Friction-Fit Spinal Receiver Assembly for Stable Screw Orientation
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Solution Overview
Problem
Existing spinal fixation systems face challenges in aligning receivers with connecting rods due to gravitational forces causing drooping or slipping, requiring complex repositioning and assembly by trained personnel, and limiting surgeon selection during surgery.
Innovation Solution
Implantable devices with a friction fit mechanism between a receiver body and bone screw, allowing modular assembly and bottom-side loading, using biasing members to maintain orientation and position through a frictional force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional receiver assemblies are preassembled by the manufacturer, then assembly precision and reliability are improved, but device complexity and limited surgeon selection worsen
Solution Approach 1:
The receiver assembly is divided into separate components (receiver body, set screw, biasing member) that can be independently selected and assembled. This allows surgeons to choose specific configurations during surgery while maintaining reliable friction-fit connections through standardized interfaces.
Solution Approach 2:
The biasing member is pre-installed within the receiver body to automatically apply downward force on the screw head during assembly. This preliminary action ensures proper friction-fit engagement without requiring complex preassembly procedures or specialized tools.
2Adaptability or versatility
If receivers are aligned manually during surgery, then adaptability to patient anatomy is improved, but time consumption and operational difficulty worsen
Solution Approach 1:
The biasing member automatically applies downward force on the screw head when the rod is inserted, self-aligning the receiver to the correct orientation. This eliminates the need for manual realignment by the surgeon, reducing time consumption while maintaining anatomical adaptability.
Solution Approach 2:
The biasing member acts as an intermediary mechanism between the screw and receiver, automatically maintaining proper orientation and friction-fit engagement. This mediator eliminates the need for complex manual alignment procedures during surgery.
3Ease of operation
If gravitational forces act on receivers during positioning, then ease of insertion is improved, but orientation stability and alignment precision worsen
Solution Approach 1:
The biasing member provides an upward counteracting force against gravitational forces that cause receivers to droop or slip. This counterforce maintains stable orientation and precise alignment during insertion and positioning, eliminating the need for repeated manual adjustments.
Solution Approach 2:
The biasing member dynamically adjusts the friction-fit pressure between the screw head and receiver based on gravitational forces and insertion conditions. This dynamic adjustment maintains optimal alignment precision throughout the insertion process without requiring manual intervention.
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
Facilitates quick and efficient assembly of spinal fixation systems by enabling modular assembly and maintaining receiver orientation relative to the screw, overcoming gravitational forces and simplifying surgeon selection during surgery.
Implementation Method 1
a first biasing member positioned at least partially within the first passage of the body and configured to apply a downward force on the pressure member relative to the body
Implementation Method 2
The implantable device is configured to apply a frictional force to a screw head so that an orientation of the receiver body can be maintained relative to the screw head
Data Source
AI summary
An implantable device may be configured to couple to a bone screw for spinal fixation. The implantable device may include one or more friction-fit features to allow the implantable device to maintain its orientation before being locked into place by a set screw. For example, an implantable device may include a body comprising a sidewall. The sidewall may define a first passage extending within the sidewall and parallel to a vertical axis of the body, and a slot extending through the sidewall and in communication with the first passage. The device may further include a pressure member coupled to the body. The pressure member may include a distal surface for engaging the head of the bone screw. The device may further include a biasing member at least partially within the first passage of the body for applying a downward force on the pressure member.