Orthopedic Impactor Cam Mechanism for Controlled Bone Implant Impaction
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Solution Overview
Problem
Orthopedic surgeons face challenges in controlling the force applied during implant installation, leading to complications such as peri-prosthetic fractures and stress-related injuries, due to the variability of manual hammers and existing impactors, which lack effective force control and often result in inefficient energy transfer.
Innovation Solution
A powered orthopedic impactor system with a motor-driven driveshaft and impaction/retraction cams, combined with high-frequency, low-amplitude vibrations, to provide precise control over force application, reducing the likelihood of fractures and surgeon fatigue.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If manual hammers or heavy unbalanced impactors are used for impacting implants, then the implant can be installed into bone, but surgeons suffer stress on wrist, arm, shoulder, and back leading to workman compensation issues and reduced working longevity
Solution Approach 1:
The patent replaces manual hammering with a powered impactor system that uses a motor-driven cam mechanism to deliver controlled impacts. The cam profile is specifically designed to convert rotational motor motion into linear impact motion, eliminating the need for surgeons to manually swing heavy hammers and reducing stress on their bodies.
Solution Approach 2:
The patent changes the parameters of impact delivery by using a cam mechanism that controls impact frequency, amplitude, and timing. The cam profile allows for adjustable impact parameters, enabling the system to deliver high-frequency, low-amplitude impacts that are more effective and less taxing on the surgeon compared to traditional low-frequency, high-amplitude manual hammering.
2Reliability
If existing impactors are used for implant installation, then implants can be impacted into bone, but force control is variable and energy transfer is inefficient leading to complications such as peri-prosthetic fractures
Solution Approach 1:
The patent incorporates a force sensor that provides real-time feedback on the impact forces being applied to the bone. This feedback mechanism allows the control system to monitor and adjust the cam mechanism to maintain forces within safe limits, preventing peri-prosthetic fractures while ensuring effective implant installation.
Solution Approach 2:
The patent uses a dynamic cam mechanism that can adjust its profile or position during operation to optimize impact delivery. The cam mechanism is designed to work in conjunction with the force feedback system to dynamically control impact parameters, ensuring both safety and effectiveness throughout the implantation process.
3Force
If high-frequency, low-amplitude vibrations are used with the cam mechanism, then precision is enhanced and force required is reduced by 20-60%, but the system complexity increases with motor-driven driveshaft and cam mechanisms
Solution Approach 1:
The patent employs high-frequency, low-amplitude vibrations generated by the cam mechanism to reduce the overall force required for implant installation. The vibratory motion helps to break down resistance and facilitate smoother impact delivery, reducing the peak forces needed by 20-60% compared to traditional methods.
Solution Approach 2:
The cam mechanism delivers impacts in a periodic, rhythmic fashion rather than continuous force application. This periodic action allows the bone and implant interface to respond to each impact, reducing the cumulative force required while maintaining effective installation through repeated, controlled loading cycles.
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 system enhances precision and reduces the force required by up to 20-60%, minimizing fractures and stress on surgeons by maintaining continuous gliding motion and reducing the stick-slip effect, thereby improving surgical outcomes.
Implementation Method 1
the impaction cam, when in an impaction position, is configured to strike the anvil when driven by the driveshaft in the first direction to drive the anvil in an impaction direction
Implementation Method 2
combined with high-frequency, low-amplitude vibrations, to provide precise control over force application, reducing the likelihood of fractures and surgeon fatigue
Data Source
AI summary
Systems and devices may include a motor operatively coupled to a driveshaft configured to be driven in a first direction in a first mode for impaction and a second direction in a second mode for retraction. Systems and devices may include an anvil configured to be operatively coupled to an implement. Systems and devices may include an impaction cam operatively coupled to the driveshaft, wherein: the impaction cam, when in an impaction position, is configured to strike the anvil when driven by the driveshaft in the first direction to drive the anvil in an impaction direction. Systems and devices may include a retractor configured to be driven by the retraction cam in the second direction, wherein the retractor is configured to strike the anvil to drive the anvil in a retraction direction.