title: Synthesis of vibroarthrographic signals in knee osteoarthritis diagnosis training.
abstract: BACKGROUND
  Vibroarthrographic (VAG) signals are used as useful indicators of knee osteoarthritis (OA) status. The objective was to build a template database of knee crepitus sounds. Internships can practice in the template database to shorten the time of training for diagnosis of OA.
  
  
  METHODS
  A knee sound signal was obtained using an innovative stethoscope device with a goniometer. Each knee sound signal was recorded with a Kellgren-Lawrence (KL) grade. The sound signal was segmented according to the goniometer data. The signal was Fourier transformed on the correlated frequency segment. An inverse Fourier transform was performed to obtain the time-domain signal. Haar wavelet transform was then done. The median and mean of the wavelet coefficients were chosen to inverse transform the synthesized signal in each KL category. The quality of the synthesized signal was assessed by a clinician.
  
  
  RESULTS
  The sample signals were evaluated using different algorithms (median and mean). The accuracy rate of the median coefficient algorithm (93 %) was better than the mean coefficient algorithm (88 %) for cross-validation by a clinician using synthesis of VAG.
  
  
  CONCLUSIONS
  The artificial signal we synthesized has the potential to build a learning system for medical students, internships and para-medical personnel for the diagnosis of OA. Therefore, our method provides a feasible way to evaluate crepitus sounds that may assist in the diagnosis of knee OA.
authors.affiliation: Medical Physics and Informatics Laboratory of Electronics Engineering, National Kaohsiung University of Applied Sciences, 415, Chien Kung Road, San-Min District, Kaohsiung, 807, Taiwan, ROC.|Graduate Institute of Clinical Medicine, Kaohsiung Medical University, Kaohsiung, 807, Taiwan, ROC.
authors.forename: Chin-Shiuh
authors.initials: CS
authors.lastname: Shieh
authors.affiliation: Medical Physics and Informatics Laboratory of Electronics Engineering, National Kaohsiung University of Applied Sciences, 415, Chien Kung Road, San-Min District, Kaohsiung, 807, Taiwan, ROC.
authors.forename: Chin-Dar
authors.initials: CD
authors.lastname: Tseng
authors.affiliation: Department of Medical Imaging and Radiological Sciences, I-Shou University, Kaohsiung, 82445, Taiwan, ROC.
authors.forename: Li-Yun
authors.initials: LY
authors.lastname: Chang
authors.affiliation: Institute of Photonics and Communications, National Kaohsiung University of Applied Sciences, Kaohsiung, 80778, Taiwan, ROC.|Department of Orthopedic, Kaohsiung Municipal Min-Sheng Hospital, Kaohsiung, 80276, Taiwan, ROC.
authors.forename: Wei-Chun
authors.initials: WC
authors.lastname: Lin
authors.affiliation: Medical Physics and Informatics Laboratory of Electronics Engineering, National Kaohsiung University of Applied Sciences, 415, Chien Kung Road, San-Min District, Kaohsiung, 807, Taiwan, ROC.
authors.forename: Li-Fu
authors.initials: LF
authors.lastname: Wu
authors.affiliation: Medical Physics and Informatics Laboratory of Electronics Engineering, National Kaohsiung University of Applied Sciences, 415, Chien Kung Road, San-Min District, Kaohsiung, 807, Taiwan, ROC.|Graduate Institute of Clinical Medicine, Kaohsiung Medical University, Kaohsiung, 807, Taiwan, ROC.
authors.forename: Hung-Yu
authors.initials: HY
authors.lastname: Wang
authors.affiliation: Medical Physics and Informatics Laboratory of Electronics Engineering, National Kaohsiung University of Applied Sciences, 415, Chien Kung Road, San-Min District, Kaohsiung, 807, Taiwan, ROC.|Department of Radiation Oncology, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung, 83342, Taiwan, ROC.
authors.forename: Pei-Ju
authors.initials: PJ
authors.lastname: Chao
authors.affiliation: Medical Physics and Informatics Laboratory of Electronics Engineering, National Kaohsiung University of Applied Sciences, 415, Chien Kung Road, San-Min District, Kaohsiung, 807, Taiwan, ROC.
authors.forename: Chien-Liang
authors.initials: CL
authors.lastname: Chiu
authors.affiliation: Medical Physics and Informatics Laboratory of Electronics Engineering, National Kaohsiung University of Applied Sciences, 415, Chien Kung Road, San-Min District, Kaohsiung, 807, Taiwan, ROC. tsairfwulee@gmail.com.|Graduate Institute of Clinical Medicine, Kaohsiung Medical University, Kaohsiung, 807, Taiwan, ROC. tsairfwulee@gmail.com.
authors.forename: Tsair-Fwu
authors.initials: TF
authors.lastname: Lee
mesh_terms: D000328:Adult; D000465:Algorithms; D053587:Arthrometry, Articular / Q000379:methods; D054459:Elasticity Imaging Techniques / Q000295:instrumentation / Q000379:methods*; D005260:Female; D005583:Fourier Analysis; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging* / Q000473:pathology; D012815:Signal Processing, Computer-Assisted; D019023:Stethoscopes
keywords: Kellgren–Lawrence grading; Knee sound synthesis; Vibroarthrographic signals