Utah Arm U3 and U3+ User Guide

Introduction

The Utah Artificial Arm, first introduced in 1981, is now in its third generation with the U3. The U3 is a microprocessor-controlled electric elbow system that manages multiple degrees-of-freedom, including elbow flexion and extension, hand/terminal device control, and wrist rotation. It is recognized as one of the lightest weight electric elbows available, offering unparalleled speed, reliability, and function, thereby providing natural-like movement for individuals with transhumeral or higher levels of amputation. The U3+ version enhances the U3 with two additional features: Silent Freeswing and a Friction Brake. Silent Freeswing permits the elbow to swing freely when not in use, while the Friction Brake allows for silent locking at any position within the range of motion, with the potential to automatically transition to high-load locking. Both the U3 and U3+ models feature an interchangeable Lithium-Ion (Li-Ion) battery for continuous operation throughout the day. A supplemental battery can also be utilized for hands and terminal devices (TDs) requiring high current draw. This guide provides an overview of the warnings, functions, and limitations of the Utah Arm U3 and U3+. It is essential to read this guide to become familiar with your elbow's functions. Your prosthetist has undergone specialized training from Motion Control for the fitting, function, and operation of the Utah Arm and can provide further information regarding your prosthesis.

Utah Arm U3+ Package (Tan)

Components

Figure 1 illustrates the various components of the Utah Arm system.

Component List:

• 1. Harness with optional linear potentiometer: Provided and fitted by your prosthetist; may offer two functions. It suspends the prosthesis and keeps it in place. A control cable might be used with a linear potentiometer or force sensor for prosthesis function (refer to Figure 2). The harness should be as comfortable as possible. Periodically examine it for tears or worn areas that could lead to failure. Adjustments or repairs should be handled by your prosthetist.
• 2. Inner Socket: Provided by your prosthetist.
• 3. Outer Socket: Provided by your prosthetist.
• 4. EMG Electrodes/preamps: Used for myoelectric control.
• 5. Supplemental battery charging port (optional): For charging an optional supplemental battery.
• 6. Humeral Friction Band: Connects the prosthetic socket to the elbow.
• 7. Humeral Friction Band Screw: A small 7/64 inch hex screw used to adjust the elbow's rotation ease.
• 8. Lithium-Ion (Li-Ion) Battery: 5 batteries are included. They are interchangeable and rechargeable.
• 9. Battery Door Lock: Secures the battery compartment.
• 10. Lock/Unlock Button: Controls the elbow's locking mechanism.
• 11. Data Port: Located on the left side, used by the prosthetist for system adjustments.
• 12. Forearm Screws: Secure the forearm cover to the elbow's structural portion.
• 13. On/Off Switch: A slide switch to power the arm on or off.
• 14. Forearm Gain (right side): Adjusts elbow flexion sensitivity.
• 15. Forearm Gain (left side): Adjusts elbow extension sensitivity.
• 16. Forearm Cover: Encloses the forearm components.
• 17. Lamination Collar: A component for socket fitting.
• 18. Hand Terminal Device (purchased separately): The user-selected hand or terminal device.
• 19. Electric Terminal Device [ETD] (purchased separately): An electric terminal device.
• 20. Electric Wrist Rotator (optional): May be located in the forearm for wrist rotation control.
• 21. Battery Charger: Two chargers are included.

Figure 2: How a linear potentiometer functions

This diagram illustrates how pressure applied to a sensor, often connected to a linear potentiometer, influences the speed of the arm's movement. Relaxing pressure causes the elbow to drop (extend).

Figure 3

This figure shows the humeral friction band, which connects the prosthetic socket to the elbow. It highlights the 7/64 inch hex screw used for adjusting the elbow's rotation resistance.

Special Precautions

Risk Management

To minimize the risk of device damage or user injury, and to maximize the device's functions, follow all installation and usage instructions as detailed in this manual.

Lithium-Ion (Li-Ion) Batteries

Lithium-Ion batteries must be installed as described in this manual and charged exclusively with the provided chargers. Do not place any objects on the battery's metal contacts. Failure to adhere to these instructions can lead to malfunction and damage to the battery pack.

