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    Implant-Chemistry And Adventures
    By Enrico Uva | June 25th 2012 02:00 AM | 7 comments | Print | E-mail | Track Comments
    About Enrico

    I majored in chemistry, worked briefly in the food industry and at Fisheries and Oceans. I then obtained a degree in education. Since then I have...

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    With my team down twelve runs, I still felt compelled to attempt a running catch with my back to the infield. Our center fielder never heard me call for it. As I dove, my foot was caught under his sliding legs. There was enough momentum and leverage to snap both my fibula and tibia. The cracking sound carried to a second floor balcony, and from there a spectator called an ambulance. 

    The hurtful jolt and the sensation of a dangling foot prevented me from holding on to the ball.

    Then the endorphins may have kicked in because, while a crowd gathered around me, the pain disappeared. But the analgesic action of endogenous opiates only lasted until I was moved to a stretcher.






    At the hospital, an orthopedic surgeon screwed a titanium plate on my tibia(shin bone). The fibula(calf bone) was left alone. It plays a role in moving the foot, but unlike the tibia, the fibula does not support much weight. The doctor had explained that such a procedure would allow me to regain activity sooner than a conventional cast and would accelerate healing. I consented and signed without hesitation.

    Titanium implants are, for the most part, biologically compatible. They don't provoke reactions by the immune system and do not interfere with bone growth. The most corrosion-resistant form of titanium is not alloyed. Grade 1 has the lowest form of oxygen; the natural coating actually protects the bulk of the metal from further oxidation, but the coating is usually acid etched. As the small percentage of oxygen goes up, the strength of titanium increases.

    After the surgery, my titanium-reinforced leg and I lay in a bed that was too small for me, so I slept diagonally. The stretcher I was on when awaiting x-rays was also too short for anyone over six feet in length. While the swelling subsided I remained in the hospital with a temporary half-cast, and then someone came to record measurements for the custom-made prosthesis. I was not supposed to be released until the prosthesis was ready, which translated into a one-week stay.

    But a few events may have influenced my early release. The school year was coming to a close, and I was worried that the substitute teacher would not be able to conduct adequate review classes. So in those pre-laptop days, I asked the nurses for paper and to fax my review assignments to my school. They were not visibly annoyed, but I overheard them complaining about it. Then four days after surgery, my roommate started to react to something shortly after he was hooked up to an I.V. His blood pressure and heart rate rocketed, and although we both buzzed for help, no one was coming. Maybe they were fearing another request for a fax. 

    After hearing my screeching whistles, a few nurses arrived and eventually the room was filled with doctors. One of them asked me what I had witnessed. On the next day, my roommate was transferred to another hospital for additional testing, and still with my temporary cast, I was sent home. 

    A month later, thanks to the prosthesis, which arrived a few days after my release, I was cycling. During the summer I borrowed my friend's medical books to examine photographs of X-rays of various stages of bone healing. About ten weeks after the fracture, I sneaked a look at my X-rays, and my tibia did not seem as fully healed as what the medical books gave as examples for when it was time for the cast to come off. 

    But the doctor disagreed. Who was I to argue with him, especially when he was telling me what I really wanted to hear? After all, the beginning of the school year was imminent, and I did not want to be seen hopping around by new students. Only two days after I stopped wearing the prosthesis, I went for what was probably too long a walk downtown with friends. When I started teaching a week later, I had to rest my leg every day after work. One evening it looked swollen, and in one of the two places where the titanium plate was screwed, about 6 inches above the foot, there was an area about the size of a half dollar that felt soft.

    I only went to see my doctor on the next scheduled visit. This X-ray revealed that the bone had continued to heal immediately above the screw, where I had noticed softness and swelling. Without that complication, surgery would have been simple. Two incisions, unscrewing, sliding the plate out, stitching and a 1 to 2 week recovery. Now we were looking at drilling through the bone, and a one-month recovery. I asked for consequences of just leaving the implant in there. He told me there would be a risk of knee problems.

    Twenty one years later, the plate and nails are still in me, and so far I have experienced no obvious complications. Prior to 9/11, it was never picked up by any airport metal detector except in Havana, where, luckily, my wife who knows some Spanish was able to explain what was going on. Researchers from the orthopedic surgery department at the Harvard Medical School published a report, in the April 2007 issue of the Journal of Bone and Joint Surgery, listing the implants most likely to trigger airport detectors with new security sensitivities. They found that cobalt-chromium and titanium implants are much more likely to be detected than stainless-steel implants, especially when they occur in the lower extremities.

