2015 ISAKOS Biennial Congress ePoster #1341

Quantitative Assessment of The Lachman Test with Joint Sound : Comparison Between Intact and ACL-Deficient Knees

Kazunori Tanaka, MD, Kashihara, Nara JAPAN
Koji Hattori, Prof., Kobe, Hyogo JAPAN
Munehiro Ogawa, MD, PhD, Kashihara, Nara JAPAN
Kota Uematsu, MD, Nara JAPAN
Yasuhito Tanaka, Prof., Kashihara, Nara JAPAN

Nara Medical University, Kashihara, Nara, JAPAN

FDA Status Not Applicable

Summary: This study indicates that the joint auscultation system is promising as an accurate judgement tool for positive and negative responses of the Lachman test and the system is useful tool to visualize the Lachman test.

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Abstract:

Purpose

The Lachman test is clinically considered to be a reliable physical examination for anterior cruciate ligament (ACL) injury. Clinically examiners judge the soft and hard endpoints subjectively. As a result, the Lachman test is not completely ideal for ACL injury. We developed a new auscultation system to assess the Lachman test and could analyze the Lachman test objectively using the porcine intact and ACL deficient knee. However it is not known that the system could detect ACL-deficient knees in human. In this study, we evaluated the joint sound of patient with ACL injury during Lachman test and compared between intact and ACL-deficient knees quantitatively.

Methods

Twenty-four patients with isolated ACL injures were undertaken the Lachman test on bilateral knees under general anesthesia. A contact microphone was placed on the medial suprapatella area of the knee and the knee joint sound (hereinafter described as Lachman sound) was recorded during five tibial translations of the Lachman test. The Lachman sound data were converted into a spectrum and spectrogram by fast Fourier transformation. The Lachman sound spectrum comprises a two-dimensional map with the x-axis and y-axis representing the frequency (Hz) and the relative amplitude (acoustic pressure) (-dB), respectively. In the previous study, we revealed that the peak relative amplitudes of intact knees were centered around 90 Hz. Therefore, as a quantitative index of Lachman sound, we measured the spectrum area from 80 Hz to 100 Hz. Five measurements were assessed for each patient. Moreover, the Lachman sound was visualized using spectrogram which was a two-dimensional map with the x-axis and y-axis representing the time (s) and frequency (Hz), respectively, and the relative amplitude is indicated by the color grade.

Results

The median spectrum area of intact and ACL-deficient knees were 1743.8(-Hz × dB) and 1176.1(-Hz × dB), respectively. Significant differences were found between intact and ACL-deficient knees (p < 0.05 by the Wilcoxon signed-rank test). The spectrogram showed obvious differences between intact and ACL deficient knees that the peak relative amplitude of intact knees centered around 90Hz whereas that of ACL-deficient knees dispersed in various frequency bands.

Conclusion

This study is the first report to assess the Lachman sound quantitatively using intact and ACL-deficient knees in human. Our study demonstrated that the spectrum of the Lachman sound showed that intact knees had larger relative amplitude around 90Hz than ACL-deficient knees. These preliminary results indicate that the joint auscultation system is promising as an accurate judgement tool for positive and negative responses of the Lachman test and the system is an useful tool to visualize the Lachman test.