Cantilever-type strain gauge device for intraoperative measurement and interpretation of bone density during spinal surgery
Patent Information
- Application Number
- JP2026543343
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2023-09-25
- Filing Date
- 2024-09-25
- Publication Date
- 2026-10-14
Smart Images
Figure 2026534325000001 
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Abstract
Description
Technical Field
[0001] Cross-Reference to Related Applications This application claims the benefit of U.S. Provisional Patent Application No. 63 / 540,249 filed on September 25, 2023, the entire contents of which are incorporated herein by reference.
[0002] Government Grant Support This invention was made with government support under Grant No. 5U01HL152392 awarded by the National Institutes of Health. The Government has certain rights in this invention.
[0003] An objective of the present invention relates to a medical device capable of intraoperatively measuring mechanical bone quality (bone strength) during spinal surgery.
Summary of the Invention
[0004] The device of the present invention includes hardware and / or software that provides visual, auditory, and / or tactile feedback in response to measurements, thus providing guidance to a user for management of inadequate bone quality measurements. More specifically, the present invention relates to a device having a single or dual contact pad designed to deflect away from bone when inserted into a pilot hole, wherein the degree to which the contact pad deflects is indicative of mechanical bone quality (strength).
[0005] This summary lists implementations of the invention, and in many instances, lists variations and modifications of the invention. This summary is merely illustrative of numerous and varied implementations. Reference to one or more representative features of a given implementation is likewise exemplary. Such implementations can exist with or without the referenced feature(s), and likewise, those features can be applied to other implementations regardless of whether they are described in this summary of the invention or not. To avoid excessive repetition, this summary of the invention does not enumerate or suggest all possible combinations of such features. [Brief explanation of the drawing]
[0006] [Figure 1A] An embodiment of the device of the present invention. A force (F) inherent to the device is opposed by the bone surface (not depicted) encountered by the device. This opposing force is detected and quantified by strain gauges present on the cantilever beam of the device. [Figure 1B] Embodiments of the device of the present invention. Schematic diagram of a strain gauge. [Figure 2] This is how stronger bone provides greater resistance to the device, resulting in greater cantilever deflection and therefore greater measured strain. [Figure 3A] This describes how opposing forces are encountered and measured within the bone. A dual device (i.e., a device with two contact pads that encounter the bone surface) or a single device is used. In a dual device (left side of A), the two contact pads are forced to move closer to each other when they encounter the bone surface, and the degree to which they move closer to each other can be quantified as a measure of bone strength and / or bone quality. In a single device (right side of A), a single contact pad is deflected away from the bone surface, and the degree to which the contact pad is deflected can be quantified as a measure of bone strength and / or bone quality. [Figure 3B] This describes how opposing forces are encountered and measured within the bone. It is a single device. [Figure 4] A-D illustrate embodiments of a single device of the present invention. As shown, a stronger bone surface causes greater deflection of the contact pad. In their implementations, where the surface of the contact pad also includes sensors for detecting physical contact along the length of the contact pad and the bone surface, greater deflection is accompanied by less contact between the contact pad and the bone surface. The degree to which the contact pad maintains contact with the bone surface can also be measured in addition to the degree to which the contact pad is deflected. [Figure 5] A graph of test results for block surfaces with different compressive strengths and strains detected by the device of the present invention. Note that in one embodiment (indicated by the dashed circle), the hole size was incorrectly too large, resulting in a deviation from the observed curve. [Figure 6] Figures A and B illustrate the dual device of the present invention. This dual device is 3D printed from a titanium alloy and has a diameter of 4 mm at the tip of the contact pad, each having a thickness of 0.5 mm. The strain gauge is located between the contact pad and the tapered handle. [Figure 7] Graphs showing the results of device testing under various block strength conditions. [Figure 8A] The present invention describes the device. The section of the device comprising the contact pad(s) and an adjacent portion of the neck is designed not only to examine the bone surface by creating a hole in the bone into which the device is inserted. [Figure 8B] The present invention describes the device. The section of the device comprising the contact pad(s) and an adjacent portion of the neck is designed not only to examine the bone surface by creating a hole in the bone into which the device is inserted. [Figure 9A] It is a single device inserted into the vertebra. It emits red / yellow / green light that provides evaluation of the bone surface and digital readout of detected bone strength and / or bone quality. [Figure 9B] It is a single device inserted into the vertebra. It emits red / yellow / green light that provides evaluation of the bone surface and digital readout of detected bone strength and / or bone quality. [Figure 10] A and B show photographs of a prototype of the device of the present invention. The device is equipped with a handle and tip and a strain gauge, and includes electronic equipment to display the detected strain. [Figure 11A] A photograph of a single device of the present invention inserted into three different compressive strength test blocks. [Figure 11B]A photograph of a single device of the present invention inserted into three different compressive strength test blocks. [Figure 11C] A photograph of a single device of the present invention inserted into three different compressive strength test blocks. [Figure 12A] A top view of the probe tip according to the present invention. [Figure 12B] A side view of the probe tip according to the present invention. [Figure 13] A schematic diagram of a probe tip and system for intraoperative measurement and interpretation of bone density during spinal surgery according to the present invention. [Modes for carrying out the invention]
[0007] The following terms are expected to be well understood by those skilled in the art, but their definitions are provided below to facilitate the explanation of the present invention.
