Multi-piece Bone Graft Assemblies Using Interference Fits
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Solution Overview
Problem
Current bone graft systems face limitations in utilizing donor bone effectively due to size constraints and waste minimization, particularly in spinal fusion surgeries, where large grafts are difficult to produce from single pieces of natural bone.
Innovation Solution
The development of multi-piece bone graft compositions that can be assembled from smaller donor pieces using unique geometries and interference fits, allowing for the creation of larger, structurally sound grafts without adhesives, and incorporating osteoconductive materials for enhanced bone growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of stationary object
If single piece bone grafts are used, then structural integrity is maintained, but graft size is limited by donor bone availability
Solution Approach 1:
The bone graft is divided into multiple separate pieces that can be manufactured from smaller donor bone segments. These individual pieces are then assembled together using interference-fit mating features to form a complete graft structure, allowing utilization of limited donor bone while achieving required graft dimensions.
Solution Approach 2:
Multiple bone graft pieces are nested or stacked together with interference-fit connections, where each piece contains geometric features that interlock with adjacent pieces. This nesting approach allows compact assembly of multiple donor-derived components into a unified graft structure.
2Volume of stationary object
If multiple bone pieces are assembled together, then graft size can be increased, but structural integrity may be compromised
Solution Approach 1:
The mating features between bone graft pieces employ asymmetric geometric shapes with non-complimentary profiles. This asymmetry creates directional interference fits that provide mechanical interlocking strength, preventing separation while maintaining the ability to assemble multiple pieces into a unified structure.
Solution Approach 2:
The interference-fit mating features incorporate curved or rounded geometric profiles rather than sharp angular transitions. This curvature distributes stress more evenly across the interface between pieces, enhancing the mechanical bond strength and structural integrity of the assembled graft.
3Ease of manufacture
If traditional bone graft assembly methods are used, then simplicity is maintained, but precision and fit quality decrease
Solution Approach 1:
The interference-fit mating features are designed to self-align and self-locate during assembly without requiring additional fasteners, adhesives, or complex alignment procedures. The geometric complementarity of the mating surfaces provides automatic positioning, simplifying the assembly process while ensuring precise fit quality.
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 approach increases the utilization of donor bone, reduces waste, and provides strong, bio-mechanically sound grafts suitable for various clinical applications, including spinal fusion, by enabling the construction of larger grafts from smaller pieces and incorporating osteoconductive materials for improved bone integration.
Implementation Method 1
The first mating feature has a shape that is non-complimentary to a shape of the second mating feature, such that when the first and second bone pieces are coupled, an interface between the first and second mating features is defined by a non-uniform press fit
Data Source
AI summary
Embodiments of the present invention encompass graft assemblies, and methods for their use and manufacture. An exemplary bone graft assembly includes first and second bone pieces having respective mating features which, when combined, define non-uniform press fit. Related embodiments encompass graft assemblies having enclosed or hidden mating features.