Bone Anchor Cord Housing for Low-Wear Spinal Tethering
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Solution Overview
Problem
Existing anchor devices for spinal correction surgeries, such as those used in vertebral body tethering (VBT) procedures, suffer from issues like premature wear and tear of flexible cords due to non-linear movement, bulkiness, rough edges causing tissue erosion, and inadequate bone support for multiple cords, particularly in younger patients with less bone mass.
Innovation Solution
The anchor device comprises a post and a cord housing with a cradle and clamp design that forms a cord channel, using flared surfaces and non-smooth features to securely hold cords without direct impingement, distributing forces evenly to prevent overtightening and damage, and accommodating multiple cords with varying configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the anchor device is designed to hold flexible cords with non-linear movement, then the cord can be secured in place, but the cord experiences premature wear and tear due to rubbing against the anchor device
Solution Approach 1:
The patent employs a soft, flexible liner material (such as silicone or thermoplastic elastomer) that lines the interior of the anchor device housing. This flexible shell contacts the cord and provides a smooth, non-abrasive surface that prevents the cord from rubbing against the rigid anchor device walls, thereby eliminating premature wear while maintaining secure retention through the flexible confinement of the liner.
Solution Approach 2:
The flexible liner acts as an intermediary element between the rigid anchor device structure and the flexible cord. Instead of the cord directly contacting the rigid anchor device interior surfaces which cause wear, the liner mediates this contact by providing a compliant, non-abrasive interface that secures the cord without damaging it over time.
2Strength
If the anchor device is designed for rigid metal rod use, then it provides adequate support, but it causes tissue erosion and cord breakage due to bulkiness and rough edges
Solution Approach 1:
The patent applies a flexible liner material that covers the interior surfaces of the anchor device housing, creating a smooth, biocompatible interface that eliminates rough edges. This flexible shell maintains the structural strength needed for bone support while preventing tissue erosion and cord damage by providing a gentle, non-abrasive contact surface.
Solution Approach 2:
The anchor device employs a composite structure combining rigid materials (for the housing and bone anchoring strength) with flexible materials (for the liner contacting the cord). This composite approach allows the device to maintain the mechanical strength required for spinal correction while the flexible liner component eliminates harmful rough edges that would otherwise cause tissue erosion and cord breakage.
3Ease of manufacture
If the anchor device uses a simple clamp design, then it is easy to manufacture, but it cannot accommodate multiple cords with varying configurations
Solution Approach 1:
The patent divides the anchor device into separate functional components: a housing structure, a flexible liner, and a clamp mechanism. This segmentation allows each component to be manufactured independently using appropriate processes, then assembled together to create a versatile device that can accommodate multiple cords with different configurations while remaining relatively simple to manufacture.
Solution Approach 2:
The anchor device is designed with universal features including a modular clamp mechanism and adjustable positioning capabilities that allow it to securely hold multiple cords in various configurations. The flexible liner and housing structure provide a universal interface that can accommodate different cord types and arrangements, making the device adaptable to various surgical needs without requiring multiple specialized devices.
Data Source
AI summary
Provided herein are several embodiments for an anchor device for insertion into a bone, all of which include a post suitable for implantation into a bone, and a cord housing coupled to the post. The cord housing has a lower housing with a cradle for receiving therein at least one cord, and an upper housing with a clamp for placement over the at least one cord inserted into the cradle. The joining of the upper housing to the lower housing forms a cord channel by the cradle and the clamp, to encase the at least one cord placed into the cradle. The cord housing also has means for fastening the upper housing to the lower housing and securing the at least one cord within the cord channel.