[0008] All technical and scientific terms used herein are intended to have the same meaning as those commonly understood by those skilled in the art, unless otherwise defined below. References to the technology used herein are intended to mean the technology in the sense commonly understood in the art, including modifications of the technology or substitution of equivalent technology that would be obvious to those skilled in the art. The following terms are expected to be well understood by those skilled in the art, but their definitions are provided below to facilitate the explanation of the present invention.
[0009] In accordance with long-standing patent law convention, the terms “a,” “an,” and “the,” when used in this application, including in the claims, refer to “one or more.”
[0010] For example, the term "about" as used herein to refer to a measurable value of a quantity such as weight, time, etc., means that in implementations of the present invention, variations of ±20% from the specified amount, in some implementations ±10%, in some implementations ±5%, in some implementations ±1%, in some implementations ±0.1%, in some implementations ±0.5%, and in some implementations ±0.01% are encompassed, so long as such variations are suitable for carrying out the disclosed methods.
[0011] As used herein, the term "and / or" when used in the context of a listing of elements refers to the presence of the elements alone or in any possible combination or subcombination. Accordingly, the phrase "A, B, C, and / or D" includes A, B, C, and D individually, but also includes any and all combinations, as well as subcombinations, of A, B, C, and D.
[0012] The term "comprising" is synonymous with "including", "containing", or "characterized by", and is inclusive or open-ended, and does not exclude additional, unrecited elements or method steps. "Comprising" is a technical term that means the named elements and / or steps are present, but other elements and / or steps may be added and still remain within the scope of the relevant subject matter.
[0013] As used herein, the phrase "consisting of" excludes any element, step, or component not specifically recited. For example, when appearing in a section of the body of a claim rather than immediately after the preamble, the phrase "consisting of" limits only the elements stated in that section, and other elements are not excluded from the entire scope of the claim.
[0014] As used herein, the phrase "consisting essentially of" is limited to materials or steps specified in the relevant disclosure or claims, and is limited to those that do not substantially affect the basic and novel features of the invention. For example, the method of the present invention may "essentially consist" of one or more of the enumerated steps described herein, meaning that one or more of the enumerated steps produce most or substantially all of the intended results that will be produced by the claimed method. However, any additional steps may be included within the scope of such a method, provided that such additional steps do not substantially contribute to the intended outcome of the method.
[0015] With respect to the terms “comprising,” “consisting essentially of,” and “consisting of,” if one of these three terms is used herein, the present invention may include the use of any of the other two terms. Similarly, it is understood that in some implementations, the method of the present invention includes the steps disclosed herein, in some implementations, the method of the present invention consists essentially of the steps disclosed herein, and in some implementations, the method of the present invention consists of the steps disclosed herein.
[0016] Disclosed herein is the design of certain medical devices that can measure bone quality and / or bone strength intraoperatively during spinal surgery. The device includes software and indicators that provide the user with feedback on the severity of bone quality and / or bone strength defects, measured to provide guidance to the user (e.g., a spinal surgeon) on managing undesirably low bone quality and / or bone strength measurements.
[0017] Spinal surgery can be risky, especially in patients with osteoporosis, because the bone may not be able to support metal implants. Hardware such as screws and plates are placed only in bone areas that are strong enough to withstand the load required for proper repair. DEXA scans are the gold standard for evaluating bone quality, but they have drawbacks. In particular, it is not always available, and it assumes bone homogeneity without measuring local bone strength. However, it is clear that bone quality and / or bone strength are not homogeneous (Banse et al., 2001), and therefore even DEXA scans may provide insufficient information to surgeons.
