The purpose of this study is to determine if platelet-rich plasma is superior to steroid/anesthetic for the treatment of sacroiliac joint pain.

All patients with sacroiliac joint pain diagnosed by a back pain specialist will undergo physical examination maneuvers and a test lidocaine injection of the joint. Patients who meet eligibility requirements will be randomized in a single-blind randomized controlled manner with a 50% chance of receiving platelet-rich plasma versus steroid/anesthetic injection of the sacroiliac joint(s).

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

Patients will be blinded to which injectate they received.