Expandable Orthopedic Implant for Bone Voids
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Solution Overview
Problem
Existing orthopaedic implants face challenges in osseointegration due to voids and depressions in patient bone anatomy, which hinder stress transfer and bone growth, as they cannot effectively fill these areas without protrusions that complicate implant placement.
Innovation Solution
The development of orthopaedic implants with expandable regions, such as three-dimensional lattices and mechanisms like concertina, screw, or press mechanisms, that can increase the external surface area to match and fill voids and depressions, enhancing osseointegration by mimicking natural bone contours.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the implant surface is designed to contour exactly to patient anatomy using protrusions, then the fit into patient bone is optimized, but the implant cannot reach the desired position in tapered voids
Solution Approach 1:
The implant incorporates expandable regions that transition from a compressed insertion state to an expanded fixation state. The outer wall includes expansion means such as bellows structures, hinge mechanisms, or shape memory materials that allow the implant to dynamically change its external dimensions, enabling it to pass through tapered voids in compressed form and then expand to fill and anchor in the target anatomical space.
Solution Approach 2:
The expandable regions are designed with nested or telescoping structures where layers or segments can be inserted one within another during the compressed state, allowing the implant to navigate through tight anatomical passages. Once positioned, these nested structures expand outward to provide the necessary surface area for osseointegration.
2Ease of manufacture
If the implant is designed with fixed surface area, then manufacturing is simplified, but it cannot fill voids and depressions in patient bone
Solution Approach 1:
The implant utilizes materials and structures that allow controlled dimensional changes after manufacturing. Expandable regions incorporate mechanisms such as shape memory alloys, superelastic materials, or mechanical expansion structures that enable the implant to transform from a compact manufactured form to an expanded in-vivo form, achieving complex surface geometries without complex manufacturing processes.
Solution Approach 2:
The implant design incorporates regions where physical parameters such as volume, surface area, or structural density can be changed in situ. This is achieved through expandable structures that alter their geometric parameters after implantation, allowing the same manufactured component to adapt to varying anatomical requirements without requiring custom manufacturing for each patient.
3Reliability
If protrusions are added to fill voids, then bone contact is improved, but implant location becomes difficult to control
Solution Approach 1:
Rather than adding fixed protrusions that interfere with positioning, the implant uses expandable regions that remain flush with the implant surface during insertion. The expansion occurs only after the implant is correctly positioned, ensuring that the expansion mechanism does not interfere with the precision of implant placement while still providing the necessary bone contact surface area.
Solution Approach 2:
The implant is designed with pre-positioned expansion mechanisms that are activated only after the implant has been correctly located in the target anatomy. This preliminary positioning phase allows the surgeon to place the implant with precision using the compact form, and only after correct positioning is confirmed do the expandable regions deploy to provide enhanced bone contact and fixation.
Data Source
AI summary
This invention relates to and orthopedic implant having an expansion means adapted to increase the external surface area of the implant, the expansion means positioned to correspond to voids or depressions in the anatomy of a patient. Also described are method for the design and manufacture of such implants.