Spinal Implant Sleeve Extension Locking Mechanism
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Solution Overview
Problem
Current spinal implant systems for treating musculoskeletal disorders, such as scoliosis and degenerative disc disease, face challenges in securely attaching vertebral rods to bone fasteners, which can lead to instability and complications during surgical procedures.
Innovation Solution
A spinal implant system comprising a sleeve with movable extensions and a bone fastener design featuring angled surfaces and locking cavities, allowing for secure attachment and easy release of the bone fastener, enabling axial translation and preventing medial/lateral disengagement, thereby facilitating stable rod placement and adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a spinal implant system uses a fixed attachment mechanism for bone fasteners, then the structural strength is improved, but the ease of operation deteriorates due to difficulty in attachment and detachment
Solution Approach 1:
The attachment mechanism transitions from a static fixed connection to a dynamic controllable connection. The extension member can change its position between engaged and disengaged states with respect to the bone fastener, allowing the system to provide strong attachment when engaged and easy detachment when disengaged, thus resolving the contradiction between attachment strength and ease of operation.
2Reliability
If the spinal implant system uses a complex locking mechanism, then the reliability of secure attachment is improved, but the device complexity increases
Solution Approach 1:
The attachment mechanism is divided into separate functional components: the bone fastener with locking cavity, the extension member with projection, and the sleeve. This segmentation allows each component to have a simple, well-defined function while collectively providing reliable secure attachment. The projection-locking cavity interface provides reliable locking without requiring a complex integrated mechanism.
3Ease of operation
If the spinal implant system allows easy detachment of bone fasteners, then the ease of operation is improved, but the stability during surgical procedures deteriorates
Solution Approach 1:
The extension member is designed to be self-locked through its geometric configuration. The projection of the extension member fits into the locking cavity of the bone fastener in a self-retaining manner, providing automatic stable engagement without requiring additional locking actions or complex mechanisms, thus maintaining stability while allowing controlled detachment.
Data Source
AI summary
A system includes a sleeve including first and second arms each including an outer ramp and an inward projection, each of the arms defining a cavity. First and second extensions are configured for disposal in the cavities. A fastener includes walls defining an implant cavity and a distal portion. The walls each include first and second end surfaces and a locking cavity. The extensions are configured for translation relative to the sleeve between a first orientation such that the extensions engage the respective ramps to fix the projections with a respective locking cavity in a configuration to capture the fastener with the sleeve and a second orientation such that the extensions move out of engagement with the respective ramps so that the projections are movable out of engagement with the locking cavities to release the fastener from the sleeve. Methods of use are disclosed.