Force Limiting Spinal Rod Persuader Mechanism
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Solution Overview
Problem
Current spinal fixation techniques face challenges in efficiently and safely advancing orthopedic rods into recesses within spinal implants, particularly due to varying anatomical and pathological conditions, which can result in excessive force application and potential damage.
Innovation Solution
A force-limiting persuader-reducer device that includes a handle, lever, translating shaft, and retractor blades, allowing for controlled force application with a force-limiting mechanism that automatically adjusts based on the type of retractor blade used, enabling either limited or full-force modes to accommodate different spinal conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high force is applied to advance the spinal rod into the spinal implant, then the rod can be inserted more effectively, but damage may occur to the rod or implant
Solution Approach 1:
The device transitions from a static force application system to a dynamic one where the force-limiting mechanism automatically adjusts the applied force based on resistance encountered. The mechanism allows high force application when the rod moves freely but automatically limits force when resistance is detected, preventing damage while maintaining insertion effectiveness.
Solution Approach 2:
The force-limiting mechanism is pre-configured with a predetermined force threshold that acts as a protective cushion. Before damage can occur, the mechanism detects excessive force and reduces it, providing advance protection to both the rod and implant components.
2Object-affected harmful factors
If a force-limiting mechanism is added to the device, then damage prevention is improved, but device complexity increases
Solution Approach 1:
The force-limiting mechanism is merged with the existing shaft and handle assembly rather than being added as a separate external device. The mechanism integrates into the force transmission path, allowing damage prevention functionality to be incorporated without significantly increasing overall device complexity.
Solution Approach 2:
The force-limiting mechanism is designed to automatically detect and respond to excessive force conditions without requiring external control or complex electronic systems. The mechanical design allows the mechanism to self-regulate force application based on the resistance encountered during rod insertion.
3Reliability
If automatic force limitation is implemented, then safety is improved, but ease of operation may be reduced due to additional mechanisms
Solution Approach 1:
The force-limiting mechanism operates automatically based on the physical conditions of rod insertion without requiring the operator to manually adjust settings or monitor force levels. The mechanism self-regulates by detecting resistance and adjusting force application accordingly, maintaining safety while requiring minimal additional operator effort.
Data Source
AI summary
An apparatus and method for advancement of a spinal rod in a spinal implant, wherein the apparatus includes a body and a handle attached to the body. A shaft is slidably attached to the body, the shaft is coupled to the handle and has a first end adapted to engage the spinal rod. At least one retractor blade is attached to the body and the spinal implant. The operation of the handle results in the shaft persuading the spinal rod in the spinal implant. The force exerted by the shaft on the spinal rod is limited to a pre-selected force. The apparatus can also be operated in a non-limiting mode when a reduction retractor blade is used.