Mechanical Elbows


The ErgoArm mechanical elbow was developed for passive or body controlled prosthesis. It has a function known as the slip stop that allows the amputee using the prosthetic arm to lower the prosthetic forearm without the need to complete release and re engage the lock. Along with this it also consists of a cable controlled internal infinite position lock that can engage and disengage depending upon the load placed on the terminal device. 

The ErgoArm plus is a modified version of the above mentioned elbow unit that consists of a flexion aid along with a ratchet-less lock. The flexion aid feature is used in storing energy given out during extension to harness it for flexion.


External Elbow – These mechanical elbows are available in 4 different design types – automatic, manual locking, free swing and friction models. The automatic joints are controlled through shoulder shrugging and are used as manual locking joints when inverted. The slim, free swing joints are used for higher lever prosthetic arms and have an 8° extension stop. Friction joints are commonly used in pediatric amputees to allow for passively pre positioning the forearm.

The Manual Elbow has 5 locking positions (flexion) and a free swing feature with a manual switch on the anterior forearm that comes with it. It also allows to control the rotation of the arm in increments. 

The Endoskeletal Elbow can lock in 4 different flexion positions (8°-135°) and consists of a forearm push button lock release mechanism. It incorporates different adapters proximally and distally that increase the length of the prosthesis, when required.


Hosmer Dorrance

It has 2 similar mechanical elbow units (E-400 and E-200) that allow for pre positioning of the forearm and locking it in 8-11 different positions. They also incorporate forearm lift assists that enable easy lifting of heavy loads.

Electronic Elbows


The ErgoArm Electronic plus is an electronic elbow with similar features to ErgoArm but the slip stop function is electronically controlled. In addition, it has an automatic forearm balance feature that provides smooth flexion-extension by using the energy given out during extension for flexion. It also has an electronic lock allowing 8 locking positions that is controlled by a switch or electrodes and EMG signals.

The Dynamic Arm Plus is used with those bionic arms whose users have more than 2 myosites. This powered elbow unit can be controlled with upto 6 electrodes and up to 2 switches and also has free swing. Due to multiple myosites, it provides the users with increased forces for lifting and holding.

Liberty Mutual

Boston Elbow comes with double battery chargers and can easily be transformed to switch control from the proportional control strategy, only by altering a single wire. Control strategy employed in the Boston Elbow is a 2 site 2 function myoelectric controller that provides speed and torque proportional to the myo signal. These electromechanical switches allow for singular speed flexion-extension and balance the elbow with respect to gravity. It has a self locking feature that is activated at the conclusion of the control signal.  

Motion Control

Utah Arm by Motion Control consists of an electronic elbow with 22 positions for locking throughout the 150° range of movement around an axis through the anterior region of the elbow. This allows the amputee to use the terminal device without much compensatory shoulder motions. It works on 2 sites proportional control strategy but does not use a switch mechanism. Elbow locking is activated when the elbow does not perform any motion for a designated period of time. To unlock the elbow, there is a need to contract the muscles either rapidly or slow the contraction of a single muscle. In the unlocked mode when there is no myo signal available, the elbow is in a free swing mode that allows flexion and extension powered by the electric motor.

Motion E2 elbow is also an electronic elbow used with pediatric or adolescent amputees, either through switch control or the ProControl feature allowing for proportional control. 

College Park

The Espire elbow is a powered intuitive elbow unit that consists of a removable battery, electronic locking mechanisms that restrict elbow flexion and extension when engaged and a free swing feature to comfortably carry out ADLs. It facilitates heavy lifting and holding weights upto 11kg (static) and 4kg (dynamic). The elbow is easily programmed using the Espire iHub application, which is user-friendly and easy to use. 

Neelima Bansal is a passionate blogger. She writes about her life experiences in the form of words. She had done masters in E-Business & working with a leading technology organization as an analyst.

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