title: Human knee joint sound during the Lachman test: Comparison between healthy and anterior cruciate ligament-deficient knees.
abstract: BACKGROUND
  The Lachman test is clinically considered to be a reliable physical examination for anterior cruciate ligament (ACL) deficiency. However, the test involves subjective judgement of differences in tibial translation and endpoint quality. An auscultation system has been developed to allow assessment of the Lachman test. The knee joint sound during the Lachman test was analyzed using fast Fourier transformation. The purpose of the present study was to quantitatively evaluate knee joint sounds in healthy and ACL-deficient human knees.
  
  
  METHODS
  Sixty healthy volunteers and 24 patients with ACL injury were examined. The Lachman test with joint auscultation was evaluated using a microphone. Knee joint sound during the Lachman test (Lachman sound) was analyzed by fast Fourier transformation. As quantitative indices of the Lachman sound, the peak sound (Lachman peak sound) as the maximum relative amplitude (acoustic pressure) and its frequency were used.
  
  
  RESULTS
  In healthy volunteers, the mean Lachman peak sound of intact knees was 100.6 Hz in frequency and -45 dB in acoustic pressure. Moreover, a sex difference was found in the frequency of the Lachman peak sound. In patients with ACL injury, the frequency of the Lachman peak sound of the ACL-deficient knees was widely dispersed. In the ACL-deficient knees, the mean Lachman peak sound was 306.8 Hz in frequency and -63.1 dB in acoustic pressure. If the reference range was set at the frequency of the healthy volunteer Lachman peak sound, the sensitivity, specificity, positive predictive value, and negative predictive value were 83.3%, 95.6%, 95.2%, and 85.2%, respectively.
  
  
  CONCLUSIONS
  Knee joint auscultation during the Lachman test was capable of judging ACL deficiency on the basis of objective data. In particular, the frequency of the Lachman peak sound was able to assess ACL condition.
authors.affiliation: Department of Orthopaedic Surgery, Nara Medical University, 840, Shijyo-cho, Kashihara, Nara, 634-8522, Japan.
authors.forename: Kazunori
authors.initials: K
authors.lastname: Tanaka
authors.affiliation: Department of Orthopaedic Surgery, Nara Medical University, 840, Shijyo-cho, Kashihara, Nara, 634-8522, Japan.
authors.forename: Munehiro
authors.initials: M
authors.lastname: Ogawa
authors.affiliation: Department of Orthopaedic Surgery, Nara Medical University, 840, Shijyo-cho, Kashihara, Nara, 634-8522, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Inagaki
authors.affiliation: Department of Orthopaedic Surgery, Nara Medical University, 840, Shijyo-cho, Kashihara, Nara, 634-8522, Japan.
authors.forename: Yasuhito
authors.initials: Y
authors.lastname: Tanaka
authors.affiliation: Department of Physical Therapy, Faculty of Nursing and Rehabilitation, Konan Women's University, 6-2-23, Morikita-machi, Higashinada-ku, Kobe, Hyogo 658-0001, Japan.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Nishikawa
authors.affiliation: Department of Physical Therapy, Faculty of Nursing and Rehabilitation, Konan Women's University, 6-2-23, Morikita-machi, Higashinada-ku, Kobe, Hyogo 658-0001, Japan. Electronic address: khattori@konan-wu.ac.jp.
authors.forename: Koji
authors.initials: K
authors.lastname: Hattori
mesh_terms: D000162:Acoustics / Q000295:instrumentation*; D000293:Adolescent; D000328:Adult; D016118:Anterior Cruciate Ligament / Q000000981:diagnostic imaging* / Q000503:physiopathology; D000070598:Anterior Cruciate Ligament Injuries / Q000175:diagnosis* / Q000503:physiopathology; D001314:Auscultation / Q000295:instrumentation*; D001696:Biomechanical Phenomena; D003937:Diagnosis, Differential; D019937:Diagnostic Techniques and Procedures / Q000295:instrumentation*; D004867:Equipment Design; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000503:physiopathology*; D008297:Male; D011237:Predictive Value of Tests; D016059:Range of Motion, Articular; D012720:Severity of Illness Index; D012738:Sex Hormone-Binding Globulin; D055815:Young Adult
chemical_list: D012738:Sex Hormone-Binding Globulin