Treatment for Sacroiliac Joint Pain Using Platelet-rich Plasma (PRP) Versus Steroid/Anesthetic

Inclusion Criteria: * Adult (\>18 y/o) males and females referred for therapeutic injection to the investigators spine interventional service by a physiatrist or pain anesthesiologist with a clinical diagnosis of SIJ pain confirmed by history * 50% or greater reduction in pain by a diagnostic anesthetic block using no more than 1.5 cc 2% lidocaine performed under imaging guidance by a pain interventionalist (PM\&R, Pain Anesthesia, or Neuroradiology Spine Intervention). * Baseline pain must be \>/=4 by numeric rating scale (NRS), at least 6 weeks in chronicity, and must not be multi-factorial (related to radiculopathy or axial pain localizing elsewhere) by physical examination or confounding medical history (infection, inflammatory spondyloarthropathy, or osseous metastatic disease). Exclusion Criteria: * SIJ steroid treatment within the prior 6 months. * Patients with a history of infection currently on antibiotic therapy * Usage of systemic immunosuppressants * Pregnancy