US20060040233A1

US20060040233A1 - Measurement element position determination

Info

Publication number: US20060040233A1
Application number: US11/193,309
Authority: US
Inventors: Uriel Weinstein; Opher Kinrot; Assaf Bernstein; Zvika Slovin
Original assignee: Tactile Technlogies LLC
Current assignee: Tactile Technlogies LLC
Priority date: 2003-01-23
Filing date: 2005-07-28
Publication date: 2006-02-23
Also published as: WO2004065893A2; US20060240379A1; WO2004064660A2; US7014461B2; US20060240378A1; US20040146830A1; WO2004065893A8; WO2004065893A3; WO2004064660A3

Abstract

An apparatus for determining measurement element positions, comprising a plurality of measurement elements; at least one trigger element corresponding to each element of the plurality of measurement elements; a positional encoder configured to register a position of each of the measurement elements when the trigger element is activated; and a controller, wherein the controller constructs a surface geometry model from the registered measurement element positions.

Description

RELATED APPLICATIONS

The present application is a continuation-in-part of PCT Application No. PCT/IL2004/000069, filed on Jan. 23, 2004, and a continuation-in-part of PCT/IL2004/000062, filed on Jan. 22, 2004, which is a continuation-in-part of U.S. application Ser. No. 10/350,288, filed Jan. 23, 2003, the disclosures of all of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to the determination of measurement element positions, for example for the measurement of surface geometries.

BACKGROUND OF THE INVENTION

There are many applications where knowing the surface structure or internal structure of an object is desirable. A typical solution for ascertaining hard tissue surface structure, especially if the tissue is hard and is underlying soft tissue as is the case in dental care, is to obtain X-Ray CT images of the hard tissue to construct a model based on the images.
Another methodology for determining the surface structure of a mandible is described by U.S. Pat. No. 5,562,448 to Mushabac, the disclosure of which is incorporated herein by reference, which uses an array of sensors that are slid over one or more teeth, to determine surface structure. However, the position of the array must be determined for each measurement of the array. This patent also describes a point-by-point digitizing of jaw-bone surface by penetrating overlying soft tissue to the bone with a sharp probe, multiple times, again, requiring position determination for each point digitization. The multiple position determination may cause registration and/or other accuracy problems.

SUMMARY OF THE INVENTION

An aspect of some embodiments of the invention relates to determining the surface structure or internal structure of an object. The object could be organic, such as a mandible, knee or spinal cord, or inorganic. Various measurement elements can be utilized, either penetrating or non-penetrating depending on the surface to be measured, in conjunction with at least one position encoder to collect position data points which when viewed in conjunction portray the surface being measured. Optionally, a single position encoder is used to accurately measure the position of a plurality of parallel measurement elements, obviating the need for multiple encoder measurement of multiple individual measurement elements. Sensory devices are used to signal measurement element contact with the object. Optionally, the sensory devices act as a mechanical and electrical fuse.
An aspect of some embodiments of the invention relates to accurately measuring the position of a measurement element, such as a needle or pin, only when the element contacts hard tissue, such as bone. Optionally, the invention relates to accurately measuring the position of a measurement element, wherein the measurement element is designed to penetrate one material type and not another. Analysis of these positions allows for a model of the surface geometry measured to be created.
An aspect of some embodiments of the invention relates to determining the surface structure of a spinal cord. By ascertaining the surface geometry of specific areas of the spinal process, pedicle screws can be attached to the patient in alignment for assisting with therapeutic procedures.
An aspect of some embodiments of the invention relates to determining the structure of a knee joint, optionally including cartilage tissue. Measurement elements are used which are optionally designed to penetrate one tissue type but not another. In some embodiments, measurement elements are used which are non-penetrating. Optionally, non-penetrating and penetrating measurement elements are used in combination. Measurement elements are advanced until they make contact with the material they were designed not to penetrate. Individual position measurements of the measurement elements are made once a controller is signaled by a sensory device. Optionally, the sensory devices act as a mechanical fuse to prevent the measurement elements from exerting undesired pressure on a target area. Analysis of these positions allows for a model of the surface geometry measured to be created.
An aspect of some embodiments of the invention relates to measuring tooth contours for customized dental implant and/or crown manufacture and installation. A plurality of measurement elements are advanced from a cartridge to make contact with a tooth. A position measurement is made of each measurement element upon its contact with the tooth, contact being signaled by a sensory device. The surface geometry of the tooth can be determined from these measurements and a dental implant, such as a crown, can be manufactured to fit the measured geometry.
An aspect of some embodiments of the invention relates to the binary measurement of measurement element position wherein a mechanical fuse and an electrical fuse are employed. In an exemplary embodiment of the invention one function of the mechanical fuse is to provide an outlet for the mechanical force being applied to the surface being measured by the measurement element. Optionally, the mechanical fuse is strong enough to not yield under a smaller pressure of penetrating an overlying layer of the surface being measured. In an exemplary embodiment of the invention, where hard tissue surface geometry is being determined, a trigger element is used to signal hard tissue contact by the measurement element and thus instigates position measurement of the measurement element. In some embodiments of the invention the mechanical fuse and the trigger element are combined as a single element. Optionally, the mechanical fuse ensures the pin is in contact with the hard tissue when position thereof is measured.
An aspect of some embodiments of the invention relates to a mechanical fuse which not only transfers motive force to measurement elements, but also aligns them for proper operation.
In an exemplary embodiment of the invention, a cartridge assembly for determining surface geometry of a hard tissue underlying soft tissue is provided. The cartridge comprises a plurality of tapered needles or other tipped elements which are advanced so that the tips penetrate the soft tissue and substantially do not penetrate, or penetrate by a known amount, the hard tissue. The surface may be reconstructed by knowing the relative positions of the tips. In an exemplary embodiment of the invention, the needles are coupled together so that their relative position, in at least one or two dimensions is known, for example, the needles each having a fixed channel along which substantially only motion along the axis of the needle is possible. As the needles move along the fixed channel, and through the soft tissue, a piston continues to exert pressure on the needles. As each individual needle contacts hard tissue, such as cortical bone, the rear end of the tapered needle contacts and eventually breaks through a sensory device. The sensory device is used to signal individual needle contact with hard tissue, prompting the cartridge assembly to take a position reading on the needle, and optionally also to provide a release for the mechanical pressure that the needle would otherwise impart to the hard tissue. Once the cartridge assembly has been signaled that all needles have contacted hard tissue, the needles can then be retracted into the cartridge and removed from the operational area.
An aspect of some embodiments of the invention relates to measuring the dimensions of objects, such as mechanical parts (e.g. spur gears), in order to determine if they are manufactured to specifications.
An aspect of some embodiments of the invention relates to three dimensional scanning using a plurality of sensory devices, or triggers, in lieu of positional encoders. Instead of reading the advancement of the element providing motive force, such as a piston or screw, a series of spaced triggers can be located along the path of motion of a printed circuit board (or microelectromechanical system device or some other substrate) being used to advance measurement elements. As the printed circuit board moves forward, it trips the triggers one by one. Analysis of the number of triggers tripped allows for the measurement of the penetration of the measurement elements.
An aspect of some embodiments of the invention relates to capturing surface contours of any object in order to read, store and/or process them electronically. Optionally, the invention can be used to read, store and/or process a mechanical signature. An example of a mechanical signature is a seal or die with a unique surface contour. The mechanical signature is pressed onto a surface out of which an array of measurement elements is advanced. The measurement elements advance until each one makes contact with the signature, displacing according to the contour of the surface of the mechanical signature. Upon the cessation of pressure applied by the mechanical signature, a surface structure of the mechanical signature can be generated and then processed, for example for storage, display or approval. In other exemplary embodiments of the invention, a “lock” is used in combination with a mechanical “key”. The surface structure of the key can be ascertained by measuring the position of each of the measurement elements at the point of contact with the key in order to portray an overall surface structure. The measured surface structure is then compared to acceptable surface structures on file, and if there is a match, the key bearer is permitted entrance to the locked area. In other aspects of the invention, an object is “scanned” by measuring its surface contour as described above.
There is thus provided in accordance with an exemplary embodiment of the invention, an apparatus for determining measurement element positions, comprising: a plurality of measurement elements; at least one trigger element corresponding to each element of the plurality of measurement elements; a positional encoder configured to register a position of each of the measurement elements when the trigger element is activated; and a controller, wherein the controller constructs a surface geometry model from the registered measurement element positions. Optionally, the trigger element is a mechanical fuse whereupon trigger activation the trigger element allows passage of the measurement element therethrough. Optionally, the trigger element is an electrical fuse, the trigger element indicating when position measurement of a measurement element should be performed upon electrical fuse activation. Optionally, the trigger element is a mechanical and an electrical fuse. Optionally, the trigger element is composed of a conductive rubber. In some exemplary embodiments of the invention, the trigger element indicates when an exerted force by the measurement element exceeds a predetermined threshold. Optionally, the exerted force is measured by a strain gauge. Optionally, the trigger element is composed of a thin wire bond. Optionally, the trigger element is composed of a conductive adhesive. In some exemplary embodiments of the invention, the trigger element is composed of a perforated flex-printed circuit board. Optionally, the measurement element is disposed to penetrate a first substance but not a second substance. Optionally, the trigger element is disposed to activate at a pre-determined threshold. Optionally, a plurality of trigger elements corresponds to each element of a plurality of measurement elements. Optionally, each of the plurality of trigger elements activates in response to a different pre-determined threshold. In some exemplary embodiments of the invention, the controller superimposes the surface geometry model onto a previously-acquired scan. Optionally, the controller compares the surface geometry model to a second surface geometry model. Optionally, the controller further analyzes the surface geometry model for the proper locations for insertion of a plurality of aligned pedicle screws. Optionally, the measurement elements serially trigger a plurality of triggering elements associated with each of the measurement elements. In some exemplary embodiments of the invention, the measurement elements are activated by hydraulics. Optionally, the measurement elements are activated by pneumatics. Optionally, the measurement elements are activated by wire. Optionally, the measurement elements are activated by screw.
There is thus provided in accordance with an exemplary embodiment of the invention, a method for determining measurement element positions, comprising: (a) instigating the movement of a plurality of measurement elements; (b) signaling at least one measurement element triggering a sensory device; and (c) measuring at least one measurement element position at time of sensory device triggering. Optionally, the sensory device is composed of a conductive rubber. Optionally, the sensory device is composed of a wire bond. Optionally, the sensory device is composed of a conductive adhesive. Optionally, the sensory device is composed of a perforated flex-printed circuit board. Optionally, the measurement element is disposed to penetrate a first substance but not a second substance. In some exemplary embodiments of the invention, the method further comprises constructing a surface geometry model from the measurement of measurement element positions. Optionally, the surface geometry model is used to accurately place a plurality of pedicle screws in alignment. Optionally, the surface geometry model is used to create an object fitted to the model. Optionally, the object is a knee meniscus. Optionally, the surface geometry model is compared to a second surface geometry model.
There is thus provided in accordance with an exemplary embodiment of the invention, an apparatus for scanning, comprising: a plurality of measurement elements; a trigger element corresponding to each element of the plurality of measurement elements; a positional encoder configured to register a position of each of the measurement elements when the trigger element is activated; and a controller, wherein the controller constructs a surface geometry model from the registered measurement element positions.
There is thus provided in accordance with an exemplary embodiment of the invention, a method of measuring the surface geometry of a jawbone, comprising: (a) instigating the movement of a plurality of measurement elements into a soft tissue surrounding the jawbone; (b) signaling at least one measurement element triggering a sensory device upon contact with the jawbone; and (c) measuring at least one measurement element position at time of sensory device triggering. Optionally, the sensory device is composed of a conductive rubber. Optionally, the sensory device is composed of a wire bond. Optionally, the sensory device is composed of a conductive adhesive. Optionally, the sensory device is composed of a perforated flex-printed circuit board. In some exemplary embodiments of the invention, the method further comprises constructing a surface geometry model from the measurement of measurement element positions. Optionally, the surface geometry model is used to create an object fitted to the surface geometry model. Optionally, the surface geometry model is used for locating a host device on the jawbone.

