AnkleMotion
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Blood circulation in the legs

Oxygenated blood pumped by the heart reaches the legs through arteries. Deoxygenated blood returns to the heart via veins. This circulation may suffer if the heart is weak (e.g. heart muscle damaged by heart attacks), if the veins that carry blood back to the heart are damaged (e.g. varicose veins) or if a person has poor mobility. In all these situations build up of fluid in the tissues causes swelling (edema).

Contraction of Soleus muscle in the calf during walking squeezes the veins and increases the flow blood flow in the veins. This is called the ‘Soleus Muscle Venous Pump’. The following diagram explains this.

Risks associated with poor mobility

Prolonged periods of immobility mean that the ‘Soleus Muscle Venous Pump’ does not work thus resulting in poor venous blood flow. Stagnation of blood in the leg veins risk dangerous blood clots

(Deep Venous Thrombosis – DVT) that could travel to the lungs causing life threatening blockage in the lungs (Pulmonary Embolism – PE).

People recovering from neurological conditions such as stroke or recovering from recent orthopedic or neurosurgery may also have poor mobility risking poor venous circulation (1). Prolonged immobility during long distance travel could also risk leg swelling and DVT /PE (2).

Several published studies have shown that motion of the ankle joint improves the venous blood flow and lessens the risk of blood clots and reduces leg swelling (3, 6).

What are the options to reduce the risks associated with poor mobility?

 Regular physical activity such as walking is without doubt the mainstay of reducing the risks associated with poor mobility. Other options would be TED stockings to squeeze the calf, External Pneumatic Compression Devices that intermittently squeeze the calf or thinning the blood with anti coagulants such as low molecular weight Heparin (LMWH).

Studies have shown that ankle motion exercises significantly outperform EPC devices (4, 7). Combination of CPM device and LMWH results in better outcomes than LMWH alone (5).

How does the AnkleMotion device work?

The unique design of the AnkleMotion device incorporates the principle of ‘Continuous Passive Motion’ in a compact, lightweight, portable device that simulates walking activity in sitting, reclining or lying down positions. AnkleMotion passively moves the ankle joint that in turn moves the Soleus muscle in the calf which results in the calf veins being squeezed, pumping the venous blood back to the heart. Improved circulation results in reduced leg swelling and reduced risk of blood clots. Other issues associated with poor mobility such as stiff joints and muscles also appear to benefit from the AnkleMotion device.

A yet to be published study comparing EPC device with AnkleMotion device in 40 healthy volunteers demonstrated a mean increase in Peak Venous Blood Flow Velocity (PVBFV) of 50% with AnkleMotion compared to currently used EPC device.

Who may not benefit from AnkleMotion?

Leg swelling can also occur due to other causes such as arthritis, infection in the joints or tissues. AnkleMotion is not indicated in such conditions.

References

1. Deep Vein Thrombosis After Total Knee Arthroplasty (TKA) in Asian Patients Without Prophylactic Anticoagulation: In Western countries, prophylactic agents against DVT are administered routinely after TKA. However, in Asia, no regular prophylaxis is generally given to patients undergoing TKA. Study results showed a relatively high incidence of DVT in an Asian population following TKA.
   https://doi.org/10.3928/01477447-20101123-05
2. A Systematic Review: Travelers for flights longer than 6 hours with 1 or more risk factors for VTE (Venous Thromboembolism) should frequently exercise leg muscles and avoid dehydration.
   http://link.springer.com/article/10.1007/s11606-006-0016-0
3. Effect of leg exercises on popliteal venous blood flow during prolonged immobility of seated subjects, implications for prevention of travel‐related deep vein thrombosis: Leg exercise regimens enhanced popliteal venous flow during prolonged immobility of seated subjects, reinforcing the importance of regular leg movement to prevent venous stasis during prolonged sitting, such as in long‐distance travel.
   http://onlinelibrary.wiley.com/doi/10.1111/j.1538-7836.2007.02664.x/full
4. Blood flow velocity of the femoral vein with foot exercise compared to pneumatic compression: Study showed significant increase in the peak blood flow velocity with ankle movements compared to currently using intermittent pneumatic foot compression device. The effect of 5 minutes foot exercise lasted for 2 hours. http://www.sciencedirect.com/science/article/pii/S0952818005000085
5. Continuous passive motion in the prevention of deep-vein thrombosis: In this study 227 post trauma or post-surgical status patients received either treatment with the CPM device and low-molecular-weight heparin (LMWH) or only with the latter. The incidence of deep-vein thrombosis was 25% in the LMWH group compared with 3.6% in those who had additional treatment with the CPM device.
   https://www.ncbi.nlm.nih.gov/pubmed/16049250
6. Preventing Deep Vein Thrombosis in Neuroscience Patients Through Foot and Ankle Range-of-Motion Exercises: Neurosurgical patients tend to have the highest rate of deep vein thrombosis (DVT) rate among other post surgical patients. Hypothesis states that a structured program of foot and ankle range-of-motion (ROM) exercises will decrease the incidence of DVT in the neuroscience intensive care patient population.
   http://journals.lww.com/jnnonline/Abstract/2011/12000/TapandTwistPreventingDeepVeinThrombosis.5.aspx
7. Continuous passive motion in the prevention of deep-vein thrombosis – a randomized comparison in trauma patients
   https://doi.org/10.1302/0301-620X.87B8.15680