Digitizer Pointer Geometry for Precise Spinal Rod Bending
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Solution Overview
Problem
Existing spinal rod bending systems are subjective, time-consuming, and prone to errors, leading to increased morbidity and potential construct failure due to the lack of precise customization and user-friendly bending options.
Innovation Solution
A digitizer pointer with adjustable offset, swivel, and translation features for precise spatial tracking and rod bending, allowing for customizable rod shaping and alignment with surgical implants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If manual rod bending using French Bender is used, then the rod can be bent to fit the screw and hook construct, but the process is subjective, time-consuming, and requires high physician skill
Solution Approach 1:
The rod is pre-bent in the laboratory using a rod bender device before implantation. The pre-bending process includes attaching the rod to a support structure, heating it to a predetermined temperature to increase flexibility, and bending it to predetermined angles and positions that match the patient's specific anatomy and surgical plan. This eliminates the need for time-consuming intraoperative bending.
Solution Approach 2:
The manual mechanical bending process using French Bender is replaced with a controlled heating and bending system. The rod is heated to a specific temperature range (e.g., 400-600°C) using a heating device, which increases its ductility and allows for precise bending to predetermined angles without requiring high physician skill or subjective judgment.
2Manufacturing precision
If iterative rod bending is performed to achieve optimal fit, then the rod can be customized to patient anatomy, but the process promotes metal fatigue and stress risers
Solution Approach 1:
The rod is bent to the precise final configuration in the laboratory before implantation, eliminating intraoperative bending. The pre-bending process uses controlled heating and a rod bender device to achieve the exact angles and positions needed, performing the bending action only once rather than through iterative adjustments.
Solution Approach 2:
The rod's physical properties are temporarily changed by heating it to a predetermined temperature range (400-600°C), which increases its ductility and allows for precise bending. After bending to the final configuration, the rod is allowed to cool and harden, locking in the precise shape without metal fatigue from repeated bending.
3Measurement precision
If custom rod bending is performed intraoperatively, then the rod can be precisely aligned with surgical implants, but the process is complex and frustrating
Solution Approach 1:
All measurements, planning, and rod bending are completed in the laboratory before surgery. The rod is bent to precise angles and positions based on preoperative imaging and surgical planning. During surgery, the pre-bent rod is simply attached to the implants, eliminating complex intraoperative bending procedures.
Solution Approach 2:
The patient's unique spinal anatomy and implant configuration are captured through preoperative imaging and used to create a digital model. The rod is then custom-bent in the laboratory to precisely match this digital model, creating a custom copy of the required geometry without needing complex bending equipment in the operating room.
Data Source
AI summary
A digitizer pointer is provided as part of a system for correcting a curvature or deformity in a patient's spine based on the digitized locations of implanted screws and tracking the placement of the rod as it is placed in a minimally invasive fashion. The digitizer pointer includes an offset adjustment feature, a swivel feature, and a translation feature.