Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B7/00—Instruments for auscultation
  • A61B7/006—Detecting skeletal, cartilage or muscle noise
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
  • G01H1/00—Measuring characteristics of vibrations in solids by using direct conduction to the detector

Definitions

• This invention relates to an apparatus for the noninvasive analysis of joint disorders. More particularly, this invention relates to a new and improved noninvasive technique for detecting and analyzing joint disorders which utilizes a novel signal processing procedure termed Arthrophonometry. This invention is particularly well suited for the detection and differential diagnosis of temporomandibular joint (TMJ) disorders, a prevalent class of disorders caused by any of a number of different underlying pathologies.
• TMJ temporomandibular joint
• TMJ temporomandibular
• the present invention is equally applicable to the diagnosis of any types of joint disorders throughout .the body. Pain and dysfunction associated with the TMJ are estimated to afflict 20%-50% of the population. Most patients probably have functional disorders, but organic joint disease is undoubtedly present in a certain percentage thereof. Unfortunately, differentiating true joint pathology -f om other conditions can be difficult or impossible due to the relatively non-specific nature of the relevant clinical signs and symptoms. Moreover, recognition of an increasing number of different types of joint abnormalities has caused the need for simple, objective, and definitive diagnostic methods to assume greater importance.
• Conditions such as myofascial pain dysfunction (MPD), meniscal displacements (internal derangements), rheumatic and degenerative arthritis, subluxation and chronic dislocation, fractures, tumors, and ankylosis are all recognized as distinct entities, but their diagnosis has generally relied on clinical impression and complex radiographic methods.
• MPD myofascial pain dysfunction
• internal derangements meniscal displacements (internal derangements)
• rheumatic and degenerative arthritis subluxation and chronic dislocation
• fractures fractures
• tumors tumors
• ankylosis ankylosis
• Radiographic assessment of the TMJ is generally confined to standard radiography, arthrography, tomography, and arthrotomography. While standard radiography and tomography are useful in evaluating gross abnormalities of osseous structures, they have little value in assessing the viability and function of soft tissue components. Not surprisingly, tomograms are completely normal in 86%-95% of patients with TMJ dysfunction. Since impressive evidence has now verified the significance of soft tissue derangements in TMJ dysfunction, the serious limitations of standard radiography and tomography have become apparent.
• arthrotomography has permitted diagnosis of certain TMJ abnormalities with unprecedented reliability, but the technique should be viewed as moderately invasive.
• a tomographic method (often performed under fluoroscopic control) patients are necessarily subjected to significant levels of radiation.
• the need to expose patients to a potentially allergenic iodine-containing contrast medium and to considerable pain has generally been balanced by the valuable diagnostic information obtained; but, these inherent disadvantages in arthrotomography emphasize the potential value of a quantitative, non-invasive, non-radiographic technique that should provide as much or more information as that available through existing methods.
• CT computed tomography
• CT offers increased sensitivity and reliability for studying both hard and soft tissues while exposing the patient to less radiation and pain than other radiographic methods. Nonetheless, CT scan of the TMJ is a hospital procedure requiring expensive equipment and facilities, specially-trained physicians, and moderate radiation dosages.
• the design of a suitable quantitative, non-invasive TMJ diagnosis procedure which overcomes the above discussed problems may be effected in light of two related premises: (1) that an abnormal joint will exhibit frictional losses that are greater than those of a normal joint and which can easily be detected instru entally, and; (2) different pathologies will present different types of frictional losses which can be identified and quantified acoustically.
• Certain noninvasive acoustical evaluation techniques are well known in the medical diagnostic art. For example, in U.S.
• Patent 3,181,528 to Brackin a method and apparatus is disclosed for analyzing joint disorders utilizing acoustical diagnostic equipment. Graphical recordings of sound (amplitude) versus signal time are derived from this procedure and analyzed in an effort to detect joint disorders.
• Graphical recordings of sound (amplitude) versus signal time are derived from this procedure and analyzed in an effort to detect joint disorders.
• the authors therein describe a technique similar to the Brackin patent wherein knee joint disorders are diagnosed by measuring and recording the emission of a unique acoustical signature and the corresponding statistical pattern. As in Brackin, this technique ,- obtains graphic results measuring sound versus time.
• a further diagnostic device, similar to the aforementioned joint noise detecting systems is described in Russian Patent 304939.
