WO2008061296A1 - Dispositif d'essai et procédé d'utilisation sur un tissu mou - Google Patents

Dispositif d'essai et procédé d'utilisation sur un tissu mou Download PDF

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Publication number
WO2008061296A1
WO2008061296A1 PCT/AU2007/001776 AU2007001776W WO2008061296A1 WO 2008061296 A1 WO2008061296 A1 WO 2008061296A1 AU 2007001776 W AU2007001776 W AU 2007001776W WO 2008061296 A1 WO2008061296 A1 WO 2008061296A1
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WIPO (PCT)
Prior art keywords
soft tissue
health
cartilage
rebound
testing device
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Application number
PCT/AU2007/001776
Other languages
English (en)
Inventor
Cameron P. Brown
Ross W. Crawford
Adekunle Oloyede
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Queensland University Of Technology
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Filing date
Publication date
Priority claimed from AU2006906470A external-priority patent/AU2006906470A0/en
Application filed by Queensland University Of Technology filed Critical Queensland University Of Technology
Publication of WO2008061296A1 publication Critical patent/WO2008061296A1/fr

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Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/44—Detecting, measuring or recording for evaluating the integumentary system, e.g. skin, hair or nails
    • A61B5/441—Skin evaluation, e.g. for skin disorder diagnosis
    • A61B5/442—Evaluating skin mechanical properties, e.g. elasticity, hardness, texture, wrinkle assessment
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/0048—Detecting, measuring or recording by applying mechanical forces or stimuli
    • A61B5/0053—Detecting, measuring or recording by applying mechanical forces or stimuli by applying pressure, e.g. compression, indentation, palpation, grasping, gauging
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/45—For evaluating or diagnosing the musculoskeletal system or teeth
    • A61B5/4514—Cartilage
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
    • G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
    • G01N21/35—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light
    • G01N21/359—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light using near infrared light
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N3/40—Investigating hardness or rebound hardness
    • G01N3/52—Investigating hardness or rebound hardness by measuring extent of rebound of a striking body
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/45—For evaluating or diagnosing the musculoskeletal system or teeth
    • A61B5/4528—Joints

Definitions

  • the present invention is directed to a testing device for use on soft tissue, particularly, but not exclusively, cartilage, to assist in characterising the health of that soft tissue.
  • the invention extends to a method for characterising the health of soft tissue, particularly, but not exclusively, cartilage.
  • the collagen meshwork in the superficial layer is aligned tangentially to the articular surface, providing a strain-limiting function [20]. Published work shows that significant stretching is seen in this meshwork during crack propagation [21].
  • the invention resides in a testing device for use in characterising the health of soft tissue, the testing device comprising: an indenter for indenting a surface of the soft tissue; a monitor for monitoring a change or changes in the surface during and after indentation; and a display for displaying information on the change or changes.
  • the indenter may include a piston.
  • the piston may be any suitable shape but semi-spherical or cylindrical is preferred, A diameter of around 0.1 to 2 mm or a spherical radius of 0.1 to .5 mm. may be particularly suitable. Other configurations may also be acceptable and a diameter of 1-5 mm may be adopted.
  • the indenter preferably further includes a driver for propelling the indenter.
  • the driver may be manually activated by an operator.
  • the driver may be activated by drive means such as mechanical, gas, electric, spring, magnetic or other suitable drive arrangement.
  • the driver may be selectively variable for speed of advance and/or applied load.
  • the soft tissue is preferably cartilage.
  • the monitor may comprise one or more of an ultrasonic monitoring component; fibreoptic monitoring component and NIR spectroscopic monitoring component.
  • the monitor may include a displacement transducer such as a linear variable displacement transducer.
  • the preferred change for monitoring is recovery of the surface after indentation. It is to be understood that recovery of the surface in this represents recovery of the tissue.
  • the change or changes may include or, alternatively comprise, stretch of the surface.
  • the changes may also include initial displacement of the surface.
  • the monitor may also provide information on structure and chemistry of the soft tissue such as the integrity of the collagen meshwork, proteoglycan content and/or chemical changes associated with osteoarthritis progression.
  • the monitor may comprise a single monitoring component or two or more monitoring components
  • the monitoring components may comprise a linear variable displacement transducer to monitor initial deformation, one or more fibreoptic and/or ultrasound transducers to monitor stretch of the surface and one or more fibreoptic and or ultrasound transducers to monitor recovery of the matrix,
  • the fibreoptic and/or ultrasound transducers to monitor stretch are preferably offset to provide information at two or more different distances from the point of indentation.
  • the ultrasound monitoring component may also scan cartilage and/or subchondral bone.
  • the display may include a processor for receiving, storing and/or analysing information on the changes.
  • the processor may be a computer.
  • the computer may determine a Recovery Index for the soft tissue.
  • the display may include a display screen.
  • the display may provide a visual, auditory and/or tactile indicium of soft tissue health.
  • the visual indicium may be displayed on the display screen.
  • the processor may determine and display on a display screen a map or fingerprint of soft tissue health.
  • the invention may reside in a testing device for use in characterising the health of soft tissue, the testing device comprising an indenter for indenting the surface of the soft tissue, a monitor for monitoring a change or changes in the soft tissue, a processor for receiving, storing and analysing data on the change or changes wherein the change or changes comprises or includes rebound of the surface after withdrawal of the indenter.
  • the soft tissue is preferably cartilage and the processor may be programmed to identify the rebound strain calculated as the distance the surface recovers from loading at a given time after withdrawal of the indenter.
  • the processor is preferably programmed to further provide a recovery index calculated with respect to relative deformations and/or quotient of dividing the rebound strain by the maximum indentation stress, where SR is the recovery index.
  • SR is the recovery index.
  • the indenter may have a diameter in the range of around 0.1mm to around 5mm and is preferably adapted for indentation for over a period up to 5 seconds.
  • the device may include one or more of a fibre optic monitoring component, an ultrasonic monitoring component, a near infrared monitoring component and a linear variable displacement transducer for determining the travel of the indenter and/or the rebound of the surface.
  • the indenter may be advanced until it reaches either a preset stress or reaches a selected strain preferably between 5 to around
  • the testing device may further comprise an ultrasonic apparatus for emitting ultrasonic waves and detecting ultrasonic echoes.
  • the processor may be programmed to determine a ratio of reflection coefficients from the surface and a related osteochondral junction for use in characterising the health of the tissues.
  • the processor may be programmed to analyse and display the frequency profile of ultrasound echoes from the soft tissue, preferably up to 25 MHz.