[0018] To address attachment difficulties in areas of weak bone, methods include, but are not limited to, the use of multiple anchorage points, longer structures, addition of bridging joints, anterior supports, undertapping, and cement reinforcement. However, since it may not be clear during the surgical procedure when and what to use, bone strength data can provide surgeons with better information and enable them to make the best decisions regarding orthopedic repair.
[0019] Accordingly, the present invention relates to a device and method for determining bone strength in real time, rapidly and specifically along several or many locations, taking surgical intervention into consideration. In one example, the screw path is mechanically explored to determine the vertebral cancellous bone strength.
[0020] The overall general design concept for the device of the present invention is depicted in Figures 3, 4, 6, 8, and 10. Referring particularly to Figures 3A and 3B, the device of the present invention is essentially cylindrical and appropriately sized for insertion into threaded holes formed within the bone being tested. The device may have two opposing contact pads (i.e., a dual device, left side of Figure 3A) or one contact pad (i.e., a single device, right side of Figure 3A), but devices having three, four, or more contact pads are also within the scope of the present invention.
[0021] At least a portion of the device, including the contact pad(s), is disposable and designed to be frequently replaced, either during use with any particular object or for use with different objects at different times. Therefore, the removable cap facilitates the quick and easy removal of the used contact pad assembly from the probe body and its replacement with another contact pad assembly, after which the removable cap can be reattached to the probe body for subsequent use.
[0022] The probe body can be introduced into the bone to be tested (as shown in Figure 9). Furthermore, the probe body can be equipped with an additional force sensor. The force sensor detects the degree to which the contact pad(s) are deflected when they come into contact with the bone surface. Furthermore, the degree to which this contact pad(s) deflects upon contact with the bone surface indicates the bone quality and / or bone strength of the bone surface.
[0023] Therefore, the force sensor further comprises an indicator and / or detector that detects whether the bone is suitable or unsuitable for use as a mounting point for orthopedic hardware (e.g., screws). The indicator and / or detector operates in a binary manner with respect to a pre-selected minimum bone quality and / or bone strength, in that if the bone has bone quality and / or bone strength below a pre-selected minimum value, the indicator and / or detector relays a signal observable by the user. The signal is a visual signal. As an example, if the indicator and / or detector operate in a binary manner to display a visual signal, one color (e.g., red) or type (e.g., flashing) of light may indicate that the bone is unsuitable, while another color (e.g., green) or type (e.g., constantly lit) of light may indicate that the bone is suitable. In a further embodiment, if the indicator and / or detector operates in a ternary manner to display a visual signal, a first color (e.g., red) or type (e.g., off) of light may indicate that the bone is unsuitable; a second color (e.g., yellow) or type (e.g., flashing) of light may indicate that the bone is an unsuitable boundary; and a third color (e.g., green) or type (e.g., always on) of light may indicate that the bone is suitable. A device having such an indicator is shown in Figure 9. Other observable and / or perceptible signals may also be used, including, but not limited to, auditory and / or tactile signals. Furthermore, any combination of signals can be generated by the probe, including signals relayed to a receiver wirelessly connected to the probe body, signals wired to the probe body, or both (e.g., WiFi, Bluetooth, and / or infrared communication).
[0024] Furthermore, the probe body, force sensor, and contact pads (or multiple pads) are made from degradation-resistant materials using technology designed to sterilize the device. Such sterilization techniques include chemical sterilization and heat sterilization (e.g., autoclaving).
[0025] The devices and methods of the present invention are not limited to measurements during pedicle screw approaches, as illustrated herein, but are applicable to the entire range of spinal procedures and can provide measurements at multiple locations. This is in contrast to DensiProbe (see also Deckelmann et al., 2010, Hoppe et al., 2015), which is limited to a single measurement. This invention enables the measurement of axial compressive strength of the vertebral column, which can be important in spinal cord instruments. Furthermore, the DensiProbe device measures 15-20 mm at only one location in the transvertebral pedicle direction, and this limitation is addressed by the present invention.
[0026] Therefore, the present invention identifies and addresses a specific underlying cause of pedicle screw failure. Most pedicle screws do not function properly in the cancellous bone near the tip of the screw, especially in osteoporotic bone. Therefore, the present invention directly measures bone quality in different segments along a screw path. If predictable failures in the spongy region can be identified, screw failure or re-replacement can be avoided.
