Vertebral Interbody Spacer with Concave Sides
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Solution Overview
Problem
Existing interbody devices for spinal support and fusion often require significant bone removal and have limited surface contact, leading to subsidence and inadequate curvature correction, as they are typically cylindrical and threaded, necessitating extensive vertebral reshaping and bone engagement only on upper and lower surfaces.
Innovation Solution
A non-threaded interbody spacer with convex, sloped surfaces that conform to the natural concavity of vertebrae, providing maximum surface contact and support, and a solid core without pass-through apertures, designed to promote normal lordosis or kyphosis while minimizing surgical alteration and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cylindrical threaded interbody devices are used, then bone engagement is achieved on upper and lower surfaces, but significant bone removal is required and device surface contact is limited
Solution Approach 1:
Instead of making the device cylindrical to fit into a drilled hole, the patent inverts the approach by making the device rectangular with concave sides that conform to the natural rectangular shape of the vertebral bodies. This eliminates the need for extensive bone removal and drilling, as the device is designed to fit the bone geometry rather than forcing the bone to accommodate the device.
Solution Approach 2:
The patent applies curvature by creating concave surfaces on the lateral sides of the rectangular device. These concave surfaces conform to the convex surfaces of the vertebral bodies, maximizing the contact area between the device and bone. This curved surface design allows for extensive surface contact without requiring bone removal, directly resolving the contradiction between reliable bone engagement and ease of manufacture.
2Ease of operation
If interbody devices engage bone on upper and lower surfaces only, then device placement is simplified, but subsidence occurs due to limited contact area
Solution Approach 1:
The patent transitions from a traditional cylindrical device that contacts bone primarily on upper and lower surfaces to a rectangular device with concave lateral sides that contact bone on four surfaces (upper, lower, and two lateral sides). This dimensional change in the device geometry enables engagement with the vertebral bodies on multiple surfaces simultaneously, dramatically increasing the contact area and distributing loads more effectively to prevent subsidence, while still maintaining simplified placement procedures.
3Strength
If device volume and weight are increased to provide better support, then load bearing capacity improves, but device compatibility with body decreases
Solution Approach 1:
The patent utilizes thin film theory by creating a rectangular device with concave lateral sides that form arch-like structures. These thin-walled concave structures provide exceptional strength-to-weight ratio, enabling the device to bear substantial loads while maintaining minimal weight and volume. The concave geometry creates structural efficiency similar to arches and shells in nature, providing high load-bearing capacity without increasing device mass, thus improving body compatibility.
4Adaptability or versatility
If vertebrae are reshaped to accommodate cylindrical devices, then device placement is achieved, but surgical complexity increases
Solution Approach 1:
The patent reverses the traditional surgical approach by not reshaping the vertebrae to fit a cylindrical device, but rather designing a rectangular device with concave sides that naturally conform to the unaltered vertebral bodies. This inversion eliminates the need for complex bone reshaping, drilling, and preparation procedures, significantly simplifying the surgical protocol while maintaining excellent device-vertebrae fit and alignment.
Data Source
AI summary
A spinal fusion interbody spacer device has a solid central core positioned between laterally opening opposed concave side surfaces. The device includes spaced apart superior and inferior abutment surfaces which are convexly arced. The spacer device is implanted between a pair of adjacent vertebrae by insertion in a tipped-over orientation and then reoriented to an upright orientation for engagement of the abutment surfaces by facing surfaces of the vertebrae.