Adjustable Cervical Implant Trial Instrument with Force Sensor

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Solution Overview

Problem

Current trialing instruments for selecting properly sized cervical prosthetic implants lack objective measures, leading to potential over-sizing issues that result in significant drops in range of motion and quasi-fusion at the replacement level.

Innovation Solution

An adjustable trialing instrument with an expandable mechanism and built-in force/pressure sensor provides objective feedback by measuring disc space at known distraction pressures, using LEDs or a display to indicate pressure within tolerance ranges, assisting surgeons in selecting the appropriate implant size.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional trialing instruments are used without objective measurement, then the procedure is simpler and faster, but implant sizing accuracy deteriorates leading to over-sized implants

Engineering Contradiction:
Improveimplant sizing accuracyVSAvoidinstrument complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The instrument incorporates a force sensor that provides real-time feedback on the distraction force applied during measurement. This feedback mechanism allows the surgeon to accurately determine the implant size by observing the force required to achieve proper distraction, eliminating guesswork and preventing over-sizing while maintaining procedural efficiency

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent replaces subjective mechanical measurement methods with an objective electronic sensing system. The force sensor electronically measures distraction force, replacing the need for complex mechanical calipers or external measurement devices, thereby simplifying the overall system while improving measurement precision

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If over-sized implants are used to ensure adequate coverage, then implant security improves, but range of motion deteriorates due to quasi-fusion

Engineering Contradiction:
Improveimplant securityVSAvoidrange of motion
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The force sensor provides real-time feedback on the exact distraction force needed for proper implant fit. This feedback enables the surgeon to select an implant size that provides adequate security without excessive distraction, thereby maintaining range of motion while ensuring implant reliability through precise sizing

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The instrument allows dynamic adjustment of the distraction force parameter during measurement. By controlling and monitoring the distraction force through the sensor, the system identifies the optimal implant size that balances security and mobility, preventing both under-sizing and over-sizing scenarios

Inventive Principle:
Principle #35Parameter changes

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 instrument minimizes the loss of range of motion by offering precise, objective measurements, ensuring proper implant sizing and preventing overstuffing, thereby maintaining native spinal mobility.

Implementation Method 1

An adjustable trialing instrument with an expandable mechanism and built-in force/pressure sensor provides objective feedback by measuring disc space at known distraction pressures

Methodology Applied
Scientific EffectForce measurement: Force

Implementation Method 2

The apparatus includes an expandable device for providing a measurement within the intervertebral space and facilitating the measurement of the angulations of the lordotic curve of the intervertebral space

Methodology Applied
Scientific EffectMechanical distraction: Mechanical Force

Data Source

PatentEP3772350B1System to determine cervical implant size
Publication Date: 2022.08.31 ZIMMER BIOMET SPINE INC
  • EP3772350B1 patent drawingFigure 1A
  • EP3772350B1 patent drawingFigure 1B
  • EP3772350B1 patent drawingFigure 1C

AI summary

An implant-trialing instrument for objectively determining a recommended implant size based at least in part on pressure sensor measurements can include a handle and an adjustable implant trial. The handle can include an elongate body and an adjustment input. The adjustable implant trial can be disposed on a distal end of the elongate body and be adapted to expand within an intervertebral space in response to input from the adjustment input, the adjustable implant trial can include a measurement sensor configured to output an objective measure of intervertebral disc space correlated to implant size. A method of utilizing the implant-trialing instrument can include operations such as distracting the adjustable trialing mechanism, determining whether the pressure measurement satisfies a pre-defined pressure criterion, and recommending an implant size.