    A more serious concern involves implant release of titanium into the bloodstream according to a 2011 study published in Analytical and Bioanalytical Chemistry (free of charge pdf file) and the subsequent possible impact on the kidneys and liver. The titanium ends up in (1) organometallic complexes---for example, by binding to theglycoprotein human serum transferrin -(2) as free metallic ion and 
    (3) inorganic metal oxides (sometimes as TiO2 nanoparticles).

    Compared to control groups, the amount of titanium found in patients with implants was `significantly higher`as reported in the media last year. According to the original paper, subjects without implants averaged a blood serum concentration of 0.25 μg of Ti per liter or 0.25 parts per billion. Patients with tibial and femural titanium implants had 5 to 6 parts per billion. But 5 years after carrying the implant, the concentration dropped to 3-4 ppb, and there was no data collected beyond that time span.

    So we have a familiar situation: thanks to a technology, in this case, inductively coupled plasma-mass spectrometry (ICP-MC)--minute concentrations of trace metals like titanium can be detected. But the science of establishing safe thresholds in these zones is a work in progress. It is reminiscent of Umberto Eco's essay Science, Technology and Magic. With its instantaneous results, technology appeals to our sense of magic.

    Science, however, cultivates patience, suspended judgment, self-criticism, an examination of history--in other words, it is the antithesis of how most of our mass media operate.

    Comments

    A little knowledge is a dangerous thing. As a recovering hypochondriac with a titanium implant, I'm not feeling so good. Who is doing research on this topic?

    MikeCrow
    My son played first base, and after about 4-5 years in youth leagues on first, his new coach put him in left field.
    At some point in the season there was a pop fly to left, the ball got lost behind his glove, when he moved it aside, the ball smacked him straight in the nose, and rolled over to the left field fence. He ran over grabbed the ball relaying it to third, and then fell to his knees holding a bloody broken nose, I was so proud :)
    Never is a long time.
    Fracture healing after surgery is always a race between the progressive strengthening of the bone and the progressive weakening of plates, nails and screws due to material fatigue and loss of bone around the implants (especially around the screws). It is part of the art of surgery, to guide the patient and his activity until the fracture is healed. Your “soft-spot-episode” (Sascha Vonghe will complain about the hyphens) probably was such an episode of to much activity. Fractures at the location of the shown X-ray are prone to slow healing.

    Titanium is not only tolerated by bone (as is steel), but it stimulates bone growth around the implant. It is therefor the first choice for Implants to stay in the body, hip prosthesis and screws to hold artificial teeth, for instance. It is rather common, that titanium plates are overgrown by bone (that has nothing to do with “healing”) and can no longer be removed with acceptable risk. That is usually not a problem until the bone brakes again or a joint nearby needs a prosthesis. The propensity to overgrow metal implants is different from patient to patient. If you get a second titanium implant, you will probably overgrow that one also.

    The release of metal from implants is not a sole problem with titanium. An otherwise rather successful hip prosthesis made of steel had to be discontinued because of high iron concentrations around it (look for “metallosis” in Wikipedia). There was almost certainly also iron from the prosthesis in the blood, but there is usually some iron in the blood and the organism can handle that. With titanium, that might be different.

    UvaE
    I've had the titanium in me for 21 years. A couple of other doctors have told me to leave the implant in there. With regard to the paper, another doctor mentioned to me recently,
    "It appears, however, that the results parallel that of most papers in that the findings are statistically significant but may not be clinically significant."

    vongehr
    “soft-spot-episode” (Sascha Vonghe will complain about the hyphens)
    Yea - damn dude! What the hell, those hyphens!! Everybody: Remember that there is now a guy who is world renown to scan the net for hyphens! He WILL complain!

    (What the hell is going on? Is it really my being on whatever spectrum or are people just 100% nuts? Anybody out there? I complain about hyphens???? I did? I forgot? I do it all the time while sleepwalking ? Is it the same instances I support communism in Mao's words? Can somebody shoot me the next time I do it please? Because I really don't remember anything even remotely like it!)
    Hi Sacha, you are right, I apologize!

    The comment I had in mind was to this
    http://www.science20.com/quantum_diaries_survivor/large_extra_dimensions...
    dated 07/13/09

    but it was not written by you (it is signed "BM"), as I had in mind. I am sorry, not having checked that befor writing.

    Peter

    vongehr
    OK - accepted. Sorry for getting carried away. Lately I get too many completely baseless charges of what I supposedly do and support, often by people who know that it is nonsense. Seems to be a fashionable strategy especially with brown swamp species, all the way starting with those on the edge who still hide behind labels like "fiscal conservative".