Battery Chargers

Use only the power supply supplied with the battery charger. Using any other power supply may result in malfunction, improper charging, fire, or explosion.

Moisture and Perspiration

The U3 and U3+ elbows are not water-resistant. Avoid exposing the elbow to excessive moisture. A jacket can provide adequate protection on rainy days. Perspiration can severely damage the system's sensitive electronics. Periodically examine your prosthesis. If perspiration appears to be entering the elbow, consult your prosthetist immediately. Perspiration can also cause electrodes in the socket to "short." If the prosthesis functions poorly due to heavy perspiration, turn the power OFF, remove the prosthesis, dry your residual limb and the inside of the socket, then reapply the prosthesis and turn the power ON. Damage from moisture and perspiration is not covered by warranty.

Dirty and Sandy Environments

Avoid dirty or sandy environments, such as beaches. Sand and grit can cause serious damage to your prosthesis. Damage from sand and dirt is not covered by warranty.

Exchanging Terminal Devices

Always turn the elbow power OFF before exchanging Terminal Devices (TDs).

Donning and Doffing

Turn the elbow OFF before doffing (removing) the prosthesis, as it may move unpredictably, potentially causing damage or injury.

Inadvertent Signals and Interference

Inadvertent signals or interference can cause unexpected prosthesis movement. Do not use the prosthesis for activities where such interference could lead to injury or death. This includes, but is not limited to, operating chain saws, circular saws, or firearms.

Driving

Turn the elbow OFF when driving. Unexpected elbow motion could lead to an accident, injury, or death.

Solvents and Volatile Substances

Avoid solvents and volatile substances, as they may damage plastic components and system electronics. The elbow's electric motors could also create a spark and explosion hazard in the presence of flammable gases.

Disassembly

Do not disassemble any part of the elbow, battery, forearm, or socket. There are no user-serviceable components. Disassembly will void the warranty.

Special Precautions (Continued)

Load Limit

The elbow can support up to 22 kg (50 lbs) when locked. Do not overload the elbow to prevent damage.

Serious Incidents

In the unlikely event of a serious incident related to the device, seek immediate medical help and contact your prosthetist as soon as possible. Clinicians should contact Motion Control immediately in case of any device failure.

U3/U3+ Components

Harness

The prosthesis harness (Figure 1) is provided and fitted by your prosthetist and may serve two functions: suspending the prosthesis and keeping it in place. In some cases, a control cable may be used with a linear potentiometer or force sensor for prosthesis function (Figure 2). The harness should be as comfortable as possible. Periodically examine it for tears or worn areas that could lead to harness failure and potential damage to the arm. Any adjustments or repairs should be performed by your prosthetist.

Socket

The prosthetic socket (Figure 1) is also provided by your prosthetist. It creates a comfortable interface between the user and the prosthesis and should be designed to maximize function and comfort. The socket may include electrodes to detect muscle signals for prosthesis control, requiring a very intimate fit. If the socket fit deteriorates, prosthesis performance may suffer. Consult your prosthetist to ensure an optimal socket fit.

Humeral Friction Band

The humeral friction band (Figure 3) connects the prosthetic socket to the elbow. A small 7/64 inch hex screw allows adjustment of the elbow's rotation ease. This band may wear and require adjustment or replacement by your prosthetist.

Elbow

The U3 and U3+ elbows contain two microprocessors, electronics, electric motors, and a transmission system. These components enable elbow flexion and extension, as well as optimal control of the hand and/or electric wrist rotator.

Battery and Charger

Lithium-Ion (Li-Ion) Batteries

Lithium-Ion batteries must be installed as per this manual and charged only with the provided chargers. Do not place objects on the battery's metal contacts; doing so can cause malfunction and damage.

Battery

Each battery pack (5 included with U3 and U3+) powers the elbow, terminal device, and electric wrist rotator. Batteries are interchangeable and rechargeable. The elbow must be fully flexed to swap a discharged battery for a charged one. Li-Ion batteries do not develop memory, so full discharge is not required. Battery life varies based on usage and the type of hand/wrist used.

