Hybrid Bone Screw with Lattice Distal Tip for Spinal Fixation
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Solution Overview
Problem
Current spinal implant systems, particularly bone screws, face challenges in providing optimal mechanical properties and stability when engaging with both dense cortical and less dense cancellous bone, leading to potential loosening and pull-out issues, and insufficient bone integration.
Innovation Solution
A hybrid manufacturing approach combining traditional subtractive methods with additive manufacturing techniques to create a bone screw with a solid core and lattice structure, featuring a tapered surface and variable thread configuration, which enhances fixation, resistance to toggle and pull-out, and facilitates bone growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional medical machining techniques are used to manufacture bone screws, then manufacturing precision and consistency are achieved, but the screws lack optimal mechanical properties for engaging both cortical and cancellous bone, leading to loosening and pull-out issues
Solution Approach 1:
The patent combines traditional subtractive manufacturing (machining the proximal portion with uniform threads) and additive manufacturing (forming the distal portion with variable pitch threads and lattice structure) to create a hybrid bone screw. This merging of manufacturing approaches allows the screw to have optimized mechanical properties for both cortical and cancellous bone engagement while maintaining manufacturability through standardized processes.
Solution Approach 2:
The bone screw features different thread configurations in different regions: uniform pitch threads in the proximal portion for cortical bone engagement and variable pitch threads with different characteristics in the distal portion for cancellous bone engagement. This local differentiation optimizes fixation stability for each bone type without requiring complete redesign of the entire screw.
2Adaptability or versatility
If uniform thread configuration is used throughout the bone screw, then manufacturing is simplified, but the screw cannot provide optimal engagement with both dense cortical and less dense cancellous bone
Solution Approach 1:
The bone screw is divided into distinct segments: a proximal portion with uniform pitch threads designed for cortical bone engagement, and a distal portion with variable pitch threads designed for cancellous bone engagement. This segmentation allows each region to be optimized for its specific function while maintaining a relatively simple overall design that is manufacturable using standardized processes.
3Strength
If solid uniform structure is used for bone screw, then manufacturing is easier, but bone integration and growth promotion are insufficient
Solution Approach 1:
The distal portion of the bone screw incorporates a lattice structure with controlled porosity that promotes bone ingrowth and integration. This porous architecture maintains sufficient mechanical strength while providing pathways for bone cells to penetrate and attach, enhancing osseointegration without requiring complex manufacturing beyond additive manufacturing capabilities.
Data Source
AI summary
A bone screw comprises a shaft defining a longitudinal axis and a minor diameter. The shaft including a core having an angled surface relative to the axis. The angled surface extending from the minor diameter adjacent a proximal portion of the shaft to a distal portion of the shaft, and a wall disposed about the angled surface. The wall including at least one thread having an external thread form. In some embodiments, systems, spinal constructs, surgical instruments and methods are disclosed.