The Anatomy: Why This Joint Matters
The sacroiliac joint is not a simple hinge. It is an irregularly shaped, partly synovial and partly syndesmotic articulation that transmits the entire weight of the upper body from the spine through the pelvis to the lower extremities. The joint surfaces are covered with cartilage and held together by what is arguably the strongest ligament complex in the human body - the dorsal sacroiliac, interosseous, sacrotuberous, sacrospinous, and iliolumbar ligaments.
These ligaments work together to create a self-locking mechanism called "form closure" and "force closure." Form closure refers to the inherent stability provided by the joint's irregular, interlocking surfaces. Force closure refers to the additional stability provided by the surrounding ligaments and muscles compressing the joint surfaces together. When the ligaments are intact, this dual mechanism allows the SI joint to bear enormous loads while permitting only a few degrees of motion - the small amount of "give" needed for shock absorption during walking and running.
When SI joint ligaments become damaged - through injury, pregnancy, repetitive loading, or degenerative changes - force closure is compromised. The joint develops abnormal motion. This hypermobility irritates the richly innervated joint capsule and ligamentous structures, producing the characteristic pain pattern: deep aching in the lower back and buttock, often radiating to the posterior thigh, sometimes to the groin or lateral hip.
Symptoms and Diagnosis
SI joint dysfunction produces a distinctive but frequently misdiagnosed pain pattern. The pain is typically unilateral, centered over the posterior superior iliac spine (the bony prominence you can feel at the top of the buttock), and may radiate into the buttock, posterior thigh, or groin. It is often worse with transitional movements - rising from a chair, getting out of a car, rolling over in bed - and with prolonged standing or walking. Many patients report that the pain is worse on one side and may shift with different activities.
The diagnostic challenge. SI joint dysfunction is one of the most commonly missed diagnoses in spine care. The pain pattern overlaps with lumbar disc herniation, facet arthropathy, piriformis syndrome, and hip pathology. Standard lumbar MRI does not adequately image the SI joint. Many patients with SI joint dysfunction have been told their lumbar MRI is "normal" and that there is no structural cause for their pain - when the problem was simply in a joint the imaging did not evaluate.
In my practice, I rely on a systematic clinical examination using validated provocation tests. The FABER (flexion, abduction, external rotation) test, sacral compression, sacral distraction, thigh thrust, and Gaenslen test each stress the SI joint through different vectors. When three or more of these tests reproduce the patient's pain, the likelihood of SI joint dysfunction is high. We then confirm the diagnosis with a fluoroscopically guided diagnostic injection - a small volume of local anesthetic placed directly into the SI joint. If this injection provides temporary but significant pain relief, it confirms the SI joint as the pain source and predicts a favorable response to regenerative treatment.
Why Conventional Treatments Fall Short
The conventional treatment pathway for SI joint dysfunction typically progresses through physical therapy, anti-inflammatory medications, SI joint belts, and corticosteroid injections. Physical therapy can strengthen the muscular force closure mechanism, and this is valuable. SI joint belts provide external compression that partially substitutes for ligamentous stability. Both provide symptomatic improvement but neither addresses the fundamental problem: damaged ligaments that cannot adequately stabilize the joint.
Corticosteroid injections suppress but do not heal. SI joint corticosteroid injections are among the most commonly performed procedures for this condition. They reduce intra-articular inflammation and can provide weeks to months of relief. But they do not restore ligament integrity, and repeated corticosteroid exposure may actually weaken connective tissue over time. The patient enters a cycle of injection, relief, recurrence, and re-injection - each cycle potentially leaving the ligaments slightly more compromised than before.
SI joint fusion has emerged as a surgical option for refractory cases. While outcomes data for minimally invasive SI joint fusion are improving, the procedure permanently eliminates motion at the joint and may transfer stress to adjacent structures. For a condition fundamentally driven by ligamentous insufficiency, restoring ligament function is a more physiologically rational first approach than eliminating the joint entirely.
Dr. Crane's Regenerative Approach
Regenerative injection therapy is the cornerstone of SI joint treatment in my practice, and SI joint dysfunction is one of the conditions where I have seen the most consistent and dramatic results. The treatment targets the specific ligaments responsible for SI joint stability: the dorsal sacroiliac ligament, the interosseous ligament (the strongest ligament in the body), the sacrotuberous ligament, the sacrospinous ligament, and the iliolumbar ligament.
Each of these ligaments has specific attachment points that can be precisely targeted with injection. I use fluoroscopic guidance to deliver regenerative biologics along the dorsal SI ligament complex and the sacrotuberous ligament attachments, initiating a controlled healing cascade at each injection point that recruits fibroblasts and stimulates collagen synthesis to progressively strengthen the ligamentous structures.
For patients with significant intra-articular inflammation or early degenerative changes within the SI joint itself, I combine extra-articular treatment (targeting the ligaments) with intra-articular regenerative therapy (targeting the joint surfaces). This dual approach addresses both the mechanical instability and the inflammatory component simultaneously. For advanced SI joint degeneration, more potent regenerative options deliver cellular resources directly to the joint to promote cartilage repair and modulate chronic inflammation.
Most patients with SI joint dysfunction require 3-5 treatment sessions spaced 3-4 weeks apart. Improvement is typically noticeable after the second or third treatment as cumulative ligament strengthening reaches a threshold sufficient to restore functional stability. In my experience, this condition has one of the highest success rates of any spinal pathology treated with regenerative medicine.
What to Expect
Each treatment session takes approximately 30-45 minutes. Post-treatment soreness in the SI joint region lasting 2-4 days is normal and reflects the inflammatory response driving the healing process. We recommend avoiding heavy lifting and high-impact activities for 3-5 days after each session. Walking and gentle movement are encouraged from day one.
Physical therapy focused on core stability, gluteal strengthening, and pelvic alignment complements the regenerative treatment and is an important part of the recovery program. We coordinate with your physical therapist to time rehabilitation exercises with the biological repair process.