Ottobock’s DynamicArm is an electric elbow with the ability to flex and extend via myoelectric control. Combined with a rotating wrist and a bionic hand or another terminal device, the DynamicArm can form an integral part of an above-the-elbow solution.
What’s On This Page?
- A Quick Look at the DynamicArm
- Basic Mechanics and Control System
- Proportional Speed Control
- Wrist Design
- Lift Capacity & Strength
- Water and Dust Resistance
- User Software
- Clinical Insights
- User Feedback Survey & Results
- Considerations Before Buying a DynamicArm
- Related Information
A Quick Look at the DynamicArm
There are not a lot of great videos demonstrating the features of Ottobock’s DynamicArm. In fact, we had to reach back to 2014 to get some decent footage of the elbow in action:
The reason for this is that the DynamicArm is merely one component in a bigger solution and most of the interest in any bionic arm system is with the hand component.
However, the choice of an elbow component involves numerous subtle features that can have a significant impact on user satisfaction.
Basic Mechanics and Control System
We apologize for the poor quality of this next video. It is from 2011 and looks as if it was recorded via screen capture, but it still does a great job describing the DynamicArm’s core mechanical and control features:
Now that you have an understanding of the main components, here are some of the DynamicArm’s most important features:
- The elbow can lift five kilograms, which may not sound that impressive but this is five times the weight of the device. Under load, the elbow automatically locks for maximum support but can be easily unlocked if needed.
- An Automatic Forearm Balance feature stores energy when the elbow is extended and then reuses that energy to help flex the arm. This significantly reduces energy consumption.
- Numerous sensors monitor the movements and load on the system, feeding data into an electronic control system up to 100 times a second. This facilitates both speed (the elbow can go from full flexion to full extension in less than a second) and fine control (soft acceleration and deceleration at the beginning and end of each movement).
- The electronic control system can control all components in an above-the-elbow solution including elbow, wrist rotator, and any hand terminal device. The signals from myoelectric sensors are fed through this central control system.
Proportional Speed Control
The DynamicArm supports proportional speed control. The strength of the myoelectric signal is relayed from the sensors to the electronic control system, which is then relayed to the elbow, wrist, or any hand terminal device.
When paired with an electric rotating wrist, the DynamicArm’s control system allows the user to rotate the wrist in either direction using the same myoelectric signals used to control the elbow or any hand terminal device.
Lift Capacity & Grip Strength
The DynamicArm can lift five kilograms by flexing at the elbow. It also has a static holding capacity of 22 kilograms.
Ottobock’s patient use guide explicitly states, “The DynamicArm should not be subjected to mechanical vibrations or impacts. Any type of excessive strain, overload, or improper use may lead to faulty control or malfunction of the DynamicArm, resulting in a risk of injury.
“The DynamicArm was developed for everyday use and must not be used for unusual activities. These unusual activities include, for example, sports with excessive strain and/or shocks to the wrist joint (pushups, downhill mountain biking, …) or extreme sports (free climbing, paragliding, etc.). Careful handling of the prosthesis and its components not only increases their service life but, above all, ensures your personal safety!”
As is the case for most bionic devices not specifically designed for added durability, it is best to view the DynamicArm as relatively fragile.
Water and Dust Resistance
Ottobock’s patient use guide explicitly states, “The electrical and mechanical systems of your DynamicArm are not water-resistant. Ensure that neither solid particles nor liquids can penetrate the DynamicArm.”
The DynamicArm is clearly not intended to operate in wet or dirty environments.
The DynamicArm comes with a lithium-ion battery with a general operating capacity of one day. We say “general” because the potential power requirements of an arm system with as many as three electric components can obviously vary.
As is the case with most bionic limbs, it is best to fully charge the battery each night. Full charging time is roughly four hours.
To our knowledge, there is no user software available for the DynamicArm. Ottobock does provide software to clinicians for setup and configuration.
Unfortunately, we do not have reliable information on the net cash price to the consumer for a typical solution involving the DynamicArm. We did run across one price of $60,000 US but it lacked a proper description of the wrist or hand terminal device, if any, so we’re unsure what this price represents.
If you have more accurate information, please write us through our contact form.
The DynamicArm comes with a standard two-year manufacturer’s warranty.
Users can extend the warranty to add a third year of coverage but we’re not sure if it can be extended beyond this point.
The DynamicArm should be serviced every 24 months.
The following comments are from clinicians with extensive experience with the DynamicArm:
We have used this elbow with 5 patients over the past few years and it is a well-designed and programmed elbow. We have utilized control with a standard 2-site myoelectric system and an in-line linear transducer. It has a very sleek and cosmetic style, with an internal battery. The difficulty of the internal battery is the charging location is right at the elbow flexion point, which can make the battery charging port difficult to charge if the elbow is fully bent. Additionally, the charging process needs to be followed precisely or the elbow will not charge. The weight of the device is very close to the elbow center, which gives the device a perceived lightness to the patient. The programming for the prosthetist can be a bit cumbersome to get the features to all work well together, but with some fitting experiences, it becomes fairly simple. A feature I like about the elbow is that it has a free swing mode, which makes it look more natural during walking. Overall a great product and in line with the functional performance of all existing elbows.
Tony Gutierrez, Bionic Prosthetics and Orthotics Group
Munster & Lafayette, Indiana
User Feedback Survey & Results
Are you or have you previously been a DynamicArm user? If so, please share your insights with others looking at the DynamicArm as a possible prosthesis.
We do not yet have a sufficient number of survey participants to publish fair and accurate results for the DynamicArm.
As soon as we do, we’ll update this section.
Considerations Before Buying the DynamicArm
We have not yet formed an opinion on the DynamicArm. It certainly looks like an interesting option for above-the-elbow limb differences. But until we get sufficient user feedback or can talk to true experts on electric elbows, we cannot add anything of value here.
For a list of competitive devices, see Current Options for Above-the-Elbow Bionic Arms.
For a comprehensive description of all current upper-limb technologies, devices, and research, see our complete guide.
Click here for more information on Ottobock.