Superelastic Compression Device for Orthopedic Bone Alignment
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Solution Overview
Problem
In orthopedic applications, existing compression methods using lag screws often fail to maintain consistent compression across joints or fracture sites due to cyclic loading, leading to gap formation between bone segments and interference with the healing process.
Innovation Solution
A compression device made of superelastic material with resilient teeth that exerts a biasing force in an axial direction, designed to be seated between the head of a screw and the bone surface, maintaining compression by deforming under the screw's head and exerting a constant force to keep bone segments aligned.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a lag screw is used to compress joint or fracture sites, then compression is initially achieved, but compression deteriorates over time due to cyclic loading causing gap formation
Solution Approach 1:
The compression device incorporates a resilient element that dynamically adapts to cyclic loading conditions. The resilient element maintains continuous contact with the bone surface and provides ongoing compression force despite movement or loading variations, transforming the static compression mechanism into a dynamic one that responds to physiological forces.
Solution Approach 2:
The resilient element serves as an intermediary between the lag screw head and the bone surface. This intermediate component absorbs and distributes compression forces, maintaining sustained contact pressure while protecting the bone from stress concentration, thereby resolving the contradiction between achieving compression and maintaining it reliably.
2Stress or pressure
If a washer is used with a lag screw to reduce stress on proximal cortical bone, then stress distribution is improved, but compression maintenance is not achieved
Solution Approach 1:
The invention merges the stress-distributing function of a washer with the compression-maintaining function of a resilient element. The compression device integrates both features: the resilient element provides continuous compression force while the overall structure distributes stress across the bone surface, combining two previously separate functions into one unified device.
Solution Approach 2:
The compression device utilizes composite structural design combining rigid materials for the screw head and resilient materials for the compression element. This composite approach allows simultaneous achievement of stress distribution (through the resilient material's compliance) and compression maintenance (through the resilient element's elastic recovery), resolving the contradiction between these two functions.
3Reliability
If compression is maintained continuously to prevent gap formation, then healing is promoted, but device complexity increases
Solution Approach 1:
The resilient element provides self-regulating compression through its elastic properties. As the bone moves or loads cyclically, the resilient element automatically compresses and recoils, maintaining compression force without requiring external control mechanisms. This self-service mechanism maintains reliable compression while keeping the device结构简单 (simple structure).
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 superelastic compression device effectively maintains sustained compression between bone segments, reducing tissue irritation and promoting healing by providing a consistent axial biasing force even under ambulation or other disturbances.
Implementation Method 1
a compression device composed at least in part of a superelastic material positioned between the head of a screw, optionally a lag screw, and a bone surface may exert a biasing force in an axial direction
Implementation Method 2
One or more resilient structures such as a plurality of resilient teeth project inwardly into the central opening and are configured to exert a biasing force in an axial direction when deformed in a direction opposite the axial direction
Data Source
AI summary
A compression device made of a superelastic material having a peripheral portion with an upper surface, a lower surface, and a central opening extending therethrough is provided. One or more resilient teeth project inward of the peripheral portion into the central opening and are configured to exert a biasing force in an axial direction when deformed in a direction opposite the axial direction.