• the acoustic signal processing diagnostic apparatus of the present invention thus provides a novel, noninvasive procedure for the detection and differential diagnosis of joint disorders, including, for example, temporomandibular (TMJ) joint disorders.
• TMJ temporomandibular
• the inventors have termed this invention Arthrophonometry.
• the apparatus measures the frictional losses of joint movements as revealed by their acoustical characteristics. Because the various diseases of the temporomandibular joint are characterized by different physical conditions (and consequently, different frictional losses), the associated joint sounds correspond categorically and uniquely to specific disease states.
• the acoustic analog of joint friction is mapped in relation to both the temporal and spatial properties of jaw movements and is further characterized using acoustic signal processing.
• the technique involves the placement of a vibration transducer over the area of the temporomandibular joint and a position sensor on the lower central incisors to record the bone-conducted joint sound and jaw movement, respectively.
• the sensors produce voltages that correspond to both the acoustic waveform radiated from the joint, and the position of the joint in space. These voltages are displayed simultaneously and graphically on a computer display terminal. The relationship between the acoustic markers and joint pathologies has been confirmed in preliminary studies by comparisons with conventional diagnostic methods and exploratory surgery.
• FIGURE 1 is a graphical representation of acoustic waveform and joint position for a normal joint taken in accordance with the present invention.
• FIGURE 2 is a graphical representation of acoustic waveform and joint position for a joint with meniscal displacement taken in accordance with the present invention.
• FIGURE 3 is a graphical representation of acoustic waveform and joint position for a joint having bilateral degenerative TMJ disease taken in accordance with the present invention.
• FIGURE 4 is a graphical representation of acoustic waveform and joint position for a joint having myofascial pain syndrome (MPD) taken in accordance with the present invention.
• MPD myofascial pain syndrome
• FIGURE 5 is a schematic view of an apparatus used in accordance with the procedure of the present invention.
• the apparatus of the present invention is based on two related premises: (1) that an abnormal joint will exhibit frictional losses that are greater than those of a normal joint and which can easily be detected instrumentally, and; (2) different pathologies will present different types of frictional losses which can be identified and quantified acoustically.
• TMJ temporomandibular
• a detectable click should appear at the actual time of displacement and replacement.
• degenerative joint disease is characterized by disc perforation and a roughening of the joint surface, then the detectable frictional losses should appear as a longer duration aperiodic noise.
• an accurate and extensive data base of graphical patterns comprising numerous classifications and sub-classifications for different joints and joint disorders
• a medical technician could use the diagnostic apparatus (discussed below) and then compare and evaluate the particular graphical pattern with the standardized patterns from the data base.
• the present invention provides a noninvasive, acoustic technique for the detection and differential diagnosis of joint disorders.
• Examples 1-4 are directed to a TMJ joint having three conditions including normal TMJ (Example 1), internal derangement (Example 2), degenerative joint disease (Example 3) and pure myofascial pain syndrome (Example 4).
• the tests for the Examples were conducted under clinical conditions including the following methodology.
• the "normal" population consisted of twenty undergraduate dental students who had no previous history or present symptoms of TMJ disorders.
• the clinical population consisted of six patients with diagnosed internal derangement (either unilaterally or bilaterally) and six with degenerative joint disease. Diagnosis was based on either or both arthrotomographic evidence or surgical observation.
• Jaw displacement was tracked in both the vertical and anterior-posterior dimensions using a mandibular kinesiograph (Myotronics Research). This device consists of an array of six sensors that detects the position of a tiny magnet attached by dental adhesive to the lower central incisors. The acoustic recordings were obtained by placing a contact microphone (mounted in a headband) directly over the zygoma. Both the jaw displacement and acoustic signals were recorded simultaneously on separate tracks of an instrumentation tape recorder, the displacement signals in FM mode and the acoustic signal in direct mode. The output of the tape recorder was input to an optical oscillograph
• FIGURE 1 a typical readout for a normal joint is shown.
• the upper trace 10 shows the vertical displacement of the jaw throughout a complete opening and closing movement.
• the lower trace 12 shows the amplified output of the contact microphone channel.
• the vertical lines are timing markers, laid down at
• jaw opening is slow and continuous throughout approximately two-thirds of the cycle whereupon the jaw closing is more rapid.
