## 4 Discussion
[9] reported no significant differences in scapulothoracic joint RoM between individuals with stroke and controls. The range of motion of the non-paretic limbs was similar to that of controls, which is different from [PERSON] et al. [11], who found a lower value of maximum thoracohumeral elevation (125.7\({}^{\circ}\)). Furthermore, no specific abnormalities were found in scapulothoracic motion and SHR, which, in flexion and abduction, showed a linear ratio similar to those reported in the literature [23]. Causes of abnormal non-paretic upper limb kinematics have been previously discussed [11] in terms of neurological impairment due to stroke consequences on neural pathways in the contralateral hemisphere and biomechanical improper function, so the non-paretic upper limb should not be considered for comparison with the affected limb. Normally, in healthy subjects, as measured via 3D kinematic evaluation [10; 12; 32], during shoulder flexion, the scapula shows upward rotation and external rotation followed by internal rotation and posterior tilt, and upward, external rotation, and posterior tilt during abduction. The findings in the present study confirm the reduced posterior tilt observed by other authors [8; 12; 33] during arm elevation. However, they differ from the literature in which a diminished scapular protraction during elevation in the sagittal plane [11], more scapular lateral rotation during active abduction and flexion [13], and increased scapular upward rotation were found. Furthermore, increased scapular internal rotation during arm elevation in a self-selected plane was found by [PERSON] et al. [12]. Our data, even from a small cohort of stroke patients, show that there is reduced scapular tilt during flexion and abduction. Furthermore, if we consider the graphs showing the scapulothoracic UD changes, we see that at the highest degrees of abduction, there is inflexion of the lateral movement of the scapula on the thorax, which could contribute to the reduced range of motion of the shoulder. Regarding the scapulohumeral rhythm, only a few authors calculated its value during wide shoulder elevation, concluding that, in some stroke patients, the SHR can be the same in the non-paretic upper limb, while in others, there can be reduced scapular upward rotation, and in others, increased upward rotation [34]. [PERSON] et al. [10] confirmed a lower non-linear SHR in the paretic upper limb. Additionally, [PERSON] and [PERSON] [35] demonstrated that, during dynamic humeral elevation, the scapulohumeral rhythm changes depend on the phase of elevation and do not have a fixed 2:1 ratio, depending on the type of arm elevation. Unfortunately, only the plot for SHR is usually shown in the literature, without providing data [5; 23]. Only one study provides SHR values in stroke patients with an arm elevation of over 80\({}^{\circ}\)[35]. The ratio was reported to be approximately 7.9:1 for the first 26 degrees and increased to 3:1 between 104 and 130 degrees of elevation. The SHR values in the present study are in overall agreement with these findings, and at a higher RoM, the scapular contribution decreases. We calculated the SHR as a pure ratio between humeral motion and scapulothoracic rotation at discrete angles of elevation and abduction, while [PERSON] and [PERSON] [35] derived it as the slope of fitted continuous values of scapular UD rotation for different degrees of humeral elevation. According to the literature, abnormalities in shoulder complex motion are correlated with the Fugl-Myers score [7; 21]. This confirms the possible role of wearable devices in monitoring patients in a home setting, although specific studies should be planned to explore the relationship between wearable motion measures and shoulder section or even overall upper limb joint FMA scores. The assessment of the individual components of the shoulder complex motion pattern in stroke patients is relevant for assessing the biomechanical impairment that underpins the abnormal kinematics for rehabilitation purposes.