Discovering Differences in Acoustic Emission Between Healthy and Osteoarthritic Knees Using a Four-Phase Model of Sit-Stand-Sit Movements

Abstract

By performing repeated sit-stand-sit movements to create stress on knee joints, short transient bursts of high frequency acoustic emission (AE) released by the knee joints were acquired from two age matched groups consisting of healthy and osteoarthritic (OA) knees, and significant differences between these two groups were discovered from the signal analysis performed. The analysis is based on a four-phase model of sit-stand-sit movements and a two-feature descriptor of AE bursts. The four phases are derived from joint angle measurement during movement, and they consist of the ascending-acceleration and ascending-deceleration phases in the sit-to-stand movement, followed by the descendingacceleration and descending-deceleration phases in the stand-to-sit movement. The two features are extracted from AE measurement during movement, and they consist of the peak magnitude value and average signal level of each AE burst. The proposed analysis method is shown to provide a high sensitivity for differentiation of the two age matched healthy and OA groups, with the most significant difference found to come from the peak magnitude value in the ascendingdeceleration phase, clear quantity and strength differences in the image based visual display of their AE feature profiles due to substantially more AE bursts from OA knee joints with higher peak magnitude values and higher average signal levels, and two well separated clusters in the space formed by the principal components. These results provide ample support for further development of AE as a novel tool to facilitate dynamic integrity assessment of knee joints in clinic and home settings.

Detection of experimental cartilage damage with acoustic emissions technique: An in vitro equine study

“…Since no studies have yet been conducted to evaluate the effectiveness of this technique in controlled environment to diagnose OA, the aim of the current study was to provide a novel alternative method to detect OA, even at a mild stage of the condition. The AE technique has previously been reported for detecting OA in human knees , and OA knees produced consistently and significantly more AE events with higher amplitudes and longer duration than healthy knees . In Shark and co‐worker's study , the discrimination was done using the four‐phase model of sit‐stand‐sit movement.…”

Biomarkers for knee osteoarthritis: new technologies, new paradigms

“…Nowadays, however, the term can include summary descriptors of an intrinsically high-dimensional object, such as a digital image, a time series or a chemical spectrum, termed 'biosignals'. Our work to explore acoustic emission (AE) as a biomarker for knee OA [16][17][18][19] illustrates some of the challenges which are being raised by the ever-broadening scope of technologies being explored as potential biosignals.…”

“…In this context, the development of techniques to measure highfrequency AE in knee joints [16][17][18][19] offers the potential to develop a biomarker reflecting the integrity of interactions between knee joint components during weightbearing movement. Since OA affects joint function, markers which assess or reflect the integrity of interactions between joint structures during knee movement offer a strong rationale for biomarker development.…”

Automatic gauge control hydraulic cylinder state identification using modified image based acoustic emission profile

“…According to the previous studies produced by the authors, the principal component analysis (PCA) could be one of good option for further highlighting the dissimilarities between the image based profiles [17][18][19][20][21]. PCA is a kind of multivariate statistical based technique that has been widely used for dimensional reduction and feature extraction, which implements by projecting the multidimensional vector onto a new plane formed by the principal components (PC) through the singular value decomposition (SVD) and the matrix inner products with the projection of original matrix onto the PC space represents by the PC scores, thereby re-organizing the variables with higher variances onto the lower dimensional space [22].…”

“…In order to reduce the dimensionalities of the AE signals, convert the AE signals emitted from each loading condition to a uniform format, as well as to create the visual effect for further inspection of the cylinder under various loadings, a modified image based AE profile, namely the hits density approach is proposed. The hits density approach and its applications were previously introduced by the authors since 2009 [17][18][19][20][21], it is a type of multivariate statistical based methodology that re-classifying the number of AE events by using the specified AE feature combinations within various value granularities. The mathematical representation of this approach is given by (1)…”