# Power Knee by Össur (Embla Medical)

Canonical page: https://technooptimist.io/neurotech/power-knee
Frontier: [Neurotech](https://technooptimist.io/neurotech.md) · Field: Bionic limbs & muscle control · Company: [Össur (Embla Medical)](https://technooptimist.io/companies/ossur.md)
Stage: Deploy (4 of 5: Research → Proto → Pilot → Deploy → Scaling)
Updated: last update 2025-04-16, facts checked 2026-10-11
Goal: Give above-knee amputees a leg that adds power like real thigh muscles, so stairs, slopes and standing up stop demanding extra effort from the hip and the other leg.
Status: On sale since the 2022 generation; own Medicare code L5827 since April 2025

## Milestones

| Status | Milestone | Date | Slip |
| --- | --- | --- | --- |
| Done | First motor-powered prosthetic knee introduced | 2006 |   |
| Done | New-generation Power Knee launched | 9 Feb 2022 |   |
| Done | Össur renamed Embla Medical (parent) | Apr 2024 |   |
| Done | Medicare code L5827 for electromechanical knees | 1 Apr 2025 |   |

## Most important updates

- **16 Apr 2025**: Medicare's new code L5827 for electromechanical knees takes effect for the Power Knee. After a request from Medicare contractor Palmetto GBA, the HCPCS committee created code L5827 for knees with electromechanical swing and stance control, replacing three codes written for fluid-controlled knees. ([our story](https://technooptimist.io/stories/medicare-s-new-code-l5827-for-electromechanical-knees-takes-effect-for-9475264c.md) · [original source](https://www.ossur.com/en-us/professionals/ossur-rr/new-coding-for-powered-knees))
- **9 Feb 2022**: Össur launches new Power Knee, which it calls the world's first actively powered microprocessor knee. Össur released a new generation of its Power Knee for people with above-knee amputation. ([our story](https://technooptimist.io/stories/ossur-launches-new-power-knee-which-it-calls-the-world-s-first-actively-6102d384.md) · [original source](https://www.ossur.com/en-us/about-ossur/newsroom/ossur-launches-new-power-knee))

## Current obstacles

- **Weight versus power**: At 2.6 kg it is heavier than passive microprocessor knees; the motor and battery that add power also add mass the hip must swing.
- **Getting users to use the power**: Earlier versions needed effortful triggering and many users rarely used stair and sit-to-stand modes; the 2022 model simplified activation.

## Physics limits

- **Batteries cap the work a leg can do**: A real knee is powered by food-fuelled muscle; a motorised one must carry every joule in a battery, so more assistance means more weight or more charging.
- **Guessing intent from motion**: Without a link to the user's nerves, the knee infers what the user wants from posture and load, so unusual moves can be misread.

## How it works

### Sensing: Reads speed, slope and posture

Sensors tell the knee's processor whether the wearer is walking, on an incline, on stairs, sitting or standing, and at what cadence.

### Motor: Electromechanical actuator

An electric actuator controls both the swing and stance phases and can drive the knee straight, doing work the missing thigh muscles once did.

### Assist and brake: Push going up, resist going down

Going up stairs, ramps or out of a chair the motor assists; going down or sitting it provides controlled resistance instead.

## Spec sheet

| Spec | Power Knee | Provenance |
| --- | --- | --- |
| Weight incl. battery | 2.6 kg | reported |
| Battery life | 25 h normal use | reported |
| Recharge time | 5 h 30 min | reported |
| Max user weight | 116 kg | reported |
| Knee flexion | 120° | reported |
| Medicare base code fee (avg) | $7,242 (L5827) | reported |

Provenance: reported = stated by the company; estimated = our estimate; sample = a sample figure.

## About Össur (Embla Medical)

Össur is an Icelandic maker of prosthetic legs, feet and braces, founded in Reykjavik in 1971. Since 2024 its listed parent is Embla Medical. It makes the Power Knee, the first motor-powered prosthetic knee.

- Össur became Embla Medical in April 2024 (ticker EMBLA, Nasdaq Copenhagen); Össur stays the product brand.
- Power Knee first appeared in 2006; a lighter generation with a 25-hour battery launched in February 2022.
- In April 2025 Medicare created code L5827 for electromechanical knees like the Power Knee.

- Founded: 1971
- Headquarters: IS
- Status: public
- Listing: EMBLA (Nasdaq CPH)
- Website: https://www.ossur.com
- People: Sveinn Sölvason (President and CEO)
- Partners, customers, investors: William Demant Invest (investor)

Company page: https://technooptimist.io/companies/ossur.md

## Related programs

Everything in Neurotech: https://technooptimist.io/neurotech.md

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