Battery Insertion (Figures 3a, 3b, 3c)

Open the battery door using your finger and thumb (Figure 3a). Slide the battery's rectangular portion into the elbow cap at the back of the elbow (Figure 3b). Gently push the battery door down until it clicks into place (Figure 3c). Ensure the battery is flush with the elbow cap before turning the elbow ON. This process can be mastered with practice, even with one hand or another prosthesis.

Battery Charger

Use only the power supply provided with the battery charger. Other power supplies may cause malfunction, improper charging, fire, or explosion.

The battery charger can remain plugged into the wall. A yellow "Fault" light indicates no battery is present.

The battery pack installs into the charger similarly to how it fits into the elbow. After inserting the battery and closing the door, the yellow "Fault" light should change to red ("Charging"). When charging is complete, the light turns green ("Complete"). (See Figure 4).

Figure 4: Battery Charger Status Lights

The battery charger has indicator lights: Yellow indicates a "Fault" (e.g., no battery inserted), Red indicates "Charging," and Green indicates the battery is "Complete" and ready for use.

Troubleshooting Charger Lights

If the yellow "Fault" light remains illuminated after inserting a battery, there may be an issue with the battery or charger. Both should be returned to your prosthetist for evaluation. The battery and charger contain no user-serviceable parts.

Supplemental Battery

Systems using multi-digit hands (e.g., Taska®, i-limb™, bebionic™) may require a supplemental battery integrated into the socket. This battery comes with its own charger, provided by your prosthetist. Charge the supplemental battery nightly. If it depletes, power automatically switches to the elbow battery. If both batteries deplete, replacing the Utah Arm battery while wearing the prosthesis can be difficult. Ensure both batteries are charged (refer to "Dead Battery Situations").

Controls and Features

Lock/Unlock Button

Pressing this button changes the elbow's lock state when power is ON. For the U3, it toggles between locked and unlocked. For the U3+, it cycles through three states: Unlock, Friction Brake, and Pin Lock, returning to Unlock. (See Figure 5).

Figure 5: Lock/Unlock Button

This diagram shows the Lock/Unlock button, which controls the elbow's locking mechanism and its different modes.

Data Port

Your prosthetist uses this port to connect your elbow to a computer for adjustments.

Forearm Screws

These screws secure the forearm cover. They may loosen over time and can be tightened with a coin. Periodically check their tightness.

ON/OFF Switch

The ON/OFF switch is a slide switch located centrally on the forearm. Pushing the left side towards the right turns the arm ON. Pushing in the opposite direction turns it OFF (Figure 6). Upon powering up, the arm emits a "whir" from the unlock motor and two beeps (which can be disabled by your prosthetist). If the elbow was locked, it will always be unlocked upon powering on.

Figure 6: ON/OFF Switch

This illustration shows the slide switch for turning the arm ON and OFF.

Forearm Gain Adjustments

These adjustments affect only the elbow function. Increasing the right gain makes flexion easier; increasing the left gain makes extension easier. These adjustments rarely need modification but can be bumped accidentally. If the elbow's function seems incorrect, verify these settings have not changed.

Electric Wrist Rotator (Optional)

An electric wrist rotator can be installed in the forearm. Your prosthetist will explain its function and control.

Quick Disconnect Wrist

The U3 and U3+ arms feature a quick disconnect wrist compatible with most manufacturers' terminal devices. Follow your prosthetist's instructions for its use.

Terminal Device

Exchanging Terminal Devices

Turn the elbow power OFF before exchanging Terminal Devices (TDs).

The Hand or Terminal Device is purchased separately. Each brand has its own instructions, which should be followed.

Donning and Doffing Your U3 or U3+

Donning

Ensure the power switch is OFF before putting on your Utah Arm. Follow the donning procedure instructed by your prosthetist and occupational therapist. Once the arm is on and the harness is secure, slide the power switch to the ON position. You will hear the unlock motor "whir" and two beeps (these can be disabled).

Doffing

For a U3 elbow, ensure it is unlocked and the power is OFF before removing the prosthesis. For a U3+ elbow, it is recommended to extend the elbow first to enable Silent Freeswing, then turn the elbow OFF and remove the prosthesis.

