Spinal Implant Tether Adjustment for Screw Pull-out Prevention
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Solution Overview
Problem
Current surgical methods for correcting spinal disorders, such as scoliosis and kyphosis, often require multiple implants and can lead to complications like screw pull-out and bone weakening, as they rely on rigid fixation and may not allow for adjustable or partial reductions.
Innovation Solution
A spinal implant system utilizing a tether-based reduction screw and a spinal construct with a tether connection to a bone screw, allowing for adjustable tension and locking mechanisms to secure the spinal rod at a selected dorsal height, enabling partial or incomplete reductions without compromising the bone-screw interface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If rigid fixation implants are used for spinal correction, then stabilization is achieved, but screw pull-out and bone weakening occur
Solution Approach 1:
The patent transitions from rigid fixed-position implants to dynamic adjustable implants that can be positioned at multiple heights. The receiver member can be adjusted to different positions along the rod member, allowing the spinal construct to adapt to changing physiological conditions while maintaining stability without excessive stress on the bone-screw interface
Solution Approach 2:
The patent changes the positional parameter of the implant components. The receiver member can be repositioned along the rod member to different heights, allowing adjustment of the spinal correction magnitude. This parameter change enables progressive correction while distributing mechanical loads more evenly, reducing screw pull-out risk
2Reliability
If multiple implants are used for spinal correction, then correction effectiveness is improved, but device complexity and surgical risk increase
Solution Approach 1:
The patent combines multiple functional elements into integrated components. The rod member with receiver member assembly integrates positioning, adjustment, and locking functions into a single construct. This merging reduces the total number of separate implants needed while maintaining correction effectiveness through the adjustable receiver-rod interface
Solution Approach 2:
The rod member serves multiple functions: structural support, height adjustment guide, and connection element for receiver members. The receiver member similarly provides positioning, adjustment, and locking functions. This multi-functionality reduces the need for additional specialized implants, simplifying the overall system
3Manufacturing precision
If adjustable tension mechanisms are added to the spinal implant, then alignment precision is improved, but device complexity increases
Solution Approach 1:
The patent introduces dynamic adjustability through the receiver member that can be repositioned along the rod member. This allows post-operative adjustment of spinal alignment and correction magnitude. The adjustable mechanism provides precise alignment control through defined positioning stops or markings, achieving high precision without overly complex mechanisms
Solution Approach 2:
The rod member is pre-formed with specific curvature or positioning features that guide the receiver member placement. This preliminary preparation of the rod allows for accurate alignment to be achieved simply by positioning the receiver at the appropriate location, reducing the need for complex real-time adjustment mechanisms during surgery
Data Source
AI summary
A spinal implant comprises a fastener including a head and defining a longitudinal axis. A member is configured for disposal of the head and defines an inner groove configured for disposal of a band that is engageable with the head to connect the fastener and the member. The member is moveable relative to the longitudinal axis. The member defines a passageway configured for disposal of a tether. Systems, spinal constructs, surgical instruments and methods are disclosed.