Dual Threaded Implant Enables Sacroiliac Joint Bony Fusion

A novel fusion system consists of partially and fully threaded implants designed to secure the sacroiliac (SI) joint and minimize micro-motion.

The Genesys Spine (Austin, TX, USA) Sacroiliac Joint Fusion System is intended to treat conditions that cause SI joint disruptions and degenerative sacroiliitis. The system consists of partially threaded and fully threaded implants made of medical grade titanium alloy (Ti-6Al-4V ELI). All screws and anchors are cannulated and self-tapping, and are offered with different diameters (up to 13.5mm), and lengths (up to 70mm) to accommodate for variations in patient anatomy and surgeon preference. A dual thread design incorporates a differential pitch for controlled compression across the joint.


Fusion across the graft space can be aided by the addition of bone graft material to the lumen of each screw, and fenestrations in each screw allow for direct allograft apposition across the SI joint. Both dual thread screws and fully threaded screws provide joint compression via a compressive thread pattern. Optional washers are included, to aid conformation to patient anatomy and to help distribute the load onto a larger area by maximizing purchase on the ilium, without burying the implant head in the bone. A delivery system uses guide pins for accurate surgical placement into pre-drilled bone.

“I am excited to see one streamlined set that can address the pathology of sacroiliitis from both the lateral and posterior approach. SI joint dysfunction is a chronically underdiagnosed pain generator of patients reporting with low back pain, one that has a relatively safe and quick surgical fix with an incredibly high rate of success,” said Kaywan Gamadia, DO, of Cape Spine & Neurosurgery (Cape Girardeau, MO, USA). “Thanks to the innovation at Genesys, I have rapid sacrum acquisition without disturbing my sight picture as I work. This system will deliver health care providers with versatile tools to treat these patients in need of an SI joint fusion.”

The SI joint connects the iliac crests to the sacrum, the triangular bone between the lumbar spine and the coccyx. Its primary function is to absorb shock between the upper body and the pelvis and legs. The Si joint has little motion, with only small movements helping with shock absorption and forward and backward bending. The joint is reinforced by strong ligaments surrounding it, some of which extend across it to the back of the pelvis. This network of soft tissues provides support, limits movement at the joint, and assists with absorbing pressure.

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