Orthopaedic Prosthesis Alignment Guide for Controlled Impaction
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Solution Overview
Problem
Existing orthopaedic joint prostheses face challenges in ensuring secure assembly without exceeding force limits, which can damage patient bone tissue or components, particularly with modular designs using self-locking tapers.
Innovation Solution
An alignment guide that engages the assembly surface of a joint prosthesis head part, allowing an impaction force to be directed along a defined axis, ensuring proper engagement and alignment of the spigot and bore, using a bearing surface seating member and optionally a pivoting arm mechanism to facilitate secure assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a self-locking taper is used to fasten modular parts of a joint prosthesis component, then the security of the joint between parts is improved, but the risk of damage to bone tissue or components increases due to excessive assembly force
Solution Approach 1:
A separate alignment guide device is introduced as an intermediary between the impaction tool and the prosthesis components. This guide device includes a guide bore that receives the spigot and a guide surface that contacts the assembly surface, mediating the force transmission to ensure proper alignment and control the assembly force, preventing excessive force from damaging the components or bone tissue while still achieving secure joint engagement
2Reliability
If sufficient force is applied to ensure proper engagement of spigot and bore surfaces, then the security of the joint is improved, but the applied force may exceed the maximum limit and cause damage
Solution Approach 1:
The alignment guide device replaces direct mechanical impaction with a controlled guidance system. The guide bore and guide surface create a constrained mechanical path that directs force along the longitudinal axis, substituting uncontrolled direct loading with a guided force transmission mechanism that maintains engagement security while preventing force exceedance
3Adaptability or versatility
If modular construction is used to meet anatomical variations and surgeon preferences, then the adaptability of the prosthesis is improved, but the complexity of assembly and the risk of improper alignment increase
Solution Approach 1:
The alignment guide device enables self-alignment through its geometric design. The guide bore is configured to receive the spigot and the guide surface is configured to contact the assembly surface, creating a self-aligning mechanism where the components automatically find their correct relative positions during assembly, eliminating the need for complex external alignment procedures or specialized surgeon skills
Data Source
AI summary
An orthopaedic joint prosthesis assembly includes a head part of an orthopaedic joint prosthesis component and an alignment guide. The head part has a spherical bearing surface for articulation with a corresponding joint surface, and an assembly surface having a first bore formed in it for receiving a spigot on another part of the orthopaedic joint prosthesis. The bore has a first axis that extends perpendicular to the assembly surface. The alignment guide has an axial portion defining a second axis and an arm extending from the axial portion. The arm includes a distal portion which is configured to engage the assembly surface, with the axial portion being arranged to engage the bearing surface of the head part when the head part is mounted within the guide such that an impaction force applied along the second axis is directed along the first axis.