[0027] Bone compression test: A bone compression test using cadaveric vertebrae was used to confirm the mechanical characteristics of cancellous bone. Based on the literature, 4 mm 2 It was estimated that the surface area would require a stress of approximately 10 MPa and a deflection of more than 0.1 mm to reach the yield point. In a compression test using a 6.25 mm diameter cylinder, a stress of 3.91 MPa was obtained, a value consistent with bone quality degradation. Additional compression tests will determine the potential yield range of the cancellous bone. In addition, the mechanical properties of plastics that mimic the expected range of mechanical properties of cancellous bone (e.g., those commercially available from General Plastics, Inc.) will be tested.
[0028] Device design and testing: Many design concepts were tested before cantilever-based mechanisms were disclosed, which were used to directly explore the mechanical properties of the underlying bone. Two exemplary devices are disclosed herein: (1) an “active device” that allows a surgeon to actively explore a target site, and (2) a “passive device” that allows a surgeon to translate a probe through a screw path. Each model can be designed to create a mechanical indentation in a weaker bone without damaging a stronger one.
[0029] Active device design: The cantilever-like behavior of the active model is driven by a piston to engage with the recess (Figure 9). The piston can be manually controlled by a torque and / or force-limited torsion mechanism at the rear end. Bone strength is determined by measuring deflection and applied torque and / or force. The device has control over both force and displacement, and the operator can choose where to engage the indenter along the pedicle thread path within the vertebra.
[0030] Passive device design: This probe generates force from passive cantilever bending. The tip of the cantilever probe can be initially tilted backward and then released once it reaches a set position. The probe translates along the screw path, and cantilever deflection (correlated with bone strength) is collected along the path. The tip will indent weaker bone, but strong bone will deflect the cantilever, thus preventing damage to strong (i.e., good) bone. The probe tip is numerically modeled to deliver a bending moment that results in a load of 10 MPa.
[0031] Alternative material: Testing will be conducted on a full-scale implementation (approximately 4mm in diameter) using 3D-printed titanium. Numerical models indicate that stronger materials (i.e., stronger than polymers) are advantageous when testing exemplary devices at a real-world device scale. Furthermore, surgeons can provide feedback regarding their preference for active or passive design.
[0032] Force and deflection transducers: Alternative methods for detecting probe deflection are being tested. Two exemplary methods are optically based displacement sensors and strain gauges. Successful implementations of these transducers provide measurements beyond "strong" or "weak," offering accurate and quantifiable measurements of bone quality, thus giving surgeons the best possible information. Furthermore, such measurements allow surgeons to provide the best possible corrective treatment based on the degree of bone deterioration.
[0033] Translational system: To address the mechanism for controlled displacement of the device, the surgeon can manually insert and translate the probe itself. A screw-based translation system is employed, which allows the surgeon to manually rotate a collar that precisely translates the probe head according to the number of threads in the translation screw. Incorporating a translational system with force and deflection transducers enables a sophisticated and unprecedented mechanism for mapping internal bone strength.
[0034] Exemplary device testing: Both designs were 3D printed in PLA plastic at a larger scale (3x) for evaluation. Geometric modifications were made (based on practical observations and numerical models) and incorporated into the following set of scale-up devices, printed from nylon through the University of Louisville's Rapid Prototyping Center. The foam blocks shown in Figure 10C are commercially available in various specific strengths. Prototype testing is performed by inserting these probes into pre-drilled holes in the foam block. Prototype measurements will be used to verify the strength of the foam block.
[0035] Titanium 3D Printed Devices: Numerical models show that full-scale probe devices can be made from stronger materials (i.e., stronger than polymers) to generate sufficient force for proper operation. Therefore, the titanium devices are manufactured via additive manufacturing through the Rapid Prototyping Center at the University of Louisville.
[0036] Optical displacement transducers: Displacement sensors are a method for measuring probe deflection. The optical fiber displacement sensor manufactured by Philtec Fiberoptic Sensors has a small diameter of 0.5 mm and sub-micrometer resolution, making it suitable for use in the device of the present invention.
[0037] Strain gauges: Strain gauges attached to the probe itself can also provide deflection measurements. For example, a linear strain gauge from Micro-Measurement has a diameter of 2 mm. 2 Smaller versions are available, and various configurations are commercially available. Then, sensing is performed via a Wheatstone bridge circuit.
