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DE GRUYTER Current Directions in Biomedical Engineering 2020;6(3): 20203133 Subke Joerg*, Krueger Sabine, Junker Heinz-Otto, Schwalbe Hans-Joachim, Franke Ralf- Peter and Wolf Udo An introduction to Acoustic Emission Analysis (AEA) based medical diagnostic techniques: Screening and Monitoring of cartilage defects in knee joint osteoarthrosis Abstract: Clinical studies have shown that during 1 Introduction standardized movements the Acoustic Emission (AE) from lesions in articular cartilage can be assessed. Specific lesions Knee joint osteoarthrosis is a progressive degenerative disease produce specific acoustic signals, therefore it is possible to affecting the knee joint cartilage. Cartilage usually does not evaluate the character of cartilage damage. Consequently it is heal in humans, therefore an early diagnosis and the possibility possible to evaluate the condition of the joint cartilage in order of real time screening of defects and monitoring of medical to enhance therapy. Patients performed series of knee bends, intervention is crucial to the therapeutic measures . first on a plane surface in order to assess the cartilage lesions. Acoustic emission analysis (AEA) in medical diagnosis is Then patients performed knee bends on boards simulating a non-destructive method for the screening of the condition of orthopaedic insoles by means of inner and outer edge articular cartilage , . AEA is carried out during elevations. Insoles aim at relieving the lesioned areas of application of standardized loads, because only active defects cartilage from loads and strain. AEA monitoring reveals the or deteriorations in cartilage produce acoustic emission. AEA effects of a shift of the zone of load transfer immediately and as a medical diagnostic technique can provide a wide scope of is an adequate tool for the diagnosis as well as the monitoring information of joint cartilage and its damage patterns . AEA of therapeutic measures. has no known health risks or side effects . In the context of a clinical study 69 patients with the Keywords: Acoustic Emission Analysis, osteoarthrosis, initial clinical diagnosis of knee joint osteoarthrosis underwent knee, clinical study, screening of damaged areas, monitoring a screening with AEA. One exemplary case of a patient with of load deviation pronounced symptoms in the left knee but unspecific symptoms in the right will serve to illustrate the application of https://doi.org/10.1515/cdbme-2020-3133 AEA based screening as a diagnostic technique. ______ *Corresponding author: Subke Joerg: THM University of Applied Sciences, Wiesenstr. 14, D—35390 Giessen, Germany, e-mail: firstname.lastname@example.org Krueger Sabine: Osteopathiepraxis, Ludwigsburg, Germany Junker Heinz-Otto: Klinik Rheumazentrum Mittelhessen, Bad Endbach, Germany Schwalbe Hans-Joachim, Franke Ralf-Peter: BoneDiaS GmbH & Co.KG, Greifenstein, Germany Wolf Udo: University of Applied Sciences, Fulda, Germany Open Access. © 2020 Subke Joerg et al., published by De Gruyter. This work is licensed under the Creative Commons Attribution 4.0 License. An introduction to Acoustic Emission Analysis (AEA) — 2 2 Method Clinical studies have shown that during standardized movements the AE from lesions in articular cartilage can be assessed. Different types of lesions emit different acoustic signals, acoustic emission therefore can be assigned to typical lesion patterns. Osteoarthrosis e.g. will emit characteristic AE- burst signals. Joints emit a basic continuous background noise. The visually nearly imperceptible movement of a person standing in an upright position is an acoustically very well perceptible load transfer in AEA. Figure 2: Person during a knee bend on boards with elevated outer edges to simulate insoles The third series of knee bends will be executed on boards with 2° outer edge elevations (see Figure 2). By variation of the joint angle position in the sagittal plane with the help of the simulated insoles a shift of the load Figure 1: Person during a knee bend with the adapted transfer zone and a rerouting of loads unto undamaged areas is BoneDiaS-system and piezo sensor at the knee possible. Here again the real time monitoring by AEA provides the necessary information on condition and depth of cartilage. The standardized movements , a series of three knee bends were examined with the help of a BoneDiaS AEA system with an integrated inclinometer. This allows the exact mapping of lesioned or damaged areas on the cartilage surface 3 Results . The patients perform the first series of knee bends on a The patient of the exemplary case showed distinct acoustic plane surface. There will always be variations in the individual signals of significant damage in the right knee during the performance of the bends which will be registered by the performance of the knee bends on the plane surface. See the inclinometer. Patients will vary their movements to avoid AE amplitude-time curve with peaks during knee bending S2, damaged areas and avoid pain which will enhance the S3 and S6 for further reference (see Figure 3, 4, 5 and 6). screening of the cartilage (see Figure 1). The examination on the boards when the inner edge was The second examination with another series of knee bends elevated produced pronounced signals while the patient will be performed on boards that simulate the effect of assumed an upright position, but the other acoustic emission orthopaedic insoles with a 2° inner edge elevation. was within the normal range in the course of the movement (see Figure 7). An introduction to Acoustic Emission Analysis (AEA) — 3 Figure 3: a) AE of the 3 knee bends on a plane surface; location of the signals S2, S3 and S6; b) angle of the 3 knee bends and the location of the signal S6 Figure 6: a) AE of the 3 knee bends on a plane surface; b) zoomed