Rotary Impactor Damping for Low-Reaction Orthopedic Reaming
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Solution Overview
Problem
Existing surgical robots face challenges in orthopedic surgery due to high reactionary forces from tools like rotary reamers, leading to navigational errors, damage, and loss of registration, which hinder their effectiveness and safety.
Innovation Solution
A rotary and linear impacting tool with a dampening mechanism and torque sensing system that reduces reactionary forces by spreading them over time and using energy storage means to minimize torque and linear push requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional rotary reamers are used in orthopedic surgery, then bone preparation can be achieved, but high reactionary torque is generated causing robot loss of registration and potential damage
Solution Approach 1:
The rotary reamer incorporates an impacting mechanism that delivers periodic impact forces during rotation. This periodic action allows the reamer to break through hard bone sections with impact loads rather than continuous torque, significantly reducing the peak reactionary torque transmitted to the robot while maintaining effective bone preparation capability
Solution Approach 2:
The reamer system transitions from static continuous rotation to dynamic impacting motion. The impacting mechanism creates variable rotational speed and intermittent contact with the bone, allowing energy to be delivered in controlled impulses rather than continuous force, thereby reducing sustained reactionary torque on the robot
2Ease of operation
If conventional rotary reamers are used, then bone cavity preparation is achieved, but surgeon fatigue increases due to high linear force requirements
Solution Approach 1:
The impacting mechanism delivers periodic impact forces during reaming, allowing the surgeon to apply significantly reduced linear push force. The impact energy is generated internally by the mechanism rather than requiring continuous high force from the surgeon, dramatically reducing surgeon fatigue while maintaining effective bone preparation
Solution Approach 2:
The impacting mechanism is self-powered through the rotational motion itself. The reamer's rotation drives the impacting mechanism to generate the necessary impact forces without requiring additional linear push force from the surgeon, making the system self-sufficient and reducing the physical burden on the operator
3Productivity
If high energy rotary reaming is performed, then effective bone preparation is achieved, but robot machinery and components may be damaged
Solution Approach 1:
The impacting mechanism delivers high energy in periodic impulses rather than continuous force. This allows effective bone preparation through high-impact forces while the intervals between impacts allow the robot structure to recover and dissipate stresses, preventing cumulative damage to robot components
Solution Approach 2:
The system incorporates damping elements and flexible couplings that absorb and dissipate impact forces before they reach the robot's precision machinery. This cushioning protects sensitive robot components from the high forces generated during impacting while maintaining the effectiveness of bone preparation
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 tool significantly reduces surgeon fatigue and robotic wear by minimizing reactionary forces, improving surgical accuracy and robot stability, allowing for safer and more efficient large bone surgeries.
Implementation Method 1
a wave spring positioned within the housing and operably coupled to the hammer such that rotation of the hammer by the motor causes compression of the wave spring and release of the wave spring causes the cam and impact rod to advance to impart a linear impact on the anvil
Implementation Method 2
A rotary and linear impacting tool for orthopedic surgery which minimizes reactionary forces during operation
Data Source
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AI summary
A rotary impactor for orthopedic surgery includes an output anvil and a hammer that is capable of imparting linear and rotary force on the anvil. The anvil may be moveable on a leadscrew element to alternately generate energy in an energy storage means and to move along the leadscrew element to impact the anvil. A viscoelastic mechanism or a dampening mechanism is used to reduce the reflected force and or torque during operation of the rotary impactor. High frequency linear impacts by the impactor obviate the need for a surgeon to provide an external push force on the impactor in order to perform a successful surgical operation.