Tulip Assembly Translation for Spinal Rod Alignment
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Solution Overview
Problem
Existing bone fixation systems require additional parts and bulk to achieve proper alignment and stabilization of rods in the spinal column, which complicates orthopedic surgery and can lead to increased surgical time and potential mechanical failure of rods.
Innovation Solution
A bone fixation assembly featuring a tulip assembly that can translate and reposition along a polyaxial screw, allowing for angular redirection without additional parts, enabling the tulip assembly to slide and lock into position along the bone fixation device, thereby simplifying rod alignment and stabilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional parts (screws, plates) are added to the bone fixation system, then rod alignment and stabilization are improved, but device complexity and surgical time increase
Solution Approach 1:
The patent combines the tulip assembly and polyaxial screw into a single integrated bone fixation device. The tulip assembly includes a cavity that receives the rod and an aperture that allows the polyaxial screw to pass through, eliminating the need for separate components. This merging reduces the number of parts while maintaining rod alignment and stabilization functions.
Solution Approach 2:
The integrated bone fixation device performs multiple functions: the polyaxial screw provides fixation to the bone, the tulip assembly receives and positions the rod, and the aperture enables adjustment of the screw's position relative to the tulip assembly. This multi-functionality reduces the need for additional specialized components.
2Reliability
If additional parts are added to achieve proper alignment, then stabilization is improved, but surgical time increases
Solution Approach 1:
The tulip assembly is pre-configured with the cavity and aperture in specific positions and orientations relative to each other. This preliminary arrangement allows the rod to be inserted and positioned correctly without requiring additional alignment steps or components during surgery, reducing surgical time while maintaining stabilization.
3Reliability
If the rod is bent or curved to accommodate non-aligned screws, then fixation is achieved, but mechanical integrity decreases
Solution Approach 1:
The polyaxial screw allows dynamic adjustment of its position and orientation relative to the tulip assembly through the aperture. This enables the fixation device to adapt to non-aligned screw positions without requiring the rod to be bent, as the screw can be positioned to achieve proper alignment while maintaining rod straightness and mechanical integrity.
Data Source
AI summary
A bone fixation assembly comprises a tulip-shaped assembly and a bone fixation device such as a surgical or pedicle screw, comprising a head and a bone fixation portion. The tulip assembly comprises an upper portion to receive a rod and a lower portion that has a cavity in which the head of the bone fixation device rests. The cavity has an aperture below. The aperture has a length through which the tulip assembly may slide with respect to the bone fixation device, for movement of the tulip assembly when the bone fixation device is in place, while also maintaining the angular movement of the tulip assembly. The bone fixation device may comprise an aperture engaging part, which locks the bone fixation device position on the aperture length. A tulip assembly translation mechanism comprises a head, a cavity, an aperture to the cavity.