Modular Spinal Screw with Polyaxial Head and Radial Expansion
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Solution Overview
Problem
Current spinal surgery techniques face challenges in efficiently and accurately placing mechanical hardware due to anatomical variations among patients, requiring adjustable and customizable fixation members that can simplify the insertion process and ensure proper alignment of spinal rods and bands.
Innovation Solution
A modular screw system comprising a post and an adjustably coupled head assembly, featuring a tapered portion with external threads and a screw shank with radial expansion capabilities, allowing for customizable height and angle adjustments to accommodate different anatomies and facilitate secure placement of spinal rods and bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional bone screws with fixed geometry are used, then the structural simplicity is maintained, but the adaptability to different patient anatomies and surgical requirements is reduced
Solution Approach 1:
The screw is divided into modular components: a cylindrical body, a polyaxial head assembly, and a set screw mechanism. This segmentation allows independent adjustment of each component's position and orientation, enabling adaptation to various anatomical configurations while maintaining manufacturing simplicity through standardized parts.
Solution Approach 2:
The polyaxial head assembly incorporates dynamic adjustment capabilities, allowing the head to be positioned at multiple angles relative to the screw body axis. The set screw mechanism enables dynamic locking of the head at the desired orientation, providing versatility without requiring multiple fixed-geometry screw variants.
2Ease of operation
If multiple adjustment capabilities are added to the screw, then the ease of operation and customization are improved, but the time and labor required for insertion increase
Solution Approach 1:
The polyaxial head assembly is pre-configured with a standardized interface and adjustment mechanism that can be quickly positioned and locked. The set screw design allows for rapid tightening to secure the head at the desired angle, minimizing the time required for adjustments during surgery while maintaining ease of customization.
3Manufacturing precision
If the screw design allows for height and angle adjustments, then the precision of rod placement is improved, but the device complexity increases
Solution Approach 1:
The polyaxial head incorporates a spherical or rounded geometry that enables rotation and angular adjustment along the screw body axis. This curved design allows precise positioning of the head at various angles while maintaining a relatively simple overall structure that does not require complex mechanical linkages or adjustment mechanisms.
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 modular screw system reduces the time and labor required for fixation, enabling precise placement and customization to match individual patient anatomy, thereby enhancing the efficiency and accuracy of spinal surgery procedures.
Implementation Method 1
the screw shank includes an engaging portion configured to expand radially outward when the elongate screw engages the engaging portion
Implementation Method 2
internal threads configured to engage the external threads of the elongate screw
Implementation Method 3
The post includes a tapered portion extending along a portion of a length of the post
Data Source
AI summary
A modular screw includes a post and a head assembly. The post includes a tapered portion extending along a length of the post, the post defining a first bore. The head assembly is adjustably coupled with the post. The head assembly includes a head defining a slot configured to receive a spinal rod therein, an elongate screw having external threads extending along a length of the elongate screw, and a screw shank defining a second bore configured to receive the elongate screw therein. The screw shank includes an engaging portion configured to expand radially outward when the elongate screw engages the engaging portion, and internal threads configured to engage the external threads of the elongate screw. At least a portion of the screw shank is dimensioned to be selectively received in the first bore of the post.