The sacroiliac (SI) joint connects the sacrum to the pelvis. Dysfunction here produces low back and buttock pain that's frequently misattributed to lumbar spine pathology. Diagnostic injection confirms the source; targeted treatments — physical therapy, injections, radiofrequency — address the issue without fusion of the lumbar spine.
Where the SI joint is and why it matters
The SI joints are the meeting points between the sacrum and the iliac bones — one on each side of the lower back, just below the lumbar spine. They have limited motion compared to the lumbar joints but they transfer load between the spine and pelvis. Dysfunction here produces a distinct pain pattern.SI joint pain is often misdiagnosed as lumbar pathology because the location overlaps and patients describe both as ‘lower back pain.’ Distinguishing them matters because the treatments are completely different. SI pain doesn’t respond to lumbar treatments, and vice versa.
Clinical pattern
Pain in the low back and buttock, often unilateral, sometimes radiating into the upper thigh but typically not below the knee. Worse with single-leg activities (climbing stairs, getting in/out of a car). The patient often points to the dimple where the SI joint is when asked to localize.Specific examination maneuvers stress the SI joint and reproduce the pain when the joint is the source. A positive response to several of these maneuvers, combined with absence of features pointing to other sources, builds the clinical case.
Confirming the diagnosis
Diagnostic intra-articular injection is the test. Anesthetizing the SI joint with local anesthetic — if symptoms substantially decrease during the block period — confirms the joint as the source. A positive response also predicts likely benefit from further targeted treatments.Imaging often shows degenerative changes at the SI joint but those changes don’t reliably predict symptoms. The clinical picture combined with the diagnostic block makes the diagnosis.
Send your MRI for a free review
Dr. McMillan reviews each scan personally. You get a candid answer about candidacy before any travel or scheduling.
What the consultation actually looks like
The initial visit with Dr. McMillan focuses on what your imaging actually shows and what your symptoms are telling us — independent of what you’ve been told previously. The $250 consultation fee covers his time to review your MRI personally and give you a candid evaluation. Most patients leave the visit with a clear answer: either you’re a candidate for the endoscopic approach (and we discuss what that would involve in your specific case), or you’re not (and we tell you why, and what we would suggest instead). No high-pressure scheduling, no surprise add-ons.
For patients traveling from outside the Upstate, the consultation can usually be coordinated with the procedure to minimize travel. A typical out-of-town pathway is: send your MRI for the free review, have a phone or video conversation with Dr. McMillan after his review, and travel for a single combined visit-and-procedure schedule when you decide to move forward. The office handles the logistics — lodging recommendations, transportation guidance, and post-op coordination with your local primary care physician.
If you have been told you need a fusion and you are not sure, or if you have been managing this with conservative care that has stopped working, the next step is the free MRI review. There is no obligation and no cost to send your scan. Dr. McMillan reviews each one personally. The response will tell you plainly whether the endoscopic approach fits your specific anatomy, or whether your situation calls for a different plan.
Treatment options
Physical therapy focused on pelvic stabilization, hip mechanics, and core strengthening forms the foundation. SI joint injections with corticosteroid can provide extended symptom relief. Radiofrequency ablation of the nerves supplying the SI joint can provide durable relief for confirmed cases.SI joint fusion exists as a surgical option for specific situations — but is generally reserved for cases where non-surgical treatments have failed and the diagnosis is firmly established. It’s not a first-line answer.
Bottom line
The sacroiliac (SI) joint connects the sacrum to the pelvis. Dysfunction here produces low back and buttock pain that's frequently misattributed to lumbar spine pathology. Diagnostic injection confirms the source; targeted treatments — physical therapy, injections, radiofrequency — address the issue without fusion of the lumbar spine.
If you’ve been told you need a fusion — or you’re trying to avoid one — a free MRI review is the most useful next step. Dr. McMillan reviews each scan personally and tells you candidly whether the endoscopic approach fits your specific anatomy.
For patients dealing with si joint dysfunction, the conversation comes down to specifics: what your imaging actually shows, what your symptoms are actually telling us, and which procedure (if any) genuinely matches that pattern. The candid answer is sometimes that you do not need surgery yet; the candid answer is sometimes that you do, but a smaller operation than the one you have been quoted. A second-opinion MRI review separates those cases and gives you the information you need to make the decision well.
