Bone Anchor Wing with Auxiliary Anchors for Fixation
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Solution Overview
Problem
Existing bone anchor assemblies often face issues with sub-optimal purchase and security due to compromised insertion states, such as stripped bone openings or insertion outside the intended trajectory, leading to potential loosening or backout over time.
Innovation Solution
The development of bone anchor assemblies that incorporate a bracket or wing extending from the receiver member to accommodate auxiliary bone anchors, providing enhanced fixation by augmenting the primary bone anchor's engagement with the bone.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a bone anchor assembly is inserted in a compromised state (stripped bone opening, incorrect placement, or outside intended trajectory), then the insertion process can be completed, but the purchase and security between the bone anchor assembly and bone become sub-optimal, leading to potential loosening or backout over time
Solution Approach 1:
The bone anchor assembly is divided into multiple independent bone engagement points (primary anchor and auxiliary anchors). This segmentation allows the system to compensate for compromised insertion at one point by maintaining engagement at other points, thereby preserving overall fixation security even when individual anchors are placed sub-optimally.
Solution Approach 2:
The system changes the configuration parameter from a single-point engagement to a multi-point engagement arrangement. By distributing fixation forces across multiple anchors positioned at different locations and orientations, the system achieves greater tolerance for compromised insertion while maintaining reliable fixation security.
2Reliability
If the bone anchor assembly is removed and re-inserted with a larger anchor to improve fixation, then fixation security is improved, but space for anchoring in the bone becomes limited and the surgical site must be expanded to additional vertebral levels
Solution Approach 1:
Instead of using a single large anchor, the system employs multiple smaller auxiliary anchors in addition to the primary anchor. This segmentation of the fixation function across multiple smaller engagement points achieves adequate fixation security without requiring the expanded surgical approach or larger single-anchor configuration.
3Device complexity
If traditional bone anchor assemblies are used, then the structure is simple, but the geometry limits the flexibility with which the bone attachment point can be located with respect to a plate, rod, or other implant construct
Solution Approach 1:
The fixation system is segmented into multiple independently positionable bone engagement points. This allows flexible configuration of the attachment points relative to the implant construct (plate, rod, or other components) while maintaining a relatively simple overall anchor structure for each engagement point.
Solution Approach 2:
The multi-point engagement design provides universal applicability across different implant constructs and surgical scenarios. The same basic anchor structure can be configured in multiple engagement points to accommodate various plate, rod, or implant construct geometries, enhancing versatility without significantly complicating the individual anchor design.
Data Source
AI summary
Bone anchor assemblies are disclosed herein that can provide for improved fixation as compared with traditional bone anchor assemblies. An exemplary assembly can include a bracket or wing that extends down from the receiver member. The distal portion of the wing can define a bone anchor opening through which one or more auxiliary bone anchors can be disposed to augment the fixation of the assembly's primary bone anchor. A distal surface of the distal portion of the wing can be obliquely angled relative to a proximal-distal axis of the spanning portion to face one of a caudal direction or a cephalad direction. A distal surface of the distal portion of the wing can be obliquely angled relative to the proximal-distal axis of the spanning portion to face one of a medial direction or a lateral direction. Surgical methods using the bone anchor assemblies described herein are also disclosed.