LOIS: Long-Term Follow-Up in INSITE/SIFI
Design: This study is extended follow-up from two ongoing multicenter prospective US clinical trials. All participants have already undergone the surgical procedure of interest (SI joint fusion with iFuse Implant System). The two ongoing trials are: * SIFI:( Sacroiliac Joint Fusion with iFuse Implant System) a single-arm trial of patients with degenerative sacroiliitis or sacroiliac joint disruption who underwent iFuse placement, and * INSITE(Investigation of Sacroiliac Fusion Treatment): a randomized clinical trial of the same patient population who underwent either non-surgical treatment or iFuse placement
• Patient enrolled and treated in SIFI or patient initially randomized to iFuse and treated in INSITE. Note: Patient may be in the initial follow up period associated with SIFI or INSITE at the same time they consent for this study and extend their post-operative follow up.
• Patient has signed study-specific LOIS informed consent form.
• Patient has the necessary mental capacity to participate and is physically able to comply with study protocol requirements.