BRIEF DESCRIPTION OF THE FIGURES

Non-limiting embodiments of the invention will be described with reference to the following description of exemplary embodiments, in conjunction with the figures. The figures are generally not shown to scale and any measurements are only meant to be exemplary and not necessarily limiting. In the figures, identical structures, elements or parts which appear in more than one figure are preferably labeled with a same or similar number in all the figures in which they appear, in which:
FIG. 1A is a perspective external view of a cartridge assembly in accordance with an exemplary embodiment of the invention;
FIG. 1B is a perspective internal view of a cartridge assembly in accordance with an exemplary embodiment of the invention;
FIG. 1C is a top view schematic of a PCB with multiplexer in accordance with an exemplary embodiment of the invention;
FIG. 2 is a perspective view of a host device incorporating a cartridge assembly in accordance with an exemplary embodiment of the invention;
FIG. 3A is a perspective view of the host device containing the cartridge assembly in its operating environment in accordance with an exemplary embodiment of the invention;
FIG. 3B is a cutaway view of the host device and cartridge assembly therein in accordance with an exemplary embodiment of the invention;
FIG. 4 is a flowchart which describes a method of use in an exemplary embodiment of the invention;
FIGS. 5A-C show a cartridge cutaway of a conductive rubber embodiment in operation in accordance with an exemplary embodiment of the invention;
FIGS. 6A-C show a cartridge cutaway of a thin wire bond embodiment in operation in accordance with an exemplary embodiment of the invention;
FIG. 6D shows a combined retraction element with the PCB in accordance with an exemplary embodiment of the invention;
FIGS. 7A-C show a cartridge cutaway of a conductive adhesive embodiment in operation in accordance with an exemplary embodiment of the invention;
FIGS. 8A-C show a cartridge cutaway of a perforated flex-PCB embodiment in operation in accordance with an exemplary embodiment of the invention;
FIGS. 9A and 9B are illustrations of the retraction ring operation in accordance with an exemplary embodiment of the invention;
FIG. 10 is a sample cartridge design in accordance with an exemplary embodiment of the invention;
FIG. 11 is a flowchart depicting a method of use for measurement of the surface geometry at or near the knee joint in accordance with an exemplary embodiment of the invention;
FIG. 12 is a view illustrating position registration in the vicinity of a knee joint in accordance with an exemplary embodiment of the invention;
FIG. 13 is a flowchart depicting a method of use for measurement of the surface geometry of a spinal cord in accordance with an exemplary embodiment of the invention;
FIG. 14 is a cross-sectional view of a spinal cord illustrating position registration in accordance with an exemplary embodiment of the invention;
FIG. 15A is a flowchart depicting a method of use for scanning in accordance with an exemplary embodiment of the invention;
FIG. 15B is an illustration of scanning an object in accordance with an exemplary embodiment of the invention;
FIG. 16 is a flowchart depicting a “key”/“lock” method of use in accordance with an exemplary embodiment of the invention;
FIG. 17 is a flowchart depicting a method of use for quality assurance in accordance with an exemplary embodiment of the invention;
FIG. 18 is a schematic showing an overall system for position measurement, in accordance with an exemplary embodiment of the invention;
FIG. 19A is a profile view of a measurement element which is optionally used in conjunction with a cartridge assembly in accordance with an exemplary embodiment of the invention; and,
FIG. 19B is a profile and top view of a measurement element which is optionally used in conjunction with a cartridge assembly in accordance with an exemplary embodiment of the invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

