## 2 Methods of Diagnosing Cartilage Lesions
As a complementary tool, VAG provides a functional perspective on joint health, enhancing diagnosis, treatment planning, and long-term patient monitoring, while offering a more comprehensive evaluation alongside conventional imaging techniques. Over the years, the possibility of using acoustic emission recording and vibroarrhythography to detect and monitor the condition of the knee at various stages of knee degenerative disease has been tested. Piezoelectric sensors, accelerometers, and stethoscopes are used to record acoustic emissions (AE) and VAG signals. It was found that knees with OA emit \begin{table}
\begin{tabular}{c c c c} \hline
**Diagnostic Method** & **Advantages** & **Disadvantages** & **Sources** \\ \hline \multirow{6}{*}{Computed tomography} & \multicolumn{3}{c}{Time} \\  & \multicolumn{3}{c}{Lack of cartilage visualisation unless} \\  & \multicolumn{3}{c}{enhanced with the administration of} \\  & \multicolumn{3}{c}{Intra-articular contrast agent} \\  & \multicolumn{3}{c}{High resolution} & Based on bone changes, it allows for the \\  & \multicolumn{3}{c}{estimation of cartilage damage} \\  & \multicolumn{3}{c}{Contrast agent exposure in} \\  & \multicolumn{3}{c}{contrast-enhanced CT} \\ \hline \multirow{6}{*}{Ultrasound} & Dynamic test & \multirow{2}{*}{The quality of the examination depends on} \\  & Noninvasive & & \\  & Low cost & & the experience of the sonographer \\  & High sensitivity for detecting soft & Lack of visibility of all knee parts as \\  & tissue and structures & & \\  & Real-time imaging & ultrasound cannot penetrate through bones \\  & Ability to assess inflammation & & \\ \hline \multirow{6}{*}{Magnetic resonance imaging} & Noninvasive & \multirow{2}{*}{High cost} \\  & High resolution & & \\  & Quantitative measurements of & Complex \\  & \multicolumn{3}{c}{articular cartilage} & Long acquisition times \\  & \multicolumn{3}{c}{3D imaging} & \\  & Detection of damage to cartilage, & & \\  & menisci, ligaments & & \\ \hline \multirow{6}{*}{Vibroarithmography} & Noninvasive & \multirow{2}{*}{No dedicated equipment} \\  & Low cost & & \\  & Provides information about the & & No test protocols \\ \cline{1-1}  & condition of the moving joint & & \\ \cline{1-1}  & Repeatability & & \\ \hline \end{tabular}
\end{table} 
Table 1: _Cont._more acoustic events with higher amplitude and longer duration compared to healthy knees [69,70]. As the cartilage in the knee joint atrophies, an increasing number of acoustic signals are emitted [71]. The change in stress distribution generates acoustic signals that are recorded from the surface of the knee joint [72]. Over the last century, the use of VAG in preclinical evaluation has been reported to be more than 90% accurate in determining cartilage loss [6]. The advantages of using vibroarthrography to diagnose knee osteoarthritis are its low cost, repeatability, speed, and lack of radiation [30,73]. Vibroarthrography is a method based on recording and further analysing the sounds or vibrations of a joint during movement, providing information about its biomechanics and cartilage quality. Unlike typical medical imaging methods (MRI and CT), which are static techniques, VAG allows real-time assessment of the dynamic functioning of a joint, which can reveal even subtle abnormalities not visible in static images. However, there are no research or acquisition protocols that are accepted broadly enough to implement this method in clinical diagnostics [19]. Imaging and physical examinations were used as a reference point for the results, which may pose a risk of bias in the tests performed [19]. In recent years, to accurately assess the type, grade (according to ICRS), and location of cartilage lesions, alongside physical examination and imaging findings, intraoperative evaluation has also been performed for patients scheduled for surgery. This approach enhances accuracy and enables the precise attribution of signals to specific lesion types.