Implant (medicine)

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Orthopedic implants to repair fractures to the radius and ulna. Note the visible break in the ulna. (right forearm) X-ray3.jpg
Orthopedic implants to repair fractures to the radius and ulna. Note the visible break in the ulna. (right forearm)
A coronary stent -- in this case a drug-eluting stent -- is another common item implanted in humans. Taxus stent FDA.jpg
A coronary stent — in this case a drug-eluting stent — is another common item implanted in humans.

An implant is a medical device manufactured to replace a missing biological structure, support a damaged biological structure, or enhance an existing biological structure. For example, an implant may be a rod, used to strengthen weak bones. [1] [2] Medical implants are human-made devices, in contrast to a transplant, which is a transplanted biomedical tissue. The surface of implants that contact the body might be made of a biomedical material such as titanium, silicone, or apatite depending on what is the most functional. [3] In 2018, for example, American Elements developed a nickel alloy powder for 3D printing robust, long-lasting, and biocompatible medical implants. [4] In some cases implants contain electronics, e.g. artificial pacemaker and cochlear implants. Some implants are bioactive, such as subcutaneous drug delivery devices in the form of implantable pills or drug-eluting stents. [5]

Contents

Applications

Implants can roughly be categorized into groups by application:

Sensory and neurological

Sensory and neurological implants are used for disorders affecting the major senses and the brain, as well as other neurological disorders. They are predominately used in the treatment of conditions such as cataract, glaucoma, keratoconus, and other visual impairments; otosclerosis and other hearing loss issues, as well as middle ear diseases such as otitis media; and neurological diseases such as epilepsy, Parkinson's disease, and treatment-resistant depression. Examples include the intraocular lens, intrastromal corneal ring segment, cochlear implant, tympanostomy tube, and neurostimulator. [3] [5] [6]

Cardiovascular

Cardiovascular medical devices are implanted in cases where the heart, its valves, and the rest of the circulatory system is in disorder. They are used to treat conditions such as heart failure, cardiac arrhythmia, ventricular tachycardia, valvular heart disease, angina pectoris, and atherosclerosis. Examples include the artificial heart, artificial heart valve, implantable cardioverter-defibrillator, artificial cardiac pacemaker, and coronary stent. [3] [5] [6]

Orthopedic

Orthopaedic implants help alleviate issues with the bones and joints of the body. [7] They are used to treat bone fractures, osteoarthritis, scoliosis, spinal stenosis, and chronic pain. Examples include a wide variety of pins, rods, screws, and plates used to anchor fractured bones while they heal. [3] [5] [6]

Metallic glasses based on magnesium with zinc and calcium addition are tested as the potential metallic biomaterials for biodegradable medical implants. [8] [9]

Patients with orthopaedic implants sometimes need to be put under magnetic resonance imaging (MRI) machine for detailed musculoskeletal study. Therefore, concerns have been raised regarding the loosening and migration of implant, heating of the implant metal which could cause thermal damage to surrounding tissues, and distortion of the MRI scan that affects the imaging results. A study of orthopaedic implants in 2005 has shown that majority of the orthopaedic implants does not react with magnetic fields under the 1.0 Tesla MRI scanning machine with the exception of external fixator clamps. [10] However, at 7.0 Tesla, several orthopaedic implants would show significant interaction with the MRI magnetic fields, such as heel and fibular implant. [11]

Electric

Electrical implants are being used to relieve pain from rheumatoid arthritis. [12] The electric implant is embedded in the neck of patients with rheumatoid arthritics, the implant sends electrical signals to electrodes in the vagus nerve. [13] [14] The application of this device is being tested an alternative to medicating people with rheumatoid arthritis for their lifetime. [15]

Contraception

Contraceptive implants are primarily used to prevent unintended pregnancy and treat conditions such as non-pathological forms of menorrhagia. Examples include copper- and hormone-based intrauterine devices. [5] [6] [16]

