Modular Tibial Tray and Insert System
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing tibial implant systems for knee joint replacements face challenges such as difficulty in implantation, weak bond with bone cement, high manufacturing costs, and stress shielding, while also requiring ease of use and resistance to fracture and wear.
Innovation Solution
A modular tibial tray and insert system featuring a polymeric tibial insert that securely engages with either a polymer or metal tibial tray through distinct connections, utilizing a locking wire and bead or barbs and undercuts for secure attachment, and a grit-blasted surface for enhanced bonding with bone cement, allowing for interchangeable trays that reduce stress shielding and manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a monolithic UHMWPE device is used, then stress shielding is reduced and in vivo survival rate is improved, but implantation difficulty increases and bond strength with bone cement decreases
Solution Approach 1:
The monolithic UHMWPE device is divided into separate components: a metal tibial tray and a UHMWPE tibial insert. This segmentation allows the metal tray to provide strong bone cement bonding and ease of implantation, while the UHMWPE insert maintains the stress-shielding benefits and long-term durability of the original monolithic design.
2Ease of operation
If a metal-backed UHMWPE modular tibia is used, then implantation ease is improved, but manufacturing cost increases
Solution Approach 1:
The metal tibial tray is designed with universal engagement features that can accommodate different UHMWPE inserts through standardized locking mechanisms. This multi-functionality allows the same tray design to work with various insert configurations, reducing overall system cost while maintaining ease of implantation.
3Adaptability or versatility
If a polymer-porous metal composite tray is used, then cementless fixation is enabled, but bond strength with bone cement decreases and manufacturing cost increases
Solution Approach 1:
The complex polymer-porous metal composite structure is extracted and replaced with a simpler metal tray design that uses traditional bone cement fixation. This extraction eliminates the high manufacturing costs and compromised bond strength associated with composite materials, while maintaining the ability to achieve strong fixation through proven cement-based techniques.
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 system provides a strong, sustained bond with bone cement, reduces stress shielding, improves wear resistance, and is cost-effective, while offering ease of use and adaptability for surgeons, with the option to use either cemented or cementless fixation.
Implementation Method 1
a grit-blasted surface for enhanced bonding with bone cement
Data Source
AI summary
A tibial implant system has an ultra-high molecular weight polyethylene tibial insert which can engage with either one of two tibial trays through differing means of engagement. The tibial insert includes a locking wire and locking tab disposed along an anterior surface and a locking recess disposed along a posterior surface. A first polymeric tibial tray includes a bead along an anterior wall and an undercut area along a posterior wall. A second metallic tibial tray includes a plurality of barbs along an anterior wall and an undercut area along a posterior wall.