If your lower back pain sits below the belt line, hits mostly on one side, and flares every time you stand up from a chair, there is a reasonable chance your sacroiliac joint is the culprit. The sacroiliac joint, where the base of the spine meets the pelvis, accounts for 15 to 30 percent of all chronic lower back pain cases according to data from the American Academy of Family Physicians and the National Center for Biotechnology Information. Yet it remains one of the most commonly overlooked sources of low back pain, frequently misdiagnosed as a herniated disc, hip arthritis, or lumbar facet syndrome because the symptoms overlap so heavily with those conditions. Consider someone in their sixties who has been told for years that their back pain is degenerative disc disease. They have tried epidural injections targeting the lumbar spine with no relief.
The pain never quite matches the textbook sciatica pattern — it does not shoot below the knee, there is no measurable weakness in the leg, and imaging shows only modest disc changes that do not fully explain the severity. When a clinician finally evaluates the sacroiliac joint with provocation testing and a diagnostic injection, the pain drops by more than 75 percent. This scenario is not unusual. Up to 40 to 63 percent of patients with failed back surgery syndrome have SI joint dysfunction as their actual pain source. This article walks through ten specific symptoms that point toward sacroiliac joint dysfunction, explains how each one differs from lumbar spine or hip problems, and covers what to do if this pattern sounds familiar. For older adults and their caregivers — particularly those managing pain alongside cognitive decline — recognizing the correct source of chronic pain matters enormously, because untreated pain worsens confusion, agitation, and quality of life in people living with dementia.
Table of Contents
- What Does Sacroiliac Joint Pain Actually Feel Like Compared to Other Lower Back Pain?
- Why SI Joint Pain Flares During Everyday Movements
- The Symptoms That Mimic Sciatica and Fool Clinicians
- How Clinicians Confirm the SI Joint as the Pain Source
- Who Gets SI Joint Dysfunction and Why It Is Missed in Older Adults
- First-Line Treatments and What to Try Before Injections
- Why Getting the Diagnosis Right Matters for Brain Health
- Conclusion
- Frequently Asked Questions
What Does Sacroiliac Joint Pain Actually Feel Like Compared to Other Lower Back Pain?
The first and most telling symptom of SI joint dysfunction is unilateral low back pain centered at or below the fifth lumbar vertebra. In practical terms, this means the pain sits near the small dimples on the lower back, right where the waistband of your pants falls. If you can press one finger into that spot and say “it’s right here,” you may be demonstrating what clinicians call Fortin’s finger test. Research shows that when a patient can localize pain with a single finger to within two centimeters of the posterior superior iliac spine, it strongly suggests the sacroiliac joint rather than the lumbar spine as the source. Lumbar disc and facet pain, by contrast, tends to be more diffuse, central, and bilateral. The second hallmark is deep buttock pain on the affected side.
People describe it as a constant, boring ache — sometimes compared to a toothache lodged deep in the gluteal muscles. This is not the sharp, shooting quality of true sciatica running down the back of the leg. It sits in the buttock and may radiate into the upper thigh or groin, but here is the key differentiator: SI joint referred pain rarely extends below the knee. When pain consistently stops above the knee and there are no reflex changes or measurable weakness in the leg, the likelihood of SI joint involvement goes up and the likelihood of lumbar nerve root compression goes down. Cleveland Clinic and Spine-Health both emphasize this buttock pain pattern as one of the most recognizable features of sacroiliac dysfunction. For someone caring for a parent with dementia who cannot articulate their symptoms clearly, watching where they rub or guard can be revealing. A person who repeatedly presses a fist into one buttock or one side of the lower back, particularly when transitioning from sitting to standing, may be signaling sacroiliac joint pain rather than the generalized spinal degeneration their doctor has been treating.
Why SI Joint Pain Flares During Everyday Movements
The third symptom — pain with transitional movements — is often what drives people to finally seek answers. Standing up from a chair, climbing stairs, rolling over in bed, or swinging a leg out of a car all load the sacroiliac joint in ways that the lumbar spine is not loaded. These are not heavy-lifting injuries. They are mundane activities that become disproportionately painful. The Southeast Texas Spine Institute and WebMD both note that this movement-triggered pain pattern is characteristic of SI joint involvement because the joint absorbs and transfers force between the upper body and legs during transitions. The fourth symptom, groin or upper thigh pain, often sends people to a hip specialist first.
SI joint dysfunction commonly refers pain into the groin and the front or back of the thigh. However, if imaging of the hip comes back relatively clean and the groin pain coincides with one-sided low back and buttock symptoms, the SI joint deserves evaluation. Weill Cornell and Mayfield Clinic both document this referral pattern. The critical caveat: if the pain does extend below the knee, particularly with numbness following a specific nerve distribution and reflex changes, that shifts suspicion back toward a lumbar radiculopathy, and a different workup is needed. A fifth symptom is morning stiffness lasting more than an hour. Waking up with a locked-up feeling in the lower back and hips that takes 60 minutes or more to work through is characteristic of SI joint involvement, though it can also indicate inflammatory conditions like ankylosing spondylitis. If an older adult is notably stiff and irritable in the mornings but loosens up by midday, this pattern is worth mentioning to their physician — especially since prolonged morning stiffness tends to worsen immobility in people who are already at risk for deconditioning.