  • the testing device may further comprise a near infrared spectroscope for conducting diffuse reflectance near infrared spectroscopy of the soft tissue and the processor may be programmed to analyse results of the spectroscopy to provide an indicator of the health of the soft tissue.
  • the testing device is mounted to or mountable to an arthroscope.
  • the invention may reside in a method of characterising the health of soft tissue, preferably cartilage, the method comprising the steps of: applying a linear load to a surface of the soft tissue; withdrawing the load; and monitoring the recovery of the surface.
  • Applying a linear load to a surface of the soft tissue may comprise operating an indenter to propel a piston against the surface.
  • the method includes the step of applying the linear load substantially perpendicularly to the surface.
  • Monitoring the recovery of the surface may include the steps of: assessing the amount of initial deformation of the surface; assessing the degree of recovery of the surface towards its original conformation; and characterising the health of the soft tissue.
  • the method may further include or, alternatively, may comprise the step of monitoring stretch of the surface around a point of indentation, deriving information on the stretch, analysing the information and characterising the health of the soft tissue based on the analysis.
  • the method may further include monitoring the stiffness at the point of indentation, deriving information on the stiffness, analysing the information and characterising the health of the soft tissue based on the analysis.
  • the preferred method utilises ultrasound.
  • the method may further include chemical/molecular analysis of the soft tissue utilising NIR spectroscopy,
  • the method may further include the steps of ultrasonically scanning the cartilage and/or subchondral bone and analysing the ultrasound scans to provide information on the health of the cartilage.
  • the method and device may be suitable for use on intravertebral discs.
  • the invention may reside in a method of assessing the health of soft tissue, the method comprising indenting a surface of the soft tissue, monitoring rebound of the surface and analysing data on the rebound to provide an indicator of the health of the soft tissue.
  • Indenting a surface of the soft tissue preferably comprises indenting a surface of cartilage, and analysing the data includes determining rebound strain calculated as the distance the surface recovered from loading at a given time after indenting.
  • the method may further comprise the step of directing ultrasonic waves into the soft tissue, detecting ultrasound echoes from the soft tissue, and characterising the health of the soft tissue.
  • the step of characterising the health of the soft tissue may include determining a ratio of reflection coefficients from the surface and a related osteochondral junction.
  • the method may include the step of determining a frequency profile of ultrasound echoes from the soft tissue and analysing the frequency profile to provide an indicator of the health of the soft tissue.
  • the orientation of an ultrasonic probe does not vary more than +/- 1.2 degrees.
  • the method may further comprise conducting diffuse reflectance near infrared spectroscopic examination of the soft tissue and analysing the result of the spectroscopic examination to assist in characterising the health of the soft tissue.
  • FIG. 1 is a plan schematic view of cartilage of a synovial joint with a defect
  • FIG. 2 comprises FIGS. 2A - 2C showing a schematic side view of the application of an indenter of the present invention
  • FiG. 3 is a schematic bottom view of an indenter of the present invention showing one arrangement of transducers
  • FIG 4. is a schematic side sectional view of the operation of a piston in an indenter
  • FIG. 5 is a schematic side sectional view of the use of an indenter on normal and degraded surfaces
  • FIG. 6 is a schematic side sectional view of the use of an indenter on normal and degraded surfaces for measurement of the stretch parameter
  • FIG. 7 is a flow chart of a map and embodiment of a method for characterising the health of cartilaginous soft tissue
  • FlG. 8 is a schematic view of a "fingerprint" provided by an indenter of the present invention along with optional indicia of the health of soft issue;
  • FIG. 9A and 9B are a graphical representations of recovery profiles for normal cartilage and degraded cartilage;
  • FIGS. 10-13 show recovery Vs time characteristics of normal and degraded samples under different conditions;
  • FIG. 14 shows a recovery profile around an osteoarthritic defect
  • FIG. 15A and 15B shows results of axial strain and effective surface stretch characteristics of cartilage
  • FIG. 16A, 16B and16C show representative data from normal and degraded joints for axial strain, effective surface stretch and their ratio
  • FlG. 17 shows a comparison of a frequency profile for normal cartilage compared to a proteoglycan depleted sample
  • FIG. 18 shows a schematic representation of an ultrasound apparatus for use in the present invention
  • FlG. 19 shows a series of ultrasound reflection patterns
  • FlG. 20 shows reflection coefficients for surface and bone.
  • FIG. 21 shows the effect of orientation on the reflected signal from the articular surface
  • FIGS 22 and 23 show the frequency profiles of the surface and osteochondral junction
  • FIG. 24 shows frequency profiles
  • FlG. 25 shows baselined ultrasound reflection frequencies of highest overlays and significance
  • FIG. 26 shows spectral profiles of articular cartilage-on-bone using DR-NIR spectroscopy
  • FIGS 27 and 28 show plots of eigenvectors
  • FIG. 29 shows box and whisker plots showing the spread of results
  • FIG 30 is a schematic view of a further testing device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
  • FIG. 1 there is seen a representation of a clinical situation in which the present invention may be of particular benefit.
  • a cartilaginous layer 15 of a synovial joint is shown having a focal defect 16 which is a lesion in the joint severe enough to require intervention by a surgeon.
  • the more problematic consideration is the area of interest 17 which may not be visibly damaged but which may have pathological changes sufficient to require surgical intervention.
  • FIG. 2 is a schematic view of the operation of the device and method of the present invention.
  • Articular cartilage 18 overlies bone 19.
  • a surface 20 of the articular cartilage is subject to indentation by the application of a linear force which is preferably substantially perpendicular to the surface.
  • the force is represented by arrow 21 which is schematically representative of an indenter which is in turn connected to a processor and a display.
  • FIG. 2B shows application of the force 21 at a point of the surface with subsequent indentation 22 of the surface 20 as well as surface stretch as shown by arrow 23.
  • the term "point” refers to the surface area of cartilage contacted by the indenter.
  • FIG. 2C shows the recovery as represented by arrow 24. Therefore, FIG.2A represents the cartilage on bone before indentation. As the load is applied, the shaded area 25 represents the volume of the indentation, which is believed to equal the amount of fluid removed. This volume will depend on how the load is applied and also resistance to the flow of the fluid which, in turn, may be related to the structure. The load is also resisted by the surface stretch as shown by arrow 23.