The Synergy approach to si joint dysfunction
Most patients arrive at Synergy Spine Center after being told their only surgical option is fusion. The practice was built on a different premise: when the imaging shows pathology that decompression can address, decompression is what’s recommended — not a fusion that locks the segment permanently. For si joint dysfunction specifically, the typical pathway begins with a careful second read of your MRI, then a candid conversation about whether coolief for si joint or cooled radiofrequency ablation would address the specific source of symptoms.
Dr. McMillan personally reviews every MRI submitted through the free MRI review portal. The review takes several business days and produces a written assessment of candidacy. If the imaging supports an endoscopic approach, you’ll receive a recommendation for the specific procedure and a transparent quote for the bundled price — surgeon, facility, and anesthesia all in one number. If the imaging shows something that wouldn’t benefit from endoscopic intervention, you’ll be told that directly, often with a referral to the appropriate specialty.
Recovery from endoscopic spine surgery for si joint dysfunction is meaningfully faster than from open laminectomy or fusion. The incision is less than ⅓ inch, the procedure is outpatient under local anesthesia, and most patients are walking the same afternoon. Office workers typically return within one to two weeks; manual labor takes four to six weeks depending on the level of physical demand. The full pathway is documented at /how-it-works/ and the typical 3-day visit for out-of-town patients is at the 3-day plan. Authoritative background on this condition is also available at Cleveland Clinic — Sacroiliac (SI) Joint Dysfunction.
Frequently asked
How is SI joint pain different from lumbar pain?
Location, pattern, and triggering activities differ. SI pain is typically below the lumbar belt line, often unilateral, worse with single-leg activities. Diagnostic injection confirms. Patients who travel for care from out-of-town typically combine consultation and procedure into a single visit — the 3-day plan documents the standard cadence and what to plan for.
Can SI pain be caused by my lumbar problems?
Sometimes. Altered lumbar mechanics (from fusion, deformity, or pathology) can change loading on the SI joints. Lumbar fusion specifically is a recognized cause of subsequent SI dysfunction. Transparent bundled pricing for the procedure is published openly at /spine-surgery-cost-transparent-pricing/, so you can plan financially before scheduling.
Do I need surgery for SI dysfunction?
Most respond to conservative care, targeted injections, and radiofrequency. Surgical fusion is reserved for cases where these have failed. If you want the full procedural detail and what to expect during recovery, the coolief for si joint page walks through technique, anesthesia, and the typical timeline.
Is COOLIEF used for SI pain?
Cooled radiofrequency techniques can target the lateral branches supplying the SI joint posteriorly. Specific candidacy varies. If you want the full procedural detail and what to expect during recovery, the coolief for si joint page walks through technique, anesthesia, and the typical timeline.
How accurate are the diagnostic blocks?
When properly performed under image guidance, intra-articular SI blocks have high diagnostic value. False positives and negatives exist but are reasonably rare. Patients who travel for care from out-of-town typically combine consultation and procedure into a single visit — the 3-day plan documents the standard cadence and what to plan for.
Will physical therapy alone fix it?
For some patients, yes. For others, PT is foundational but additional targeted treatments are needed. If you want the full procedural detail and what to expect during recovery, the coolief for si joint page walks through technique, anesthesia, and the typical timeline.
How this page was prepared
This page summarizes the clinical approach taken at Synergy Spine Center for the topic above. It is based on peer-reviewed literature, professional society guidelines (NASS, AAOS), federal patient education resources (NIH, AHRQ, CMS), and Dr. McMillan’s experience as Director of Spinal Medicine and Endoscopic Spinal Surgery. Outcome language is qualified. Individual results vary. Pricing where shown is current for 2026 and may change.
References
- PubMed — SI joint dysfunction literature. — source
- OrthoInfo — sacroiliitis. — source
- NASS — SI joint resources. — source
- Cleveland Clinic — Sacroiliac (SI) Joint Dysfunction — clinical reference on si joint dysfunction.
- NIH NCBI — Sacroiliac Joint Injury — clinical reference on si joint dysfunction.
Synergy Spine Center publishes patient education content for general information only; it is not medical advice and does not establish a physician-patient relationship. For specific medical guidance, schedule a consultation. No identifiable patient information is included on this page.