The Symptoms That Mimic Sciatica and Fool Clinicians
Perhaps the most confusing aspect of SI joint dysfunction is how convincingly it can imitate sciatica. The seventh symptom on this list — sciatic-like leg symptoms without true nerve compression — describes patients who report burning, tingling, or numbness in the buttock and posterior thigh. These sensations feel exactly like what people imagine sciatica to be. But when a neurological exam is performed, reflexes are intact, there is no measurable muscle weakness, and nerve conduction studies come back normal. Research published in PMC and clinical data from SI-BONE confirm that the SI joint can generate these pseudo-radicular symptoms through referred pain mechanisms rather than actual nerve root compression. The eighth symptom, leg instability or a sensation of the leg “giving way,” further muddies the diagnostic picture.
Thawrani and colleagues documented in a 2017 PubMed study that SI joint dysfunction can produce a buckling sensation in the leg. This is distinct from the true motor weakness caused by nerve root compression — the leg is not actually weak on strength testing, but the patient feels unstable. For older adults, particularly those with dementia, this instability increases fall risk substantially. A fall attributed to “weakness” or “balance problems” may actually stem from untreated sacroiliac joint dysfunction, and addressing the joint could reduce fall frequency. The overlap between these symptoms and lumbar spine conditions is precisely why SI joint dysfunction is so frequently misdiagnosed. Cedars-Sinai notes that it is commonly confused with lumbar facet syndrome, hip pathology, and lumbar disc disease. A person can undergo lumbar MRI, receive a reading showing some degree of disc degeneration — which is nearly universal in older adults — and be treated for a disc problem that was never generating their pain.
How Clinicians Confirm the SI Joint as the Pain Source
The ninth and tenth symptoms on this list are really diagnostic tools, but they function as symptoms in the sense that the patient’s response to them reveals the source. Fortin’s finger test, as described earlier, is the patient’s ability to localize pain to one specific point over the SI joint. The tenth is the cluster of provocation tests: clinical guidelines from the AAFP and StatPearls recommend that positive responses to at least three out of five physical provocation tests — the FABER or Patrick’s test, compression test, thigh thrust, Gaenslen’s test, and sacral thrust — strongly suggest SI joint dysfunction. No single test alone is reliable enough, but three or more positives together have meaningful diagnostic value. The gold standard for confirmation remains a diagnostic SI joint injection.
A physician injects local anesthetic directly into the joint under fluoroscopic guidance. If the patient experiences 75 percent or greater pain reduction, the SI joint is confirmed as the primary pain generator. This is a critical step before pursuing more invasive treatments, because it separates SI joint pain from the many conditions that mimic it. However, this test has limitations: it requires imaging guidance to ensure accurate needle placement, it measures pain relief at a single point in time, and some patients with genuine SI joint pathology may not achieve the 75 percent threshold due to concurrent pain sources. For dementia caregivers, the provocation test cluster is particularly useful because it does not require the patient to fill out detailed pain questionnaires or describe symptoms in nuanced language. A clinician can perform the physical maneuvers and observe whether each one reproduces pain — a grimace, a withdrawal, or guarding behavior can be as informative as a verbal pain report.
Who Gets SI Joint Dysfunction and Why It Is Missed in Older Adults
The bimodal age distribution of SI joint dysfunction means it clusters in two groups: younger adults, often from sports injuries or pregnancy, and older adults from joint degeneration. Women are more likely to develop it than men, partly because hormonal changes during pregnancy loosen the ligaments supporting the SI joint, and this laxity may not fully resolve afterward. In older adults, degenerative changes in the joint — cartilage thinning, osteophyte formation, and altered mechanics after lumbar fusion surgery — make the SI joint increasingly vulnerable. The sixth symptom, pain worsened by prolonged sitting or standing, is particularly relevant for the elderly population. Unlike some disc-related pain that improves in certain positions, SI joint pain does not let you find a comfortable posture.
It punishes immobility in any position. For someone with dementia who spends long stretches in a wheelchair or recliner, this creates a pain cycle that may manifest not as a verbal complaint but as increased agitation, resistance to care, or restlessness. Caregivers and clinicians should be aware that up to 25 percent of adults with chronic low back pain have the SI joint as the primary pain generator, and this percentage does not decrease with age. A major limitation in diagnosing SI joint dysfunction in people with cognitive impairment is the reliance on patient-reported symptom descriptions. Most diagnostic algorithms assume the patient can clearly describe their pain location, quality, and triggers. When that capacity is diminished, the physical provocation tests become even more essential — but they require a clinician who thinks to perform them, which in turn requires suspecting the SI joint in the first place.
