Intervertebral Implant

What is this patent about?

’743 is related to the field of spinal fusion, specifically addressing the need for improved intervertebral implants. Traditional spinal fusion techniques often involve supplemental fixation methods like pedicle screws or anterior plating, which can lead to complications such as nerve injury, vascular damage, and adjacent segment disease. The patent aims to provide a stand-alone device that minimizes these risks while still achieving effective spinal fusion.

The underlying idea behind ’743 is to create a bi-directional fixating transvertebral (BDFT) screw/cage apparatus that combines the functions of an intervertebral spacer and a bone fixation device. This is achieved by integrating angled screw guides within the cage structure, allowing screws to pass through the vertebral bodies above and below the implant. A key element is a screw locking mechanism using leaf springs that engage with ratcheted screw heads, preventing screw back-out after insertion.

The claims of ’743 focus on an intervertebral implant designed for insertion between vertebral bodies to promote fusion. The implant includes a cage with a space for bone filling, a top wall with a top surface, and internal screw guides. These guides have entry openings on the top surface and exit openings on the bottom surface and side surface of the top wall. A screw with a threaded body and head is inserted through the guide, and the screw head's abutment against a surface within the guide inhibits back-out. Importantly, the side walls of the implant exclude any portion of any entry opening of an internal screw guide .

In practice, the surgeon selects an appropriately sized cage and packs it with bone fusion material. The cage is then inserted into the prepared disc space. Self-drilling screws are guided through the internal screw guides, penetrating the adjacent vertebral bodies. As the screws are tightened, the ratchet mechanism and leaf spring ensure unidirectional movement, locking the screws in place and preventing loosening. This design eliminates the need for supplemental fixation in many cases, reducing surgical time and potential complications.

The invention differentiates itself from prior approaches by integrating the fixation mechanism directly into the intervertebral cage. Unlike traditional methods that rely on separate plates and screws, this design provides a more streamlined and potentially less invasive solution. The internal screw guides with a predetermined angle simplify screw placement and reduce the risk of misdirection. The leaf spring locking mechanism offers a reliable way to prevent screw back-out, a common issue with conventional spinal implants.