Human Motion Capture and Identification for Assistive Systems Design in Rehabilitation. Pubudu N. Pathirana

ST [343] [299]

      Upper motor neurone disorders–

      Conditions such as a cerebrovascular accident (stroke), Parkinson's disease, multiple sclerosis, Huntington's disease (Huntington's chorea) and Creutzfeldt‐Jakob disease are examples of upper motor neurone diseases.

      Lower motor neurone disorders – spinal muscular atrophies

      Lower motor neurones are located in either the anterior grey column, anterior nerve roots (spinal lower motor neruones) or the cranial nerve nuclei of the brain stem and cranial nerves with a motor function (cranial nerve lower motor neurones) [1]. All voluntary movement relies on spinal lower motor neurones, which innervate skeletal muscle fibres and act as a link between the upper motor neurons and muscles [2, 3]. Cranial nerve lower motor neurones control movements of the eyes and tongue, and contribute to chewing, swallowing and vocalisation [4]. Damage to the lower motor neurone can lead to flaccid paralysis.

Table 1.2 Examples of musculoskeletal injuries in joints of the lower extremities.

	Hip	Knee	Ankle
Movements	Flexion, extension, abduction, adduction, internal and external rotation [149]	There are two ways to describe the degree of freedom (DOF) in a knee. One is with two DOFs (flexion‐extension and axial rotation) [234] and the other is with six DOFs (flexion‐extension, varus‐valgus, internal‐external rotation and mediolateral, anteroposterior and superoinferior translation around mediolateral, anteroposterior and superoinferior axis) [122].	Extension, flexion, valgus and varus [301]
Inj1	Hamstring strain	Patellofemoral pain syndrome	Achilles tendonitis
Description	It usually associated with lower extremity activities, like football, soccer, dancing and so on, while this condition occurs in different phases of motions in various types of activity [149].	It is an anterior knee pain and mainly resulted from “aberrant motion of the patella in the trochlear groove” [123].	The physical findings of this condition include soft tissue swelling, local tenderness and sometimes crepitus [256].
ST	[326]	[214]	[222]
Inj2	Groin pain	Anterior cruciate ligament (ACL) injury	Lateral sprain
Description	It contributes 2–5% of all sport injuries [243]. Vincent et al. [243] also mentioned that the diagnosis of this pain is hard because of its complex anatomy in the affected region, as well as the coexistence of multiple injuries.	The causes are in two major categories, including non‐contact (usually resulted from sudden deceleration before changing direction or a landing motion) and contact (valgus collapse) [45].	It can be deemed as the most common injury in ankles [114], which is usually cause by inversion of the foot [114].
ST	[302]	[74]	[103]

      Neuropathies

      Neuropathies involve dysfunction of the peripheral nerves, which consist of: motor neurones, that carry the electrical signals directly from the spinal cord and brain stem to activate muscle movement; the sensory neurones, which convey sensory information such as pain, temperature, light touch, vibration and position to the brain; and the autonomic neurons, which go to the internal organs and control blood vessel reflexes.

      Neuromuscular junction disorders

      Myasthenia gravis and Lambert-Eaton syndrome are examples of neuromuscular junction disorders. Muscular dystrophies and inflammatory myopathies such as polymyositis are examples of primary muscular (myopathic) disorders.

      Neurodegenarative classification encapsulates the progressive loss of structure or function of the neurone and a number of conditions exhibit this form of progression. Hence, amyotrophic lateral sclerosis (ALS), Parkinson's and Huntington's are classified as neurodegenerative diseases that affect movement. These conditions exhibit characteristically slower movement compared to healthy people – hypokinesis – or excessive and abnormal involuntary movements – hyperkinesis [156]. Some common examples of hypokinesis include bradykinesia, freezing, rigidity and stiff muscles, while those belonging to hyperkinesis are chorea, dyskinesia, myoclonus, tics and tremor [242].

      The most common neurological [215] and adult movement disorder, essential tremor (ET), is about 20 times more prevalent than Parkinson's disease itself. Patients with ET are likely to have tremors with 4–12 Hz and the risk factors associated with this are age, ethnicity and family history [215]. The condition affects the performance of work-related tasks and activities of daily living (ADLs) and a number of medical and physical rehabilitation approaches are in use as treatments for the condition [39, 295].

      An estimated 7 to 10 million people worldwide are living with the second‐most common neurodegenerative disorder, Parkinson's disease (PD) [90]. Approximately 60 000 Americans are diagnosed with PD each year while in western Europe this figure is 160 for every 100 000 over the age of 80 [89]. In China, approximately 1.7 million above the age of 55 [396] are suffering from the condition. The movement disorders experienced by a PD patient can be classified into three stages [244]. In the initial stage, the patient may exhibit a forward stooped posture, festinating gait, rigidity, etc. During the first 10 years of PD, characteristic movements such as resting tremor, hypokinesia and micrographic handwriting are common. During the later phase, patients may exhibit dyskinesia, akinesia, postural instability, etc. In terms of treatment, various kinds of medical therapies, such as levodopa, as well as surgical approaches and deep brain stimulation are utilised to control symptoms in addition to physical rehabilitation therapies [171].

      Although these two conditions are common and have a significant impact on the quality of life, they are not fatal diseases. In contrast, stroke is one of the most fatal conditions in developed countries [374]. However, a majority of stroke suffers may be alive after the initial injury, albeit losing some motor functions lifelong or for a prolonged period of time [193]. In 2005, there were 5.7 million deaths in low‐ and middle‐income countries due to stroke, which has increased significantly to 6.5 million and 7.8 million, respectively, in 2015 [338]. Age, gender, race, ethnicity and heredity are considered as important markers of risk factors [273], while hypertension, cardiac disease, diabetes, glucose metabolism, lipids, cigarette smoking, alcohol, illicit drug use, lifestyle, etc., are considered to have an adverse influence on the likelihood of stroke [273]. Similar to other disorders, physiotherapy is widely used as a rehabilitation therapy to assist stroke patients to regain physical functionality [291].

Such a complex locomotor and neural system are frequently influenced by various injuries and disorders. Therefore, a number of approaches have been explored to treat people suffering from conditions leading to abnormal movements and