Tenon Medical CATAMARAN™ SI Joint Fusion System CT Scan Study

Inclusion Criteria: Patient >18 years of age at time of treatment with the CATAMARAN SI Joint Fusion System Patient implanted with the CATAMARAN Fixation Device within the last 12 months Diagnosis of sacroiliac joint disruption or degenerative sacroiliitis Patient, or authorized representative, signs a written Informed Consent form to participate in the study Patient is willing and able to complete study follow-up requirements Exclusion Criteria: Known or suspected active drug or alcohol abuse Previously diagnosed osteoporosis (defined as prior T-score <-2.5 or history of osteoporotic fracture) or prior/current use of drug therapy for osteoporosis. Prior fracture of any bone related to cancer/tumor (i.e., pathologic fracture) Prior diagnosis of tumor in sacrum or ilium Unstable fracture of sacrum and or ilium involving the targeted SIJ Osteomalacia or other metabolic bone disease Use of medications known to have detrimental effects on bone quality and soft-tissue healing Patient is pregnant or wishes to become pregnant during the study period Patient is not likely to comply with the follow-up evaluation schedule Patient is a prisoner or a ward of the state