Wedge-Shaped Spinal Cage with Angled Teeth for Fusion
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Solution Overview
Problem
Existing spinal implants lack a large open vertebral contact area for bone ingrowth and a locking structure to prevent migration, and they do not effectively mimic the natural curvature of the spine.
Innovation Solution
A wedge-shaped spinal cage with a hollow interior and angled teeth on its periphery to secure the implant to the vertebrae, allowing for rotation to engage the teeth and prevent ventral and dorsal movement, while providing a large contact area for bone growth material and promoting fusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a traditional spinal cage is used with closed sides, then structural strength is maintained, but the contact area for bone ingrowth is reduced
Solution Approach 1:
The cage incorporates porous coating on its surface to enhance bone ingrowth while maintaining structural integrity. The porous structure provides increased surface area for bone attachment without compromising the overall strength of the cage structure.
Solution Approach 2:
The cage is designed with open sides rather than completely closed structure, creating segmented regions that allow bone ingrowth from multiple directions while maintaining sufficient structural support through the remaining walls and reinforced sections.
2Ease of operation
If a spinal cage without locking structure is used, then ease of implantation is improved, but migration prevention is reduced
Solution Approach 1:
The cage is pre-loaded with bone graft material before implantation, and the distractor device is pre-assembled with the cage. This preliminary preparation allows for straightforward insertion without requiring complex intraoperative assembly, while the pre-positioned locking structures are ready to engage immediately upon implantation.
Solution Approach 2:
A distractor device serves as an intermediary tool during implantation to deliver the cage into the intervertebral space and subsequently activate the locking mechanisms. This intermediary device simplifies the implantation process by providing mechanical leverage and control while ensuring reliable engagement of the locking structures.
3Ease of manufacture
If a straight spinal cage is used, then manufacturing simplicity is improved, but natural spine curvature mimicry is reduced
Solution Approach 1:
The cage is designed with a wedged shape featuring curved surfaces that mimic the natural lordotic curvature of the spine. The curvature is achieved through precision molding or machining processes that create the desired angular geometry while maintaining manufacturing feasibility through standardized forming techniques.
Solution Approach 2:
The cage geometry incorporates variable parameters including different wedge angles and curvature radii that can be adjusted based on the specific spinal level and patient anatomy. These parameter variations allow the same basic design to adapt to different curvature requirements without requiring completely different manufacturing processes.
4Reliability
If a cage with open sides is used, then bone vascularization is improved, but structural stability is reduced
Solution Approach 1:
The open side design is complemented by porous coating on the internal and external surfaces, which enhances bone vascularization and ingrowth. The porous structure provides a scaffold for bone tissue formation while the remaining cage walls maintain structural stability and load-bearing capacity.
Solution Approach 2:
The cage may incorporate composite material construction combining metal framework with porous ceramic or polymer coatings. This composite approach allows the metallic structure to provide mechanical strength and stability while the porous material portions facilitate bone vascularization and integration.
Data Source
AI summary
A spinal implant for insertion in the intervertebral space is formed as a hollow cage, wedge shaped in profile, with a lesser height leading end for a low profile entry. The cage has two open sides with a plurality of angled teeth along opposite longitudinal edges for engaging the end plates of adjacent vertebrae when the cage is rotated into position. One portion of the angled teeth are angled toward an end of the cage and another portion of the angled teeth are angled away from that end to provide a lock preventing the cage from migrating ventrally or dorsally from the spine. Upon rotation, the leading end has a greater height than the trailing end.