• the acoustic track is essentially silent except for a sharp transient identified at 14 that corresponds to the time of tooth contact at the end of the closing phase of the movement.
• EXAMPLE 2 In this example, a surgical procedure indicated that the patient had internal derangement of his TMJ. Prior to that surgery, Arthrophonometry in accordance with the present invention was performed. A typical readout obtained for simple opening-and-closing movements of the jaw is shown in FIGURE 2. Again, the upper trace 16 shows jaw displacement in the vertical dimension and the lower trace 18 shows the output of the contact microphone. Note that the contact microphone track shows two separate short duration transients 20,22 that appear during both the opening and closing components of the jaw movement cycle. The opening click 20 complex is approximately 75 msec in duration and appears to contain two separate components. The onset of the click appears shortly after the onset of jaw opening, approximately 100 msec after onset of that movement.
• the closing click 22 complex is slightly shorter in duration (approximately 50 msec), appears later in the closing phase, but its offset is approximately 100 msec before tooth contact; this suggests reciprocity with the opening click. Note also that each click complex consists of two separate components and appears actually as a doublet. It is speculated that each of the individual spikes represents a different physiological event, the first perhaps reflecting passage over the meniscal ridge and the second either a condylar bounce or rebound. The temporal pattern of click-reciprocal click is typical of the other patients with diagnosed internal derangement of the TMJ.
• FIGURE 3 shows the graphical readout for a patient surgically diagnosed as having bilateral degenerative TMJ disease.
• Presurgical Arthrophonometry in accordance with the present invention shows that the acoustic pattern of the joint-propagated sounds is totally different than that of the previous patient (FIGURE 2).
• this patient presents a long duration frictional loss 24 that accompanies essentially the entire opening component of the jaw movement shown at 26.
• the onset of the noise occurs approximately 125 msec into the opening phase and continues for almost 600 msec to a point in time corresponding to maximum opening. It then ceases during the closing phase of the movement.
• This pattern of a long duration noise is typical for all of the other patients in this diagnostic group.
• EXAMPLE 4 The graphical readout for a patient diagnosed as having pure myofascial pain syndrome (MPD) is shown . in FIGURE 4.
• the present invention is able to provide differential diagnoses for diseases of the temporomandibular joint as presently accepted, by the medical arts. It can recognize a normal joint, a joint with meniscal displacement, and a joint with degenerative arthritis by quantifying the unique mechanical conditions of each of these diseases using joint sounds as the frictional analog.
• FIGURE 5 a schematic diagram of a typical apparatus used in accordance with the process of the present invention is shown.
• jaw induced sounds may be detected by a microphone or vibration transducer 28 whereupon the voltage signals are amplified through amplifier 30, band pass (100 hz - 5 khz), filtered through filter 32 and then recorded on one axis of an X-Y plotter or oscilloscope 34 as shown in FIGURES 1-4.
• the position of the joint in the X, Y and/or Z planes is measured in time and space by accelerometer 36.
• the voltage signals derived therefrom are then sent through amplifier 38 to integrators 40 and 42.
• Switch 44 of the electronic apparatus selects one or more of the X, Y or Z signals.
• the signals from switch 44 are recorded on a second axis of X-Y plotter or oscilloscope 34 whereby a precise, quantitative correlation between joint induced sound patterns and joint position in time and space is effected.
• the accelerometer 36 could be replaced by velocity or position transducers (with appropriate changes in electronics).
• the accelerometer could be moved instead of switched.
• the entire system as shown in FIGURE 4 could be implemented with a single chip microprocessor with analog to digital and digital to analog capabilities.
• Arthrophonometry of the TMJ could provide an objective and graphic representation of changes occurring over decades and may illuminate basic changes in joint function secondary to dental treatment. Sequential Arthrophonometry could find important applications in assessing effectiveness of various treatments. The adequacy of surgical correction of meniscal dislocation could be evaluated in this manner. The efficacy of splint therapy and other treatments might similarly be determined. At the very least, the method should reduce the number of post-treatment radiographic studies.

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• 1985
  • 1985-04-01 EP EP19850901807 patent/EP0179806A1/en not_active Withdrawn
  • 1985-04-01 JP JP60501434A patent/JPS61501823A/ja active Granted
  • 1985-04-01 WO PCT/US1985/000482 patent/WO1985004564A1/en not_active Ceased

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