A method for treating a sacro-iliac joint comprises the steps of: identifying a target of a posterior superior iliac spine of a body determining a selected trajectory that includes the target and at least a portion of a sacrum of the body creating a pathway in the body along the selected trajectory from a posterior approach to the body and delivering an implant along the pathway such that the implant is disposed for fixation with an ilium of the body and the sacrum. Systems for treating a sacro-iliac joint are disclosed.