**2. Clinical implications and evaluation of proprioception**

The loss of proprioceptive afferents may affect the control of muscle tone, disrupts postural reflexes, and severely impairs spatial and temporal aspects of movement [33]. Proprioceptive impairments are associated with various neurological conditions such as stroke [34], Parkinson's disease [35], peripheral neuropathy [36], as well as orthopedic conditions such as low back pain [37], neck pain [38], sports injuries like chronic ankle instability [39], ACL injuries [40], post-operatively such as mastectomy [41], knee arthroplasty [42], and aging [43]. Considering the importance of proprioception for motor control, a detailed evaluation of proprioceptive sense and application of treatment approaches focusing on training the proprioceptive sense is important for restoring motor function. Proprioception can be measured by using specific and non-specific tests in clinical practice.

*Specific Tests of Proprioception:* assess an individual's status regarding the joint position sense and kinesthesia [21]. *Joint position sense* tests assess precision or accuracy in repositioning the joint at a predetermined target angle and can be measured as active joint position detection (AJPD) [e.g., position matching task, position copying task] and passive joint position detection (PJPD) [e.g., thumb finding test, dual-joint position test] [44]. *Kinesthesia* tests assess the ability to perceive joint movement. For evaluating the perceptual aspect of proprioception, psychophysical thresholds represent the gold standard [33]. These tests are usually performed passively and can be measured by using passive motion detection threshold (PMDT) and passive motion direction discrimination (PMDD) [e.g., distal proprioception test, Rivermead Assessment of Somatosensory Perception] [44].

*Non-specific Tests of Proprioception:* for determining the contribution of proprioceptive signals on balance control, functional balance tests can be used to provide an estimate of potential proprioceptive disturbances [33]. These tests involve all body and other sensory and motor functions; therefore, they are considered non-specific tests of proprioception [21]. *Balance tests* can be modified to challenge proprioception, such as unilateral/bilateral stance with eyes open/closed, different supporting surfaces (i.e., stable or unstable), and with/without perturbations [44, 45]. *Stereognosis* and *skilled motor function tests* are important as they indicate the contribution of proprioceptive system in the performance of many activities of daily living [46].