[0038] Torque and / or force limiting operation and precise translation: A torque and / or force limiting driver is used in the device of the present invention. Various commercially available torque and / or force limiting drivers (e.g., Bradshaw Medical and In'Tech Medical) are available to control the force delivered from the active probe of the present invention. The translation of the rotary probe can include a simple system consisting of a rotary encoder coupled with a threaded collar.
[0039] Data acquisition: A data acquisition system is used to simultaneously acquire measurement values from the probe and record them in a log. For this purpose, National Instruments' USB-6003 multifunction I / O device can be used in conjunction with the LabVIEW software used to run the I / O device.
[0040] Device Mapping Accuracy: The device is tested on randomized bone block stacks of variable bone quality to test, demonstrate, and validate the mapping accuracy of an exemplary device.
[0041] Next, the device is deployed into a cadaveric spine to demonstrate its clinical feasibility. The cadaveric vertebrae are scanned with microCT and / or DEXA to determine bone density, which correlates with the output from the deployed device.
[0042] As shown in Figures 12A and 12B, the probe tip 20 is a handheld surgical device that provides a quantified measurement of in situ bone strength during surgery. No additional surgical steps are required to use the probe tip 20, and this can be incorporated into current surgical procedures. The probe tip 20 includes an insertion tip 24 sized to be inserted into the pedicle orbital drilled into the bone. The insertion tip 24 then defines a diameter similar to that of the pedicle orbital. The mounting pad 28 for the strain gauge is formed adjacent to the insertion tip 24 and defines a reduced thickness compared to the insertion tip 24. Furthermore, the mounting pad 28 has a width equal to the diameter of the insertion tip 24, but defines a reduced thickness. The mounting pad 28 is designed to be flexible. The mounting pad 28 is connected to the extension shaft 32 by a tapered shaft segment 36, and the wire channel 40 extends through the extension shaft 32 and the tapered shaft segment 36 to provide wire management. The extension shaft 32 includes a threaded body 44 sized to receive a threaded handle 46. Furthermore, the threaded body 44 includes male threads sized to be received by the female threads of the handle 46.
[0043] As shown in Figure 13, the probe tip 20 includes a strain gauge 44 that is connected to a mounting pad 28 (for example, via adhesive) and configured to transmit strain information indicating the strain on the mounting pad 28. Distortion information can be received by a controller 48 having a processor 52 and a memory device 56. The circuitry of the controller 48 is provided in the form of a machine-readable medium or a computer-readable medium that can be executed by a processor such as the processor 52. Computer-readable program code is executed on a single processor, multiple co-located processors, multiple remote processors, or any combination of local and remote processors. The remote processors are connected to each other via any type of network (e.g., a CAN bus). In an alternative configuration, the controller 48 circuitry is implemented as a hardware unit, such as an electronic control unit. Therefore, the controller 48 circuit is implemented as one or more circuit components, including, but not limited to, processing circuits, network interfaces, peripheral devices, input devices, output devices, sensors, etc. The controller 48's circuitry can take the form of one or more analog circuits, electronic circuits (e.g., integrated circuits (ICs), discrete circuits, system-on-a-chip (SOC) circuits, microcontrollers, etc.), telecommunications circuits, hybrid circuits, and any other type of “circuit.” In this regard, the circuit of the controller 48 includes any type of component for achieving or facilitating the operation described herein. For example, the circuits described herein include one or more transistors, logic gates (e.g., NAND, AND, NOR, OR, XOR, NOT, XNOR, etc.), resistors, multiplexers, resistors, capacitors, inductors, diodes, wiring, etc. The controller 48's circuitry also includes programmable hardware devices such as field-programmable gate arrays, programmable array logic, and programmable logic devices.
[0044] Hardware and data processing components (e.g., processor 52) used to implement the various processes, operations, exemplary logic, logic blocks, modules, and circuits described in connection with the implementations disclosed herein may be implemented or carried out by general-purpose single or multi-chip processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor is a microprocessor, or any conventional processor, or a state machine. Furthermore, processors are implemented as combinations of computing devices, such as a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors combined with a DSP core, or any other similar configuration.
[0045] The memory device 56 (e.g., memory, memory unit, storage device) includes one or more devices (e.g., RAM, ROM, flash memory, hard disk storage device) for storing data and / or computer code to complete or facilitate the various processes, layers, and modules described in the present invention. The memory device 56 is communicatively connected to the processor 52 and provides the processor 52 with computer code or instructions for executing at least a portion of the processes described herein. Furthermore, the memory device 56 is a tangible, non-temporary, volatile memory or a non-volatile memory, or includes both. Therefore, the memory device 56 includes database components, object code components, script components, or any other types of information structures to support the various operations and information structures described herein.