  • FIG. 2C shows the tissue after the load has been withdrawn. It is thought that the process involves a solid structure- dominated instantaneous recovery coupled with a fluid recovery. This recovery provides a measure of structural integrity without being influenced by the load. The inventors do not wish to be bound to any one or more theories expressed in this specification and directed to the possible reasons for the effectiveness and physiological mechanism or operation of the invention. All comments on any theory of operation of the present invention are offered only as non-binding suggestions.
  • FIG. 3 shows the bottom view of one embodiment of an indenter 26.
  • Initial deformation caused by the load can be measured by using a linear variable displacement transducer ("LVDT", not shown) attached to the piston 31 of the indenter and placed within the cylinder.
  • the surface profile around the indenter is measured by fibreoptic and/or ultrasound transducers to analyse the stretch.
  • These transducers 27,28,29,30 are shown in this embodiment as offset to provide measurements at two distances from the indenter. They can also be used to ensure that the indenter is perpendicular to the surface on operation.
  • the piston 31 is centrally located for extrusion outwardly and into contact with the cartilaginous surface.
  • the present testing device may be used as a stand alone instrument for assessment of soft tissue health, in one particularly useful embodiment, the device may be incorporated into an existing arthroscope using simple rigid snap-on/off components. This arrangement may provide great utility during procedures such as arthroscopic joint surgery.
  • the present invention is particularly well suited for an assessment of cartilage.
  • soft tissues and materials with soft matrices and cores such as brain tissue, muscles, tendons, ligaments, flesh and cancerous tissue, eyes, fruits, vegetables, foams, fabrics, environmental/ground water probing, soil and clay evaluation and grading, tissue engineering scaffolds and cell-scaffold interfaces, and outcomes of soft tissue treatments.
  • FIG. 4 shows a schematic representation of the operation of a piston 33 of an indenter.
  • An air supply 34 is provided and operated by switch 35. Air is passed through a pressure reduction arrangement 36 before delivery to a cylinder 37 and activation of the piston 33.
  • a coiled spring 38 biases the piston into a retracted position so that release of the pressurized air from the cylinder 37 causes automatic retraction of the piston 33. Retraction is preferably accomplished in under 1 second. It is essential that the design provides a safe repeatable and simple way of applying the initial load. While a mains voltage electric arrangement may provide a suitable motive force for the device, it is generally not considered safe at surgery.
  • a battery powered arrangement may be used to power the driving mechanism. Most devices used in surgery are powered by pressurised air.
  • the present invention may be operated from hospital's pneumatic supply which allows safe repetitive load application. Indentation can be provided by a single cylinder and piston returned by a spring. The piston may then act as the indenting object using pneumatic pressure to apply the load and the spring to retract it. A similar effect may be achieved using a double acting cylinder.
  • FIG. 5 shows a schematic operation of a testing device comprising an indenter with piston 39 applied to a cartilaginous surface 40 of articular cartilage 41 on top of subchondral bone 42.
  • the piston is urged downwardly by a driving force represented by arrow 43.
  • the left- hand side 44 of the figure shows the reaction of normal or healthy cartilage to the piston 39.
  • the right-hand side 45 shows the reaction of a degraded surface.
  • a normal surface layer will deform less than a degraded one forcing the matrix to deform around the indenter and creating the appearance of a classic elastic deformation.
  • a degraded surface may simply stretch around the matrix adjacent to the indenter as shown.
  • FIG. 7 there is shown a flow chart for one embodiment of the method of the present invention.
  • a cartilaginous surface is indented 50 after which monitors in the indenting device monitor recovery 51 and stretch 52.
  • Information from the monitors is passed on for data processing 53 using the application of algorithms and preferably in calculating a recovery index.
  • Data processing provides information which is then measured against a referenced database to provide a decision 54,
  • the decision may be communicated on a display.
  • the display may be as simple as a green light 55 for healthy tissue, red light 56 for definite removal and an intermediate light for the surgeon's decision 57.
  • the information may be stored in a storage device 58. Additional information, such as three dimensional location, may be inputted into the storage device 59.
  • the information may be displayed as a graphic representation of the joint, such as an osteoarthritis/defect "fingerprint" 60.
  • the device may also include positioning monitors for displaying a fingerprint 59, 60.
  • the parameters are compared to experimental results for normal joints, collagen-specific and proteoglycan-specific degradations and arthritic joints. This may be performed in a simple regression algorithm. This regression is used to decide whether the tissue is healthy and should be kept, or degraded and should be removed. Results may be included into the reference database to thereby broaden the basis of comparison. It is preferred that new results are added to the database to increase its contents and accuracy.
  • the present invention may be combined with existing three dimensional positional technologies to thereby provide an arthritic/defect "fingerprint" for the surgeon.
  • FIG. 8 shows one schematic view of such a display wherein the three indicator lights 55,56,57 as shown above an outline 61 of the cartilaginous layer with a defect 62 apparent plus an area of degraded tissue 63 and an intermediate or unknown area 64.
  • a surgeon may therefore be informed by the present invention that he/she needs to exercise more widely than just the obvious defect and can also exercise clinical judgement in deciding where to terminate the excision of the tissue.
  • the fingerprint provides the surgeon with information on structural degradation in the joint on which the surgeon can act with far more confidence than with any other available system. This extends visual grading systems to provide a decision making too! that will optimize transplantation procedures and have significant benefits for patients.
  • FIGS 9A and 9B The difference between normal and degraded tissue is highlighted in FIGS 9A and 9B in which the recovery index of normal cartilaginous tissue is plotted against proteoglycan depleted tissue. Both are after a one hour treatment with trypsin.
  • Fig 9A is with load applied at
  • FIG 9B 0.1 s '1 and FIG 9B at 0.025 s "1 .
  • the plot is recovery index against time.
  • the inventors have found that the use of recovery of the surface and therefore matrix and surrounding cartilage is a reliable guide to the health of the tissue. It is preferred to determine a recovery index to give an objective indicator of tissue health.
  • an assessment of surface stretch may be incorporated to provide specific information on the integrity of the surface, which is often the starting point of a degradation process.
  • the recovery and stretch assessments may be usefully supported by techniques to provide secondary information on the structure and function of the tissue. Ultrasound can provide information about underlying bone changes that occur with arthritis and other joint defects, and also physical information about the cartilage matrix. Spectroscopy particularly, using a near infra-red technique, can provide information about the nature of the tissue including its chemical components.
  • the recovery index is measured by the amount the tissue
  • the profile of the recovery curve over time is indicative of aspects of soft tissue health.
  • a preferred period of time is one to five seconds which will usually be sufficient for analysis.
