Liberating Technologies, Inc.

LTI Boston Digital™ Arm Systems for Adults

LTI Boston Digital™ Arm Systems for Adults
  • Powerful high-torque adult prosthetic elbow system
  • State-of-the-art digital technology
  • Compatible with all manufacturer’s hands, grippers including bebionic & iLimb
  • Clutch automatically locks/unlocks
  • Dozens of control options
  • New high-capacity Lithium-polymer battery
  • Compatible with Bebionic and iLimb Ultra hands
  • Wrist rotator option
  • Accepts inputs from; myoelectrodes, Touch Pads™, Linear Transducers and switches
  • TMR version for Targeted Muscle Reinnervation patients

LTI introduced the Boston Digital™ Arm System early in 2001. This state-of-the-art prosthetic system incorporates microprocessor technology for improved performance and optimal patient adjustment. The system retains the same drive mechanism as the Boston Elbow II because of its long history of reliable service. Also, this drive unit provides greater torque than most other powered prosthetic elbows on the market today - a feature most users soon recognize as a significant benefit. The Boston Digital Arm is not just for positioning a terminal device like many other elbow prostheses. This system can perform work, whether it be on-the-job, at home or doing hobbies.

The Boston Digital Arm System has many advanced features and capabilities. It can control up to four other prosthetic devices in addition to the elbow. For example; hands, grippers, wrist rotators, shoulder lock actuators, etc. can be operated through the Boston Digital Arm’s microprocessor-based controller. These prosthetic devices can be sequentially selected and operated by the user through co-contraction switching (or a switch), a feature often preferred by multi-device users. The system can also control multiple devices simultaneously when adequate input sensors are provided.

A variety of other advanced set-up and control features are also available. On-board software-settable notch filters allow the clinician to set the noise filter for the type of line power (i.e. 110V, 60Hz or 220V, 50 Hz) of the country where the user resides or intends to travel. LTI Remote Electrodes provide un-rectified myoelectric signals for greater resolution, thus providing superior low speed control of the prosthesis. Several EMG signal processing algorithms allow the clinician to select the most appropriate one to optimize the user’s control of the prosthesis.

In 2008 the Boston Arm drive was upgraded to improve torque and reduce drive system noise. Ball bearings on the motors replace bushings and gear ratios were changed to reduce noise. The clutch was refined for optimal performance.

In 2010 the system was further enhanced and several new features were added. To accommodate the new multi-articulating prosthetic hands, the main circuit board was redesigned and the battery system was changed. A new light-weight, high-capacity lithium-polymer battery was provided, replacing the Ni-Cad battery previously used. The lithium chemistry provided several benefits in addition to the significantly greater energy density, like a fuel gauge to keep the user informed of the condition of their battery. This new battery chemistry resulted in a doubling of capacity (2000 mAHr), making it ideal for more power-hungry accessories (like multi-articulating hands). It reduced the overall weight of the elbow system to approximately 2 pounds.

Changes to the main circuit board included; fuses to protect the individual motor drivers, a new voltage regulator approach to provide constant voltage and greater current required by the new multi-articulating hands and a new molded high-strength urethane forearm.
LTI also added a new feature enabling the clinician to up-load the patient’s software settings to their computer. This is helpful when a user arrives at a site where their original settings are not stored. The Boston Digital Arm System also has the ability to store user settings as the prosthetist adjusts them during the initial and subsequent fitting visits.

Boston Digital Arm Graphical User Interface Screen

In 2010 LTI also created the Boston Digital Arm System – TMR for use with patients who had undergone Targeted Muscle Reinnervation surgery. Working with the Rehabilitation Institute of Chicago, LTI built the first TMR shoulder disarticulation prosthetic system for a bilateral SD patient. The goal was to enable the patient to operate 5 powered prosthetic devices using their new EMG sites; elbow (flexion/extension), wrist (pro/supination), wrist (flexion/extension), Humeral (internal/external) rotation, and shoulder (flexion/extension). The Boston Digital Arm was chosen because it has the ability to control 4 prosthetic devices in addition to the elbow itself, so it was ideal for this application. The other benefit was the elbow’s ability to work with other manufacturer’s devices. Since the initial fitting, dozens of other TMR patients have been fit with Boston Digital Arm –TMR systems.

Additional Information

Product Catalog:

Boston Digital Arm System(PDF)

Electric Hands for Adults(PDF)

Linear Transducer(PDF)

Locking Shoulder Joint(PDF)


Product Manuals:

Boston Arm Clinician's Guide(PDF)

Boston Arm Input Connector Board Instructions(PDF)

Boston Arm Lamination Collar Instructions(PDF)

Boston Arm Lamination Collar Instructions(PDF)

Boston Arm Lithium Battery Replacement(PDF)

Boston Arm Lithium Battery Upgrade(PDF)

Boston Arm User's Guide(PDF)

Promotional Information:

Boston Arm & Multi-articulating Hands(PDF)

Boston Arm HIgh-Capacity Lithium Battery(PDF)

Boston Arm Upgrades(PDF)

Boston Digital Arm System(PDF)

LTI Locking Humeral Rotator(PDF)

LTI Remote AC Electrodes(PDF)

Technical Specifications:

Boston Arm - Factors to Consider(PDF)

Boston Digital Arm Specifications(PDF)

LTI Programming Cable Kits(PDF)


Boston Arm tutorial - servo/myo program(PDF)

Boston Digitral Arm Clinician's Manual(PDF)

iLimb Revolution Data Sheet(PDF)

Justification for Powered Upper-Limb Prosthesis(PDF)

LTI Credit Application(PDF)

Wrist Rotator Warning - Bock 10S17(PDF)


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