Realistic or Futuristic: serious injuries and assistive technology in the Marvel Comic Universe (MCU) films (Part 3)
Written by Rosti Readioff and Alice Faux-Nightingale.
Here, we present the final part of our series about the assistive devices used by Marvel superheroes and how they compare to current healthcare technologies. So far we have looked at War Machine’s exoskeleton armour and Professor X’s wheelchair. This month we complete our investigation with a post about Bucky Barnes and his prosthetic arm.
One of the later additions to the Avengers team, Bucky Barnes is one of the best friends of Steve Rogers (Captain America). In the early Captain America films, Bucky is experimented on by HYDRA and becomes the Winter Soldier, a brainwashed killing machine. This mental programming is reversed in later films and Bucky fights alongside the Avengers against Thanos in Infinity War and Endgame.
Bucky is perhaps best known for his prosthetic arm. Early in his career, a fall from a train moving at full speed caused him to lose his left arm which was replaced with a prosthetic arm as part of the HYDRA regime which turned Bucky into the Winter Soldier. This prosthetic arm was made completely of metal and was fused to his body at the chest, as shown in the picture below. In the films it has superhuman strength and endurance, protecting Bucky from gunshots, falls and numerous attacks, all while functioning fluidly, allowing him equal levels of dexterity and the same range of motion as his biological arm.
In the later MCU films, Bucky is given a replacement ‘vibranium’ cybernetic arm by the Wakandans. This is an upgrade on the earlier model and continues to offer him superhuman strength and durability, whilst still maintaining the dexterity to carry out fine motor skills like using a rifle accurately.
The movie suggests that Bucky is a shoulder level amputee with a fully integrated wireless advanced prosthetic limb. Bucky’s prosthetic limb seems very futuristic because of its fluid movement and feedback. In real life, the development of prosthetic limbs has not moved forward quite so far! Unlike Bucky’s prosthetic limb, current devices do not provide high-level sensory feedback to the user and are not easy to control, which can leave amputees struggling to cope with everyday tasks.
The human upper limb has 30 degrees of freedom (planes of movement) which are necessary for dexterous arm functions. Three of these degrees of freedom are in the shoulder, one in the elbow and three in the wrist. There are 23 degrees of freedom from the tip of the fingers to the wrist. Mimicking realistic arm functions using prosthetic devices is challenging because of the need to recreate the large number of these degrees of freedom, whilst accurately controlling the prosthesis is another challenge that we are still working on.
There are some advanced prosthetic devices controlled by electromyography (EMG) signals generated by the user’s muscles and recorded by surface electrodes attached on top of the skin (Sudarsan et al. 2012). For example, the Hero Arm, a myoelectric prosthetic hand, works when a user intentionally flexes specific muscles in their residual limb. EMG electrodes within the Hero Arm detect tiny electrical signals, allowing them to activate motors to achieve different grips with precise, proportional control.
However, using skin attached electrodes to record EMG signals can be unreliable, inconsistent, and it might encourage individuals with upper limb amputation to abandon using their prosthetic devices (check out this video where Dr. Chadwick briefly discusses myoelectric prostheses). One of the main limitations of current myoelectric prostheses is that they can use limited locations from the residual limb to acquire EMG signals for controlling the prosthetic device and that limits the number of movements the device can produce. To overcome this, researchers are working on using implanted myoelectric sensors to detect EMG signals from multiple locations to offer multiple degrees of control, closer to a more natural movement, of prosthetic hands (Geethanjali 2016). The use of implantable electrodes also offers access to long-term stable and physiologically appropriate sources of control, as well as the possibility to elicit appropriate sensory feedback via neurostimulation.
Bucky’s prosthetic arm, which unfortunately is science fiction, has perhaps unfairly put pressure on our expectations from the current technology. However, we look forward to exciting outcomes from DeToP, which is a major European funded research project that aims to develop and clinically implement robotics, sensing and long-term interfacing technologies for the next-generation prosthesis.
If you have enjoyed reading this short blog, then why don’t you visit Part 1 and Part 2 of this series? In the meantime, if you would like us to write about different assistive technologies related to human movements, then please feel free to comment below or get in touch.
