Polyaxial Pedicle Screw Tulip Assembly for Stable Rod Fixation
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Solution Overview
Problem
Existing bone screw designs for spinal stabilization lack improvements in design, instrumentation, and assembly methods, leading to suboptimal stabilization and potential complications.
Innovation Solution
The development of orthopedic fixation devices featuring tulips with modular fixation heads, including tulips, saddles, and retaining rings that allow for secure attachment of polyaxial pedicle screws to spinal rods, utilizing multiple threads and innovative clamping mechanisms to enhance stability and ease of assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional bone screw designs are used, then the structure is simple, but the stabilization effectiveness is insufficient
Solution Approach 1:
The fixation device is divided into multiple functional segments: a tulip head component, a rod, and a locking mechanism. This segmentation allows each component to perform its specific function optimally while maintaining overall simplicity. The tulip head provides angular adjustment capability, the rod provides structural support, and the locking mechanism provides secure fixation, collectively improving stabilization effectiveness without excessive complexity.
Solution Approach 2:
The device incorporates dynamic elements including polyaxial rotation capability that allows the screw to adjust its angle relative to the rod, and a ratcheting locking mechanism that provides progressive engagement. These dynamic features enhance stabilization effectiveness by allowing adaptation to anatomical variations and ensuring secure locking, while the mechanisms remain mechanically simple.
2Reliability
If complex assembly methods are used, then the stabilization is improved, but the ease of assembly is reduced
Solution Approach 1:
The tulip head component is pre-configured with integrated locking features and the rod is pre-formed with corresponding engagement surfaces. The polyaxial screw is pre-assembled with the tulip head before implantation. These preliminary actions ensure proper alignment and stabilization while significantly simplifying the actual assembly process during surgery, as the components are ready to engage without complex manipulation.
3Adaptability or versatility
If modular fixation heads are added, then the adaptability is improved, but the device complexity is increased
Solution Approach 1:
The tulip head component serves multiple functions: it provides structural connection between the screw and rod, enables polyaxial angular adjustment, incorporates a locking mechanism, and allows for easy assembly and disassembly. This multi-functionality in a single component design provides high adaptability for different surgical requirements while avoiding the complexity of multiple separate modular parts.
Data Source
AI summary
An orthopedic fixation device for affixing the screw head of a polyaxial pedicle screw has a tulip, a saddle, and a ring. The tulip has an interior cavity and two opposed threaded arms and a lower ledge. The saddle is inserted into the tulip body, and has a U shaped groove for receiving a spinal fixation rod. The ring has a diameter that is smaller than the widest diameter of the screw head, and is formable into a diameter larger than the widest diameter of the screw head when the screw head is pushed into the ring. The ring has a connection portion that mates with a connection portion of the saddle. The screw head is clamped within the tulip body between the saddle and the ring when a cap is threaded between the tulip arms.