(30 days)
The TWIST and TWIST R are add-on drive accessories for wheelchairs.
The TWIST and TWIST R devices are intended to provide auxiliary power to manual wheelchairs to reduce the pushing power needed by their users.
TWIST and TWIST R devices are designed to provide support to active wheelchair users who are physically and mentally able to safely control a manual wheelchair in typical situations, including inclines, even manually.
The device is an add on accessory for manual wheelchairs.
1. TWIST
TWIST device is meant to be added to the wheelchair in 5 different combinations of position and control:
- Front mounted without handlebar, driven by the wheelchair occupant
- Front mounted without handlebar, driven by the attendant
- Front mounted position with handlebar, driven by the wheelchair occupant
- Rear mounted without handlebar, driven by the wheelchair occupant
- Rear mounted without handlebar, driven by the attendant
Coupling the TWIST device in front position to the wheelchair raises the front castors off the ground. The single wheel of the "traction unit" is then used for steering.
2. VARIATION TWIST R
VARIATION TWIST R device is meant to be added to the wheelchair in 1 only position (rear) and 2 ways of control
- Rear mounted without handlebar, driven by the wheelchair occupant
- Rear mounted without handlebar, driven by the attendant
The provided FDA 510(k) clearance letter pertains to a powered wheelchair accessory (Klaxon TWIST/TWIST R), which is a physical device, not an AI/software as a medical device (SaMD).
Therefore, many of the requested criteria related to AI/SaMD performance evaluation (such as multi-reader multi-case studies, expert consensus for ground truth establishment, training set details, or standalone algorithm performance) are not applicable to this submission.
The acceptance criteria and supporting study described in the document relate to the physical and mechanical properties and safety of the device, specifically addressing changes in maximum speed and maximum user weight.
Here's an analysis based on the provided document, addressing the applicable criteria for a physical medical device:
Acceptance Criteria and Device Performance Study for KLAXON (TWIST); KLAXON (TWIST R)
The submission describes changes made to a previously cleared device (K240267) and the non-clinical tests performed to demonstrate that these changes maintain the device's safety and effectiveness.
1. Table of Acceptance Criteria and Reported Device Performance
The acceptance criteria are implicitly defined by the safety and performance requirements outlined in the referenced ISO consensus standards. The "performance" is the demonstration of compliance with these standards.
| Acceptance Criteria (Defined by Standards) | Reported Device Performance (Conclusion) | Related Change(s) Validated |
|---|---|---|
| Static Stability (ISO 7176-1:2014) | Demonstrated acceptable static stability | Max user weight (120kg to 140kg) |
| Dynamic Stability (ISO 7176-2:2017) | Demonstrated acceptable dynamic stability | Max speed (10 km/h to 15 km/h) and Max user weight (120kg to 140kg) |
| Effectiveness of Brakes (ISO 7176-3:2012) | Demonstrated acceptable braking effectiveness (specific data provided: With Handlebar 0.89 m, Without Handlebar 0.97 m) | Max speed (10 km/h to 15 km/h) |
| Static, Impact, and Fatigue Strengths (ISO 7176-8:2014) | Demonstrated acceptable structural resistance | Max user weight (120kg to 140kg) |
| No compromise to Intended Use/Indications for Use | Indications for Use remain unchanged and are substantially equivalent to the predicate. | Max speed and Max user weight changes are supported. |
2. Sample Size Used for the Test Set and Data Provenance
- Sample Size: Not explicitly stated in terms of a "sample size" as one might see for a diagnostic study. For mechanical and performance testing of a physical device, testing typically involves a representative number of units (e.g., a few prototypes or production units) to demonstrate compliance with standards. The document states "Both the TWIST, and variation TWIST R, devices... have been subjected to the same testing requirements." This implies physical testing of the devices.
- Data Provenance: The tests were conducted by the manufacturer, KLAXON-MOBILITY GmbH, in Austria (their listed address). The data is implicitly "prospective" in that it was generated for this specific 510(k) submission to validate the design changes.
3. Number of Experts Used to Establish Ground Truth for the Test Set and Qualifications of Those Experts
N/A. For mechanical and physical performance testing of a medical device like a powered wheelchair accessory, "ground truth" is established by the specifications and performance metrics within recognized consensus standards (e.g., ISO 7176 series). There aren't "experts" in the sense of clinicians establishing a diagnostic ground truth, but rather engineers and technicians performing standardized tests.
4. Adjudication Method for the Test Set
N/A. Mechanical and performance tests typically involve objective measurements against predefined criteria/tolerances specified in the standards, rather than subjective interpretation requiring an adjudication process.
5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study was done, what was the effect size of how much human readers improve with AI vs without AI assistance
N/A. This device is a physical powered wheelchair accessory, not an AI/SaMD diagnostic tool.
6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) was done
N/A. This is not an algorithm or software device.
7. The Type of Ground Truth Used
The "ground truth" or "reference standard" is the compliance with recognized international consensus standards for wheelchairs, specifically:
- ISO 7176-1:2014 (Static stability)
- ISO 7176-2:2017 (Dynamic stability)
- ISO 7176-3:2012 (Braking effectiveness)
- ISO 7176-8:2014 (Static, impact, and fatigue strengths)
These standards define the test methodologies and acceptable performance limits.
8. The Sample Size for the Training Set
N/A. There is no "training set" as this is a physical device, not an AI/machine learning model.
9. How the Ground Truth for the Training Set was Established
N/A. Not applicable for a physical device.
§ 890.3860 Powered wheelchair.
(a)
Identification. A powered wheelchair is a battery-operated device with wheels that is intended for medical purposes to provide mobility to persons restricted to a sitting position.(b)
Classification. Class II (performance standards).