  • the patterns of the time-dependent recovery index for normal cartilage is consistently and significantly higher than that for degraded cartilage. In this case, the cartilage is degraded by proteoglycan removal.
  • Deformation can also be measured with light by using a fibreoptic displacement transducer.
  • the absorbed and reflected light at different wave lengths is useful as a secondary parameter to gather chemical information about the cartilage matrix.
  • a preferred approach uses a Near infra-Red ("NIR") probe or apparatus to analyse the chemical constituents of the tissue and identify changes with degeneration. Chemical profiles of normal and arthritic joints may be mapped to establish a reference system for use in analysing the health of tissue at surgery.
  • NIR Near infra-Red
  • This example highlights structural response of the tissue, independent of the manner in which a load is applied.
  • a measure of the recovery which is governed by the integrity of the collagen fibres and their interactions, in addition to the proteoglycan content and configuration, provides important information about the health of the tissue.
  • the compliance functional tftc presented here is the recovery index or, also known as the hybrid functional index. This is calculated based on the original deformation, or strain ⁇ o, and the short-term time dependent reduction in strain ⁇ j.
  • osteoarthritic patellae To test the application of the technique to the characterisation of naturally degraded tissue, a second group of 10 normal and 10 osteoarthritic patellae was obtained and tested under the same conditions as the previous normal samples.
  • samples were subjected to load-unload tests in the areas of focal fibrillation, and adjacent regions of visually normal tissue at distances of 6 and 12 mm from the edge of the defect, After testing, these samples were subjected to histological analysis to quantify the proteoglycan content and the presence of an orientated collagen meshwork.
  • the normal and degraded samples were subjected to two loading regimes on a Hounsfield Testing Machine (Hounsfield Testing Equipment, Salsford, England), using a ⁇ 4 mm plane ended inde ⁇ ter. These regimes included 0.1 s "1 and 0.025 s "1 quasi-static loading to 30% strain, at which point the load was immediately removed and the deformation measured for 60 seconds: The normal/osteoarthritic group were tested at 0.1 s ' ⁇ representing the load rate that can be expected to be applied by a surgeon at arthroscopy. The rebound strain was then calculated as the distance that the sample recovered from loading at a given time.
  • the level of variation within the normal samples was calculated as a relative difference, in order to take into account magnitude differences between measurement types.
  • the relative difference was
  • FIGS 9A and 9B show the characteristic unloading behaviour under 0.1 s ⁇ 1 0.025 s '1 driven load scenarios respectively, comparing normal behaviour with that after 1 hour of trypsin treatment.
  • Table 1 presents the variation in the rebound and stiffness for norma! samples as a relative difference. It was observed that the variation in stiffness across the joint was approximately double that of the rebound for the same sites and the same indentation.
  • the overlap scores for each load rate are presented in Table 2, below:
  • FIGS 9A and 9B show that the artificial degeneration of normal cartilage by proteoglycan depletion resulted in a consistent 20 to 30% reduction in rebound.
  • the proteoglycan depleted samples showed a significant change, particularly for the first 15 seconds of rebound (p ⁇ 0.001), with p ⁇ 0.005 and p ⁇ 0.01 at 30 and 60 seconds respectively. Similar results were observed under the higher loading rate, with the exception of a reduced statistical significance for proteoglycan depleted samples at 2 and 5 seconds (p ⁇ 0.005).
  • the measurement of rebound can be easily incorporated into current indentation probes such as ARTSCAN [8] and ACTAEON [22] which use ultrasound and fibreoptic displacement measurements respectively. While the stress measured at indentation provides a useful parameter for a quasi-static indentation with controlled displacement, this parameter will preferably be an indentation displacement parameter for statically applied loads or to calculate a rebound strain when the sample thickness is unknown.
  • FIGS. 10-13 Load rate dependent variation in a representative normal sample.
  • the recovery v's time characteristics of normal and artificially degraded samples are presented in FIGS. 10-13.
  • FIGS. 10 to 12 show the characteristic unloading behaviour after 1 hr of trypsin treatment under 4.5 mm/min, 1.5 mm/min and static loading scenarios.
  • FIG. 13 discloses the unloading behaviour before and after collagenase treatment.
  • FIG. 14 presents the recovery as a function of the distance from a focal osteoarthritic defect. It can be seen that the characteristic recovery increases with distance until approximately.8mm, after which it plateaus.
  • the measurement system is preferably sufficiently robust to allow for the different abilities of the surgeon. From the information presented in Table 1 it is apparent that the recovery index is considerably less dependant on the applied loading rate. It should be noted, however, that after static loading for 30s, the recovery was reduced in all of the tested tissues due to the gradual outflow of fluid from the matrix over this time. In general, therefore, it is preferred that the loading is applied for a short ( ⁇ 5s) time. As the load rate dependence is an order of magnitude smaller than for stiffness, the recovery index is. far superior in this respect.
  • the artificial degeneration of normal cartilage has resulted in a consistent 20 to 30% reduction in recovery index, with the exception of the static loading of trypsin-treated samples, which showed a smaller change due to the fluid flow during the 30s creep period. This response was not seen in the static loading of collagen-disrupted cartilage.
  • the artificial degeneration times and solution strength in this study were smaller than those generally used by researchers in this field producing a very mild, but easily detectable degenerative change.
  • the arthritic changes measured in this example were considerably larger than the artificially induced changes and fell well outside of the natural variation in normal samples.
  • the recovery index can be expected to detect naturally degenerative changes with a high level of confidence.
  • the method was able to successfully track the transition from degenerated to normal tissue, as shown in FIG. 14.
  • the results show a gradual increase in recovery to a distance of approximately 8mm, after which the response plateaus.
  • the value at the plateau is smaller than the recovery index of normal tissue.
  • the general change in the joint is considered reversible and can be returned to homeostasis.
  • the focal change is irreversible and the focal area described by this test will need to be removed in a localised treatment procedure such as mosaicplasty or tissue engineered cartilage replacement,
  • the recovery method can be implemented in a hand held testing device for assessing soft tissue and in particular, used to determine the extent of arthritic damage in a joint and optimise the amount of tissue removed at surgery.
  • the recovery methodology is significant in improving decisions relating to the treatment of osteoarthritis.
  • the recovery method is useful at arthroscopy in any case that potentially involves a focal tissue replacement, such as mosaicplasty, artificial biomaterial implants, artificial biomaterial or tissue engineered replacement and similar. Unicompartmental knee replacement will also benefit from this technology. This provides procedural benefits in surgery where more precise decisions can lead to the optimisation of the amount of cartilage removed in the treatment of osteoarthritis.
