Bi-Directional Fixating/Locking Transvertebral Body Screw/Intervertebral Cage Stand-Alone Constructs

What is this patent about?

’753 is related to the field of spinal fusion, specifically addressing the need for improved intervertebral devices. Traditional spinal fusion techniques often involve supplemental fixation methods like pedicle screws or anterior plating, which can lead to complications such as nerve or vascular injury, blood loss, and adjacent segment disease. The background highlights the limitations of existing solutions and the ongoing need for less invasive and more reliable methods for achieving spinal stability and fusion.

The underlying idea behind ’753 is to create a stand-alone intervertebral device that combines the functions of a spacer and a bi-directional fixation system. This is achieved by integrating angled screw guides within an intervertebral cage, allowing screws to be inserted through the cage and into the adjacent vertebral bodies in opposing directions. This bi-directional screw fixation aims to provide immediate stability and promote fusion without the need for additional hardware like plates or pedicle screws.

The claims of ’753 focus on an intervertebral apparatus with internal screw guides and fixation. The apparatus includes an intervertebral spacer with a top wall, a bottom wall, and sidewalls, defining an open space for bone filling. The key feature is the integration of internal screw guides within the spacer, directing screws into adjacent vertebral bodies. A screw lock mechanism is included to prevent screw back-out. The claims also cover specific features like indentations on the cage surface and the geometry of the screw locks.

In practice, the device is inserted into the prepared disc space, and screws are then inserted through the internal guides into the vertebral bodies above and below. The angled trajectory of the screw guides ensures that the screws engage the vertebral bodies in a way that provides immediate stability. The screw locking mechanism, which may involve a separate component or indentations in the cage itself, prevents the screws from loosening over time, ensuring long-term fixation and promoting fusion.

This design differentiates itself from prior approaches by eliminating the need for supplemental fixation hardware. The integrated screw guides simplify the surgical procedure and reduce the risk of misplaced screws. The bi-directional screw placement provides enhanced stability compared to traditional interbody spacers, while the screw locking mechanism addresses the common problem of screw back-out, a frequent cause of revision surgeries. The indentations on the cage surface further enhance screw engagement and prevent loosening, contributing to a more robust and reliable fusion.