Zero-Profile Expandable Intervertebral Spacer Devices For Distraction And Spinal Fusion And A Universal Tool For Their Placement And Expansion

What is this patent about?

’797 is related to the field of spinal fusion , specifically to intervertebral spacers designed to restore disc height and promote bone growth between vertebrae. The background involves traditional spinal fusion techniques that often require supplemental fixation like pedicle screws or anterior plating, which can lead to complications such as nerve damage, blood loss, and adjacent segment disease. Existing non-expandable spacers require forceful distraction of the vertebral bodies and may not perfectly fit the disc space.

The underlying idea behind ’797 is to provide a zero-profile, expandable intervertebral spacer that can be inserted in a collapsed state and then expanded in situ to precisely match the patient's anatomy. This calibrated expansion allows for controlled distraction of the disc space, nerve root decompression, and promotion of spinal fusion, all while minimizing the need for supplemental fixation and reducing the risk of complications associated with traditional methods.

The claims of ’797 focus on an expandable intervertebral fusion device comprising first and second movable portions and an expansion mechanism configured to move the first movable portion with respect to the second movable portion, wherein the expansion mechanism comprises at least a rotation screw having a screw head and a threaded shaft, wherein the expandable intervertebral fusion device defines first and second tool engagement indentations on first and second sides of the expandable intervertebral fusion device.

In practice, the device is inserted into the prepared intervertebral space using a specialized tool that engages indentations on the sides of the spacer. Once in place, a rotation screw is turned, which actuates a linkage mechanism to separate the top and bottom portions of the spacer. This expansion provides calibrated distraction of the vertebral bodies. The device includes cavities for packing bone fusion material to promote bone growth between the vertebrae. Some embodiments also incorporate bi-directional fixating transvertebral screws for added stability.

The key differentiation from prior approaches lies in the combination of a zero-profile design, calibrated in-situ expansion, and the potential for stand-alone use without supplemental fixation. The various embodiments offer different expansion mechanisms, including scissor jacks, tapered threads, and worm drives, allowing surgeons to choose the most appropriate design for a given patient and surgical approach. This individualized approach aims to reduce morbidity and improve the effectiveness of intervertebral spacer placement compared to traditional methods.