General Description of an Exemplary Embodiment

Referring to FIG. 18, a schematic showing an overall system 1800 for determining measurement element positions is shown. Measurement elements 102 are depicted protruding out of a cartridge assembly 100 generally in the direction of an object whose surface geometry is to be measured. Measurement elements 102 and cartridge assembly 100 are described in greater detail below. A control module 1804 is provided in operative communication with at least one cartridge assembly 100. In some exemplary embodiments of the invention, communication comprises data generated by at least one cartridge assembly 100. Optionally, communication comprises data generated by control module 1804. Optionally, communication is achieved via electronics. In some exemplary embodiments of the invention, communication is comprised of movement impetus generated at control module 1804. Optionally, communication is achieved via hydraulics. Optionally, communication is achieved via pneumatics. Optionally, communication is achieved via a mechanical mechanism, such as by wire or screw. In some exemplary embodiments of the invention, control module 1804 is also operationally in communication with a data processing device (not shown). Optionally, a data processing device is a computer.
A hub 1802 is optionally positioned between at least one cartridge assembly 100 and control module 1804, in an exemplary embodiment of the invention. Hub 1802 optionally receives at least one assembly tube 1806 from at least one cartridge assembly 100. In some exemplary embodiments of the invention, an assembly tube 1806 has located within its lumen a tube 1808 for imparting forward movement (movement towards an object to be measured) to the plurality of measurement elements 102, and a tube 1810 for imparting a retracting movement to measurement elements 102. In an exemplary mode of operation, tubes 1808, 1810 are filled with a substantially non-compressible fluid, such as water. Optionally, the non-compressible fluid is transported in a closed system. Application of force on a control located at control module 1804 moves the column of water located within tube 1808 towards cartridge assembly 100. This forward motion results in the movement of measurement elements 102 towards the object whose surface geometry is being measured. In some exemplary embodiments of the invention, the control is operationally connected to at least one piston which is in communication with the non-compressible fluid in tube 1808. Optionally, the control is operationally connected to a motor which drives the piston in communication with the non-compressible fluid in tube 1808. Application of force on an optional, additional control, forces the movement of the water column through tube 1810 towards cartridge assembly 100 thereby causing a retracting movement of measurement elements 102. In some exemplary embodiments of the invention, the additional control is operationally connected to at least one piston which is in communication with the non-compressible fluid in tube 1810. Optionally, the additional control is operationally connected to a motor which drives the piston in communication with the non-compressible fluid in tube 1810. The appropriate application of force on the first, forward control and then the additional, retraction control permits a measurement of a surface geometry to be taken and the retraction of the measurement elements, in some exemplary embodiments of the invention. As described herein, movement is optionally effectuated using pneumatic and/or mechanical means in addition to hydraulics. An electrical and/or data communication conduit 1812 is also provided in some exemplary embodiments of the invention.
In some exemplary embodiments of the invention, hub 1802 receives a plurality of assembly tubes from a plurality of cartridge assemblies. Optionally, hub 1802 bundles the plurality of assembly tubes in order to make a less space consuming and/or more unitary tubular connection to control module 1804. In some exemplary embodiments of the invention, hub 1802 permits the addition and/or removal of substances from tubes 1808, 1810. For example, fluids can be added or removed from tubes 1808, 1810 at hub 1802. Optionally, air can be added or removed from tubes 1808, 1810 at hub 1802. In some exemplary embodiments of the invention, none, some or all of the elements of overall system 1800 are reusable. Optionally, none, some or all of the elements of overall system 1800 are designed to be replaced after a pre-determined number of uses. Optionally, element failure is designed by incorporating pre-determined failure level seals. Optionally, none, some or all of the elements of overall system 1800 are disposable. In some exemplary embodiments of the inventions, removably interlocking interfaces are provided between disposable and reusable elements of overall system 1800.
FIG. 1A is a perspective view of a cartridge assembly 100 containing an array of measurement elements 102 in accordance with an embodiment of the present invention. Referring now to FIG. 1B, what is provided is a cutaway detail of an example cartridge assembly. In this embodiment of the invention, the cartridge assembly contains surgical grade needles 104 as measurement elements. It should be noted however, that in other exemplary embodiments, the measurement elements are adapted to be non-penetrating. Non-penetrating configurations include blunt and/or flat tips. The rear ends of the needles 104 are optionally slightly larger than the element bodies, causing the needles 104 to be at least slightly tapered. The needles 104 can optionally be tapered by pressing the ends until they deform to be wider, by manufacturing the needles 104 using an over-mold or by coating the rear ends with a UV-curable resin. Many other methods of expanding the rear end of the needle are well known in the art and can be utilized to provide a needle with an expanded rear end. In some exemplary embodiments of the invention, measurement elements 102 are coated. Optionally, measurement elements 102 are coated with a non-electrically conductive coating. Optionally, measurement elements 102 are coated with a sterile coating. Optionally, measurement elements 102 are coated with a drug eluting coating. In some exemplary embodiments of the invention, the tips of measurement elements 102 are conical. In some exemplary embodiments of the invention, the tips of the measurement elements 102 are beveled. Optionally, the tips are angled no more than 60°. Optionally, the tips are angled more than 60°.
In addition, the motion guides 106 used for providing a transit channel to the needles 104 are shown. The motion guides 106 are optionally made of a rigid material and have drilled holes that match the needle array arrangement (e.g square, hexagonal grid). The guides 106 also optionally serve as the external case for the cartridge 100. Located at the rear end of each of the needles 104 is at least one sensory device, optionally of the types depicted in FIGS. 5A, 6A, 7A and 8A. Also depicted is the printed circuit board 110, or PCB, which optionally or alternatively transfers movement force from a piston 150 to the needles 104, provides contacts for the sensory devices and/or interfaces electrically with the cartridge assembly 100. In some exemplary embodiments of the invention, piston 150 is moved forward towards an object being measured by application of force via tube 1808. A contrary force is optionally applied to piston 150 via tube 1810 to effectuate a retraction of piston 150. Optionally, the PCB has a flex-PCB extension which connects to external wires. In some embodiments of the invention, the external wires are braided with hydraulic tubes used for providing motive force to the needles. Various other methods may optionally be used to electrically connect flex-PCB to the piston 150, including for example: a ball grid array on the flex-PCB electrically connected to flat contacts on the piston 150; a flat contact electrically connected to spring contacts on the piston; a connector that electrically contacts as the piston is pressed against the flex-PCB; and, a connector that is manually placed into electrical contact when attaching the cartridge 100. To decrease the number of connectors out of the PCB 110, a multiplexer is optionally used, for example formed using simple parallel to serial converter chips (e.g. 74165). Each chip provides 8 parallel inputs and the chips can be cascaded to allow an arbitrary number of input lines, with only 4 output lines (2 for power, 2 for serial data output).
In some embodiments of the invention, the piston 150 is a dual-action piston which applies pressure in both directions of movement, pushing and pulling, for the needles. During insertion, the piston 150 pushes, via PCB 110, the needles into the area where the surface geometry is being measured. Upon retraction, the piston pulls the needles out. In some exemplary embodiments of the invention, piston 150 operates on hydraulic pressure. Optionally, flow through tube 1808 forces piston 150 movement towards the surface geometry is measured. Flow in tube 1810 causes an opposite effect on piston 150. Optionally, the piston exerts up to 20 atmospheres of pressure. Retraction elements 112 located near the rear end of the needles 104 are optionally used to assist with needle retraction after position measurements have been made. Retraction of the needles is described in more detail below. In some exemplary embodiments of the invention, piston 150 is located on a back-plate which is attached to back of cartridge assembly 100 such that piston 150 extends through cartridge assembly 100 and abuts PCB 110 in order to provide movement to PCB 110.
Turning to FIG. 1C, the top view of an exemplary PCB 110 is shown. This provides a view of the PCB 110 which is on the opposite side of the cartridge assembly 100 from the needle 104 tips. A multiplexer 114 is located on the PCB 110 in this example. In this configuration, the various sensory devices are operationally connected to the multiplexer 114 for data processing. Data output from the multiplexer 114 is optionally wireless. The multiplexer 114 is optionally located elsewhere within the cartridge assembly.
Optionally, the needles can be located in a reusable portion of the cartridge assembly 100. In an exemplary embodiment of the invention, the PCB 110 and the piston 150/movement force portion of the cartridge assembly 100 removably attach onto the back of a reusable needle packet. Between each use the needles and/or the needle portion of the cartridge assembly are sterilized while the PCB/movement portion is discarded.
