Soft Robotic Sock Intervention for Robot-assisted Ankle-foot Mobility in Post-stroke Patients

Stroke is closely associated with high mortality among patients in hospitals and immobility leading development of deep vein thrombosis (DVT) leading to pulmonary embolism (PE) and Venous thromboembolism (VTE) and/or ankle joint contracture, which impairs mobility resulting in bedridden. Worldwide, the incidences of DVTs is 0.75-2.69 per 1000 individuals and 2-7 per 1000 for individuals aged \> 70 years and accounts for 600,000-800,000 deaths yearly.

Pharmacological treatment for DVTs include anti-coagulants to prevent blood clot development and VTE but may cause haemorrhagic stroke leading to death. Non-invasive treatment such as intermittent pneumatic compression (IPC) and anti-embolism stockings may prevent DVT but not ankle joint contractures, which affects 50% of all stroke patients. Joint contractures exacerbate pedal edema and fluid retention, hamper proper joint movement and decreases ADLs and quality of life. Regular physiotherapy is vital for preventing ankle joint contracture and DVT but is labour intensive hence posing an increased workload on physiotherapists resulting in decreased physiotherapy duration.

This study will investigate the use of an automated robot-assisted ankle exercise solution (Venous Assistance and Contracture Management System, VACOM) to mimic therapist-assisted on bed passive ankle exercises to preclude the development of ankle joint contracture and facilitate venous flow in lower extremities to reduce DVT risk. The investigators hypothesize that the Venous Assistance and Contracture Management (VACOM) system can prevent ankle contracture, improve ankle range of motion (ROM) and flexibility while reducing the risk of DVT incidence among stroke patients more than using IPC alone. Additionally, through early ankle mobilization, rehabilitation can be optimized to achieve better neurological recovery.

Stroke is one of the top medical conditions resulting in high mortality among patients in hospitals, where complications related to immobility such as deep vein thrombosis (DVT) and/or ankle joint contracture can affect patients in their road to recovery. Patients may often take months or even years to fully recover their limb functions, where certain activities of daily living cannot be easily achieved prior to recovery. In the case of the affected lower limbs, immobility can affect common activities such as getting out of bed resulting in bedridden. Bedridden is also highly susceptible to the vicious cycle which developing ankle joint contracture and DVT.

In severe DVT cases, the blood clots in the deep veins can dislodge into the bloodstream and circulate in the whole body. There is a chance to occlude the arteries in the lungs, leading to pulmonary embolism (PE). Venous thromboembolism (VTE), including DVT and PE, occurs at an annual incidence rate of 0.75-2.69 per 1000 individuals worldwide; this incidence rate increased to 2-7 per 1000 for individuals aged \> 70 years (ISTH Steering Committee, 2014). Among those diagnosed with DVT, 10-30% dies within 1 month of diagnosis (Beckman et al., 2010), and 600,000-800,000 people die from DVT worldwide annually (worldthrombosisday.org), which equates to approximately 1 DVT-related death per minute.

Current treatment approaches include pharmacological prophylaxis can be often used as the blood thinner to prevent blood clot development. Low-dose anticoagulation reduces the incidence of VTE, however, the benefit can be often offset by haemorrhagic complications which can lead to death, especially for patients suffering from haemorrhagic stroke (Roderick et al., 2005).

Other non-invasive treatment or mechanical prophylaxis, such as intermittent pneumatic compression (IPC) and anti-embolism stockings, have some efficacy in preventing DVT based on clinical reports (Mazzone et al., 2004; Caprini, 2010); however, these devices do not prevent ankle joint contractures as their action mechanism is related with passive compression and decompression of lower limb muscles without the actual mobilization of joints. Approximately 50% of all stroke patients develop at least one contracture within six months of stroke (Li et al. 2012). Once the ankle joint contracture developed, it can exacerbate pedal edema and fluid retention, and hamper proper joint movement, which is indispensable for regaining ambulatory function and quality of life. These patients usually have to rely on regular physiotherapy sessions that provide therapist-assisted ankle exercises to prevent ankle joint contracture and reduce the risk of DVT. However, given growing manpower constraints and a greying global population, there is an increasing workload on physiotherapists, resulting in insufficient time to complete their physiotherapy routines.

This study is important for the following reasons:

1. To investigate the efficacy of the VACOM system in providing assisted ankle movement and promoting lower limbs venous return for stroke patients in the hospital rehabilitation setting.
2. This study intends to 1) observe the ankle joint mobility and flexibility by using the range of motion measure, 2) monitor the presence of blood clots in lower limbs by using compression Duplex ultrasonography, 3) evaluate the functional recovery by providing early mobilization in the bed.
3. To study the economic impact of the VACOM system in the current healthcare system by collecting the survey forms and statistical data.
4. To examine the cost-effectiveness, such as healthcare workload reduction, the probability of the intervention being cost-effective, etc.
5. To generate evidence on this innovative device and further deploy it in clinical practice.

The automated robot-assisted ankle exercise solution (Venous Assistance and Contracture Management System, VACOM) aims to mimic therapist-assisted on bed passive ankle exercises to preclude the development of ankle joint contracture and facilitate venous flow in lower extremities to reduce DVT risk.

The VACOM uses soft pneumatic extension actuators, which is capable of providing robot-assisted ankle exercises, specifically dorsiflexion-plantarflexion and inversion-eversion movements. Through these natural movements to improve blood flow and venous return and maintain ankle joint flexibility. Furthermore, it can facilitate and stimulate the neurologic recovery in walking by early mobilization.

The investigators will conduct a multi-site clinical trial on around 100 stroke patients across different hospitals and healthcare institutions in Singapore to establish the efficacy of our soft robotic system (VACOM) in preventing ankle joint contracture and reducing DVT risk. Importantly, to investigate the effect and impact of the current healthcare system on the cost-effectiveness and workload reduction for the healthcare staff.

The Investigators hypothesize that the Venous Assistance and Contracture Management (VACOM) system can improve ankle range of motion (ROM) and flexibility by preventing ankle contracture while reducing the risk of DVT incidence among stroke patients. It might have a better outcome than using IPC alone. Additionally, through early ankle mobilization, rehabilitation can be optimized to achieve better neurological recovery.

Eligibility Criteria:
Inclusion Criteria:

* Acute ischemic or haemorrhagic stroke.
* Affected Ankle Dorsi-Flexor MMT \< 3.
* Modified Ashworth Scale (MAS) = 1+ (Ankle Dorsi-Flexor/Plantar Flexor).
* Not able to ambulate without assistance except during therapy time.

Exclusion Criteria:

* Medically unstable.
* Known pulmonary embolism (PE) or deep vein thrombosis (DVT).
* Pre-existing lower limb deformity, irreversible contracture, amputation, and foot drop.
* Open wound or ulcer, poor skin condition over the lower limb.
* On anti-coagulation (treatment dose).