain or worsen the condition instead of helping the patient,” Dr. Palsson warned. “Dr. Samantha Bunzli and her colleagues had shown us that by helping patients making sense of their pain and changing their pain beliefs may help them overcome e.g. movement-related fear, which is often one of the hurdles patients need to overcome during recovery. This can be achieved by giving them insight into their own condition and helping them to gain independence from health care professionals.” (6)
How Clinicians Apply the Modern Narrative of Sacroiliac Joint Pain
While there has been more than 10 years of data and research that did not support the biomechanical narrative, many manual therapy schools are still behind in catching up to the current research. Updating the curriculum seems like an obvious solution, but this would involve “a consensus at many levels” from management to teachers, Dr. Palsson said. And if manual therapists are not palpating the pelvis, what can they do based on current evidence?
Dr. Palsson suggested the following:
Explain how pain works tailored to the individual presentation based on the biopsychosocial model;
Constructively address unhelpful/aberrant health beliefs;
Promote reassurance regarding structural integrity of the pelvis or SI joint;
Design and discuss a management plan that is aligned with points 1 to 3.
“Even though these suggestions are reduced to four points, we are aware that this is not an easy task. Explaining how pain works, for example, is contingent upon us understanding how it works,” Dr. Palsson said. “This is an evolving field where more and more knowledge is continually emerging. A lot of what we know about pain can and should be implemented in curricula and be used in combination with other course modules, especially those focusing on assessment of the musculoskeletal system.
“I have no doubt that many clinicians are on board with this line of thinking and have aligned their clinical practice with the current evidence way before [our research] was published. The purpose of the article was not to encourage clinicians to abandon certain management approaches, like manual therapy and exercise. Rather, we wanted to encourage clinicians to place themselves as the sources of truth for their patients instead of contributing to mis-information.
“The outcome of any given intervention will always to some extent relate to clinician and patient preferences. What we want clinicians to take away from this article is that they consider and choose their words and interventions wisely and avoid mixed messaging based on a thin foundation, like providing mobilizing treatment and prescribing stabilizing exercise. These messages should be limited to what we do know from the available evidence and explained in laymen terms.”
1. Palsson TS, Gibson W, Darlow B, Bunzli S, Lehman G, Rabey M, Moloney N, Vaegter HB, Bagg MK, Travers M. Changing the Narrative in Diagnosis and Management of Pain in the Sacroiliac Joint Area. Phys Ther. 2019 Jul 29. pii: pzz108. doi: 10.1093/ptj/pzz108.
3. Goode A, Hegedus EJ, Sizer P, Brismee JM, Linberg A, Cook CE. Three-dimensional movements of the sacroiliac joint: a systematic review of the literature and assessment of clinical utility. J Man Manip Ther. 2008;16(1):25–38. doi:10.1179/106698108790818639.
4. Wong M, Kiel J. Anatomy, Abdomen and Pelvis, Sacroiliac Joint. [Updated 2019 Feb 6]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2019 Jan-.
5. Szadek KM, Hoogland PV, Zuurmond WW, de Lange JJ, Perez RS. Nociceptive nerve fibers in the sacroiliac joint in humans. Reg Anesth Pain Med. 2008 Jan-Feb;33(1):36-43.
6. Bunzli S, Smith A, Schütze R, Lin I, O’Sullivan P. Making Sense of Low Back Pain and Pain-Related Fear. J Orthop Sports Phys Ther. 2017 Sep;47(9):628-636. doi: 10.2519/jospt.2017.7434.