Determining the Surface Geometry of a Mandible
Referring now to FIG. 2, it can be seen in an embodiment of the invention that at least one cartridge assembly 100 can be used in conjunction with a host device 200. While various configurations of a host device can be employed with the inventive cartridge assembly 100, such as depicted in Pub. No. WO 2004/65893, the disclosure of which is incorporated herein by reference, it is to be understood that the cartridge assembly of this embodiment is preferably disposable and should be sized to be used intra-orally. Alternatively, the cartridge assembly 100 is configured so that it can be sterilized between uses. Optionally, the host device 200 is operationally connected to cartridge assembly 100 such that activation of the cartridge assembly is triggered by the host device 200. A visual or audio indicator that the cartridge assembly 100 is operating is optionally provided. Optionally, the location of each cartridge used in the host device is known by coding the cartridges and/or specific locations on the host device. By using the coding on the cartridges in conjunction with the coding on the host device it can be known where each cartridge is located. For example, two bumps on the host device and two pins in the cartridge can be used where the bumps are unique to the location on the host device and pins are unique to the cartridge.
A view of the host device containing the cartridge assembly in its operating environment is provided in FIGS. 3A and 3B. The host device 200 is depicted in temporally fixed position in the patient's mouth. From the FIG. 3B view, it can be seen that the cartridge assembly 100 is faced with the needle tips towards the patient's gums 300 and underlying jaw 302.
FIG. 4 is a flowchart which describes a method of use in an exemplary embodiment of the invention. At action 400, the host device 200 is secured to a patient's gums 300, and therefore jaw 302, to provide a stable operating environment for the cartridge assembly 100. The cartridge assembly 100 is then inserted into the host device 200, at action 402. Once the host device 200 is affixed to the jaw 302, and the cartridge is in place within the host device, the cartridge is activated at action 404. It should be noted that host device 200 is optionally positioned in a patient's mouth after an analysis of an image previously made of the patient's jaw for the optimal position of host device 200. Optionally, the image is a CT image.
Following cartridge assembly activation, the needles 104 penetrate, at action 406, into the soft tissue 300 (i.e. gums) of the patient. It should be noted that upon activation, in some exemplary embodiments of the invention the rear ends of the needles 104 abut the sensory devices. However, the sensory devices have sufficient strength to withstand the pressure exerted by the rear ends of the needles 104 while they penetrate soft tissue 300. While the needles 104 are in motion, the sensory devices are constantly monitored, indicated by action 408, for a broken/not broken condition. In an exemplary embodiment of the invention, the fuses are polled one by one to detect a change in their resistance.
Eventually, the needles 104 begin to contact hard tissue 302 (i.e. the jaw bone). As pressure is maintained on the needles 104 after they have contacted the jaw bone 302, the rear end of the needles 104 exert sufficient pressure on the sensory devices to trigger and break them. This has two basic effects, the first is that mechanically the sensory device is broken, the needle 104 no longer exerts unwanted pressure on the jaw bone 302 because the needle 104 is not being pushed by the piston via the sensory device, and the second is that the cartridge electronics and/or controller can detect that the needle 104 has contacted bone 302, because of the triggering of the sensory device, and therefore a position measurement on the needle is to be made.
Once the sensory device is triggered, a signal indicating that the sensory device has been triggered is received by the cartridge electronics and/or controller. Therefore, at action 410 the cartridge electronics and/or controller calculate the penetration of the needle 104 corresponding to the triggered sensory device. In one embodiment of the invention, measurement is made by calculating the distance moved by the pushing piston at the time the signal was received and then attributing the distance moved by the piston to the needle which triggered the sensory device. By using the piston as the basis for distance measurement for all of the needles, only one position encoder needs to be used per cartridge. An additional benefit of the invention derives from the fact that a measurement of a specific needle's penetration is made only once, at the time that it triggers its corresponding sensory device. In other words, position measurement is not conducted multiple times or continuously for each needle.
In an exemplary embodiment of the invention, the measurement system consists of an optical scale printed on Mylar and attached to a reflective metallic substrate (USdigital 180 CPI linear encoder strip on polished Aluminum backing), and an optical encoder chip that senses the relative motion with respect to the scale and provides a position-sensitive digital output (e.g. Agilent ADER8300).
An alternate option is to operate the motion of the piston by a screw (rotational) mechanism. In this case a low cost optical encoder (e.g. USdigital ER4) can be used to count screw rotations so that position can be extracted therefrom.
Optionally, a plurality of position coders are used with a plurality of pistons in order to gauge if the measurement elements are being advanced in parallel by the cartridge assembly. Measurement using the plurality of positional encoders if the advancement is not in parallel allows for correctional calculations to be performed in order to accurately portray the measured surface geometry.
In an exemplary embodiment of the invention hydraulic pressure is provided as the motive force. At action 410 displacement measurements are optionally made by measuring the amount of hydraulic fluid used to move the needle 104 up to the point of contact. For instance, it is known what volume of hydraulic fluid correlates to a specific distance of movement of the needle 104. Therefore, upon the breaking of the sensory device, rather than using an encoder to measure the displacement of the needle in the cartridge assembly 100, a measurement is made of the hydraulic fluid expended to that point and an equivalent distance of displacement is calculated. Optionally, the hydraulic fluid is measured by calculating the loss of fluid volume from a reservoir.
In an exemplary embodiment of the invention, at action 410 displacement measurement can be made by using thin wire bonds as extra encoder sensors. In operation, these wire bonds are tom by accurately placed bumps in the cartridge assembly 100. Instead of reading the advancement of the element providing motive force, such as a piston or screw, a series of spaced thin wire bonds can be located along the path of motion of a printed circuit board being used to advance measurement elements. As the printed circuit board moves forward, it trips the thin wire bonds one by one. Analysis by the cartridge electronics and/or controller of the number of triggers tripped allows for the measurement of the penetration of the measurement elements. Optionally, a combination of measuring hydraulic volume and using thin wire bonds as extra encoder sensors is used to measure the penetration of the measurement elements.
In some embodiments of the invention, sensory device trigger information is relayed in similar fashion to the way some charge-coupled devices operate. That is using a vertical/horizontal shift register operation to read out the last row of an array. The array is optionally comprised of a plurality of capacitors which receive electric charge as long as a sensory device remains unbroken and provides an operative electric circuit. A capacitor or a line of capacitors corresponds to each sensory device. As electric charge passes through the sensory device and to the capacitor the electric charge is eventually read out in a register and where voltage is detected the sensory device is regarded as untriggered. When the sensory device is broken, electric charge can no longer accumulate in the capacitor corresponding to the sensory device and therefore the voltage reading for that sensory device will be 0. A 0 voltage reading is regarded as a broken sensory device. In an exemplary embodiment of the invention, operation of the array is regulated by a control circuit. The control circuit causes each element of the array to transfer its contents to a specific neighbor, eventually the contents being read by a register.
In an exemplary embodiment of the invention, at action 410 displacement measurement is optionally made by measuring a thread or wire. In this embodiment, the needles 104 are advanced mechanically by a screw which is operationally attached to the thread and which turns as the thread is pulled. It is known what length of thread correlates to a specific distance of movement of the needle 104. Therefore, when the needle breaks the sensory device, the amount of thread pulled to that point can be measured to determine an equivalent displacement of the needle 104.
Action 412 indicates that movement of the needles 104 is sustained until the cartridge electronics and/or controller detect that most or all sensory devices have been broken. In some embodiments of the invention, not all sensory devices need to break, some may stay intact but the motion end can still be detected by encoder or encoder wires in the cartridge assembly 100. Based on the measurements taken of needle positions at the time of sensory device rupture, at action 414 a three dimensional surface geometry model can be generated of the subject jaw 302 by the cartridge electronics and/or controller by mapping the position of each of the measurement elements. Optionally, the cartridge 100 can be tested, at action 416, for its operational status prior to use by testing the electrical connectivity of the sensory devices in the cartridge. The needles 104 are optionally retracted 418 from the patient's gums 300 prior to generation of a model, or alternatively, after the model is created.
Pressure-Activated Conductive Rubber as a Sensory Device
