Orthopaedic Strain Sensor for Fracture Risk Monitoring
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Solution Overview
Problem
Current orthopaedic procedures lack a reliable mechanism to determine the risk of fracture during and after implant procedures, leading to a high incidence of periprosthetic fractures, particularly in Total Hip Arthroplasty and revision procedures, due to excessive hoop stress caused by implant insertion.
Innovation Solution
A device comprising an encircling member with a strain sensor that monitors bone strain and provides visual or auditory signals to indicate the risk of fracture, including a threshold detector for alarm generation, and a force limiting member to prevent excessive force application during implantation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If force is applied by a mallet/hammer and through an impactor to drive the implant into position, then the implant is securely positioned in the bone, but excessive force causes fracturing of the bone
Solution Approach 1:
The patent employs a strain sensor that provides real-time feedback on bone strain levels during implant insertion. The sensor is integrated into the impactor or broach, continuously monitoring the mechanical stress applied to the bone and transmitting this data to the surgeon, enabling dynamic adjustment of insertion force to prevent fracture while ensuring secure implant positioning.
Solution Approach 2:
The patent replaces the purely mechanical force application system with a sensor-integrated system that combines mechanical insertion with electronic monitoring. The strain sensor substitutes for traditional tactile feedback, providing objective, quantifiable data on bone stress levels that replaces the surgeon's subjective assessment of insertion force.
2Manufacturing precision
If a broach is hammered into the bone to prepare the bone, then the bone is adequately prepared for implant insertion, but excessive force creates hoop stress exceeding bone strength and causes periprosthetic fracture
Solution Approach 1:
The strain sensor integrated into the broach provides real-time feedback on the hoop stress being applied to the bone during broaching. This allows the surgeon to monitor bone response continuously and adjust the hammering force to achieve adequate bone preparation without exceeding the bone's structural limits and causing fracture.
Solution Approach 2:
The strain sensor is pre-installed on the broach before the procedure, allowing for preliminary calibration and setup. The system enables proactive monitoring of bone stress levels throughout the broaching process, allowing the surgeon to anticipate potential fracture risks before they occur and adjust techniques accordingly.
3Reliability
If a trial implant is hammered into the bone to test fit, then the implant fit is evaluated, but the force applied may cause fracture in fragile bone
Solution Approach 1:
The strain sensor provides continuous real-time monitoring during trial implant insertion, giving immediate feedback on bone strain levels. This allows the surgeon to evaluate implant fit while simultaneously monitoring for fracture risk, enabling safe trial insertions even in patients with fragile bone such as the elderly.
Solution Approach 2:
The strain sensor acts as an intermediary between the trial implant and the bone, mediating the interaction by providing objective data on the mechanical stress being applied. This intermediary system allows the surgeon to indirectly assess both implant fit and bone integrity without relying solely on direct mechanical feedback that may be ambiguous in fragile bone.
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 device effectively reduces the risk of periprosthetic fractures by providing real-time strain feedback to surgeons, allowing controlled force application and preventing excessive stress on the bone, thereby minimizing the risk of fracture during and after orthopaedic procedures.
Implementation Method 1
a sensor member connected to said encircling member, said sensor member including a strain sensor; wherein said strain sensor generates one or more strain signals representative of the strain in said bone in response to a force applied to said bone
Data Source
AI summary
An orthopaedic device for generating one or more strain signals representative of the strain in a bone in response to a force applied to the bone. The device includes an encircling member (11) for encircling the bone of a subject and a sensor member (13) connected thereto, the sensor member including a strain sensor (14). In a preferred embodiment the strain sensor comprises one or more bridging members configured to break when subjected to a particular strain.