Control of Your Prosthesis

EMG Control

The elbow can be flexed (raised) or extended (lowered) based on muscle contractions in the arm, typically the biceps and triceps. The elbow can reach up to 150° above vertical. Greater muscle contraction results in faster arm movement. Proficient control allows for smooth, steady, or quick motions (Figure 7).

Harness-Mounted Input

With harness-mounted inputs, the pressure exerted on the sensor dictates the arm's speed. Relaxing pressure allows the elbow to drop (extend); less pressure results in a faster drop.

Silent Freeswing (U3+ only)

When inputs to the elbow are completely relaxed, it swings freely, providing a more natural look and feel, such as swinging by the side during walking. The elbow can also be lowered quickly without muscle effort. This freeswing function is motor-driven and consumes battery charge. The elbow drive disconnects upon reaching full extension with a bump; it reconnects automatically when the motor raises the elbow. Battery life is extended by turning the arm OFF when freeswing is not needed.

Automatic Lock

The arm's motor automatically engages the lock when the elbow is held motionless. A steady input signal maintains stillness and activates the lock. The lock time is set by the prosthetist. The lock will not engage if the elbow is hanging freely or if the forearm's weight is supported (e.g., on a table or knee).

Automatic Unlock

The elbow unlocks via a rapid contraction and subsequent relaxation of the control inputs. The speed of the signal, not the effort, triggers the unlock. The lock disengages only when the arm's weight is lifted off the mechanism, by raising or slightly pushing the arm up.

Figure 7: Myoelectric Elbow Control

This diagram illustrates myoelectric control. It shows contracting the "up" muscle to raise the arm, and relaxing both muscles to lower it with "Silent Freeswing."

Prosthesis Function Chart

The Utah Arm's microprocessors allow various control inputs and schemes, programmed via the User Interface by your prosthetist. Occupational therapy training helps optimize prosthesis function. You and your prosthetist should complete the following chart to document your body actions for each prosthesis motion, as control improves.

Troubleshooting

Dead Battery Situations

To change a Utah Arm battery, the elbow must be fully flexed. If the elbow is extended and the battery is discharged, replacement may be difficult. Following donning/doffing procedures helps, but multi-articulating hands can discharge batteries unexpectedly. Always start the day with fully charged batteries.

If the battery is inaccessible and discharged: turn the power OFF, let the prosthesis sit for at least 3 hours (preferably overnight). Turn the power ON; listen for the unlock motor "whir" and double beep. If this occurs, immediately flex the elbow completely and turn the power OFF to replace the battery. If this is not possible, return to your prosthetist.

For more information, see the YouTube video "Patient Guide to Utah Arm Battery Care" at https://youtu.be/ujG5il_ZuxM.

Elbow functions fine but Terminal Device (hand) does not function

Ensure the TD's ON/OFF switch is active. Gently pull the TD to check for accidental disconnection and ensure it is securely engaged in the wrist.

Hand functions fine but Elbow will not function (or only flexes partially)

Check that the elbow forearm gains have not been moved.

Neither the Elbow nor the Hand function (no whir or beeps from the system)

Replace the battery with a fully-charged one (indicated by the green "Complete" light on the charger). If the battery is inaccessible, follow "Dead Battery Situations" instructions. Also, check that forearm gains have not been changed.

Elbow and Hand function sluggishly

If using EMG signals, immediately after doffing, check the skin of your residual limb for red marks where electrodes are placed. Lack of distinct marks indicates poor function and requires socket adjustment by your prosthetist.

General Considerations

Your Prosthetist

Your prosthetist has received specialized training from Motion Control, which is required for fitting U3 or U3+ elbows. They can provide service and troubleshooting for issues beyond basic user support. Regular annual visits to your prosthetist are recommended for preemptive problem resolution. The system may need to be returned to Motion Control for repairs; loaner systems are available on a limited basis. Your prosthetist can arrange this.

Avoid Extreme Temperatures

Motion Control products are tested in normal temperatures (0° - 44° C / 32° - 110° F). Avoid extreme temperatures, including leaving the prosthesis in a hot car or trunk, or wearing it in very hot conditions.

