## 4 Vibroarthrography of the Knee Joint
### Data Acquisition
\begin{table}
\begin{tabular}{p{113.8 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline \hline
**Authors of Research Study** & **Population** & **Sensor Type and Model** & **Sensor Placement** & **Knee Movement During the Examination** & **Data Acquisition** \\ \hline \multirow{6}{*}{\begin{tabular}{} \end{tabular} } & \multirow{6}{*}{220 normal} & \multirow{6}{*}{220 normal} & Accelerometer with a multichannel & & Frequency range: 0.7–1000 Hz, sampling rate 10 kHz, signal filtering: fourth-order zero-phase Butterworth zero-phase Butterworth band-pass digital filter with cutoff frequencies 50–1000 Hz, software: no data \\  & & & & \\ \cline{1-1}  & & & & \\ \cline{1-1}  & & & & \\ \cline{1-1}  & & & & \\ \cline{1-1}  & & & & \\ \cline{1-1}  & & & & \\ \cline{1-1}  & & & & \\ \cline{1-1}  & & & & \\ \cline{1-1}  & & & & \\ \cline{1-1}  & & & & \\ \cline{1-1}  & & & & \\ \cline{1-1}  & & & & \\ \hline \multirow{6}{*}{\begin{tabular}{} \end{tabular} } & \multirow{6}{*}{51 normal} & PK3I–30 kHz AE & & & \\ \cline{1-1}  & & & & \\ \cline{1-1}  & & low-power, integral preamp, & & & \\ \cline{1-1}  & & & & \\ \cline{1-1}  & & & & \\ \cline{1-1}  & & & & \\ \cline{1-1}  & & & & \\ \hline \multirow{6}{*}{\begin{tabular}{} \end{tabular} } & \multirow{6}{*}{51 normal} & Piezoelectric contact & & Bandwidth from 10 Hz \\  & & microphone & & & \\ \cline{1-1}  & & & & & \\ \cline{1-1}  & & & & & \\ \cline{1-1}  & & & & & \\ \cline{1-1}  & & & & & \\ \cline{1-1}  & & & & & \\ \hline \multirow{6}{*}{\begin{tabular}{} \end{tabular} } & \multirow{6}{*}{38 normal} & Accelerometer with a multichannel & & Frequency range: 0.7–1000 Hz, sampling rate 10 kHz, signal filtering: fourth-order zero-phase Butterworth band-pass digital filter with cutoff frequencies 50–1000 Hz, software: no data \\  & & & & & \\ \cline{1-1}  & & & & \\ \cline{1-1}  & & & & \\ \cline{1-1}  & & & & \\ \hline \multirow{6}{*}{\begin{tabular}{} \end{tabular} } & \multirow{6}{*}{63 normal} & Piezoelectric contact & & & \\ \cline{1-1}  & & & & & \\ \cline{1-1}  & & & & & \\ \cline{1-1}  & & & & & \\ \cline{1-1}  & & & & & \\ \cline{1-1}  & & & & & \\ \hline \multirow{6}{*}{\
\begin{tabular}{} \end{tabular} } & \multirow{6}{*}{220 normal} & Piezoelectric contact & & & \\ \cline{1-1}  & & & & & \\ \cline{1-1}  & & & & & \\ \cline{1-1}  & & & & & \\ \cline{1-1}  & & & & & \\ \cline{1-1}  & & & & & \\ \hline \multirow{6}{*}{
\begin{tabular}{} \end{tabular} } & \multirow{6}{*}{51 normal} & Piezoelectric contact & & & \\ \cline{1-1}  & & & & & \\ \cline{1-1}  & & & & & \\ \cline{1-1}  & & & & & \\ \cline{1-1}  & & & & & \\ \cline{1-1}  & & & & & \\ \cline{1-1}  & & & & & \\ \hline \hline \end{tabular} } \end{table} 
Table 2: _Cont._The data acquisition method is the first step in the analysis of the knee joint VAG signal. In the presented literature, the most commonly used type of sensor was accelerometers. One important factor in signal recording is the location of the sensor because the VAG signal received is based on the recording site. Accurate assessment of the knee joint condition is closely related to the location of the sensors. In the literature, the medial compartment below the midline of the patella is indicated as the optimal location due to the proximity of the contact area between the moving surfaces of the knee joint, which increases sensitivity [8]. This sensor placement is also advantageous due to the fact that actual knee joint movement and muscle contraction interference do not affect positional stability [8; 96; 112; 113; 114]. The most common knee movement is from flexion to full extension where in the full knee extension position the angle between the femur and the tibia is 0\({}^{\circ}\), and in the flexion position the knee forms a 90\({}^{\circ}\) angle [114]. The selection of an accelerometer is significantly influenced by its parameters, such as sensitivity and frequency response. The typical bandwidth used is 10 kHz, while the sensitivity ranges from 100 to 600 mV/g [115; 113; 116; 113].