Expandable Interbody Implant with Hinged Endplates and Locking Screw
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Solution Overview
Problem
Conventional mechanically operated interbody implants for spinal procedures, particularly in the cervical region, often have cumbersome mechanisms that require a large footprint, making them unsuitable for anterior cervical discectomy and fusion (ACDF) surgeries.
Innovation Solution
An expandable interbody implant with a superior and inferior endplate hingedly coupled, featuring a locking element to secure the endplates in a desired configuration, and an external inserter to adjust the implant's expanded and angled positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional mechanically operated interbody implants are used, then spinal stabilization function is achieved, but the device requires a large footprint and cumbersome mechanisms that are unsuitable for cervical ACDF procedures
Solution Approach 1:
The implant is divided into separate endplates (superior and inferior) that can be independently positioned and secured. The endplates are hingedly coupled to allow relative movement for expansion while maintaining structural integrity, enabling simplified insertion through small incisions typical of ACDF procedures.
Solution Approach 2:
The implant incorporates a dynamic hinged connection between endplates that allows controlled movement from a compressed insertion state to an expanded final position. This dynamic mechanism enables the implant to adapt to the surgical approach while providing stable stabilization once deployed.
2Strength
If conventional mechanically operated interbody implants are used, then spinal stabilization function is achieved, but the device requires a large footprint making it unsuitable for cervical region procedures
Solution Approach 1:
The inferior endplate is designed to nest within or alongside the superior endplate during insertion, allowing the implant to be introduced through a small surgical corridor. The endplates then expand to their full stabilized configuration once positioned, providing strong spinal support without requiring a large initial footprint.
Solution Approach 2:
The implant transitions from a low-profile compressed state during insertion to a three-dimensionally expanded state after deployment. The endplates separate and expand in the vertical dimension while maintaining a compact horizontal footprint, providing strong stabilization without occupying excessive surgical space.
3Ease of operation
If break-off tangs are used for gripping and inserting the implant, then insertion is facilitated, but the tangs must be broken off and removed adding surgical steps
Solution Approach 1:
The implant incorporates self-retaining features such as threaded locking screws that secure the endplates together without requiring separate retention components. The locking screws engage with threaded apertures in the endplates, automatically securing the implant in position once inserted, eliminating the need for additional retention steps or component removal.
4Reliability
If threaded locking screws are used to secure endplates, then stable fixation is achieved, but the screws require precise threading and alignment increasing manufacturing complexity
Solution Approach 1:
The locking screw integrates multiple functions into a single component: it provides structural reinforcement, secures the endplates through threading, and may include self-tapping features that create their own thread paths in the bone or implant material. This merging of functions simplifies the overall assembly while maintaining reliable fixation.
Data Source
AI summary
An expandable implant may include an expandable body defined by a superior endplate and an inferior endplate that are hingedly coupled and may be expanded and lordosed by an external surgical tool. The superior endplate may include a first core having a distal engagement surface and the inferior endplate may a second core having a proximal engagement surface and a threaded screw aperture. The implant may include a threaded locking screw disposed in the threaded screw aperture and movable between a locked position and an unlocked position, for example. In the locked position, the threaded locking screw may urge the distal engagement surface of the first core into direct contact with the proximal engagement surface of the second core. The implant may include a pair of mounting tangs that may be sheared off and/or recesses. The locking screw may be a break-off screw.