  • This example is directed to the superficial zone in its functional role.
  • the collagen network in the superficial layer produces a strain- limiting behaviour, which plays a significant role in maintaining cartilage thickness in the consolidation process.
  • the superficial zone will stretch under the indenter, and will also act in the region adjacent to the indentation.
  • a measure of the surface stretch, which is governed by the integrity of the collagen fibres and their interactions, for a given stress- strain characteristic will provide important information about the integrity of the collagen network in this zone.
  • a strongly bonded network will resist this stretch, but a weakly bonded network will be able to deform more.
  • the joints Prior to testing, the joints were thawed in saline, sectioned into 14 x 14 mm squares and labelled according to their position on the patella.
  • the cartilage samples were taken off the bone and immediately glued to stainless steel disks in order to eliminate the influence of the bone on the mechanical response of the tissue.
  • a fine grid was imprinted using a waterproof marker and the samples returned to saline to recover for 2 hours at 4°C.
  • 6 visually normal samples from different patellae were harvested adjacent to focal arthritic defects and were tested under the same conditions as the normal samples.
  • the focal defects in the 6 arthritic patellae were all characterised by exposed bone and occurred in either the lateral-distal area of the joint or the central-distal area.
  • Samples were harvested from the nearest visually normal tissue to the defect on the lateral side.
  • a custom-built indenter was used to facilitate the photographing of the indentation imprint and stretching of the area around the indenter.
  • This indenter comprises a 6 mm diameter glass disk glued onto a 20 mm thick glass plate of 100 mm diameter. The plate was set in a stainless steel frame with an angled mirror to allow direct viewing through the indenter.
  • the visible articular surface strain continued in an outward direction for up to 2 mm.
  • the inside end of each ray showed the initial position of a point, while the outer end shows its position after 20s at 0.33 MPa.
  • the effective surface stretch measurement was calculated by normalising the length of the rays against the indenter size. Evaluation based on effective stretch as defined in this study was considered appropriate. Use in surgery is based on a known indenter geometry rather than a parameter that requires calculation based on the initial positions of grid points relative to the centre of indentation.
  • Each specimen was removed after testing and a 2mm by 4mm biopsy taken.
  • Each biopsy sample was placed on a metal mount and embedded in optimal cutting temperature (OCT) medium (IA018, ProSciTech) and rapidly frozen in liquid nitrogen to limit damage to the tissue samples.
  • OCT optimal cutting temperature
  • the sample was then placed within a cryostat and sectioned at 7 ⁇ m in the transverse direction. The sections were immediately picked up by a microscope slide and left to dry within a sealed container, at 4°C overnight. The presence and concentration of proteoglycans was determined by Safrani ⁇ -O staining.
  • Safranin O is a cationic dye that binds stoichiometrically to mucopolysaccharides, that is, one positively charged dye molecule binds to one negatively charged carboxyi or sulphate group [25-28].
  • Slides were fixed in 95% alcohol for 30 seconds and left to dry in air. Proteoglycans are hydrophitic and easily extracted during conventional histological aldehyde fixation, hence the use of a less disruptive fixative regime. The slides were then hydrated in distilled water, rinsed in 1% Acetic Acid for 8 dips and then stained in 0.1% Safranin-0 for 5 minutes. Finally, the slides were dehydrated in 95% alcohol for 6 dips, followed by 8 dips in 100% alcohol. Colour photographs were captured by light microscope.
  • Polarised light microscopy was used to detect the presence of an oriented collagen network. PLM measurements were performed using a Nikon Labo-Phot PLM. To ensure reproducibility, the camera was calibrated to the light intensity of a ⁇ /4 wave plate, with a known birefringence. The exposure time was then adjusted to the thin section of cartilage and kept constant for the remaining samples. Slides were placed on the moveable stage, with the articular surface facing toward the body of the microscope. The stage was then turned 45" to ensure maximum light emittance through the polarisers and therefore maximum brightness. The image was captured, and converted to ImageJ software for analysis of the retardance profiles.
  • P-values of greater than 0.1 accepted the null hypothesis of no change (equivalent to 90% confidence interval). P-values of less then 0.1 were labelled for comparison.
  • FIG. 15 shows the variations across a normal joint as measured by each technique.
  • the axial strains at 0.33 MPa at different positions on the same normal patella are illustrated in FIG. 15A.
  • FiG. 15B shows the variation in the effective surface stretch for the same indentation.
  • These graphs illustrate the considerably larger variation in axial strain than effective surface stretch across the joint.
  • the mean axial strain and effective surface stretch were 0.24 and 0.027 respectively.
  • the range as a percentage of the mean was 42 and 14% respectively.
  • FIG. 16 Representative data from specimens subjected to collagenase and trypsin treatments, and visually normal specimens harvested adjacent to arthritic defects are illustrated in FIG. 16. These graphs show the axial strain, effective surface stretch and their ratio (ESS : ⁇ ) respectively.
  • ESS effective surface stretch
  • Four and eight hour degradation in collagenase resulted in a considerably higher effective surface stretch, p ⁇ 0.01 and p ⁇ 0.001 respectively, with a visible but a smaller increase in axial strain.
  • the axial strains for the samples that underwent collagenase degradation fell within the normal range.
  • One hour degradation in trypsin produced a large increase in axial strain p ⁇ 0.01. This degradation also resulted in an increased effective surface stretch, but this was lower than for the 8hr collagenase treatment.
  • Osteoarthritic samples labelled OA-1 to OA-6, were characterised by increased effective surface stretch (all p ⁇ 0.001), but only OA-4 showed an increased axial strain p ⁇ 0.01.
  • the ratio of effective surface stretch to axial strain increased for collagenase treatment and decreased for trypsin treatment.
  • the arthritic samples show similar effective surface stretch to axial strain ratios, all higher than the normal (p ⁇ 0.1).
  • the effective surface stretch measurement is very sensitive to degenerative changes originating at the surface of the cartilage layer, and appears to be superior in detecting this mode of arthritic change.
  • the compliance measurement is likely to be more effective.
  • Axial strain values demonstrate a wider variation across the normal joint than the effective surface stretch measured under the same compressive load.
  • the variation in effective surface stretch under the same level of loading is considerably smaller (14%), and is therefore more sensitive to the changes in the integrity of the collagen network induced by collagenase treatment.