First-Line Treatments and What to Try Before Injections
The AAFP recommends physical therapy focused on pelvic stabilization and stretching as the first-line treatment for SI joint dysfunction, alongside NSAIDs for pain management. This is a reasonable starting point, though it requires consistency — a few sessions of therapy are unlikely to produce lasting results. The exercises typically target the gluteal muscles, hip flexors, and core stabilizers that support the pelvis and reduce abnormal stress on the SI joint. For older adults, a physical therapist experienced in working with deconditioned or cognitively impaired patients is worth seeking out, because standard exercise programs may need significant modification.
When conservative treatment fails, interventional options include intra-articular steroid injections, radiofrequency ablation of the nerves supplying the joint, and prolotherapy. Steroid injections can provide weeks to months of relief but are not a permanent fix and carry risks with repeated use. Radiofrequency ablation offers longer-lasting relief by disrupting the nerve signals from the joint, though the nerves can regenerate over time. The tradeoff is that ablation is more invasive and requires the diagnostic injection to first confirm the SI joint as the pain source. For someone with advanced dementia, the risk-benefit calculation of procedural interventions should involve a careful discussion with the care team about goals of care, procedural tolerance, and whether pain reduction will meaningfully improve daily function and comfort.
Why Getting the Diagnosis Right Matters for Brain Health
Chronic untreated pain has documented effects on cognitive function, sleep quality, mood, and overall brain health. For someone already living with dementia, uncontrolled pain accelerates behavioral symptoms and can be mistaken for disease progression. A person who becomes increasingly agitated, combative during transfers, or unable to sleep through the night may be experiencing worsening SI joint dysfunction rather than worsening dementia.
Identifying and treating the correct pain source can, in some cases, reduce the need for antipsychotic or sedative medications that carry their own cognitive risks. Looking ahead, the growing recognition of SI joint dysfunction as a distinct and common pain entity is slowly changing clinical practice. More orthopedic and pain medicine specialists are incorporating SI joint evaluation into their standard workup for chronic low back pain, and diagnostic imaging techniques are improving. For caregivers advocating for a loved one with dementia and chronic back pain that has not responded to conventional treatment, asking specifically about sacroiliac joint evaluation is a reasonable and informed next step.
Conclusion
The sacroiliac joint is responsible for a substantial share of chronic lower back pain — 15 to 30 percent by most estimates — yet it remains chronically under-recognized. The ten symptoms outlined here form a recognizable pattern: one-sided pain below the belt line, deep buttock ache, pain with transitions, groin or thigh referral that stops above the knee, prolonged morning stiffness, intolerance of static positions, pseudo-sciatic symptoms without neurological deficits, leg instability, point-specific tenderness over the SI joint, and positive provocation testing. When three or more of these features are present, SI joint dysfunction deserves serious diagnostic consideration.
For older adults and those living with dementia, the stakes of a missed diagnosis extend beyond pain. Untreated SI joint dysfunction contributes to immobility, falls, behavioral disturbance, and unnecessary medication use. Caregivers who recognize these symptom patterns can advocate for targeted evaluation, starting with physical provocation tests and potentially a diagnostic injection. The path from chronic undiagnosed back pain to meaningful relief may be shorter than expected — if someone thinks to check the right joint.
Frequently Asked Questions
Can SI joint dysfunction cause pain on both sides at the same time?
While SI joint pain is typically unilateral, it is possible for both joints to be affected, particularly in people with inflammatory conditions like ankylosing spondylitis or those with significant pelvic asymmetry. However, bilateral SI joint pain is less common than unilateral, and bilateral low back pain should prompt evaluation for other causes as well.
How is SI joint dysfunction different from sciatica?
True sciatica involves compression of a lumbar nerve root and typically causes pain, numbness, or weakness extending below the knee, often into the foot, with measurable neurological deficits like reflex changes. SI joint dysfunction can mimic the buttock and upper thigh pain of sciatica but rarely extends below the knee and does not produce true neurological deficits on examination.
Can SI joint problems show up on an MRI or X-ray?
Standard imaging may show degenerative changes in the SI joint, but these findings are common in older adults and do not necessarily confirm the joint as the pain source. The gold standard for diagnosis is a fluoroscopically guided diagnostic injection that produces 75 percent or greater pain reduction, not imaging alone.
Is SI joint dysfunction permanent?
Not necessarily. Many people improve with physical therapy focused on pelvic stabilization and core strengthening. Others require periodic injections or radiofrequency ablation to manage symptoms. The condition tends to be chronic and recurrent rather than self-limiting, but it is treatable.
Why would someone with dementia have undiagnosed SI joint dysfunction?
People with cognitive impairment may be unable to describe their pain clearly, making it difficult for clinicians to distinguish SI joint pain from other causes. Pain may instead present as behavioral changes — agitation, resistance to movement, sleep disruption — that get attributed to the dementia itself rather than to a treatable musculoskeletal condition.
