Expandable Vertebral Implant with Gear-Driven Telescopic Alignment
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Solution Overview
Problem
Current vertebral body replacement devices face challenges in achieving a precise fit and optimal alignment during spinal surgery, particularly due to limited clearance and variability in surgical approaches, which can complicate the insertion and stability of prosthetic implants.
Innovation Solution
An expandable prosthetic implant design featuring an inner and outer member with a gear mechanism, endplates, and a locking system that allows for adjustable expansion and alignment, utilizing markings for precise orientation and a tool-assisted expansion mechanism to ensure secure placement and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an expandable prosthetic implant is used to replace a vertebral body, then the implant can accommodate various sizes and facilitate distraction across the resected vertebral defect, but the device complexity increases due to the expansion mechanism and alignment requirements
Solution Approach 1:
The implant consists of an inner member with an outer member that telescopes over it, creating a nested structure. The inner member includes a proximal end, distal end, and lateral surface, while the outer member has a corresponding telescoping structure. This nested design allows the implant to be compact for insertion and then expanded to various sizes in situ, accommodating different vertebral body dimensions without requiring multiple implant sizes.
Solution Approach 2:
The implant incorporates a dynamic expansion mechanism where the outer member can telescope relative to the inner member along the longitudinal axis. This dynamic structure allows the implant to transition from a compressed insertion state to an expanded functional state, enabling size adjustment and distraction of the vertebral defect while maintaining structural integrity.
2Ease of operation
If the implant is designed to be adjustable in situ for optimal fit, then insertion is simplified and immediate load bearing is possible, but the alignment precision and surgical approach variability become more challenging
Solution Approach 1:
The implant is pre-configured with an inner member and outer member assembly that can be inserted in a compact state. The markings are pre-positioned on the outer member to guide alignment during insertion. The gear mechanism is pre-assembled to engage with the inner member, allowing for controlled expansion after insertion. This preliminary configuration simplifies the insertion process while maintaining alignment precision through the marking system.
Solution Approach 2:
The implant replaces complex mechanical alignment systems with a marking-based guidance system. The markings on the outer member provide visual cues for proper orientation and alignment during insertion, eliminating the need for complex mechanical alignment devices or specialized insertion tools, thereby simplifying the surgical procedure while maintaining precision.
3Reliability
If the implant includes a gear mechanism and locking system for secure placement, then the stability and reliability improve, but the device complexity and difficulty of insertion increase
Solution Approach 1:
The gear mechanism is designed to engage automatically between the inner and outer members upon insertion, without requiring external actuation or complex control systems. The locking system utilizes the telescoping action itself to trigger engagement, where the relative movement between inner and outer members causes the gear teeth to mesh and the locking features to engage, securing the implant in place through self-actuation.
Solution Approach 2:
The gear mechanism acts as an intermediary between the telescoping motion and the locking function. As the outer member telescopes over the inner member, the gear mechanism translates this linear motion into rotational engagement of the locking features, providing a mechanical intermediary that converts one type of motion into another to achieve secure locking without direct mechanical connection.
Data Source
AI summary
An expandable implant for engagement between vertebrae includes an inner member, an outer member, and a gear member positioned coaxial with respect to each other such that the inner and outer members are moveable relative to each other along an axis. The inner member includes a longitudinal groove configured to engage a pin extending through the outer member such that the pin prevents the inner member from translating completely through the outer member and aids in alignment and limits rotation of the second endplate. Portions of the implant may be provided with a series of markings such that when the markings are aligned, the implant is aligned in a specific configuration and for a specific implantation approach.