  • the increase in effective surface stretch for the artificially degraded samples was 34 (p ⁇ 0.01), 119 (p ⁇ 0.001) and 89% (p ⁇ .001) for 4hr collagenase, 8hr collagenase and 1hr trypsin treatment respectively.
  • the measured effective surface stretch for the osteoarthritic samples was at least 37% higher than the largest stretch measured in the normal samples. As each of these values falls well outside of the natural range it appears that the effective surface stretch measurement can detect degenerative changes with a high degree of confidence.
  • FIG. 16C shows that a reduction in the integrity of the collagen network increases the ratio of effective surface stretch to axial strain, while the depletion of proteoglycan decreases the ratio.
  • ultrasound is incorporated into the testing device as a way of measuring the deformation and recovery. It may also provide information on the physical characteristics of underlying bone and matrix by measuring reflection ratio or using frequency analysis.
  • a total of 160 ultrasound echoes were taken from both the saline-cartilage and cartilage-bone interfaces across a normal joint, a joint with an artificially compromised surface, a joint with an artificially compromised matrix and a naturally arthritic joint to determine the effect of different modes of degeneration on the ultrasonic patterns of the cartilage laminate.
  • Intact joints were taken from oxen within 24 hours of slaughter, wrapped in a 0.15M saline soaked cloth and stored at -20C.
  • A-mode echograms were obtained randomly over the surface of normal patellae immersed in saline, which were then artificially degraded to either compromise the surface by removing surface active phospholipids (SAPLs), or compromise the general matrix by depleting the proteoglycan content or disrupting the collagen meshwork of the tissue.
  • SAPLs surface active phospholipids
  • SAPLs were removed by wiping the surface with a methanol soaked cloth, and immediately returning the joint to saline. Following treatment and retesting, the surface was further degraded by light abrasion with a coarse cloth.
  • the ultrasonic examinations were made at an approximate distance of 3mm using a 10MHz transducer (Panametrics Inc., Massachusetts USA) connected to a pulser/receiver. This was in turn connected to an oscilloscope and a PC through an analogue to digital converter (Pico Technology Limited, Cambridgeshire, UK).
  • the reflected amplitudes were compared to that of an acoustic mirror, which was made from a highly polished stainless steel disk and tested in saline under the same conditions as the cartilage samples.
  • the reflection coefficient of the mirror was calculated to be approximately 0.941 Rayl from the known acoustic impedance values of the two materials.
  • FIG. 17 shows a comparison of a frequency profile for normal cartilage compared to that of a proteoglycan depleted sample. The top two printouts are obtained from normal tissue while the bottom two printouts are from proteoglycan depleted tissue.
  • FIG. 18 shows a schematic of one suitable ultrasound apparatus for assembly with the other component or components of the testing device.
  • the ultrasound apparatus 80 comprises an oscilloscope 81 , a pulser/receiver 82 and a transducer 83.
  • An analogue/digital converter 84 is in communication with the other components and the processor 85 which may be a laptop or other computer.
  • FIG. 19 presents the typical ultrasonic reflections from normal (A), proteoglycan depleted or collagen disrupted (B), surface delipidized (C), abraded (D) and arthritic (E) tissues. These patterns are similar in approximately 80% of the tests, with deviations from these patterns generally occurring when a weaker signal was obtained for either the surface or bone reflections. Bone reflections showed more variation than surface reflections.
  • the normal sample (FIG. 19A) gives strong signals from both the surface and bone, with the bone signal having slightly higher amplitude.
  • Proteoglycan depletion by exposure to trypsin or collagen depletion (FlG.19B) reduced the surface amplitude (p ⁇ 0.01) and slightly increased the bone reflection, though this increase was not statistically significant.
  • Surface disruption by the removal of SAPLs (FIG. 19C) had a non-significant, but visible effect of reducing the surface echo and increasing the bone echo. Further disruption of the surface by abrasion significantly reduced the surface echo (p ⁇ 0.1), with no further change in the bone echo.
  • soft tissue may include the osteochondral junction and calcified cartilage sublayer in general.
  • the ratio of the reflection coefficients from the cartilage surface and osteochondral junction form a coefficient that describes degenerative changes to the articular surface, the superficial and deep zones of the cartilage matrix, and the osteochondral junction. It provides a more consistent indicator of artificial degeneration than the reflection coefficients from the individual surface or osteochondral junction echoes, and was found to be particularly effective in distinguishing naturally degraded from normal tissue. Due to the complementary effect of combined degradations on the value of the ratio, it may provide an effective coefficient for distinguishing degraded from normal tissue in the osteoarthritic joint, independent of the site of initiation of the osteoarthritic process.
  • the bone reflections provide important information for characterising degradation.
  • the patterns of ultrasonic response remained similar across the samples within each group, and when quantified by the ratio of surface to bone reflection coefficients, gave more significant information about the change than either the bone or surface individually, even though the individual averages often changed by a large amount.
  • the complementary relationship between the reflections in degraded samples, and the results presented in Table 5 show that the application of this ratio may allow a better discrimination between normal and degraded tissues (all p ⁇ 0.001), particularly in arthritic joints (p ⁇ 0.001). Combining this with the matrix sensitive surface reflection may further provide information about the nature of degeneration in macroscopically normal tissues.
  • the frequency profile remained consistent up to +/- 1.2°after which an increased peak in the 3-5 MH Z band was observed, as well as a left shifted overall peak. This effect may indicates a difference between the specular and diffuse reflection profiles. With a change in orientation of less than +/- 1.2°, the value of the amplitude at any single frequency changed, but the overall pattern/profile of the reflected signal's frequency response remained the same. This suggests there may be advantage if the angle of incidence can be controlled within a +/- limit.
  • a total of 240 ultrasound echoes (20 per joint in a 4x5 grid) were taken from the saline-cartilage and cartilage-bone (osteochondral junction) interfaces of 12 normal bovine patellae. 6 of these patellae were then depleted of their proteoglycan content and 6 were treated to disrupt the collagen network, before retesting. Both of these types of modification are commonly observed in naturally degraded articular cartilage, and can therefore be argued to represent discrete parts of the degradation process [2,3,13]. Finally, a joint with focalised osteoarthritis was tested to examine the application of the reflection coefficient to the natural degradation process.
  • Intact joints were taken from oxen within 24 hours of slaughter, wrapped in a 0.15 M saline soaked cloth and stored at -20 0 C. Prior to testing, the joints were thawed overnight in saline, according to the method of Broom and Flaschmann [16]. Ultrasound scans were obtained over the surface of normal cartilage-on-bone samples immersed in saline. All ultrasonic examinations were made at a fixed distance of approximately 3 mm using a ⁇ 3 mm, plane 10 MHz contact transducer (V129 Panametrics Inc., Massachusetts USA), sampling at 50 MHz and connected to a pulser/receiver as illustrated in Figure 2.