Dyes

Dyes from clothing (e.g., blue jeans, newsprint) can stain plastic components and cosmetic gloves. Be aware that these stains can be permanent.

Cleaning Your Prosthesis

Clean the inside of your socket at least weekly using a cloth dampened with rubbing alcohol. Clean the outside of the prosthesis and elbow with glass cleaner or another mild cleaner. Do not spray cleaners directly onto the prosthesis, and prevent cleaning liquid from entering the prosthesis.

Forearm Screws

Periodically check the forearm screws for tightness, as they may loosen over time.

Technical Specifications

Declaration of Conformity

The product complies with Medical Device Regulation 2017/745 and is registered with the United States Food and Drug Administration (Registration No. 1723997).

ROHS COMPLIANT, CE, Bluetooth®

Home Training Program for PNF Exercises

Proprioceptive Neuromuscular Facilitation (PNF) is a strengthening exercise recommended as part of a conditioning program under a qualified Physical or Occupational Therapist. Refer also to Motion Control's video course, "Training the Client with an Electric Arm Prosthesis."

Your prosthetist or therapist can guide you through this exercise program, which takes about 10 minutes. It aims to improve muscle strength and control in your residual limb, enhancing prosthesis control and potentially reducing phantom limb pain.

Note: Perform exercises while lying comfortably and relaxed. Concentrate on imagining your amputated arm is present, especially the thumb, if experiencing phantom sensations. Instructions are for unilateral amputees; for bilateral amputees, replace "uninvolved arm" with "one amputated arm."

Biceps

Step 1

Lie on your back. Close your eyes, breathe slowly and rhythmically, and relax.

Step 2

Practice flexing the biceps muscles (flexion pattern). Move your uninvolved arm through the full pattern: with your arm at your side, palm rotated up, and thumb out, pull your arm up and across your nose, bending the elbow and turning the arm so your thumb points up. Repeat several times, concentrating on the movement.

Step 3

Move both arms together through the biceps pattern. Imagine the movement of the amputated elbow and thumb. Repeat several times, concentrating on the movement.

Step 4

Move your amputated arm through the pattern while using your uninvolved hand over the biceps muscle to resist its movement. Repeat several times, concentrating on imagining the movement of the missing elbow and thumb.

Step 5

Practice the biceps pattern with your amputated arm, focusing on not moving your shoulder. Start with your shoulder and arm relaxed at your side, hand over the biceps muscle. Contract the biceps while imagining the elbow bending and palm turning up. Feel the contraction with your hand. Relax completely. Repeat 10 times, then rest. Perform Step 5 a total of 3 times.

Triceps

Step 1

Move your uninvolved arm through the full pattern. With your arm across your face, elbow bent, and thumb up, push your arm down and to the side, straightening the elbow and turning your arm so your thumb points out. Repeat several times, concentrating on the movement.

Step 2

Move both arms together through the triceps pattern. Imagine the movement of the amputated elbow and thumb. Repeat several times, concentrating on the movement.

Step 3

Move your amputated arm through the pattern while resisting the movement with your hand over the triceps. Repeat several times, concentrating on imagining the movement of the elbow and thumb.

Step 4

Practice the triceps pattern without moving your shoulder. Start with your shoulder and arm relaxed at your side, hand over your triceps muscle. Imagine the elbow straightening and the palm turning down. Feel the contraction with your hand. Relax completely. Repeat 10 times, then rest. Perform Step 4 a total of 3 times.

Co-contraction Exercise

Place your hand around the amputated arm to feel both triceps and biceps muscles. Quickly contract both muscles simultaneously, then immediately relax. Then, contract only the biceps. Repeat 10 times.

Customer Support

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motioninfo@fillauer.com

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Fillauer Europe
Kung Hans väg 2 192 68 Sollentuna, Sweden
+46 (0)8 505 332 00
support@fillauer.com

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Fillauer LLC

2710 Amnicola Highway Chattanooga, TN 37406
423.624.0946
customerservice@fillauer.com

Fillauer Europe

Kung Hans väg 2 192 68 Sollentuna, Sweden
+46 (0)8 505 332 00
support@fillauer.com