location of the signal S6 and c) the location of the signal S6 Figure 4: a) AE of the 3 knee bends on a plane surface; b) Figure 7: a) AE of the 3 knee bends on surfaces with inner zoomed location of the signal S2 and c) the location of the elevations and b) the trajectory of angle signal S2 Figure 8: a) AE of the 3 knee bends on surfaces with outer elevations and b) the trajectory of the angle The examination on the boards when the outer edge was elevated revealed no acoustic emission significant of damage Figure 5: a) AE of the 3 knee bends on a plane surface; b) zoomed location of the signal S3 and c) the location of the at all, but the typical acoustic spectrum of the intact joint. In signal S3 this case the relative presentation of the amplitudes shows a wide band of the noise amplitudes (see Figure 8). An introduction to Acoustic Emission Analysis (AEA) — 4 further deterioration of the lesioned area and restored the 4 Discussion patient’s mobility. The AEA of acoustic signals from the exemplary case study of Author Statement a patient on a plane surface revealed distinct friction signals Research funding: The author state no funding involved. indicative of damage of the articular cartilage. Conflict of interest: Authors state no conflict of interest. The steep rise of the amplitude at the beginning of signal Informed consent: Informed consent has been obtained from st S2 (1 knee bend, plane surface) actually represents the abrupt all individuals included in this study. Ethical approval: The entry or drop into a cartilage lesion and at the end the gradual research related to human use complies with all the relevant exit out of the lesioned area at a joint angle position of 20°, the national regulations, institutional policies and was performed patient moving upward into a standing position. in accordance with the tenets of the Helsinki Declaration, and nd Signal S3 (2 knee bend, plane surface) shows a slightly has been approved by the authors' institutional review board or different load transfer path due to a slight variation in the equivalent committee. patient’s execution of the knee bend. The joint angle is within the 20° range but the moderate rise of the amplitude indicates a thicker and healthier layer of cartilage that is dampening the References acoustic emission at this point. rd Signal S6 (3 knee bend, plane surface) again reveals a  Schwalbe HJ, Bamfaste G, Franke RP. Non-destructive and non-invasive observation of friction and wear of human joints distinct friction suggestive of damaged cartilage for the same and of fracture initiation by acoustic emission Proc. Instn joint angle position. The inclinometer reveals that in S6 the Mech Engrs Vol 213 Part H, 1999, 41- 48 patient again slightly varied the knee bend.  Schwalbe HJ, Franke RP, Dörner P, Ziegler B. The AE versus time of signals S2, S3 and S6 reveal that Orthopädische Diagnose des menschlichen Femurs und Kniegelenks mit Hilfe der Schallemissionsanalyse. Deutsche the patient already suffers from degenerative defects of the Gesellschaft für zerstörungsfreie Prüfung 14. Kolloquium articular cartilage in the right knee and that the development Schallemission, Berichtsband 2003. of osteoarthrosis is imminent. Therefore it is advisable to  Franke RP, Schwalbe HJ, Kiselev J, Wolf U, Subke J, Ziegler apply therapeutic measures to stop the progression of the B. Schallemissionsanalyse zum Nachweis von Gelenkdefekten in der medizinischen Diagnostik. Deutsche symptoms. Gesellschaft für zerstörungsfreie Prüfung 18. Kolloquium Consequently, the following AEA examinations with Schallemission, Berichtsband 2011. simulated insole effects aim at finding healthy areas of joint  Schwalbe HJ, Franke RP, Dörner P, Kiselev J, Wolf U, cartilage and at shifting the load transfer zone from lesioned to Subke J, Ziegler B. Nachweis der Rissbildungsgrenze des un-lesioned areas. humanen Femurs mit Hilfe der Schallemissionsanalyse (SEA). Deutsche Gesellschaft für zerstörungsfreie Prüfung Both alterations, lateral and medial elevation allow to 18. Kolloquium Schallemission, Berichtsband 2011. avoid the lesioned areas in the course of the knee bend. With  Titze M. Schallemissionsanalys als Nachweis des the medial, i.e. inner edge elevation, however, the joint Reibverhaltens im menschlichen Kniegelenk in produced pronounced signals while the patient assumed an verschiedenen Belastungssituationen. Diplomarbeit FB Maschinenbau und Feinwerktechnik, FH-Gießen-Friedberg, upright position. Therefore, the lateral, i.e. outer edge elevation has to be preferred. The monitoring of the insoles’  Schwalbe HJ, Schmale J, Subke J, Ziegler B, Kellotat A, effect can be assessed in real time again by AEA. Dörner P, Franke RP, Wolf U. Detection of Defects in the Human Skeletal System and Production of Failure Optimized Artificial Bone Applying Acoustic Emission Analysis (AEA). st 31 Conference of the European Working Group on Acoustic 5 Conclusion Emission (EWGAE) Proceedings, Dresden 2014  Kiselev J, Wolf U, Ziegler B, Schwalbe H-J, Franke R-P. Detection of early phases os ostearthritis using acoustic The application of different test boards in the course of an emission analysis. Med. Eng. Phys. 2019, 65, 57-60. AEA screening proves that the contact area between femur and tibia can be examined (real time) in the active joint in order to detect and map the cartilage surface and probable cartilage defects. In the exemplary case it was possible to find an area of undamaged cartilage onto which the effect of an insole with an outer edge elevation rerouted the load transfer. This avoided a
Current Directions in Biomedical Engineering – de Gruyter
Published: Sep 1, 2020
Keywords: Acoustic Emission Analysis; osteoarthrosis; knee; clinical study; screening of damaged areas; monitoring of load deviation
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