SMORGASBORG #7: Endoskeletons part B

What do Sam Worthington, Peter Weller, and Will Smith have in common? They're all dreamy, and they all play characters in movies who have devices implanted into their bodies. In their films the only issues they seem to have with their artificial parts are emotional ones, but putting a foreign object into a human body without adverse physical effects is actually pretty hard to do.

Marcus.

Note the chiseled endoskeletal cheekbones.

Marcus (Worthington) in Terminator Salvation, is apparently the lone humanoid organism to have survived Skynet's experimentation to build a cyborg with a metallic endoskeleton. Why would this be so hard? (Other than the fact that a machine dominated society using humans as lab rats wouldn't really care that much if there were a lot of casualties.) Living tissue and many types of metals have problems getting along together.

YOU PUT WHAT, WHERE?

Metals for making cyborgs, or hip or knee replacements, have to be corrosion resistant and biocompatible. If you have an allergy to nickel, you sure don't want a nickel implant, or a nickel belt buckle, or a phone with nickel in it.

The consequences of nickel allergies.

Metals shed ions. In order for the body to tolerate the metal well, it can't leach too much into the surrounding tissue. Although your body uses some metals for metabolism (copper, iron, magnesium, etc.), too much can cause toxicity. You don't want that metal plate in your head shedding too much of anything near your brain(1).

So you can imagine that corrosion resistant types of metals, plastics, or ceramics, would be a good idea. Using incompatible metals could interfere with normal tissue growth near the implant(2). Blood acidity and ph balance can have a corrosive effect on metals. If metals shed into the bloodstream, your whole body may have a (systemic) reaction. Organs that filter blood, like the liver and kidneys may accumulate unhealthy amounts of metal ions, which is bad. And don't forget cancer! You have to be careful that whatever you're implanting isn't carcinogenic 20 years after you've implanted it.

Cobalt-chromium alloys, stainless steel, and titanium have been reported to have minimal tissue reactions in rabbits, dogs, and people. If Terminator Salvation was going to be really accurate, we should have seen some rabbit cyborgs hopping around killing humans.

Kelli Doyle's Cyborg-Bunny puppet

Although there are always many things to consider, many people enjoy their artificial joints (made of plastics and metals) or eye lenses (plastics), or boobs (silicone) and never have any problems. 300,000 women per year receiving breast implants can't be all wrong, can they(3)?

Lens implant

CYBORG FATIGUE

Once you find biocompatible materials to implant in the body, you also want them to last. Fatigue resistance is important. You don't want parts to break or bend like a lug nut on an airplane wing.

If we're talking about hip replacements, "... chrome is favoured if tensile and fatigue strength are required, titanium is favoured if load sharing with adjacent bone (uncemented prostheses) is required (titanium has a similar modulus to cortical bone)(4)." So it really depends on what you're going to do with that hip and whether you glue the prosthetic, or just jam it in there really tight.

Bo Jackson, cute enough to be a cyborg, and a super-human athlete.

The metal and the bone it's embedded in, making up the structure of an artificial joint, are able to withstand normal physical stresses. Professional athletes with joint replacements often end up with complications because they put super-human stress on their bodies. The metal may bend, the bone holding it may break, or the prosthetic starts to work its way lose. For this reason, RoboCop with his combination of exoskeleton and implanted sensory parts, Spooner and his entirely prosthetic limb, and Marcus with a full body endoskeleton are the creme de la creme of the Hollywood Cyborgs.

1. Which is why they use titanium or niobium in the skull.

2. This can lead to chronic inflammation and scarring in the area.

3. Women with breast implants do not qualify as cyborgs.

4. Page 394 from Imaging of the Hip and Bony Pelvis: techniques and applications, by Arthur Mark Davies, Karl J.Hohnson, Richard Wihehouse. Read it on Google books, otherwise it costs over $200!

SMORGASBORG #3: Exoskeletons part B

RoboCop

MAN AND/OR MACHINE?

Biomechatronic(1) feedback and motor systems could be used for prosthetic devices that replace limbs, or for exoskeletal structures that support and enhance function of an intact body.

External devices that interface intimately with human internal anatomy are represented in RoboCop, as Murphy's (Peter Weller) shattered corpse is resuscitated, amputated, and implanted into an exoskeleton that also serves as a prosthetic(2). The bullets from the men who murder him, and the surgeries of the people who "save" him, leave Murphy very little that can be physically recognized as the man he was. Once he is implanted within his carapace, and once additional devices are implanted within what's left of his body, he becomes even less recognizable as a man. Murphy is deliberately brainwashed in this cyborging process. He is rendered less than human by the people who re-make him. This movie is an engrossing investigation of our corporeal attachment to human identity(3). It's also a kick-ass action film.

Del Spooner (Will Smith) defending himself against an evil robot.

In I, Robot, Del Spooner has lost his arm as the result of a car accident. The arm has been replaced by a prosthetic. To Spooner's mind it is a robotic prosthetic, and Spooner hates robots. Although Isaac Asimov is light years away from this film, the amputee who hates his life-like robotic prosthetic (and himself, by extension) makes for good drama, I guess.

But in this film, Spooner remains a human and a man. Although he is conflicted about his acceptance of a prosthetic arm, he is unquestioningly human to all who know and see him. He retains his personality. He works out. He is a guy with a motorcyle. Unlike RoboCop, he is sexually attractive and has his 'nads(4).

