Model note · Prosthetic Limbs
Össur RHEO KNEE XC microprocessor knee
The RHEO KNEE XC is a microprocessor controlled prosthetic knee for transfemoral and knee disarticulation users. Instead of hydraulics it uses a magnetorheological actuator: a fluid whose stiffness changes in a magnetic field, so the controller can vary resistance continuously through stance and swing. It is set up by the prosthetist with the Össur Logic app, and has a mechanical lock that can carry full weight if power is lost.
The model
Maker, model and type.
- Maker
- Össur hf.
- Model
- RHEO KNEE XC microprocessor knee
- Device type
- Prosthetic Limbs
- Main document
- Open the public document
Key specifications
What the public record says.
| Item | Value | Source |
|---|---|---|
| Actuator | Magnetorheological actuator with mechanical lock (full extension, 10 or 20 degrees) | Source |
| Weight limit | 136 kg; moderate to high impact, walking and occasional running | Source |
| Device weight | 1.6 kg | Source |
| Battery | Lithium ion, 2350 mAh, 33.84 Wh; about 3 hours to charge from empty; 48 to 72 hours per charge | Source |
| Power supply | FRIWO FW8030M/24, 100 to 240 VAC input, 24 VDC 1.25 A output | Source |
| Use temperature | -10 to 40 C; charging 0 to 40 C | Source |
| Environmental rating | Weatherproof: fresh water splashes allowed, no submersion, no salt or chlorinated water | Source |
| Service interval and life | Professional check recommended every 40 months; expected life 6 million steps, about 4 to 6 years | Source |
| RF immunity | 10 V/m radiated (IEC 61000-4-3); keep portable RF equipment at least 30 cm away | Source |
Recalls
Known FDA recalls.
- Z-1789-20242024-03-25
RHEO KNEE XC (RKNXC0003): firmware issues could cause unintended warnings and shutdown, with fall risk.
FDA record - Z-1787-20242024-03-25
RHEO KNEE (RKN130002): same firmware issue causing unintended warnings and shutdown.
FDA record - Z-1322-20152015-02-26
RHEO KNEE units released without completing the full assembly process, found in a service line audit.
FDA record
Safety
Safety warnings from the record.
- Unexpected power loss or battery depletion stops normal function and can cause a fall; users must recognise the power loss warnings. Source
- Misreading of the user's activity by the knee increases the risk of falling. Source
- Components from other makers are untested with this knee and risk structural failure. Source
- Keep away from strong fields such as MRI and CT scanners, transformers and electrosurgical equipment. Source
- Always unplug the power supply before donning; a damaged supply can cause electric shock. Source
Sources
Where this note comes from.
- Össur RHEO KNEE XC Instructions for Use (copy hosted by distributor Ortoped)
- FDA recall Z-1789-2024, RHEO KNEE XC firmware
- FDA recall Z-1787-2024, RHEO KNEE firmware
- FDA recall Z-1322-2015, RHEO KNEE assembly
- openFDA MAUDE problem counts, brand RHEO KNEE
Not covered: The IFU used is an Össur document but was opened from a distributor's site; Össur's own download was not checked for a newer revision. No IP code is given, only a weatherproof description. The service manual, calibration procedure and any numbered fault codes for the prosthetist app are not public; error entries are the warning patterns in the user IFU. The manufacturerUrl product page was not opened. MAUDE numbers are very small and not failure rates.
BMEssentia knowledge drafted from public information, reviewed by Hasan Khaled Ismail on 2026-10-24. Always follow the manufacturer's instructions for use and service manual.
Prosthetic Limbs