Cosmetic

Cosmetic implants — often prosthetics — attempt to bring some portion of the body back to an acceptable aesthetic norm. They are used as a follow-up to mastectomy due to breast cancer, for correcting some forms of disfigurement, and modifying aspects of the body (as in buttock augmentation and chin augmentation). Examples include the breast implant, nose prosthesis, ocular prosthesis, and injectable filler. [3] [5] [6]

Other organs and systems

AMS 800 and ZSI 375 artificial urinary sphincters Artificial urinary sphincters.jpg
AMS 800 and ZSI 375 artificial urinary sphincters

Other types of organ dysfunction can occur in the systems of the body, including the gastrointestinal, respiratory, and urological systems. Implants are used in those and other locations to treat conditions such as gastroesophageal reflux disease, gastroparesis, respiratory failure, sleep apnea, urinary and fecal incontinence, and erectile dysfunction. Examples include the LINX, implantable gastric stimulator, diaphragmatic/phrenic nerve stimulator, neurostimulator, surgical mesh, artificial urinary sphincter and penile implant. [5] [6] [17] [18] [19] [20] [21]

Classification

United States classification

Medical devices are classified by the US Food and Drug Administration (FDA) under three different classes depending on the risks the medical device may impose on the user. According to 21CFR 860.3, Class I devices are considered to pose the least amount of risk to the user and require the least amount of control. Class I devices include simple devices such as arm slings and hand-held surgical instruments. Class II devices are considered to need more regulation than Class I devices and are required to undergo specific requirements before FDA approval. Class II devices include X-ray systems and physiological monitors. Class III devices require the most regulatory controls since the device supports or sustains human life or may not be well tested. Class III devices include replacement heart valves and implanted cerebellar stimulators. Many implants typically fall under Class II and Class III devices. [22] [23]

Materials

Commonly implanted metals

A variety of minimally bioreactive metals are routinely implanted. The most commonly implanted form of stainless steel is 316L. Cobalt-chromium and titanium-based implant alloys are also permanently implanted. All of these are made passive by a thin layer of oxide on their surface. A consideration, however, is that metal ions diffuse outward through the oxide and end up in the surrounding tissue. Bioreaction to metal implants includes the formation of a small envelope of fibrous tissue. The thickness of this layer is determined by the products being dissolved, and the extent to which the implant moves around within the enclosing tissue. Pure titanium may have only a minimal fibrous encapsulation. Stainless steel, on the other hand, may elicit encapsulation of as much as 2 mm. [24]

List of implantable metal alloys

Stainless Steel

  • ASTM F138/F139 316L
  • ASTM F1314 22Cr-13Ni–5Mn

Titanium Alloy

Cobalt Chrome Alloy

  • ASTM F90 Co-20Cr-15W-10Ni
  • ASTM F562 Co-35Ni-20Cr-10Mo
  • ASTM F1537 Co-28Cr-6Mo

Tantalum

Porosity in Implants

Porous implants are characterized by the presence of voids in the metallic or ceramic matrix. Voids can be regular, such as in additively manufactured (AM) lattices, [25] or stochastic, such as in gas-infiltrated production processes. [26] The reduction in the modulus of the implant follows a complex nonlinear relationship dependent on the volume fraction of base material and morphology of the pores. [27]

Experimental models exist to predict the range of modulus that stochastic porous material may take. [28] Above 10% vol. fraction porosity, models begin to deviate significantly. Different models, such as the rule of mixtures for low porosity, two-material matrices have been developed to describe mechanical properties. [29]

AM lattices have more predictable mechanical properties compared to stochastic porous materials and can be tuned such that they have favorable directional mechanical properties. Variables such as strut diameter, strut shape, and number of cross-beams can have a dramatic effect on loading characteristics of the lattice. [30] AM has the ability to fine-tune the lattice spacing to within a much smaller range than stochastically porous structures, enabling the future cell-development of specific cultures in tissue engineering. [31]

Porosity in implants serves two primary purposes

1) The elastic modulus of the implant is decreased, allowing the implant to better match the elastic modulus of the bone. The elastic modulus of cortical bone (~18 GPa) is significantly lower than typical solid titanium or steel implants (110 GPa and 210 GPa, respectively), causing the implant take up a disproportionate amount of the load applied to the appendage, leading to an effect called stress shielding.