In FIG. 5A, an embodiment of the present invention utilizing a layer of pressure-activated conductive rubber 500, such as Zoflex®brand by Xilor company, is used for mechanical and electrical fusing instead of sensory devices. Optionally, the conductive rubber layer is up to 0.5 mm in thickness. Optionally, the conductive rubber layer is 0.5 mm to 1 mm in thickness. Optionally, the conductive rubber layer is greater than 1 mm in thickness. In some exemplary embodiments, conductive rubber is used because it can act both as a mechanical fuse and an electrical fuse. Conductive rubber is also well suited for use in the invention because metal fuses can be subject to elastic deformation, thereby causing inaccuracy in the position measurement of the needles 104. An additional advantage of using rubber is its low cost and ease of manufacture. FIG. 5B shows movement of this embodiment as the needles 104 penetrate the patient's gums 300. The motive force of the piston can derive from mechanical means, like a screw, or from hydraulic pressure, or from pneumatic pressure, as is commonly found in dental clinics. As each needle 104 encounters the jawbone surface 302 the needle base touches a sheet of pressure-activated conductive rubber 500. The increased pressure on the rubber 500 eventually penetrates it and once the cartridge electronics and/or controller register needle penetration of the rubber, the position of the needle 104 is registered. The rubber 500 thus also acts as a “mechanical fuse” that breaks down at a certain pressure after activation and prevents unwanted pressure on the jaw bone 302.
Optionally, rubber is used which changes conductivity based on its state of elastic deformation. In an exemplary embodiment of the invention, conductivity of such a rubber is known in a non-deformed state and in various stages of elastic deformation. In order to make position measurements, the rubber is tested for its conductivity and based on the readings and the values known to correlate to different degrees of deformation, the position of the measurement element can be calculated.
In an exemplary embodiment of the invention, rubber is used to detect multiple layers of tissue (e.g. soft tissue and hard tissue). For example, as the measurement elements are advanced and make contact with soft tissue, the rear ends of the elements will begin to elastically deform the rubber. A position measurement can be made at the time the rubber begins to deform, in order to locate the surface of the soft tissue. As the measurement element is advanced through the soft tissue and on to the hard tissue, the rubber may continue to deform, however it does not break until contact with the hard tissue. Upon breakage, the position of the measurement element is again taken in order to determine the surface of the hard tissue. In an exemplary embodiment of the invention, a rubber is used which deforms and a certain threshold but does not break until reaching an additional, higher threshold.
FIG. 5C illustrates the resultant condition of the cartridge assembly 100. At the end of the piston motion all needle position measurements should be registered. It is important to note that the electrical interface to the cartridge enables separate registration of individual needle 104 position measurements. After registration of all needle bone contact displacements, the needles are pulled back into the cartridge. At the end of the pullback operation all the needles 104 are inside the cartridge and the cartridge 100 can be safely disengaged from the host device 200.
In an exemplary embodiment of the invention, the cartridge is a disposable item and used only once. Since it has needles that penetrate the gums, it requires a safe disposal package that will ensure no accidental future contamination. The disposal package optionally also ensures that all needles are unbroken and contained in the disposed-of cartridge.
In an exemplary embodiment of the invention, the cartridge is made reusable by pre-boring holes in the rubber. As the cartridge advances, the rubber begins to elastically deform until finally the rear end of the measurement element passes through the pre-bored hole upon contact with hard tissue. After the measurement elements are removed from the area being measured, the needles can be pulled back out of the holes and the cartridge can be used again after sterilization.
Thin Wire Bonds as a Sensory Device
Another exemplary embodiment of the invention, utilizing thin wire bonds 600 for mechanical and electrical fusing, is shown in FIG. 6A. In FIG. 6B, as the PCB 110 is moved towards the gums 300, the wire bonds 600 push on the backs of the needles 104 and press them into the gums 300. When each needle 104 encounters the jawbone 302 surface, the needle base begins to exert further pressure on the thin wire bond 600. Pads encircling each needle 104 provide the contact to the wire bond sensor 600. The thin wire is bonded to the pads on two sides of each needle 104. Optionally, there is a plurality of thin wire bonds used for each needle 104. The increased pressure on the wire-bond 600 eventually breaks the wire-bond 600 and the needle position at that time is registered. In an exemplary embodiment, the pads are electrically connected to the cartridge electronics and/or controller that sense when the wire 600 is torn and is not conducting. In FIG. 6C, the resultant condition of the cartridge assembly is illustrated. As in the conductive rubber 500 exemplary embodiment, the wire-bond 600 thus acted as a “mechanical fuse” that broke down at a certain pressure after activation thereby providing that no excessive unwanted force was transferred to the bone 302. The wire bond exemplary embodiment also optionally includes a retraction foil/surface that catches the needles 104 after bone contact to ensure full retraction of all needles. It should be noted that force can be calibrated to different values by varying the wire bond thickness and/or changing the bonding process (loop height, wire tension, etc.).
Conductive Adhesive as a Sensory Device
Referring now to FIG. 7A, yet another exemplary embodiment of the current invention can be seen utilizing conductive adhesive 700 stabbing for mechanical and electrical fusing. Similar to the conductive rubber, use of a conductive adhesive as a sensory device presents certain potential advantages over metal fusing. For example, the conductive adhesive is not as susceptible as metal fuses to elastic deformation prior to “breaking” and therefore it can be more accurate. In addition, conductive adhesive is cheaper and easier to manufacture than some other alternatives. Conductive adhesive can be screened onto the PCB by using an underlying tray of Teflon® pins which match up to the holes in the PCB for the sensory devices. Use of the Teflon® pins prevents the adhesive from falling into the holes in the PCB during manufacture. FIG. 7B shows the PCB 110 to driving the needles 104 of the cartridge assembly 100 into the gums 300 of the patient. As the individual needles 104 come into contact with the underlying hard tissue 302 (i.e. jaw bone) the backside of the needle presses the conductive adhesive (e.g. Cookson Polysolder). As the PCB 110 continues to apply pressure to the needle 104, the back side of the needle eventually pushes through the conductive adhesive 700, relieving the pressure on the bone. By eventually allowing passage of the needle 104, the conductive adhesive 700 provides a “mechanical fuse” to prevent over-penetration of the needles 104 into the hard tissue 302 being measured. Ideally, a conductive adhesive 700 is used that breaks or tears without significant elastic deformation. FIG. 7C shows the cartridge assembly 100 after the needles 104 have penetrated through the conductive adhesive 700.
Optionally, a thin non-conducting layer is located between the conductive adhesive 700 and the needle 104. The thin non-conducting layer can optionally be used to regulate the pressure required to activate position measurement of the needle. Once the predetermined breaking pressure of the non-conducting layer is reached, the needle 104 penetrates the non-conducting layer, and then contacts the conductive adhesive 700, thereby instigating a position measurement. In this embodiment, the non-conducting layer acts as a mechanical fuse in place of, or in addition to, the conductive adhesive. In an exemplary embodiment of the invention, replacement of the thin non-conducting layer allows for reuse of the cartridge.
Perforated Flex-Printed Circuit Board as a Sensory Device
FIG. 8A depicts an additional exemplary embodiment which utilizes tearing of a perforated flex-PCB 800 for mechanical and electrical fusing. FIG. 8B shows the PCB 110 to driving the needles 104 of the cartridge assembly 100 into the gums 300 of the patient. As the individual needles 104 come into contact with the underlying hard tissue 302 (i.e. jaw bone) the backside of the needle presses the perforated flex-PCB 800 (e.g. a layered FR4/copper/polyimide composite). As the PCB 110 continues to apply pressure to the needle 104, the back side of the needle eventually pushes through the perforated flex-PCB 800, relieving the pressure on the bone. By eventually allowing passage of the needle 104, the perforated flex-PCB 800 provides a “mechanical fuse” to prevent over-penetration of the needles 104 into the hard tissue 302 being measured. Ideally, a perforated flex-PCB 800 is used that breaks or tears without significant elastic deformation. FIG. 8C shows the cartridge assembly 100 after the needles 104 have penetrated through the perforated flex-PCB 800. After registration of all needle bone contact displacements, the needles are pulled back into the cartridge.
Strain Gauge as a Sensory Device
In an exemplary embodiment of the invention, a breaking strain gauge is used as a sensory device. The strain gauge not only provides a mechanical fuse, and optionally an electrical fuse, it is capable of measuring force during insertion. The strain gauge begins to stress as the measurement elements are made to come into contact with a surface. In some embodiments of the invention, where a second, underlying surface is to be measured, the strain gauge is strong enough to withstand the stresses placed on it by penetrating the measurement elements through the first surface. In other embodiments of the invention, the strain gauges are adapted to break at a level of strain commensurate with a first surface. In still other embodiments of the invention, strain gauges of varying strength are used if multiple surfaces are to be measured.
Retraction of Measurement Elements
