Rotary Orthopedic Impactor With Damped Reaction Torque
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Solution Overview
Problem
Current surgical robots face challenges in orthopedic surgery due to high reactionary forces from tools like rotary reamers, which can cause navigational errors, damage to robotic machinery, and increased surgeon fatigue, as they are unable to handle the magnitude of forces required for large bone procedures.
Innovation Solution
A rotary and/or rotary/linear surgical tool with a mechanism to reduce reactionary forces, incorporating a dampening mechanism using viscoelastic or non-Newtonian fluids and a torque sensing system to initiate rotational impacting, along with a hammer and anvil mechanism with energy storage, to minimize peak forces and decouple the hammer from the anvil, allowing for efficient bone penetration with reduced torque.
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 to robotic machinery
Solution Approach 1:
The patent applies periodic impacting action through a hammer mechanism that delivers repeated blows to the reamer, replacing continuous rotary motion with periodic impacts. This periodic action reduces peak reactionary torque on the robot while maintaining effective bone preparation through cumulative impact forces
Solution Approach 2:
The patent introduces a hammer as an intermediary element between the motor and the reamer. The hammer absorbs and isolates the reactionary forces generated during bone engagement, preventing these forces from being transmitted directly to the robotic system while still enabling effective reaming through impact transmission
2Ease of operation
If conventional rotary reamers are used, then bone cavity preparation is achieved, but surgeon fatigue increases due to manual force requirements
Solution Approach 1:
The impacting mechanism provides periodic blows that perform the cutting and removal work, eliminating the need for the surgeon to continuously apply manual linear force. The periodic impacts do the work of bone removal while the surgeon only needs to guide and position the tool
Solution Approach 2:
The impacting mechanism enables the reamer to perform its own work through self-generated impact forces. The hammer delivers blows that drive the reamer forward and perform bone removal without requiring external manual forcing, making the tool self-sufficient in generating its own operational forces
3Measurement precision
If conventional rotary reamers are used, then bone preparation is achieved, but navigational errors occur due to destabilizing forces
Solution Approach 1:
The periodic impacting action creates brief, controlled force pulses rather than continuous destabilizing forces. The intermittent nature of the impacts allows the robotic system to maintain registration between blows, and the short duration of each impact minimizes the opportunity for navigational drift or error accumulation
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 significantly reduces the reactionary forces felt by surgeons and robots, allowing for better control and reduced fatigue, enabling robots to maintain registration and complete surgeries with minimal external force, thereby improving surgical precision and robot stability.
Implementation Method 1
a mechanism that decreases the peak reactionary forces from the tool end that act on a gripping surface of the tool
Implementation Method 2
incorporating a dampening mechanism using viscoelastic or non-Newtonian fluids
Implementation Method 3
a torque sensing system to initiate rotational impacting
Implementation Method 4
a hammer and anvil mechanism with energy storage
Data Source
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.