Autograft Cancellous Bone Packing for Hip Prosthesis Support
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Solution Overview
Problem
Current methods for primary total hip arthroplasty (THA) do not adequately prepare patients for potential future revision surgeries, as they involve removing healthy cancellous bone, leading to increased risk of cortical bone damage, reduced bony support, and stress shielding, which can result in fractures and implant failure over time.
Innovation Solution
A method using autograft cancellous bone as packing material within the intramedullary canal, where tamps shaped like the prosthesis are used to create a cavity that matches the implant, preserving the patient's native bone and reducing the risk of cortical bone exposure and stress shielding, while utilizing the patient's own bone to support the prosthesis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If healthy cancellous bone is removed during primary THA, then the prosthesis can be implanted, but the patient's bony support is reduced and cortical bone is exposed to damage risk
Solution Approach 1:
The invention recovers the cancellous bone that would otherwise be discarded during broaching by collecting it and re-implanting it as a packed graft within the intramedullary canal. This transforms waste material into a beneficial component that maintains bone stock and supports the prosthesis, directly resolving the contradiction between ease of implantation and preservation of bone support.
Solution Approach 2:
The broaching process, which necessarily removes some cancellous bone to create space for the prosthesis, is transformed from a harmful loss into a beneficial preparation. The removed bone is processed and re-implanted as a packed graft, converting the harmful effect of bone removal into the beneficial effect of creating a prepared cavity that will be filled with structured bone support.
2Ease of operation
If the intramedullary canal is fully broached, then the prosthesis can be easily implanted, but cortical bone is exposed and at risk of damage during revision surgery
Solution Approach 1:
The invention applies beforehand cushioning by packing the intramedullary canal with cancellous bone graft before final prosthesis implantation. This creates a protective cushion of bone material between the prosthesis and the cortical bone, preventing direct contact and potential damage to the cortical bone during current and future revision surgeries.
Solution Approach 2:
The cancellous bone is preliminarily processed, packed into the intramedullary canal, and allowed to stabilize before the final prosthesis is implanted. This preliminary preparation creates a protective bone bed that will safeguard the cortical bone during the main implantation procedure and any future revisions.
3Device complexity
If cancellous bone is removed during primary THA, then implantation is simplified, but stress shielding occurs leading to implant failure over time
Solution Approach 1:
Instead of discarding the cancellous bone during broaching, the invention recovers it and re-implants it as a packed graft. This maintains the bone's structural integrity and load-bearing capacity, preventing stress shielding and ensuring the implant can withstand physiological loads for 30 years or more.
Solution Approach 2:
The invention creates a composite structure within the intramedullary canal by combining the packed cancellous bone graft with the prosthesis. This composite construction allows the cancellous bone to share mechanical loads with the implant, preventing stress shielding and enhancing long-term durability.
4Reliability
If graft material is packed into the intramedullary canal using traditional methods, then bone support is provided, but the cavity shape does not match the prosthesis
Solution Approach 1:
The invention uses a template or model of the actual prosthesis to guide the packing of cancellous bone. This ensures the cavity created by the packed graft precisely matches the geometry of the prosthesis to be implanted, achieving both accurate shape and optimal bone support.
Solution Approach 2:
The cancellous bone packing is applied with local quality by strategically placing and compacting the bone material in specific regions of the intramedullary canal. This ensures dense, well-structured bone support in areas where the prosthesis requires maximum stability while maintaining the precise cavity shape needed for proper implant fit.
Data Source
AI summary
Methods and instruments for use of a patient's native and existing cancellous bone as a packing material for the intramedullary canal in total hip arthroplasty and subsequent revision hip surgery. A series of tamps of progressively larger size are used to pack the native cancellous bone, the tamps having a shape substantially similar to that of the hip prosthesis. The methods and instruments are bone conserving. If the patient later needs a revision surgery, the doctor has more bone to work with and there is less risk of complications.