The retraction principles described are capable of being used with any of the embodiments described herein. Optionally, the backside of the needles are wider than the tip to enable retraction of the needles. Optionally, the measurement elements have a ratchet mechanism that cooperates with a conical hole. In use, the needles pass through a retraction element 112, one retraction element 112 per needle 104. Optionally, linear holes for lines of measurement elements are used. The ring element has a shaped hole that allows passage of the main part of the needle but not the expanded backside. It can be either a plastic or metal membrane that is attached to the front of the PCB 110, such that the needle's expanded backside is held in place before gum penetration. In this configuration, the retraction element 112 also serves to hold the needles 104 in place and prevent needles from ‘falling out’ of the package.
Another option is to combine the retraction element 112 with the PCB 110. In manufacturing, the needles 104 are inserted through the PCB 110 prior to wire bond 600 manufacture, see FIG. 6D. The PCB holes 680 serve as the retraction ring, being smaller in diameter than the widened end 682 of the needles. The needles 104 can be constrained between the PCB 110 and wire bonds (in the exemplary embodiment depicted in FIGS. 6A-C).
As described above, the piston 150 is optionally a dual-action piston which applies pressure in both directions of movement, pushing and pulling, for the needles. During insertion, the piston 150 (not shown in FIG. 6D) pushes the needles into the area where the surface geometry is being measured. Upon retraction, the piston pulls the needles out. Pulling the needles out is optionally accomplished using an embodiment wherein the rear end of the needles is wider than the main body. The main body of the needles is passed through a hole in the PCB 110, but the rear end is too large to pass through. When the PCB 110 moves forward to penetrate the needles into the area being measured, the sensory devices exert pressure on the rear ends of the needles to enable penetration. However, when the PCB 110 moves in a retracting direction, the needles are pulled out because the expanded rear ends are larger in diameter than the holes, and cannot pull through, thereby the needles retract from the area being measured. Optionally, the needles 104 are retracted or allowed to retract (e.g. having spring retraction), prior to cartridge removal. Alternatively or additionally, the host 200 is pulled away from the jaw bone 302, so that the needles 104 are manually retracted. Alternatively or additionally, the cartridge 100 is extracted from the host 200 such that the needles 104 are removed from the soft tissue 300.
Referring to FIG. 19A, an exemplary measurement element 1900 is shown which is comprised of a tip 1902, which is optionally adapted and constructed to penetrate and/or not penetrate predetermined materials as described herein, and a rear end 1904. In some exemplary embodiments of the invention, rear end 1904 is provided with an enlarged head 1906 by which measurement element 1900 is optionally retracted. FIG. 19B is a profile view wherein, in an exemplary embodiment, measurement element 1908 is provided with a rear end 1910 with an enlarged head 1912 that is optionally manufactured by pressing or coining rear end 1910 to cause deformation, until rear end 1910 deforms to be wider. As described previously, the enlarged head 1912 optionally permits retraction of measurement element 1908 from the patient.
Exemplary Cartridge Assembly
FIG. 10 is an example of a possible cartridge assembly 1000 configuration. The cartridge assembly 1000 has an electrical interface 1050 with 4 ports (2 power, 2 serial data) on a front PCB 1006 by direct contact to PCB pads (a few cartridges can be cascaded to the same external serial line). Mechanically, the front PCB 1006 functions as motion guides and are part of cartridge 1000, and spring loading is applied to keep cartridge open and enable quick retraction of needles. In an exemplary embodiment of the invention, screws 1002 are used to advance the rear PCB 1100 and thus the measurement elements 1004. Upon triggering of the sensory devices 1108 located on the rear PCB 1100 an optical encoder is used to count the distance traveled by the screw. Optionally, this is performed by counting screw threads. An overall surface geometry is assembled by examining the readings of each measurement element together.
In an exemplary embodiment of the invention, a cartridge is assembled by first inserting the measurement elements into a plastic stiffener/holder. The PCB is then attached to the stiffener by placing the PCB on plastic pins on the stiffener. Optionally, the pins are melted to further secure the PCB into place. These assembled components are known as the sensor assembly. The sensor assembly with the needles and PCB attached is then attached to the piston and piston related components. Encoder bumps are optionally located on special flat pieces which are inserted into a housing for the cartridge. The sensor assembly and the piston part are then inserted into the housing which is itself attached to a piston. Optionally, the piston is filled with fluid prior to its assembly.
Knee-Joint Surface Geometry
Turning now to FIG. 11, a flowchart 1100 is depicted which describes a method of using a cartridge assembly 1148 to measure the surface geometry of a knee joint, in an exemplary embodiment of the invention. The cartridge assembly 1148 is provided with measurement elements 1250, depicted in FIG. 12, optionally used to measure: soft tissue (e.g. cartilage, ligaments) and hard tissue (e.g. bone); just hard tissue; and/or just soft tissue. Ascertaining the surface geometry of a knee joint is helpful for knee cartilage replacement operations, for example. Soft tissue that is optionally measured includes the patella, the articular cartilage, the lateral meniscus, the medial meniscus, the collateral ligaments, the posterior cruciate ligament and/or the anterior cruciate ligament. Hard tissue that is optionally measured includes the femur, the tibia and/or the fibula. Some or all of the hard tissue and/or soft tissue can be measured for surface geometry alone or in combination. Furthermore, non-radiological methods for measuring the surface geometry of a knee joint can save costs while maintaining accuracy of measurement.
In an exemplary embodiment of the invention, non-penetrating measurement elements are used. Non-penetrating measurement elements are adapted to have a tip that does not substantially penetrate soft tissue prior to triggering the sensory devices. Optionally, penetrating measurement elements, like needles 104, are used. As described above, this arrangement is useful for measuring the surface geometry of hard tissue, like bone, where soft tissue or cartilage may be found overlying the hard tissue.
Additionally or alternatively, non-penetrating and penetrating measurement elements can be used in combination. Such an arrangement is useful for measuring both the surface geometry of the soft tissue and the hard tissue. At action 1102, the cartridge assembly 1148, depicted in FIG. 12, is inserted into a host device. At action 1104, the host device is then inserted into a patient's knee 1122, so that the cartridge assembly 1148 is in close proximity, with the measurement elements facing the desired target area 1123, to the soft tissue and/or hard tissue being measured. Once the host device is appropriately located within the knee 1122, the cartridge is activated at action 1106. Optionally, various sized cartridges are provided depending on the approximate size of the target area 1123 within the knee 1122. If accurate registration is needed, the cartridge assembly 1148 can optionally be attached to hard tissue prior to activation.
Following cartridge assembly activation at action 1106, the procedure 1106-1116 for determining the surface geometry of the desired target area 1123 is similar to that described in various embodiments above.
The measurement elements 1250 are retracted 1118 from the patient's knee target area 1123 prior to generation of a model, or alternatively, after the model is created. Optionally, the surface geometry model created using the described procedure is compared at action 1120 to another model, such as one created through magnetic resonance imaging or computerized tomography. Once a therapeutic course of action is determined for the patient, any excess tissue is removed from the implant area at action 1122 and an implant, or prosthesis, is placed in the appropriate location, at action 1124.
FIG. 12 illustrates a knee joint surface geometry measurement configuration, in an exemplary embodiment of the invention. A cartridge assembly 1148 is shown in close proximity to a knee target area 1123 after having been inserted through a minimally invasive opening near the patient's knee 1122. In an exemplary embodiment of the invention, the cartridge assembly 1148 is used to measure the surface geometry of any cartilage 1202 that may be present in the target area 1123 and/or the underlying hard tissue 1126. In some instances, the hard tissue 1126 is only partially covered by cartilage 1202. The surface geometry of the hard tissue and cartilage can optionally be measured together, using a cartridge assembly 1148 with non-penetrating measurement elements. In the areas where there is cartilage 1202, the measurement elements 1250 will advance to the point of contact with the cartilage 1202 and then trigger the sensory devices (not shown) in the cartridge 1148. Where there is hard tissue 1126, the measurement elements 1250 will advance and similarly trigger the sensory devices upon measurement element contact with hard tissue 1126. As each sensory device is broken, a position measurement is taken of the measurement element 1250 corresponding to that sensory device, as described in other embodiments herein.
In some exemplary embodiments of the invention, the cartridge assembly 1148 is used to measure the surface geometry of the hard tissue 1126 without regard for the presence of cartilage 1202 or soft tissue in the target area 1123. The cartridge assembly is thusly configured to use penetrating measurement elements.
Optionally, penetrating and non-penetrating measurement elements 1250 are provided to measure both soft and hard tissue. Optionally, sensory devices are provided which are adapted to trigger according to the type of tissue being measured. For example, sensory devices used in conjunction with soft tissue measurements can have a lower pressure tolerance than sensory devices used in conjunction with hard tissue measurement.
Spinal Cord Surface Geometry
