Adjustable-Height Pedicle Screw for Intraoperative Rod Alignment
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Solution Overview
Problem
Current pedicle screws have fixed heights, leading to difficulties in intraoperative height adjustments, especially in minimally invasive spinal surgery, and can compromise fixation quality when manually adjusted.
Innovation Solution
Development of adjustable height pedicle screws with features like variable height ramps, telescoping components, and polyaxial designs to allow for incremental or infinite adjustments of screw height during and after installation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If fixed height pedicle screws are used, then manufacturing and installation are simplified, but intraoperative height adjustment becomes difficult and may compromise fixation quality
Solution Approach 1:
The pedicle screw is divided into multiple segments: a fixed lower portion anchored in the vertebra and an adjustable upper portion that can be elongated or shortened. This segmentation allows independent adjustment of the upper segment without affecting the anchored lower segment, enabling intraoperative height adjustment while maintaining fixation stability.
Solution Approach 2:
The screw transitions from a static fixed-height design to a dynamic adjustable-height design. The upper portion can be dynamically adjusted in length during surgery through mechanisms such as telescoping segments or expandable structures, allowing the surgeon to optimize screw height after initial placement.
2Productivity
If washers or reduction tools are used to adjust screw height, then alignment can be achieved, but the process becomes tedious and time-consuming
Solution Approach 1:
The screw system provides self-adjustment capability through integrated mechanisms. The upper portion can be directly elongated or shortened using simple rotational or telescoping actions built into the screw structure itself, eliminating the need for external washers or complex reduction tools. This self-service feature streamlines the adjustment process and reduces surgical time.
3Ease of operation
If pedicle screws are backed out for alignment, then height matching may be achieved, but fixation quality is compromised
Solution Approach 1:
By segmenting the screw into fixed and adjustable portions, the design allows height adjustment of the upper segment without disturbing the lower anchored segment. This eliminates the need to back out the entire screw, preserving the fixation quality achieved during initial placement while still enabling necessary height adjustments.
Solution Approach 2:
The dynamic adjustment mechanism allows the screw to be elongated or shortened in place after placement, maintaining continuous fixation throughout the adjustment process. This dynamic capability eliminates the static limitation of fixed-height screws and avoids the fixation compromise associated with backing out and re-tightening.
4Ease of manufacture
If fixed height screws are used in minimally invasive surgery, then implantation is straightforward, but height alignment is even more critical due to limited access
Solution Approach 1:
The adjustable-height design provides dynamic adaptation capability that is particularly valuable in minimally invasive surgery where access is limited. The screw can be adjusted after placement through the small incision, allowing precise height alignment to be achieved without requiring extensive exposure or complex manual adjustment techniques.
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
Enables precise alignment of longitudinal members, enhances fixation stability, and facilitates further correction of residual deformities by allowing height adjustments post-implantation, improving surgical efficiency and outcome.
Implementation Method 1
Incremental elongation is achieved by means of a helical ramp
Implementation Method 2
a positive ratchet locator may be utilized
Implementation Method 3
the variable height upper portion may telescope into the stationary threaded lower portion to accomplish overall shortening of the pedicle screw
Data Source
AI summary
Described herein is a pedicle screw for use in the thoracolumbar spine where the height can be adjusted intra-operatively before or after installation member of the longitudinal member. The pedicle screws with adjustable height may be made with a monoaxial or polyaxial configuration. The height of the pedicle screw can be lengthened or shortened.