Sacroiliac (SI) Joint Dysfunction

Etiology — what causes it

Pain from the sacroiliac joint complex, which transfers load between the spine and pelvis. Contributors include peripartum ligamentous laxity, post-traumatic capsular injury, repetitive asymmetric loading, leg-length discrepancies, and altered movement patterns after hip or low back injury. The joint has limited motion but high mechanical demand.

Epidemiology — who gets it

SI joint is responsible for roughly 15–30% of chronic low back pain cases when assessed with provocation testing and diagnostic blocks (Cohen, Anesth Analg). More common in women, especially peripartum and postpartum.

Clinical signs

Laslett cluster of provocation tests (compression, distraction, thigh thrust, Gaenslen, sacral thrust) — three or more positive yields roughly 91% sensitivity and 78% specificity for SI-mediated pain (Laslett et al., Spine 2003). Fortin finger sign (patient localizes pain within 1cm of PSIS). Absent neurological findings.

Symptoms

Pain localized over the PSIS area, often unilateral, that may refer into the buttock, groin, or posterior thigh. Aggravated by single-leg standing, asymmetric loading (climbing stairs, getting out of a car), transitions, and prolonged sitting. Often described as deep and dull with sharp catches.

Best evidence for chiropractic treatment

Manual therapy (mobilization, manipulation) combined with progressive exercise focused on the gluteal complex, deep stabilizers, and hip strength has supporting evidence (Kamali & Shokri, J Manual Manip Ther; Bronfort et al.). The Hungerford and Vleeming form-closure / force-closure models guide rehabilitation. SI belt is a useful short-term adjunct for peripartum and post-traumatic presentations. Image-guided diagnostic and therapeutic injection can be considered for refractory cases.