Bone Plate System with Cable Locking for Sternal Fixation
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Solution Overview
Problem
Current bone plate systems for securing and stabilizing bones, particularly after sternum surgery, face issues with loosening wires that allow relative movement of bone halves, affecting post-operative fusion and requiring separate tools for cutting wires and plates, which increases access time in emergency situations.
Innovation Solution
A bone plate system with a cable and locking device that tightens around bone portions, using both cable tension and bone anchors for secure fixation, and a rotary tensioning device for efficient cable tensioning, allowing rapid approximation and secure seating of the bone plate without exclusive reliance on bone screws.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If twisted wires are used to secure sternal halves, then the bones can be secured together, but the wires may loosen over time and permit relative movement of the sternal halves
Solution Approach 1:
The bone plate is divided into two laterally spaced halves that are inserted separately through the bone, with a cable passing through both halves. This segmentation allows the fixation system to be assembled in situ around the bone, creating a more reliable connection that prevents loosening compared to pre-installed twisted wires.
Solution Approach 2:
The locking device transitions from an unlocked configuration that allows cable adjustment to a locked configuration that rigidly fixes the cable to the bone plate. This dynamic transformation ensures proper tensioning can be achieved during surgery while maintaining long-term stability to prevent relative movement of bone halves.
2Manufacturing precision
If separate tools are used for cutting wires and plates, then precise cutting can be achieved, but access time increases in emergency situations
Solution Approach 1:
The bone plate and cable are designed as an integrated system where the cable passes through the bone plate halves and is secured by a locking device. This merging of components into a single fixation unit eliminates the need for separate wire cutting tools, reducing the number of steps and tools needed during emergency procedures while maintaining secure fixation.
Solution Approach 2:
The bone plate system is designed to perform multiple functions: the cable provides tensioning and compression, the locking device secures the cable to the plate, and the plate halves distribute load across the bone. This multi-functionality reduces the need for additional specialized tools, streamlining emergency access procedures.
3Strength
If bone screws are used exclusively for fixation, then rigid fixation can be achieved, but the system lacks the high tensile strength of cables
Solution Approach 1:
The fixation system combines two different load-bearing mechanisms: the cable provides high tensile strength through its flexible, high-strength construction, while the bone plate and anchors provide rigid fixation and compression. This composite approach leverages the complementary strengths of both cable and rigid fixation systems.
Solution Approach 2:
The cable is tensioned and secured to the bone plate before final bone healing occurs. This preliminary action of establishing high-tensile-strength fixation allows the bone to heal under optimal compression and stability conditions, combining the immediate benefits of rigid fixation with the long-term advantages of high-tensile cable support.
Data Source
AI summary
A bone plate system for securing a plurality of bones is provided including a plate member, a locking device of the bone plate, and a surgical cable having a trailing end for being connected to the bone plate and a leading end for being advanced around the bones and into the locking device. The surgical cable may be tensioned to approximate the bones, urge the bones together, and seat the bone plate against the bones. The locking device may be reconfigured to a locked configuration to fix the bone plate to the surgical cable. The bone plate further includes a plurality of throughbores for receiving bone anchors that rigidly fix the bone plate to the bones. The bone plate system utilizes the tensile strength of the surgical cable and the rigid fixation between the bone anchors and the bone plate to resist relative movement of the bones.