## 2 Materials and Methods
### Experimental Procedures and Instruments
#### Range of Motion (Orthyo System)  
The patients were assigned to their groups and registered in the Orthyo online panel. Orthyo contains three parts: motion sensors, a mobile app, and an online panel. The sensors record 3 types of sensory data: magnetic field, acceleration, and velocity. After preliminary analysis, data are sent to the Orthyo app through Bluetooth Low Energy. Subsequently, all positions between the sensors in relation to each other are calculated and then stored in the online database. The Orthyo system has been discussed in detail in an article by [PERSON] et al. [12].  
Before the diagnostic examination, two motion sensors were attached to the patient's lower limb using elastic Velcro bands. The first one was attached to the lateral thigh area 15 cm from the trochanter of the femur, and the other on the anterior side of the lower leg, 5 cm distally from the tibial tuberosity. The maximum range of knee motion was measured using the sensors during two tests:  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Variable** & **Group** & **Mean \(\pm\) SD** & **Median** & **Min–Max** & \(p\) \\ \hline \multirow{3}{*}{age (years)} & E & 62.4 \(\pm\) 5.4 & 62.0 & 55.0–75.0 & \\  & MT & 65.2 \(\pm\) 3.1 & 65.0 & 58.0–70.0 & 0.13 \\  & C & 64.0 \(\pm\) 5.7 & 63.0 & 55.0–75.0 & \\ \hline \multirow{3}{*}{weight (kg)} & E & 78.0 \(\pm\) 12.2 & 75.0 & 58.0–100.0 & \\  & MT & 78.2 \(\pm\) 12.5 & 75.0 & 58.0–105.0 & 0.15 \\  & C & 71.1 \(\pm\) 12.2 & 68.0 & 56.0–90.0 & \\ \hline \multirow{3}{*}{height (m)} & E & 1.68 \(\pm\) 0.08 & 1.67 & 1.53–1.82 & \\  & MT & 1.65 \(\pm\) 0.08 & 1.64 & 1.55–1.81 & 0.88 \\  & C & 1.68 \(\pm\) 0.07 & 1.68 & 1.56–1.80 & \\ \hline \multirow{3}{*}{body mass index (BMI)} & E & 27.6 \(\pm\) 3.7 & 27.1 & 20.4–36.1 & \\  & MT & 28.6 \(\pm\) 4.3 & 28.3 & 20.9–38.3 & 0.40 \\ \cline{1-1}  & C & 25.1 \(\pm\) 3.9 & 24.0 & 19.8–34.3 & \\ \hline \hline \end{tabular}
\end{table}
Table 1: Basic anthropometric data of the study population (Kruskal–Wallis test).  
1. Range of active knee motion: test in the open kinematic chain. The patient performed the test in the prone position with the lower limbs extended. The patient was requested to perform maximum knee flexion that would not elicit pain. The test was recorded by the motion sensors that calculated the difference between the initial and maximum angle (Figure 1).
2. Maximum range of knee motion test while squatting. The patient performed the test in a standing position with the lower limbs hip-width apart. Subsequently, the patient was asked to squat as much as possible without feeling pain (Figure 2).  
Figure 1: Measuring the range of motion in the open kinematic chain. (**A**) Starting position. (**B**) End position.  
Figure 2: Measuring the range of motion in the closed kinematic chain. (**A**) Starting position. (**B**) End position.  
Both tests were performed three times for both lower limbs. Both limbs were similarly affected by the osteoarthritis in the patients, as confirmed by radiography. Therefore, differences between the right and left side were not included in the study.