Spinal Implant Bone Screw Retention Ring
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Solution Overview
Problem
Existing bone screw retention mechanisms for spinal implants are inadequate in preventing backout of bone screws, leading to potential instability and reduced clinical outcomes in spine surgery.
Innovation Solution
A spinal implant with a bone screw bore featuring a resilient closed curve band or ring, composed of nickel titanium alloy, that extends radially into the bore to form springs, allowing the bone screw head to ingress but preventing egress, thereby enhancing retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional anti back out devices are used to prevent bone screw backout, then bone screw retention is improved, but device complexity increases and reliability is reduced due to deficiencies in existing mechanisms
Solution Approach 1:
The patent employs a resilient retention ring made of flexible material that can deform elastically. The ring features resilient sections or protrusions that flex outward to allow bone screw head insertion, then spring back to prevent backout. This flexible membrane approach provides reliable retention while maintaining simple device architecture, directly resolving the contradiction between retention reliability and device complexity.
2Reliability
If a resilient retention ring with multiple resilient sections is used, then bone screw retention is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent utilizes elastic modulus and resilient properties of the retention ring material as key parameters. By carefully selecting materials with appropriate elastic characteristics and designing the resilient sections with specific geometric parameters (height, width, spacing), the device achieves reliable bone screw retention. These parameter optimizations allow the resilient sections to provide sufficient retention force while accommodating reasonable manufacturing tolerances, thus resolving the contradiction between retention reliability and manufacturing precision requirements.
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 solution effectively inhibits bone screw backout, providing secure fixation and improved stability of spinal implants, which enhances clinical outcomes by ensuring reliable attachment and preventing screw egress.
Implementation Method 1
a resilient closed curve band or ring. The resilient closed curve band has a plurality of resilient sections or portions that extend into the bore. Each one of the plurality of resilient sections that extend into the bore form a spring that allows a head of a bone screw to ingress there through but prevents the head of the bone screw from egress there from
Implementation Method 2
The resilient closed curve band is preferably, but not necessarily, made from a nickel titanium alloy
Data Source
AI summary
A spinal implant has a mechanism for inhibiting a bone screw used in attaching the spinal implant to the spine from backing out from the spinal implant once the bone screw has been received in the spinal implant. The spinal implant has a bone screw bore defining a bore wall in which is disposed a resilient closed curve band or ring. The resilient closed curve band has a plurality of resilient segments that extend into the bore. Each one of the plurality of resilient segments form a spring that allows a head of a bone screw to ingress there through but prevents the head of the bone screw from egress there from. The resilient closed curve band forms a retention ring that is received in one or more slots, channels, grooves or the like in the bore hole wall. The plurality of resilient segments are formed as arcs, curves and/or configured arcs/curves that extend radially inward from outer arced or curved portions of the retention ring.