Empower Ankle

Reclaim your power

Empower is the next generation design of the BiOM Ankle and still the only prosthesis with powered propulsion. It is characterized by the following clinically proven features:


  • Emulates the function and power of lost muscles and tendons (1)
  • Provides energy instead of taking it away – even up ramps, hills and stairs (1,6)


  • Life-like ankle movement that normalises userʼs walking gait (4)
  • Reduces joint forces which may result in less pain and fewer long-term orthopaedic problems (1,2,5)


  • Adjusts ankle power, resistance and flexion in real-time
  • Provides balance on variable terrain (3)

(View full list of clinical studies in the section "Clinical References".)

Rechargeable battery

The integrated battery lasts for up to 8 hours depending on user activity. The dual bay charger can charge two batteries simultaneously in as little as 90 minutes.

Ankle Display

The power button and battery indicator lights reflect the state of charge are located in front of the Ankle.

Powered Propulsion

A battery-powered, motorized actuator coupled with a high energy spring provide powered propulsion that emulates the gastrocnemius and soleus muscles.

Dynamic Adaptation

Intrinsic control firmware analyzes ankle joint torque and angle data from high resolution sensors, in real-time, to mimic the user’s physiological ankle function.

Advantages at a glance

Covering longer distances in less time

The Empower Ankle provides the exact amount of propulsion needed for every step you take. In doing so, weight is distributed gently over the remaining limb, allowing you to conserve energy. This means you are less fatigued, so it is easier to cover longer distances in a faster walking speed.

Safety and stability on different terrains

The Empower Ankle stabilizes your movement as its decelerates the body during rollover of the foot before accelerating again for toe-off. In addition, the entire surface of the foot lowers itself immediately to the floor. You can control every step regardless of the surface, which gives you a secure feeling.

Coping better with everyday life

In everyday life, ramps, slopes and especially stairs repeatedly pose challenges. It takes a great deal of energy to compensate for missing muscle functions. This is where the Empower Ankle comes into play, restoring the propulsion which is needed for forward and upward motion. This enables you to cope effortlessly with stairs and sloping terrain.

Gentler on joints

Many users suffer from painful joints as a result of changing their gait pattern. Unbalanced movement patterns and compensatory movements can even lead to osteoarthritis. With its active powered propulsion, the Empower Ankle improves your gait pattern. This helps to prevent joint pain as well as long-term orthopaedic problems.


The Empower Ankle mimics your lost muscle functionality when you walk, resulting in a more physiological gait pattern. A unique feature is the powered propulsion of the foot, providing high-energy support for every step. In this way, the foot and entire body are propelled forwards. At the same time, high resolution sensors regulate the intensity of the forward thrust and the foot position you need for the relevant situation.

Clinical References

1. H. Herr, A. Grabowski, ‘Bionic ankle–foot prosthesis normalizes walking gait for persons with leg amputation’, Proc Biol Sci. Vol. 7, 279(1728): 457–464. 2012.

2. A. Ferris, J. Aldridge, J. Sturdy, J. Wilken, ‘Evaluation of the Biomimetic Properties of a New Powered Ankle-Foot Prosthetic System’, Dept. of Orthopedics and Rehabilitation, Center for the Intrepid, Brooke Army Medical Center, Fort Sam Houston, TX, USA. Presented at American Society of Biomechanics 2011.

3. D. Gates, J. Aldridge, J. Wilken. ‘Kinematic comparison of walking on uneven ground using powered and unpowered prostheses’, Clinical Biomechanics, 28, 467–472, 2013.

4. J. Aldridge, A. Ferris, J. Sturdy, J. Wilken, ‘Kinematics and Kinetics with a Powered Lower Leg System During Stair Climbing Ascent Following Transtibial Amputation’, Gait & Posture, Vol. 36, 291–295, June 2012.

5. A. Grabowski, S. D’Andrea. J., ‘Effects of a powered ankle-foot prosthesis on kinetic loading of the unaffected leg during level-ground walking’, Neuroeng Rehabil., 10:49, 2013.

6. E. Esposito, et al., ‘Step-to-step transition work during level and inclined walking using passive and powered ankle-foot prostheses’, Prosthet Orthot Int. 2015 Jan 27.