Sternal Cerclage Tensioning for Adjustable Bone Compression
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Solution Overview
Problem
Existing surgical procedures, such as heart procedures that require cutting the sternum, often face challenges in effectively immobilizing and securing the separated bone portions for proper healing, as existing devices may not provide adequate compressive force or ease of installation.
Innovation Solution
A closure system comprising a bracket, band, and tensioning device, where the band is looped around the bone portions and tightened using a threaded member or tensioning member to secure the sternum, allowing for adjustable tensioning and implantation within the body.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If existing closure devices are used to secure separated bone portions, then the bone portions can be immobilized, but adequate compressive force may not be applied
Solution Approach 1:
The closure device incorporates an adjustable tensioning mechanism that allows dynamic adjustment of compressive force applied to the bone portions. The tensioning member can be rotated to incrementally increase compression, and the ratchet mechanism maintains the dynamic state by preventing relaxation while allowing further tightening. This resolves the contradiction by enabling the system to achieve and maintain adequate compressive force levels.
Solution Approach 2:
The device allows changing the compression parameter through rotation of the tensioning member, which adjusts the tension in the band. By modifying this physical parameter, the system can transition from insufficient compression to adequate compressive force, directly addressing the technical contradiction between force application and healing effectiveness.
2Ease of operation
If existing closure devices are used to secure bone portions, then immobilization is achieved, but ease of installation may be compromised
Solution Approach 1:
The closure device is divided into distinct functional segments: a flexible band for circumferential attachment, a tensioning mechanism for force application, and a ratchet mechanism for maintaining tension. This segmentation allows each component to be optimized independently and simplifies the installation process by enabling sequential assembly and adjustment, resolving the contradiction between ease of installation and device complexity.
Solution Approach 2:
The band is pre-formed into a loop configuration that can be easily placed around the bone portions before tensioning. The tensioning member is pre-positioned within the band, allowing the device to be implanted in a simplified sequence: first the band is looped around the bone, then the tensioning mechanism is activated. This preliminary preparation reduces installation complexity while maintaining adequate device functionality.
3Ease of repair
If a tensioning device is used to apply compressive force, then bone portions are secured, but the device may not be removable without releasing tension
Solution Approach 1:
The ratchet mechanism acts as an intermediary between the tensioning member and the band. It maintains compressive force through its one-way locking action while allowing the tensioning member to be independently manipulated. This intermediary mechanism enables the tensioning force to be preserved while the removable components can be detached, resolving the contradiction between maintaining force and enabling removal.
Solution Approach 2:
The tensioning member is designed as a separate, extractable component from the band structure. The ratchet mechanism allows the tensioning member to be removed from the band without releasing the stored tension, as the ratchet teeth maintain the compressed state independently. This extraction capability enables device removal or adjustment while preserving the compressive force benefit.
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 system provides secure immobilization and adjustable tensioning of bone portions, facilitating effective healing by applying compressive force and enabling easy installation and removal without releasing tension.
Implementation Method 1
The tensioning device may include a body and a threaded member. The threaded member may be received in the body and may engage the band such that rotation of the threaded member relative to the body moves a first end of the band relative to a second end of the band.
Implementation Method 2
It is often desirable to apply a compressive force urging the bone portions together to facilitate healing of the bone.
Data Source
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AI summary
A closure system may secure a first bone portion to a second bone portion. The closure system may include a bracket, a band and a tensioning device. The bracket may include a first portion adapted to engage the first bone portion and a second portion adapted to engage the second bone portion. The band may engage the bracket and may be adapted to be looped around the first and second bone portions. The tensioning device may include a body and a threaded member. The threaded member may be received in the body and may engage the band such that rotation of the threaded member relative to the body moves a first end of the band relative to a second end of the band.