Spooner's prosthetic upper extremity includes all of his shoulder and a number of ribs. This type of device probably has a surgically implanted interface, since there would have to be a design element that allowed the prosthetic rib replacement to maintain a vacuum between the lung and chest wall. I bet the prosthetic ribs even act and react to Del's rib movement and breath rate. This would require some kind of invasive interface with the nervous system. To support my logic, we see that the inside of the fake arm is all lit up and sparkly. It just screams fancy technology capable of anything. I rest my case.

WHAT ELSE CAN YOU DO WITH THAT?

Discussion of biomechatronics and the developments in prosthetics and exoskeletons brings us to what they could (and probably should) be used for, beyond killing and superhuman strength, I mean. What is that use? To restore normal function to a body that is missing a part, or that has been weakened, paralyzed, or otherwise damaged.

A VERY SIMPLISTIC INTRODUCTION TO PARALYSIS; MAKING BROAD STATEMENTS AND LACKING IN SUBTLETY

Some bodies are intact but unable to respond voluntarily to the will of the brain. This is the result of damage to the nervous system. Damage from injury or disease can happen in a number of different ways, and cause a variety of symptoms. Insult to a nerve may cause a complete flaccid paralysis(5) or a partial paralysis(6) to the part of the body the nerve served. Injury to the spinal cord can lead to paralysis or paresis of one or more limbs.

"Wrist drop" a.k.a. radial nerve palsy.

This painter suffered lead poisoning and lost the use of the muscles that extend the wrist.

Damage to the brain can lead to spasticity, rigidity, tremors(7) etc., anywhere in the body, depending on what part of the brain is damaged. A person with any of these conditions may have partial control over the limb, or no control at all. It depends on the extent of the damage to the nervous system.

Josh Blue

A really funny comedian (with cerebral palsy).

What could damage, alter, traumatize, or injure the nervous system? Direct trauma(8), poisoning(9), or diseases(10) are the usual culprits.

Paralysis Resource Center

ENVISION A LIFE WITH PARALYSIS

Imagine, if you can, what it would be like to never stand up again. Imagine how your day would change if you could use your shoulder and elbow, but not use your hand, or what would it be like to walk with a foot that doesn't respond. Think about how your body would change if you could no longer contract muscles in your arms or legs. If a muscle stops contracting it shrinks (atrophies), just as it will grow in size if you exercise it. How would you feel about your physical appearance if your limbs were atrophied and much smaller than those of a more physically active person?(11)

This young man in New Delhi contracted polio myelitus.

Polio is caused by a virus that attacks motor nerves, leading to flaccid paralysis.

As a massage therapist, I have thought about these questions a lot. When you are touching a disabled body, and you develop a relationship with the body and the person, it forces you to think really hard. I have an intellectual understanding of the causes of many of these conditions, and the basics of various therapies one can undergo to recover from nerve and/or brain damage. I can appreciate the heroic efforts of my patients, even when they are at their pissy worst. But frankly, that knowledge doesn't help much. I know I've been lucky so far, and that my luck could change. I don't know how I would react to being struck by any disease or debilitating injury, until it happens.

As you would expect, my massage patients have all viewed their conditions differently. From observation, I have concluded that descriptive terms like "the worst thing imaginable," "pain in the ass," and "extremely frustrating," don't begin to describe the impact of losing physical function has on someone's life.

Yes, we are ending on a downer. Next time, exoskeleton technology applications for persons with paralysis.

1. See SMORGASBORG #2 for more on biomechatronics.

2. What is a prosthetic? An artificial substitute or replacement for a part of the body (eye, leg, breast, tooth) or a replacement for a joint (hip, knee). A prosthesis can be used for functional or cosmetic purposes, or both. You can go to Medterms.com for a more in depth definition.

3. Sorry for that last sentence, folks! I'm reading too much academic writing and it's causing me to "act out."

4. We assume Spooner's testicles and penis weren't harmed in the accident. With Murphy in RoboCop, the corporation orders the amputation of his viable leg. Through that act, it is implied that any other unneeded parts are also removed. He doesn't eat normal food. Digestion and excretion have been altered to fit his new being. Murphy wouldn't need a functional reproductive system, either.

5. Paralysis where there is a loss of tone, loss of reflexes, and atrophy (shrinkage) and degeneration of affected muscles.

6. Partial paralysis is called paresis. Partial flaccid paralysis may manifest as weakness in the body part.

7. Spasticity and rigidity are produced by excessive uncontrolled muscular contraction and are due to brain (as opposed to nerve or spinal cord) injury. Tremors can have a variety of causes, and like spasticity and rigidity, cannot be willed to stop.

8. Car accident, birth trauma, gunshot, stabbing, etc.

9. Lead, mercury, etc.

10. Multiple sclerosis, amyotrophic lateral sclerosis (ALS or Lou Gherig's disease), Parkinson's etc.

11. I teach lessons on massage for different deformities, and I'm used to using clinically descriptive language to describe these conditions. Terms like "valgus" or varus", etc. If I'm massaging a patient with a deformity, we're talking about their body, the state of the tissues, anatomical structures, goals for the session, etc. Or we're talking about movies, our pets, or food. I'm not current on the acceptable social language used to describe atrophy or other conditions. I'm not even sure that there are socially acceptable non-clinical adjectives out there. Any comments?