Expandable Trial Mounting Assembly for Orthopaedic Implant Orientation
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Solution Overview
Problem
Current shoulder prosthesis systems face challenges in accurately matching the humeral resection angle to the predetermined angle of the prosthesis, particularly during implantation, which affects biomechanics and requires cumbersome adjustments or modular components that limit flexibility and precision.
Innovation Solution
A trial system with an expandable mounting assembly that includes a cavity and an expandable portion, where an expansion element is rotated to expand within the cavity, allowing for variable angular orientations without impaction, ensuring accurate duplication of angles and maintaining the center of rotation's coincidence with the final implant.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a predetermined prosthesis angle is used, then manufacturing simplicity is improved, but adaptability to patient anatomy deteriorates
Solution Approach 1:
The prosthesis head is made dynamically adjustable relative to the stem through a mounting assembly that allows intraoperative angular adjustment. The head can be positioned at multiple angles and locked in place, transforming a static predetermined-angle design into a dynamic adjustable one that adapts to patient anatomy while maintaining manufacturing simplicity.
Solution Approach 2:
The prosthesis is divided into separable components (head and stem) with an independent mounting assembly. This segmentation allows the head to be adjusted relative to the stem without requiring custom manufacturing of the entire prosthesis, maintaining ease of manufacture while improving adaptability.
2Adaptability or versatility
If modular blocks are used for angular adjustment, then adaptability is improved, but device complexity increases
Solution Approach 1:
Multiple angular adjustment functions are merged into a single mounting assembly structure. Instead of requiring separate modular blocks for different angular adjustments, the mounting assembly integrates all adjustment capabilities into one unified mechanism, reducing device complexity while maintaining adaptability.
3Strength
If impaction is used to secure the prosthesis, then fixation strength is improved, but measurement precision deteriorates
Solution Approach 1:
The prosthesis head is pre-positioned at the desired angle using the adjustable mounting assembly before final securing. This preliminary positioning allows precise angular measurement and adjustment, and subsequent fixation (whether by impaction or other means) maintains this pre-established accurate orientation rather than altering it.
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
This solution enables precise and flexible angular positioning of the humeral head relative to the stem, ensuring anatomically accurate alignment and reducing the need for impaction, thus improving the accuracy and stability of the prosthesis fit without compromising the center of rotation's position.
Implementation Method 1
an expansion element rotatable within the mounting element and cooperating with the expandable portion upon rotation to expand the expandable portion within the cavity
Data Source
AI summary
A trial implant system includes a stem component and an articulating component forming part of a joint of a patient. A trial mounting assembly mounts the articulating component to the stem component at variable relative angular positions. The trial mounting assembly includes an expandable ball portion and an expansion element configured to expand the ball portion upon rotation of the expansion element. In an expanded state, the ball portion contacts a cavity within the stem at three points of contact to fix the center of rotation of the ball portion at a pre-determined location within the stem. The stem cavity defines an inwardly projecting circumferential lip that bears against ball portion as it expands to ensure the three-point contact.