[0046] While the term "processor" is briefly defined above, the terms "processor" and "processing circuit" are meant to be interpreted more broadly. In this regard, and as stated above, “processor” is implemented as one or more general-purpose processors, application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), digital signal processors (DSPs), or other suitable electronic data processing components configured to execute instructions provided by memory. One or more processors can take the form of a single-core processor, a multi-core processor (e.g., a dual-core processor, triple-core processor, quad-core processor, etc.), or a microprocessor. Furthermore, one or more processors are located outside the device; for example, one or more processors are remote processors (e.g., cloud-based processors). Alternatively or additionally, one or more processors are located inside and / or locally within the device. In this regard, a given circuit or its components may be located locally (e.g., as part of a local server or local computing system) or remotely (e.g., as part of a remote server such as a cloud-based server). For that purpose, the “circuit” described herein includes components distributed across one or more locations.
[0047] The present invention includes a program product comprising a machine-readable medium for carrying or having stored machine-executable instructions or data structures. Such machine-readable media can be any available media accessible by a general-purpose or dedicated computer or other machine equipped with a processor. For example, such machine-readable media may include RAM, ROM, EPROM, EEPROM, or other optical disk storage devices, magnetic disk storage devices, or other magnetic storage devices, or any other media that can be used to transport or store desired program code in the form of machine-executable instructions or data structures and that can be accessed by a general-purpose or dedicated computer or other machine equipped with a processor. The above combinations are also included within the scope of machine-readable media. Machine-executable instructions include instructions and data that cause a general-purpose computer, a dedicated computer, or a dedicated processing machine to perform a specific function or set of functions.
[0048] The controller 48 is configured to receive strain information from the threaded body 44 and to determine bone strength parameters based on the strain information. The controller 48 and probe tip 20 are then calibrated based on a known bone strength sample or calibration device. Bone strength parameters are output to the display 60 by the controller 48. The display 60 is located away from the probe tip 20 (for example, it is placed on a monitor stand). The display 60 is then attached to the handle 46 or molded into the handle 46.
[0049] The bone strength testing procedure involves exposing the vertebrae of the spine, planning the screw orbits, and drilling pedicle orbits (e.g., approximately 3-4 mm in diameter) within the vertebrae. Before tapping and / or screw insertion, the probe tip 20 is used to determine bone strength. The surgeon inserts the insertion tip 24 of the probe tip 20 into the pedicle orbit and obtains bone strength measurements in real time (via stress information) without changing the preparation of the site. Bone strength correlates with the force applied to the threaded shaft 44, and quantitative measurements (e.g., bone strength parameters) are provided to the surgeon via the display 60. Using the measured data and bone strength parameters, surgeons can determine the best strategy for the patient, including potential implementation forms of screw reinforcement. There are several screw augmentation strategies, including bone cement, auxiliary hooks, and segmental fixation. The probe tip 20 is non-destructive, and no additional surgical preparation is required for its use.
[0050] Prototype testing has demonstrated (i) a correlation between sensor readings and foam block compression strength, (ii) consistent readings across different manufactured probes, and (iii) consistent readings across different users. Based on extensive testing by the inventors, the extension shaft 32 was lengthened. The experiment also involved using probe tip 20 on a human spinal specimen from the corpse of a 96-year-old woman. A DEXA scan of the specimen was obtained, the vertebrae were prepared and tapped, and measurements were taken at the probe tip 20.
[0051] In summary, the probe of the present invention offers a competitive advantage over current devices in that it provides direct mechanical measurement of bone quality and / or bone strength, and thus bone conformity for the placement of orthopedic hardware; it can provide better prediction of fracture through three-dimensional directional measurement that takes into account the typical three-dimensional heterogeneity of bone; it gives the user the freedom to rapidly map multiple target sites in real time; and it does not destroy the target bone or alter the surgical procedure itself, even when using screw holes as access points.
Claims
1. A bone quality and / or bone strength measuring device, It comprises a main body and a detector located inside, A bone quality and / or bone strength measuring device, wherein the detector is configured to interact with bone, determine its bone quality and / or bone strength, and communicate the evaluation of the bone quality and / or bone strength to the user.
