Bone Anchor with Flexible Wings for Cannula-Free Insertion
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Solution Overview
Problem
Existing bone anchor insertion systems require larger bone holes due to the need for a cannula to maintain the bone anchor in a compressed state, which increases patient recovery times.
Innovation Solution
A bone anchor with a drive feature that allows coupling and decoupling with an inserter, enabling the bone anchor to be inserted through smaller bone holes without a cannula, utilizing shape-memory material wings that expand in softer bone to secure the anchor in place.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cannula is used to insert the bone anchor, then the bone anchor can be maintained in a compressed state during insertion, but the bone hole size must be larger to accommodate the cannula
Solution Approach 1:
The patent removes the cannula from the insertion system, allowing the bone anchor to be inserted directly through the bone hole without requiring the additional space that a cannula would occupy. The bone anchor is designed with self-retaining features that eliminate the need for cannula support during insertion.
Solution Approach 2:
The bone anchor incorporates flexible wings that can dynamically change shape during insertion - bending inward to fit through the bone hole and then expanding outward once inserted to provide secure anchoring. This dynamic shape change allows the anchor to be inserted without a cannula while still providing reliable fixation.
2Loss of time
If the bone hole size is reduced, then patient recovery time is reduced, but the bone anchor must maintain sufficient pull-out strength
Solution Approach 1:
The flexible wings of the bone anchor dynamically transition from a compressed insertion state to an expanded anchoring state. During insertion, the wings bend inward to fit through the small bone hole. Once inserted into the bone, the wings expand outward to engage the bone tissue, providing sufficient pull-out strength despite the small hole size.
Solution Approach 2:
The bone anchor utilizes shape-memory material that changes its physical parameters (shape and size) in response to environmental conditions. The material is shaped to fit through a small bone hole in its temporary state, then returns to its original expanded shape once inserted, providing both small hole compatibility and strong anchoring.
3Area of stationary object
If the bone anchor is made small enough to fit through a small bone hole, then recovery time is reduced, but the bone anchor may lack sufficient pull-out strength
Solution Approach 1:
The bone anchor features flexible wings that dynamically change configuration. During insertion, the wings are compressed inward to allow the anchor to pass through the small bone hole. Once positioned in the bone, the wings expand outward to engage the bone tissue, providing sufficient surface area and mechanical interlocking for reliable pull-out strength.
Solution Approach 2:
The bone anchor design incorporates nested structures where the flexible wings can be compressed inward to fit within the confines of the small bone hole during insertion, then expand outward to provide anchoring. This nested configuration allows the anchor to be smaller for insertion while maintaining larger effective dimensions for fixation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution allows for smaller bone holes, reducing patient recovery times, while maintaining reliable pull-out strength and secure tissue attachment to bone.
Implementation Method 1
A bone anchor, however, must have sufficient pull-out strength so that it stays in place and allows tissue to properly reattach to bone. Therefore, it is desired that a bone anchor is small enough to be inserted through a bone hole while also having reliable pull-out strength such that it is not pulled back through the bone hole.
Implementation Method 2
The bone anchor may be shape-set in an expanded state with the wings splayed outward, though may be compressed to a smaller size with the wings bent inward as it is translated through a bone hole. Once the bone anchor reaches softer bone (e.g., cancellous bone), the bone anchor returns to its expanded state.
Data Source
AI summary
Bone anchors and bone anchor insertion systems are provided that enable smaller bone holes for inserting a bone anchor by eliminating the need for a cannula. Smaller bone holes may help reduce patient recovery times. The provided bone anchor includes two flexible wings extending from a base portion that splay away from the base portion's central axis at rest, though may be bent towards or away from the central axis in response to an applied force. The bone anchor includes a drive feature that enables an inserter to couple and decouple to the bone anchor. A surgeon may drive the bone anchor through a bone hole via the coupled inserter while the bone hole maintains the bone anchor in a compressed state, and may decouple the inserter when the bone anchor is properly positioned, thereby eliminating the need for a cannula.