Spinal Rod Reduction Instrument for Stress-Free Screw Engagement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current spinal rod reduction techniques in spinal surgery often cause stresses and strains on pedicle screws and rods, are time-consuming, and may require expensive specialty screws or instruments, lacking a streamlined solution for use with various screw types and reusability.
Innovation Solution
A mini-reduction instrument with a first threaded member and a second axially movable threaded member, featuring a spinal rod urging member with a bearing surface to gradually reduce the spinal rod into engagement with pedicle screws, compatible with monoaxial, polyaxial, and sagittal screws, and designed for reuse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If segmental reduction techniques are used to reduce the rod one level at a time, then the rod can be reduced into pedicle screws, but large axial loads are produced on the pedicle screws
Solution Approach 1:
The reduction process is divided into multiple incremental steps using a threaded reduction instrument that engages with the rod and screw assembly. The instrument is rotated in small increments to gradually reduce the rod into the screw head, distributing the reduction force over time and avoiding sudden large axial loads.
Solution Approach 2:
The reduction instrument is rotated in periodic incremental steps rather than continuously or in one large motion. This periodic rotation allows for controlled, gradual reduction while giving the screw assembly time to adapt to the changing loads, preventing excessive axial stress accumulation.
2Ease of operation
If the rod is conformed to a specific deformity and then seated within an implanted pedicle screw, then the deformity can be corrected by bending the rod in situ, but the process is time-consuming and places stresses and strains on the rod prior to implantation
Solution Approach 1:
The rod is pre-conformed to the desired deformity shape before implantation into the pedicle screw. This preliminary conformation allows the rod to be properly shaped and sized prior to insertion, and the threaded reduction instrument can then efficiently reduce it into the screw head without requiring time-consuming in-situ bending operations.
3Manufacturing precision
If specialty reduction pedicle screws with integrated upwardly extending tabs are used, then the rod can be reduced gradually over the entire length of a deformity, but the implant becomes expensive and the technique is limited to the reduction screw only
Solution Approach 1:
A threaded reduction instrument serves as an intermediary device between the rod and the pedicle screw. This separate, reusable instrument performs the gradual reduction function that would otherwise require integrated tabs on the screw itself, eliminating the need for expensive specialty screws while maintaining the ability to reduce the rod gradually over the entire deformity length.
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 solution provides a efficient, stress-reducing method for spinal rod reduction, compatible with multiple screw types, allowing for incremental reduction without overstressing the screws or rods, and enabling reuse of the instrument, thus improving the spinal corrective procedure.
Implementation Method 1
A second threaded member is configured to threadably engage with the first threaded member. The second threaded member is axially movable with respect to the first threaded member with rotation of the second threaded member.
Implementation Method 2
The urging member includes a bearing surface that is configured to selectively abut the spinal rod and selectively urge the spinal rod toward the implantable screw assembly
Data Source
AI summary
Spinal rod reduction apparatuses, systems, and methods are provided. In various examples, a rod reduction apparatus includes a first threaded member including an engagement feature configured to selectively anchor the first threaded member to the implantable screw assembly. A second threaded member is configured to threadably engage with the first threaded member. The second threaded member is axially movable with respect to the first threaded member with rotation of the second threaded member. A spinal rod urging member is axially movable with the second threaded member. The urging member includes a bearing surface that is configured to selectively abut the spinal rod and selectively urge the spinal rod toward the implantable screw assembly with rotation of the second threaded member in a first rotational direction.