Cement-directing Orthopedic Implants with Differential Permeability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for treating vertebral and other bone defects, such as vertebroplasty and balloon tamping, face challenges in containing bone cement within the defect margins, preventing cement flow into vascular systems, and achieving effective interdigitation with cancellous tissue, leading to complications like embolism and post-operative dislodgement.
Innovation Solution
A collapsible and self-restoring stent-type device with a wire lattice or braided primary structure and flow-directing features, including baffles and differential porosity, is used to maintain cavity patency and control cement flow, preventing unwanted cement distribution and promoting interdigitation with cancellous bone.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If bone cement is injected directly into the defect under fluoroscopic control, then the procedure is minimally invasive and can stabilize fractures, but there is a risk of cement flowing beyond the confines of the bone into the body cavity or venous system
Solution Approach 1:
A collagen sponge barrier is introduced as an intermediary material between the bone cement and the surrounding tissue. The barrier physically blocks cement from leaking into the body cavity or venous system while allowing the minimally invasive injection procedure to proceed. The sponge absorbs excess cement and provides a controlled release mechanism.
Solution Approach 2:
The collagen sponge acts as a flexible biocompatible film that conforms to the defect geometry. This thin film barrier allows the cement to be contained within the desired area while maintaining the minimally invasive nature of the procedure, preventing catastrophic cement embolism.
2Stability of the object's composition
If balloon tamp is used to create a void and compact cancellous bone, then cavity patency is maintained and cement flow is controlled, but the cancellous bone is compacted forming a barrier layer that prevents cement interdigitation
Solution Approach 1:
The patent removes the balloon tamp device after it has served its purpose of creating the void and controlling initial cement flow. By taking out the compaction mechanism, the barrier layer effect is eliminated, allowing direct contact between the cement and cancellous bone for proper interdigitation and bonding.
Solution Approach 2:
The balloon tamp performs preliminary actions of void creation and initial cement flow control before being removed. This preliminary compaction stabilizes the cavity shape, but subsequent removal allows the cement to properly interdigitate with the cancellous bone without the barrier effect.
3Reliability
If open procedure with direct visualization is used to inject bone cement, then the surgeon can identify adjacent structures and prevent inadvertent cement placement, but the procedure is more invasive
Solution Approach 1:
The collagen sponge barrier and other materials in the system are made radio-opaque, allowing them to be visualized under fluoroscopy. This enables the minimally invasive procedure to maintain reliability by allowing the surgeon to track the barrier and cement placement in real-time without open visualization.
Data Source
AI summary
A cement-directing structure for use in cement-injection bone therapy includes a collapsible, self-restoring braided structure with regions of differential permeability to the bone cement. The regions of differential permeability may be provided by areas where the braided mesh density is greater or lesser than surrounding areas and/or by means of a baffle. After the structure is placed in a void within a bony structure, cement is injected into the interior of the structure then oozes out in preferred directions according to the locations of the regions of differential permeability.