Orthopedic Screw Insert With Flexure Slots for Bone Anchoring
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Solution Overview
Problem
Conventional bone screws have limited anchoring strength, particularly in defective bone tissue or compromised bores, due to factors like osteoporotic bone and errors in placement, which can lead to inadequate load distribution and fixation issues in spinal devices.
Innovation Solution
A screw insert with an elongate sleeve featuring elongate slots for flexibility and expansion, designed to engage bone screws and enhance anchoring strength by expanding against both cortical and cancellous bone, made from biocompatible materials with optional surface treatments for improved fixation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional bone screws are used directly in the bone, then the device complexity is low, but the anchoring strength is limited especially in defective bone tissue
Solution Approach 1:
The patent employs a nested structure where an insert (inner component) is placed inside a sleeve (outer component). The insert features expansion elements that can expand within the sleeve to engage with bone tissue, creating a multi-layered anchoring system that provides enhanced strength without excessive complexity.
Solution Approach 2:
The anchoring device is divided into distinct functional segments: the insert with expansion elements for bone engagement, and the sleeve that provides structural support and guidance. This segmentation allows each component to perform its specific function optimally, improving overall anchoring strength.
2Strength
If the bore placement is precise, then the anchoring strength is improved, but the difficulty of operation increases due to placement precision requirements
Solution Approach 1:
The insert is designed to change its geometric parameters dynamically - specifically, the expansion elements transition from a compact state during insertion to an expanded state after placement. This parameter change allows the device to accommodate variations in bore placement while maintaining strong anchoring, reducing the precision requirements for initial bore placement.
Solution Approach 2:
The expansion elements provide dynamic adaptation capability, allowing the insert to adjust to the actual bore dimensions and placement variations. This dynamic behavior compensates for placement errors and ensures reliable anchoring without requiring extremely precise initial bore placement.
3Strength
If the insert expands to engage bone tissue, then the anchoring strength increases, but the volume of the insert increases
Solution Approach 1:
The expansion capability is segmented into discrete expansion elements distributed along the insert rather than uniform expansion throughout. This allows localized expansion only where needed for anchoring, minimizing overall volume increase while achieving sufficient bone engagement.
Solution Approach 2:
The insert exhibits local quality variations where expansion elements are concentrated in specific regions that require enhanced anchoring, while other regions maintain a compact profile. This localized expansion approach increases anchoring strength in critical areas without proportionally increasing the total volume of the insert.
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
The insert significantly increases the anchoring strength of bone screws by providing a flexible and expandable interface that accommodates bone screw threads, improving fixation in various orthopedic applications, including spinal and joint procedures, and can be used to repair failed fixations.
Implementation Method 1
At least one elongate slot is formed in the wall of the sleeve for promoting flexure of the insert
Implementation Method 2
A distal section of the inner peripheral surface of the sleeve can be configured and adapted to expand against threads of a bone screw received in the sleeve
Data Source
AI summary
An insert for receiving a bone screw includes an elongate sleeve having opposed proximal and distal ends and a wall defined by an outer peripheral surface configured for engaging bone and an inner peripheral surface configured for receiving a bone screw extended therethrough. At least one elongate slot is formed in the wall of the sleeve for promoting flexure of the insert. A tool for affixing an orthopedic screw insert within bone tissue includes a socket portion configured and adapted to engage a proximal section of an outer peripheral surface of an orthopedic screw insert. A driver extends distally from the socket portion. The driver is configured and adapted to engage a section of an inner peripheral surface of the orthopedic screw insert distal from the socket portion.