Minimally Invasive Inferior Intra-Articular Sacroiliac Joint Fusion: Successful Application of Osseous Stabilization Using Allograft Bone.

Minimally invasive sacroiliac joint (SIJ) fusion is the preferred surgical method for managing patients with recalcitrant, chronically severe SIJ pain and dysfunction refractory to conservative medical measures. The primary surgical objective of all minimally invasive SIJ fusion procedures is to provide immediate stabilization within the joint space to support osseous consolidation and the development of a mechanically solid arthrodesis. The intra-articular surgical approach to the SIJ with allograft bone placement utilizes a trajectory and easily identifiable landmarks that allow the surgeon to control the risk of violating important neuro-vascular structures. The intra-articular approach can employ a superior or inferior operative trajectory, with the former restricted to allograft placement in the ligamentous portion of the SIJ. The inferior approach utilizes decortication to surgically create a channel originating in the purely articular portion of the joint space allowing for truly intra-articular implant placement within the osseous confines of the ilium and sacrum. Positioning the implant along the natural joint line and securing it within the underlying sub-chondral bone, mortise and tenon fashion provides stabilization and large surface area contact at the bone implant interface. The inferior, intra-articular approach also places the implant perpendicular to the S1 endplate, near the sacral axis of rotation, which addresses the most significant biomechanical forces across the joint. Short-term, post-surgical observational data from a 57 patient multi-center registry using the inferior, intra-articular approach show uniform and statistically significant improvement in all clinical outcomes (p < 0.001 for all comparisons), including an average 3-point improvement in back pain severity from 6.8 preoperatively to 3.8 at 6 months. Further clinical evaluation with longer-term follow-up of the inferior, intra-articular SIJ fusion procedure is encouraged.