  • the osteoarthritic patellae contained a 7 mm diameter International Cartilage Repair Society grade 4 (exposed bone) [23] focal defect at the distal extremity of the patellar ridge. The remaining joint surface was visually normal. Ultrasound scans were taken at the edge of the defect and at intervals along the patellar ridge, measured by distance from the edge of the defect. After completion of the degradation programme, the joints were sectioned and frozen for histology, arresting the enzyme action. The histological quantification techniques are fully explained above. In summary, the proteoglycan content and distribution was measured by staining with Safranin-O, followed by absorbance profiling under monochromatic light source using a Nikon Labo-Phot polarized light microscope (PLM). PLM was also used without staining to detect and quantify the presence of an oriented collagen network, quantified by birefringence. Standard histological procedures were employed.
  • the captured ultrasound signals from the cartilage surface and osteochondral junction were processed and converted to the frequency domain using a Fast Fourier Transform routine in MATLAB (The MathWorks Inc, USA, version 7.0.4.352). Zero padding was employed to increase the apparent spectral resolution. Two parameters were used to determine the most appropriate frequencies for distinguishing normal from degraded articular cartilage, statistical significance of the change in reflection derived from the student's t-test, and the level of absolute overlap.
  • the t-test while powerful, assumes a normal distribution in the samples and as such may be limited in its ability to elucidate the changes if the distribution of samples is non-normal.
  • the overlap parameter was therefore used in addition to the statistical significance parameter to describe the probability of distinguishing a randomly selected sample as being either normal or degraded, without assuming a particular sample distribution. An overlap value closest to 1 is preferred as it represents a better discrimination between the sample groups.
  • results from the student's t-test and overlapping test were obtained and the values were plotted in their respective graphical formats.
  • the resulting frequency bands were then compared for the two parameters.
  • results were baselined against a set frequency.
  • Fo for the frequencies from the original data
  • F 1 for the frequencies adjusted against the baseline frequency FBL-
  • the student's t-test and the overlapping test were also coded in the MATLAB environment, using a band criterion of >0.5 MHz to reduce the influence of noise.
  • the frequency profile of- the signal reflected from the acoustic mirror (highly pofished stainless steel) in saline is used as a reference.
  • the peak reflection occurred at a frequency of 8.4 MHz, with a gradual decay with increasing and decreasing frequency.
  • the bandwidth of interest for this study is limited to the 0-10 MHz range.
  • the collagen meshwork was found to be reduced in the superficial area of the cartilage following the 18 hour treatment but the deeper zones did not appear to be affected. It was apparent that the proteoglycan content is almost completely depleted after the four hour treatment.
  • FIGS 22 and 23 show the typical frequency profiles of the ultrasound echoes obtained from the surface and osteochondral junction respectively. Both sets of curves were characterised by a band of low reflection between 1 and 2.2 MHz, and a reflection peak between 7 and 8.4 MHz.
  • the average frequency profile of the surface echo for proteoglycan-depleted samples showed distinct differences when compared to the normal samples. In this respect, it was characterised by a right-shifted and lower amplitude band of low reflection, and a more exaggerated 3.6 MHz peak. Further differences included a lower amplitude and left-shifted reflection peak at approximately 7.8 MHz and a more distinct trough at 4.4 MHz.
  • the surface echoes from the collagen-disrupted samples showed a generally lower amplitude compared to the normal and proteoglycan-depleted samples. The profile was similarly proportioned to that of the normal samples, with an extended and more complex band in the 1-5 MHz range.
  • the proteoglycan-depleted samples were characterised by a right-shifted band of low reflection, and a consistently lower amplitude signal in the 1 to 5.6
  • FIG. 24 shows the frequency profiles, baselined at the frequency corresponding to the reflection peak, for the data presented in
  • the penetrating nature of ultrasound allows it to be more readily applied for detecting changes in deeper zones of articular cartilage than the more commonly used surface echo or mechanical indentation techniques.
  • the surface echoes shown in FIG.22, are most likely to give information and insight into the general bulk modulus and density of the matrix, as well as superficial damage such as fibrillation and microcracki ⁇ g.
  • the osteochondral junction echoes for which the signal passes through the full depth of the cartilage matrix, is expected to allow more insight into the deeper zone changes to the collagen meshwork and proteoglycan macromolecules.
  • the reflected signals from the osteochondral junction do not necessarily provide a more complex profile when compared to the cartilage surface echoes in FIG.22.
  • the amplitude of the ultrasound signal from articular cartilage is highly dependent on the orientation of the transducer with respect to the reflective surface, the strongest signal occurring when the transducer is perpendicular to the surface, with signal strength rapidly decreasing with increasing deviation.
  • the frequency profiles from the osteochondral junction echoes show a more distinct qualitative change, particularly in the region within 5 mm of the defect, than the profile from the surface echo, most likely due to changes on the surface of the subchondral bone coupled with structural changes in the overlying cartilage matrix.
  • These profiles appear similar to the collagenase-treated samples shown in FIG. 23, with more exaggerated reflection bands in the lower frequency range at approximately 3.2 and 5 MHz.
  • the more subtle changes in the frequency profiles of the reflections from the osteochondral junctions of the trypsin- treated samples were not clearly observed in the profile for the osteoarthritic osteochondral junctions, relative to the normal samples.
  • the ultrasound reflection taken from within the defect (0 mm) which shows a complex pattern with multiple, sharp peaks and troughs due to the highly degraded state of the reflecting surface and the absence of the overlying cartilage matrix.
  • the ratios provided a generally consistent profile around an osteoarthritic defect.
  • the surface reflection parameters based on collagen meshwork disruption peaked at 6-8 mm from the defect, before decreasing slightly and levelling out,
  • the reflection parameters from the osteochondral junction, based on proteoglycan depletion dropped considerably in the first 5 mm before levelling out. Each of these parameters reached a plateau at approximately 10 mm from the edge of the defect.
  • DR-NIRS non-destructive, diffuse reflectance near infrared spectroscopic
  • DR-NIRS may be used to detect changes in proteoglycan quantity, using principal components analysis as the statistical basis of characterisation.
  • a useful comparison is of the results from a directly applied probe to those obtained from a probe that was offset by 1.5 mm. The results show that this technique, particularly using the offset probe, can reliably (R 2 >0.9) distinguish normal intact cartilage from cartilage that has lost some of its proteoglycan content using vector normalising and second derivative pre- treatments.
