Post-Market Clinical Study on a Modular SI Joint Fusion System

Inclusion Criteria: * Subjects meeting all of the following inclusion criteria by the end of the screening phase should be considered for admission to the study: * Age 18-85\* (\*Over 85 is allowed with H\&P assessment screening upon approval by Medical Monitor); * Absent condition of high-risk surgical candidate (see training manual for definition); * Patient has lower back pain with a confirmed diagnosis of sacroiliac joint disruption or degenerative sacroiliitis for a period of \>6 months and who has not responded to optimal conservative care (PT or prescribed HEP, optimal medical management including NSAIDs); * Diagnosis of sacroiliac joint disruption or degenerative sacroiliitis based on ALL of the following: a. Patient has pain at or close to the posterior superior iliac spine (PSIS) with possible radiation into buttocks, posterior thigh or groin and can point with a single finger to the location of pain (Fortin Finger Test), and b. at least three positive findings with provocative maneuvers (FABER, Gaenslen, Thigh Thrust or Posterior Shear, SI Compression, SI Distraction, and Yeoman Test); * Patient has a diagnostic SIJ injection (SIJI) that provided a minimum of 75% relief of primary (index) pain with the diagnostic SIJI on two separate occasions; * Patient meets Medicare and payer requirements for medical necessity, see detailed requirements in training manual; * SI joint disruption: Asymmetric SI joint widening on X-ray or CT scan or degenerative sac…