FIG. 13 depicts a flowchart 1300 which describes a method of use for determining the surface geometry of a spinal cord, in an exemplary embodiment of the invention. Pedicle screws are used commonly in conjunction with spinal surgery. Often times, when a plurality of pedicle screws are used and need to be connected together, it is difficult to screw them into the spinal cord so that they are aligned. This is primarily due to the uneven nature of the surface of the spinal cord, but also because it can be difficult to align multiple pedicle screws which are screwed into multiple vertebra. Pedicle screw insertion can be assisted by accurate measurement of the surface geometry of the patient's spinal cord. Proper pedicle screw insertion also realizes safety benefits, including minimizing the likelihood of needing to reinsert a pedicle screw and providing adequate support for the screw.
In some embodiments of the invention, the surface geometry of a spinal cord 1322 is determined in order to assist with pedicle screw insertion. At action 1302, a pre-operative CT scan is conducted of the patient's spinal cord 1322. Referencing the results of the CT scan for incision location determination, at action 1304 minimally invasive incisions are made to expose the patient's spinous process 1323. The host device 1320, in which the cartridge assembly 1301 resides, is then secured to a patient's exposed spinous process 1323 to provide a stable operating environment for the cartridge assembly 1301 at action 1306. At action 1308, a guiding tube 1325 is aligned with and pushed into the area where the surface geometry is to be determined. In an exemplary embodiment of the invention, the surface geometry is measured where each pedicle screw is to be attached to the patient's spinal cord 1322.
At step 1310, the cartridge assembly 1301 is activated. Following cartridge assembly activation, the needles 104 penetrate, at action 1312, into the spinal cord area 1322 of the patient. It should be noted that upon activation, in some exemplary embodiments of the invention the rear ends of the needles 104 optionally abut the sensory devices. While the needles 104 are in motion, the sensory devices are constantly monitored, indicated by action 1314, for a broken/not broken condition. A displacement measurement is made 1316 at the time of break, and motion is optionally continued 1317 to advance needles 104 which have not broken sensory devices. In an exemplary embodiment of the invention, the fuses are polled one by one to detect a change in their resistance.
The needles 104 are retracted 1319 from the patient's spinal cord 1322 prior to generation of a model, or alternatively, after the model is created. Based on the model created at action 1318, pedicle screws are inserted into pre-designated vertebra at action 1321 with the object of making them aligned. Optionally, the surface geometry model created using the described procedure is compared at action 1320 to another model, such as one created through magnetic resonance imaging or computerized tomography, prior to pedicle screw insertion. Once pedicle screws are attached to the patient at action 1321, a connecting element is attached to each screw, jointly and severally, to align them at action 1330.
In an exemplary embodiment of the invention, a surface geometry measurement is used to enhance the features and detail of a pre-operative scan, such as a CT scan. Such an enhancement is capable of facilitating accurate pedicle screw insertion and alignment. For example, the surface geometry model is optionally superimposed onto a pre-operative scan thereby providing the scanned area with surface features that are valuable for properly situating aligned pedicle screws.
Turning now to FIG. 14, a host device 1320 is depicted which provides a housing for the cartridge assembly 1301 in an exemplary embodiment of the invention. Optionally, the host device 1320 is comprised of a clamp 1402, an articulated arm 1404, and a guiding tube 1325. In some exemplary embodiments of the invention, the cartridge assembly 1301 is affixed to the end of the guiding tube 1325. It should be noted that Figures are not necessarily drawn to scale and any configuration shown is by way of example only. In operation, the cartridge assembly 1301 is moved into position by the guiding tube 1325. The cartridge is activated and the surface geometry of the pedicle 1406 is determined, optionally using the methods described herein.
Non-Medical Uses
While various medically related embodiments are shown and described above, it should be appreciated that measurement of a surface geometry conducted by the present invention is useful for a wide range of non-medical purposes, including, but not limited to: scanning objects to acquire a near three dimensional construct of the surface of the object; providing security using an object as a “key” while the present invention acts as part of the “lock”; providing verification of a mechanical signature; and, quality assurance testing to ensure that manufactured parts are to specification, or within tolerances.
Surface Geometry Acquisition of Objects, Like a Key or Mechanical Signature
FIG. 15A is a flowchart 1500 which depicts a method for using measurement elements as a three dimensional scanner in order to determine the shape of an object 1554. In an exemplary embodiment of the invention, an object 1554 is placed, in action 1502, in a position to be measured by a “scanner” comprising at least an array of measurement elements. In an exemplary embodiment of the invention, the method for measurement of the surface geometry of an object is conducted as described in the above embodiments, actions 1504-1512.
As shown in FIG. 15B, the plurality of cartridge assemblies 1560, 1562 are arrayed around the object 1554 being scanned. The measurement elements of the cartridge assemblies are advanced and a surface geometry measurement is performed, as described in other embodiments herein. Optionally, the object 1554 is measured from a plurality of directions simultaneously. Optionally, a curved cartridge assembly is used.
In some embodiments of the invention, the object 1554 being scanned is affixed to a scanning device in a manner that least affects the scanning accuracy of the cartridge assemblies being used. For example, the object 1554 can be attached to the scanner at the base and/or the top of the object. Additionally or alternatively, the object can be scanned a first time except for the locations which are being held, and then the object can be reaffixed at different, already scanned, locations and the areas not previously scanned can be scanned in a second scanning procedure. A composite surface geometry can be constructed of the various scan attempts.
Optionally, a scanning device is used which is cylindrical in shape and which, when activated, measures an object centrally located within the device.
In an exemplary embodiment of the invention, scanning is achieved in one continual motion by providing the scanning device with a piston which applies a turning force in a spiral motion to each measurement element.
FIG. 16 is a flowchart 1600 which depicts a method for using measurement elements 102 as a “lock” in combination with a mechanical “key”. Briefly, a “key” is used which consists of a specific pre-defined shape. The “lock” in this embodiment is at least one cartridge assembly of the present invention, which utilizes the surface geometry measurement system and method described herein to ascertain the surface geometry of the key, or optionally a portion of the key. A comparison is made of the measurement made by the lock to pre-approved key surface geometries which are stored on a database. A positive match between the measured surface geometry and an approved surface geometry on file permits the key holder access to the previously locked area.
In an exemplary embodiment of the invention, a “key” is placed, in action 1602, in a position to be measured by a “lock” comprising at least an array of measurement elements. The method for acquiring the surface geometry of the key is shown in actions 1604-1614, and which is similar to methods previously described herein.
Similar systems and methods can be utilized for recording a mechanical signature, such as a seal or die as depicted in FIGS. 9A and 9B. In some exemplary embodiments of the invention, triggers 908 are activated by elements 902 of the signature 901 by moving signature 901 towards a trigger plate 906. Optionally, the signature is two or three dimensional.
Quality Assurance Testing
FIG. 17 is a flowchart 1700 which depicts a method for using measurement elements to provide quality assurance (e.g. of the manufacture of mechanical parts) by measuring the surface geometry of the part. In an exemplary embodiment of the invention, an object is placed, in action 1702, in a position to be measured by at least one cartridge assembly comprising an array of measurement elements. The method follows actions 1704-1710, which are similar to others described herein. Once the calculated surface geometry model is created 1712, it is compared to an ideal surface geometry for the object at action 1714. Generally speaking, the more the geometries match, the better the quality of the object.
Optionally, a plurality of cartridge assemblies are arrayed around the object being evaluated. In an exemplary embodiment of the invention, an apparatus similar to that depicted in FIG. 15B is used to perform measurement.
The present invention has been described using non-limiting detailed descriptions of embodiments thereof that are provided by way of example and are not intended to limit the scope of the invention. It should be understood that features and/or steps described with respect to one embodiment may be used with other embodiments and that not all embodiments of the invention have all of the features and/or steps shown in a particular figure or described with respect to one of the embodiments. Variations of embodiments described will occur to persons of the art. Furthermore, the terms “comprise,” “include,” “have” and their conjugates, shall mean, when used in the disclosure and/or claims, “including but not necessarily limited to.”
It is noted that some of the above described embodiments may describe the best mode contemplated by the inventors and therefore may include structure, acts or details of structures and acts that may not be essential to the invention and which are described as examples. Structure and acts described herein are replaceable by equivalents, which perform the same function, even if the structure or acts are different, as known in the art. Therefore, the scope of the invention is limited only by the elements and limitations as used in the claims.