  • DR- NIRS enables the probing of the deeper layers of cartilage, thus allowing the assessment of both the osteochondral junction and the advancing calcification front associated with osteoarthritis.
  • IR system with OMNIC v5.1 software both ThermoNicolet, UK.
  • the ⁇ 4 mm fibre optic probe was coupled to the FT-IR system via a Grasby SPECAC NIR fibre port accessory.
  • the spectrum was acquired from the 4000 to 12500 cm "1 region: The calibration of NIR spectra becomes quite complex when dealing with biological samples. This often results in detection limits as high as 0.5-1% absolute, even for major constituents. Further, Beer's law and Hooke's law break down for diffuse reflectance at high overtones/harmonics, leading to the need for multivariate analysis.
  • Principal component analysis is a matrix method that was used to manipulate the data set to probe for relationships between variables. This method reduces the dimensionality of the original data without loss of information and with an added benefit of reduction in noise.
  • PCR was employed to determine the number of useful principal component, preventing the over-fitting of the data by PLS. The PLS then used these principal components to create a more accurate model.
  • This investigation used categorical regression assignments, using a value of 1 for the normal samples and -1 for the proteoglycan depleted samples.
  • Figure 26 shows the spectral reflectance profiles of articular cartilage-on-bone using directly applied and offset probes respectively. Bands of very low reflection, and therefore low signal to noise ratio, are apparent in the profiles of the directly applied probe at 4000-5300 and 6500-7150 cm “1 . Consequently, the data from the directly applied probe was only analysed in the region above 7300 cm "1 .
  • the eigenvectors for the PCA are presented in Figures 27 and 28.
  • PCR and PLS R 2 values for reflectance and its 2nd Derivative are shown for raw and vector normalised data in Figures 5a and b respectively. These results show that, although the PLS correlations appear strong, the PCR results were relatively weak, indicating that the PLS results may be including noise in its prediction.
  • the R 2 results take 'longer' to reach a good value using the directly applied probe, compared to the air-gap probe.
  • the inventors have identified the ability of the DR-NIRS method to detect proteoglycan loss in articular cartilage-on-bone using both a directly applied probe and an offset probe, separated from the articular surface by an air-gap.
  • the probe Based on the geometry of the sample, the probe measured a combination of the effects of scattering by the cartilage ultrastructure, absorbance, and transmittance through to the bone.
  • the eigenvectors for the PCA showed similar trends for both the directly applied and offset arrangements.
  • the first few components appear to consist of variation relating to the absolute offset in the spectra, while the middle (PC's 3-9) shows more interesting peaks, indicating frequency bands of interest.
  • For the directly applied probe these bands occur in the 7500-9000 cm '1 region. Higher components generally appear noisy and may be of .little value to the analysis.
  • For the offset probe the principal components show a number of peaks throughout the spectrum, particularly at approximately 5100 cm '1 . This peak is the most apparent feature of PC 5 which, as shown in Figure 29, is capable of separating normal from proteoglycan depleted tissue on its own.
  • the inventors have shown that normalised and second derivative DR-NIRS reflectance can be used to reliably discriminate between normal and proteoglycan-depleted cartilage.
  • FIG 30 shows a schematic view of a testing device with a single ultrasound transducer 81 and an array of NIR fibreoptics having sending outlet s82 and receiving inlet 83s scattered aorunfd the base.
  • the benefits of the present invention are numerous and significant. A surgeon may reliably assess the health status of a soft tissue, especially cartilage. This will lead to better, more focussed surgical interventions and beneficial outcomes. However the advantages are not so limited.
  • the invention may be used to assess the quality of tissue engineered cartilage for example, prior to its recruitment in a therapeutic environment.

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Abstract

La présente invention concerne un dispositif et un procédé conçus pour examiner l'état de santé et/ou les caractéristiques d'un tissu mou. Le dispositif et le procédé conviennent particulièrement bien à l'examen d'un cartilage. L'invention porte sur un dispositif d'essai constitué d'un pénétrateur (50), d'un appareil de surveillance (51, 52) permettant de suivre le rétablissement de la matrice superficielle et sous-jacente. Le pénétrateur est connecté à un processeur (53, 54, 58) destiné à recevoir les données et à évaluer l'état de santé du cartilage sur la base d'un indice de rétablissement hybride ou d'autres caractéristiques. Il est possible d'observer le résultat sur un indicateur visible (55, 56, 57). Le dispositif peut, de plus, incorporer des appareils de surveillance permettant d'évaluer les caractéristiques d'extension de la surface. Ces appareils de surveillance peuvent en outre consister en un appareil de surveillance à ultrasons et/ou un simple appareil de surveillance à rayonnement infrarouge. L'appareil à ultrason est susceptible de détecter des échos en vue de calculer un coefficient de réflectivité entre la couche superficielle et les jonctions ostéo-chondrales. L'appareil à ultrason peut également être utilisé pour établir le profil du tissu mou. Il est aussi possible d'avoir recours à la spectroscopie de réflectivité diffuse en proche infrarouge pour obtenir des données sur l'état de santé du tissu.
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DE102013206966A1 (de) * 2013-04-17 2014-10-23 Pohlig Gmbh Vorrichtung und Verfahren zur Messung der Kompressibilität eines biologischen Gewebes
CN110006790A (zh) * 2019-04-09 2019-07-12 中国人民解放军总医院 软骨渗透性测量装置及测量方法
CN110346207A (zh) * 2019-04-19 2019-10-18 浙江省人民医院 一种前交叉韧带生物力学特性测量装置
CN112535481A (zh) * 2020-11-24 2021-03-23 华中科技大学 一种基于近红外光的关节接触力测量方法及装置
CN116539463A (zh) * 2023-06-20 2023-08-04 广东惠和工程检测有限公司 一种混凝土强度的检测方法

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CN112535481A (zh) * 2020-11-24 2021-03-23 华中科技大学 一种基于近红外光的关节接触力测量方法及装置
CN112535481B (zh) * 2020-11-24 2022-11-01 华中科技大学 一种基于近红外光的关节接触力测量方法及装置
CN116539463A (zh) * 2023-06-20 2023-08-04 广东惠和工程检测有限公司 一种混凝土强度的检测方法
CN116539463B (zh) * 2023-06-20 2023-10-13 广东惠和工程检测有限公司 一种混凝土强度的检测方法

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