2. The detector comprises at least one contact pad, The bone quality and / or bone strength measuring device according to claim 1, wherein at least a portion thereof is configured to deflect away from the bone surface when the at least one contact pad contacts the bone surface in a manner that indicates the bone quality and / or bone strength of the bone surface.
3. The bone quality and / or bone strength measuring device according to claim 2, wherein the degree to which a portion of the at least one contact pad is deflected away from the bone surface when it comes into contact with the bone surface indicates the bone quality and / or bone strength of the bone surface.
4. The degree to which the aforementioned portion is deflected away from the bone surface is detected by a strain gauge that is in operational communication with the portion that is deflected away from the bone surface. The bone quality and / or bone strength measuring device according to claim 3, wherein the strain gauge communicates the evaluation of bone quality and / or bone strength to the user.
5. The bone quality and / or bone strength measuring device according to claim 4, wherein the device comprises a single contact pad.
6. The bone quality and / or bone strength measuring device according to claim 4, wherein the device comprises two contact pads that interact with different surfaces of the bone.
7. The bone quality and / or bone strength measuring device is sized to be inserted into a bone threaded pathway introduced into the bone. The bone quality and / or bone strength measuring device according to any one of the prior claims, wherein the size is such that the bone quality and / or bone strength measuring device fits into the bone screw path while minimizing the gap between the body of the bone quality and / or bone strength measuring device and the surface of the bone screw path.
8. A bone quality and / or bone strength measuring device according to any one of the prior claims, further comprising an output unit that provides the user with visual, auditory, and / or tactile feedback based on the bone quality and / or bone strength of the bone determined by the detector.
9. The bone quality and / or bone strength measuring device according to claim 8, wherein the output unit is equipped with a visual display that notifies the user whether the bone quality and / or bone strength of the bone exceeds or does not exceed a pre-selected minimum value.
10. The bone quality and / or bone strength measuring device according to any one of the prior claims, wherein the bone is a vertebral bone, optionally a spinal bone.
11. The bone quality and / or bone strength measuring device according to any one of the prior claims, wherein the device is manufactured at least partially from a metal, and optionally the metal is titanium and / or an alloy thereof.
12. The bone quality and / or bone strength measuring device is the bone quality and / or bone strength measuring device according to any one of the prior claims, having a maximum diameter of about 2 mm to about 4 mm.
13. The bone quality and / or bone strength measuring device according to any one of the prior claims, further comprising a plurality of threads on the outer surface of the at least one contact pad so that the bone quality and / or bone strength measuring device can be used to introduce the bone thread path into the bone immediately before and / or simultaneously with the detector interacting with the bone.
14. A method for determining whether a bone region is suitable for the placement of orthopedic hardware components, The method comprises determining the bone quality and / or bone strength of the region of the bone using a bone quality and / or bone strength measuring device according to any one of claims 1 to 13, wherein the region of the bone is suitable for placement of the orthopedic hardware component if the bone quality and / or bone strength of the region of the bone exceeds a predetermined minimum threshold.
15. The method according to claim 14, wherein the bone is a bone of the spine, and optionally a vertebra.
16. The method according to claim 14 or claim 15, wherein the orthopedic hardware component is a screw.
17. A method for reducing the risk of complications in spinal surgery associated with failure of orthopedic hardware components, The aforementioned method, (a) To allow for the possible placement of orthopedic hardware components, the spinal region, optionally the vertebral region, (b) Determining the bone quality and / or bone strength of the region of the vertebra using the bone quality and / or bone strength measuring device described in any one of claims 1 to 13, (c) If the region of the bone has bone quality and / or bone strength that exceeds a predetermined minimum threshold, or if the region of the bone has bone quality and / or bone strength that does not exceed a predetermined minimum threshold, the orthopedic hardware component is placed in the region of the vertebra. (d1) Repeat steps (a), (b), and (c) until a region of the bone exceeding a predetermined minimum threshold is identified, and then position the orthopedic hardware component in the region of the vertebra, or (d2) A method comprising not only arranging the orthopedic hardware component in the region of the vertebra, but also implementing a salvage strategy including the use of multiple fixation points, the use of an orthopedic hardware component longer than the length used in other methods, the addition of one or more crosslinks to the orthopedic hardware component, the use of one or more anterior supports, the use of undertapping in the arrangement of the orthopedic hardware component, the use of cement reinforcement, or any combination thereof.