Claims

1. An apparatus for determining measurement element positions, comprising:

a plurality of measurement elements;

at least one trigger element corresponding to each element of the plurality of measurement elements;

a positional encoder configured to register a position of each of said measurement elements when said trigger element is activated; and

a controller, wherein said controller constructs a surface geometry model from said registered measurement element positions.

2. An apparatus according to claim 1, wherein said trigger element is a mechanical fuse whereupon trigger activation, said trigger element allows passage of the measurement element therethrough.

3. An apparatus according to claim 1, wherein said trigger element is an electrical fuse, said trigger element indicating when position measurement of a measurement element should be performed upon electrical fuse activation.

4. An apparatus according to claim 1, wherein said trigger element is a mechanical and an electrical fuse.

5. An apparatus according to claim 1, wherein said trigger element is composed of a conductive rubber.

6. An apparatus according to claim 5, wherein said trigger element indicates when an exerted force by said measurement element exceeds a pre-determined threshold.

7. An apparatus according to claim 6, wherein said exerted force is measured by a strain gauge.

8. An apparatus according to claim 1, wherein said trigger element is composed of a thin wire bond.

9. An apparatus according to claim 1, wherein said trigger element is composed of a conductive adhesive.

10. An apparatus according to claim 1, wherein said trigger element is composed of a perforated flex-printed circuit board.

11. An apparatus according to claim 1, wherein the measurement element is disposed to penetrate a first substance but not a second substance.

12. An apparatus according to claim 1, wherein said trigger element is disposed to activate at a pre-determined threshold.

13. An apparatus according to claim 1, wherein a plurality of trigger elements corresponds to said each element of a plurality of measurement elements.

14. An apparatus according to claim 13, wherein each of said plurality of trigger elements activates in response to a different pre-determined threshold.

15. An apparatus according to claim 1, wherein said controller superimposes said surface geometry model onto a previously-acquired scan.

16. An apparatus according to claim 1, wherein said controller compares said surface geometry model to a second surface geometry model.

17. An apparatus according to claim 1 wherein said controller further analyzes said surface geometry model for the proper locations for insertion of a plurality of aligned pedicle screws.

18. An apparatus according to claim 1, wherein said measurement elements serially trigger a plurality of triggering elements associated with each of said measurement elements.

19. An apparatus according to claim 1, wherein measurement elements are activated by hydraulics.

20. An apparatus according to claim 1, wherein measurement elements are activated by pneumatics.

21. An apparatus according to claim 1, wherein measurement elements are activated by wire.

22. An apparatus according to claim 1, wherein measurement elements are activated by screw.

23. A method for determining measurement element positions, comprising:

(a) instigating the movement of a plurality of measurement elements;

(b) signaling at least one measurement element triggering a sensory device; and

(c) measuring at least one measurement element position at time of sensory device triggering.

24. The method according to claim 23, wherein the sensory device is composed of a conductive rubber.

25. The method according to claim 23, wherein the sensory device is composed of a wire bond.

26. The method according to claim 23, wherein the sensory device is composed of a conductive adhesive.

27. The method according to claim 23, wherein the sensory device is composed of a perforated flex-printed circuit board.

28. The method according to claim 23, where the measurement element is disposed to penetrate a first substance but not a second substance.

29. The method according to claim 23, further comprising constructing a surface geometry model from said measurement of measurement element positions.

30. The method of claim 29, wherein said surface geometry model is used to accurately place a plurality of pedicle screws in alignment.

31. The method according to claim 29, wherein said surface geometry model is used to create an object fitted to said model.

32. The method according to claim 31, wherein said object is a knee meniscus.

33. The method according to claim 30, wherein said surface geometry model is compared to a second surface geometry model.

34. An apparatus for scanning, comprising:

a plurality of measurement elements;

a trigger element corresponding to each element of the plurality of measurement elements;

35. A method of measuring the surface geometry of a jawbone, comprising:

(a) instigating the movement of a plurality of measurement elements into a soft tissue surrounding said jawbone;

(b) signaling at least one measurement element triggering a sensory device upon contact with said jawbone; and

36. The method according to claim 35, wherein the sensory device is composed of a conductive rubber.

37. The method according to claim 35, wherein the sensory device is composed of a wire bond.

38. The method according to claim 35, wherein the sensory device is composed of a conductive adhesive.

39. The method according to claim 35, wherein the sensory device is composed of a perforated flex-printed circuit board.

40. The method according to claim 35, further comprising constructing a surface geometry model from said measurement of measurement element positions.

41. The method according to claim 35, wherein said surface geometry model is used to create an object fitted to said surface geometry model.

42. The method according to claim 35, wherein said surface geometry model is used for locating a host device on said jawbone.