Biphasic Bone Graft Cement Strength and Resorption
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Solution Overview
Problem
Current synthetic bone graft materials for bone repair lack ideal functional characteristics, such as desirable resorption rates, mechanical strength, ease of handling, and osteoconductivity, with many exhibiting either too rapid or too slow resorption, and difficulties in setting or injecting, and adding biologically active substances for controlled release.
Innovation Solution
A particulate composition comprising calcium sulfate hemihydrate powder combined with a brushite-forming calcium phosphate mixture, which forms a biphasic cement upon mixing with an aqueous solution, providing high mechanical strength, controlled resorption, and ease of handling, with the ability to incorporate biologically active agents for enhanced bone repair.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If calcium sulfate cement is used for bone repair, then high initial strength and good handling properties are achieved, but rapid resorption rate occurs which is undesirable in certain applications
Solution Approach 1:
The patent combines calcium sulfate hemihydrate particles with beta-tricalcium phosphate particles to create a composite bone graft cement. The calcium sulfate phase provides high initial strength and good handling properties, while the beta-tricalcium phosphate phase reduces the overall resorption rate. This composite material resolves the contradiction by integrating two materials with complementary properties - one that sets quickly and strongly, and another that resorbs slowly and predictably.
2Reliability
If hydroxyapatite is used for bone repair, then excellent biocompatibility and osteoconductivity are achieved, but extremely slow resorption rate occurs that may be unsuitable in certain applications
Solution Approach 1:
The patent changes the chemical composition parameters by using calcium sulfate hemihydrate and beta-tricalcium phosphate instead of hydroxyapatite. This parameter change maintains osteoconductivity and biocompatibility while fundamentally altering the resorption kinetics from extremely slow (hydroxyapatite) to a more balanced rate where calcium sulfate resorbs faster and beta-tricalcium phosphate provides sustained presence.
3Ease of operation
If allograft bone is used for bone repair, then avoidance of donor site morbidity is achieved, but lower osteogenic capacity and higher resorption rate occur
Solution Approach 1:
The patent employs a synthetic bone graft cement that serves as a temporary, short-lived scaffold for bone regeneration. Like a disposable object, this cement provides structural support and osteoconductive properties during the healing process, then resorbs predictably without requiring a second surgical site for removal. The controlled resorption rate ensures the scaffold disappears as new bone forms, replacing the need for long-term permanent implants.
4Duration of action of stationary object
If certain calcium phosphate materials are used for bone repair, then faster resorption rate than hydroxyapatite is achieved, but less mechanical strength occurs
Solution Approach 1:
The patent creates a composite system where calcium sulfate hemihydrate provides the mechanical strength component while beta-tricalcium phosphate provides the controlled resorption component. The calcium sulfate phase contributes high compressive strength and tensile strength, particularly in the early setting period, while the beta-tricalcium phosphate phase ensures predictable, controlled resorption. Together they resolve the contradiction between strength and resorption rate that plagues single-material calcium phosphates.
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 resulting bone graft substitute cement exhibits high compressive and diametral tensile strengths, a balanced resorption rate, and facilitates the development of high-quality bone at the defect site, while allowing for ease of application and handling, addressing the limitations of existing materials.
Implementation Method 1
a particulate composition adapted for forming a bone graft substitute cement upon mixing with an aqueous solution... a reaction product formed by mixing a particulate composition with an aqueous solution
Data Source
AI summary
The invention provides a particulate composition adapted for forming a bone graft substitute cement upon mixing with an aqueous solution, including i) a calcium sulfate hemihydrate powder having a bimodal particle distribution and a median particle size of about 5 to about 20 microns, wherein the calcium sulfate hemihydrate is present at a concentration of at least about 70 weight percent based on the total weight of the particulate composition; ii) a monocalcium phosphate monohydrate powder; and iii) a β-tricalcium phosphate powder having a median particle size of less than about 20 microns. Bone graft substitute cements made therefrom, a bone graft substitute kit comprising the particulate composition, methods of making and using the particulate composition, and articles made from the bone graft substitute cement are also provided.