Tapered Peg Glenoid Component for Shoulder Fixation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current glenoid components in shoulder replacements face issues with fixation stability due to overhanging loads and high cement stresses, leading to loosening, as they do not adequately account for varying constraint levels and curvature of the natural glenoid, resulting in inadequate restoration of shoulder joint function.
Innovation Solution
A glenoid component with a concave articulating surface and pegs having a proximal portion with a larger diameter and a distal portion with a smaller diameter, designed to anchor securely to the scapula bone, reducing overhanging forces and cement stresses through a press-fit mechanism and potential bone ingrowth, and featuring complex surfaces to mimic natural constraint levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a glenoid component with standard pegs is used for shoulder replacement, then the component can be anchored to the scapula bone, but the pegs experience high cement stresses and overhanging loads that lead to loosening and fixation instability
Solution Approach 1:
The peg geometry is modified by changing the diameter parameter along its length, creating a tapered structure with a larger proximal diameter and smaller distal diameter. This parameter change optimizes the stress distribution in the cement mantle, reducing peak stresses that lead to loosening while maintaining secure anchorage to the scapula bone.
Solution Approach 2:
Different sections of the peg are given different diameters to perform different functions: the proximal portion with larger diameter provides enhanced anchorage and load distribution at the bone interface, while the distal portion with smaller diameter reduces stress concentration in the cement mantle. This local differentiation of properties resolves the contradiction between secure fixation and stress resistance.
2Ease of manufacture
If the peg diameter is uniform throughout, then the manufacturing is simpler, but the cement mantle experiences high stresses and overhanging loads that cause loosening
Solution Approach 1:
The peg transitions from a uniform diameter design to a tapered diameter design, where the diameter parameter varies along the length of the peg. This change, while slightly increasing manufacturing complexity, dramatically improves fixation stability by optimizing stress distribution in the cement mantle and preventing overhanging loads that cause loosening.
3Device complexity
If the glenoid component does not account for varying constraint levels and curvature of the natural glenoid, then the design is simpler, but the fixation stability is inadequate and loosening occurs
Solution Approach 1:
The glenoid component incorporates a concave articulating surface that mirrors the curvature of the natural glenoid, and the pegs are strategically positioned and dimensioned to account for varying constraint levels across different regions. This local adaptation to anatomical variations improves fixation stability without requiring excessive overall design complexity.
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 solution enhances fixation stability, reduces loosening tendencies, and distributes loads more evenly, thereby improving the longevity and functionality of shoulder replacements by minimizing cement mantle failure and preserving bone health.
Implementation Method 1
press fitting the proximal portion of the at least one peg in the proximal portion of the at least one hole
Implementation Method 2
distributes loads more evenly, thereby improving the longevity and functionality of shoulder replacements by minimizing cement mantle failure
Data Source
AI summary
A glenoid component is provided to reduce glenoid loosening when implanted in orthopedic joint replacement/reconstruction, such for a shoulder. The glenoid component can include pegs or a keel and articulating surface geometry that uses complex, non-spherical geometry to recreate a level of constraint that is adequate, but not excessive, to thereby mitigate loosening of the glenoid component after implantation. In addition, some embodiments provide that peak stresses both within cement and at an interface of the cement and a supportive component can be reduced. Further, geometry of the pegs can allow stresses to be evenly applied to a cement mantle formed in the supportive component. Finally, the pegs can be configured to desired lengths in order to avoid placement in areas of the supportive component, for example, that have insufficient bone stock.