Modular Glenoid Implant Fixation for Severe Bone Loss
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Solution Overview
Problem
Current glenoid implants suffer from poor fixation, wear, fatigue failure, and are contraindicated in patients with significant bone loss, leading to potential neuromuscular injuries and early loosening, limiting their lifespan and necessitating multiple surgeries.
Innovation Solution
A glenoid implant design featuring a base element, coupling element, and augment, with movable components that rotate relative to the base element, and multiple fastening points to secure the implant to different portions of the scapula, providing bi-cortical or uni-cortical support.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If current glenoid implants use keel or peg designs to secure the implant, then fixation is achieved, but the implant may injure the suprascapular nerve or fracture the scapula in patients with significant bone loss
Solution Approach 1:
The implant is divided into multiple components: a base element with a keel for primary fixation, and a separate coupling element with augments that can be selectively positioned. This segmentation allows the fixation function to be distributed, avoiding the need for a single long keel that would penetrate the glenoid vault and cause nerve injury or fracture.
Solution Approach 2:
The coupling element and augments provide an additional dimension of fixation by enabling bi-cortical or uni-cortical support through multiple fastening points. This distributes the fixation load across different spatial dimensions rather than relying solely on deep penetration in one direction, thereby avoiding harmful effects while maintaining reliability.
2Duration of action of stationary object
If glenoid implants are designed for long-term durability, then implant lifespan is extended, but fixation reliability decreases due to poor bonding with bone
Solution Approach 1:
The base element keel is designed to be inserted first into the glenoid cavity to establish primary fixation and create a stable foundation. This preliminary action prepares the bone bed and allows subsequent components to be securely attached, ensuring both immediate fixation reliability and long-term durability through progressive osseointegration.
Solution Approach 2:
The implant uses composite construction with a metal base element and keel providing structural strength and initial fixation, while the coupling element and augments provide additional fixation points. This composite approach combines different material properties to achieve both reliable fixation and long-term durability without requiring a single material to fulfill all functions.
3Strength
If glenoid implants use polyethylene material for the implant body, then wear resistance is improved, but fixation to bone deteriorates due to cement dependency
Solution Approach 1:
The implant separates the wear-resistant polyethylene glenoid surface from the fixation function, which is handled by a metal base element with keel and additional coupling elements. This segmentation allows each component to be optimized for its specific function: polyethylene for wear resistance and metal with multiple fastening points for reliable bone fixation.
Solution Approach 2:
The metal base element and coupling elements act as intermediary structures between the polyethylene glenoid surface and the bone. These intermediary components provide the mechanical anchorage to bone through keel and multiple fastening points, while the polyethylene surface maintains its wear-resistant properties without needing direct bone contact.
4Object-affected harmful factors
If surgeons avoid glenoid replacement in young patients with early arthritis, then neuromuscular injury risk is reduced, but patient suffering increases due to continued pain and disability
Solution Approach 1:
The implant design changes the fixation parameters by using a modular structure with adjustable coupling elements and augments that can be positioned to match varying anatomical conditions. This allows safe installation in young patients with different bone quality and anatomy, expanding the indication range while maintaining safety by avoiding fixed deep-keel designs that cause nerve injury.
Solution Approach 2:
The coupling element is designed to be movable relative to the base element, allowing dynamic adjustment during surgery to optimize positioning and fixation. This dynamic capability enables surgeons to adapt the implant configuration to each patient's specific anatomy and bone loss pattern, making the procedure safer and more effective for young patients who were previously considered poor candidates.
Data Source
AI summary
A glenoid implant includes a base element, a coupling element, and an augment. The base element has a central aperture, a second aperture, and a wedge element. The coupling element has a first portion and a second portion. The first portion has a first plurality of apertures and the second portion has a central aperture aligned with the central aperture of the base element. The augment is received within a receiving space of the coupling element. The augment has a second plurality of apertures, each of which is aligned with each of the first plurality of apertures to receive respective second fastening elements. The coupling element and the augment are configured to rotate about an axis of the base element such that the coupling element and the augment are movable relative to the base element.