2) Porosity enables osteoblastic cells to grow into the pores of implants. Cells can span gaps of smaller than 75 microns and grow into pores larger than 200 microns. [26] Bone ingrowth is a favorable effect, as it anchors the cells into the implant, increasing the strength of the bone-implant interface. [32] More load is transferred from the implant to the bone, reducing stress shielding effects. The density of the bone around the implant is likely to be higher due to the increased load applied to the bone. Bone ingrowth reduces the likelihood of the implant loosening over time because stress shielding and corresponding bone resorption over extended timescales is avoided. [33] Porosity of greater than 40% is favorable to facilitate sufficient anchoring of the osteoblastic cells. [34]

Complications

Complications can arise from implant failure. Internal rupturing of a breast implant can lead to bacterial infection, for example. Ruptured implant.JPG
Complications can arise from implant failure. Internal rupturing of a breast implant can lead to bacterial infection, for example.

Under ideal conditions, implants should initiate the desired host response. Ideally, the implant should not cause any undesired reaction from neighboring or distant tissues. However, the interaction between the implant and the tissue surrounding the implant can lead to complications. [3] The process of implantation of medical devices is subjected to the same complications that other invasive medical procedures can have during or after surgery. Common complications include infection, inflammation, and pain. Other complications that can occur include risk of rejection from implant-induced coagulation and allergic foreign body response. Depending on the type of implant, the complications may vary. [3]

When the site of an implant becomes infected during or after surgery, the surrounding tissue becomes infected by microorganisms. Three main categories of infection can occur after operation. Superficial immediate infections are caused by organisms that commonly grow near or on skin. The infection usually occurs at the surgical opening. Deep immediate infection, the second type, occurs immediately after surgery at the site of the implant. Skin-dwelling and airborne bacteria cause deep immediate infection. These bacteria enter the body by attaching to the implant's surface prior to implantation. Though not common, deep immediate infections can also occur from dormant bacteria from previous infections of the tissue at the implantation site that have been activated from being disturbed during the surgery. The last type, late infection, occurs months to years after the implantation of the implant. Late infections are caused by dormant blood-borne bacteria attached to the implant prior to implantation. The blood-borne bacteria colonize on the implant and eventually get released from it. Depending on the type of material used to make the implant, it may be infused with antibiotics to lower the risk of infections during surgery. However, only certain types of materials can be infused with antibiotics, the use of antibiotic-infused implants runs the risk of rejection by the patient since the patient may develop a sensitivity to the antibiotic, and the antibiotic may not work on the bacteria. [35]

Inflammation, a common occurrence after any surgical procedure, is the body's response to tissue damage as a result of trauma, infection, intrusion of foreign materials, or local cell death, or as a part of an immune response. Inflammation starts with the rapid dilation of local capillaries to supply the local tissue with blood. The inflow of blood causes the tissue to become swollen and may cause cell death. The excess blood, or edema, can activate pain receptors at the tissue. The site of the inflammation becomes warm from local disturbances of fluid flow and the increased cellular activity to repair the tissue or remove debris from the site. [35]

Implant-induced coagulation is similar to the coagulation process done within the body to prevent blood loss from damaged blood vessels. However, the coagulation process is triggered from proteins that become attached to the implant surface and lose their shapes. When this occurs, the protein changes conformation and different activation sites become exposed, which may trigger an immune system response where the body attempts to attack the implant to remove the foreign material. The trigger of the immune system response can be accompanied by inflammation. The immune system response may lead to chronic inflammation where the implant is rejected and has to be removed from the body. The immune system may encapsulate the implant as an attempt to remove the foreign material from the site of the tissue by encapsulating the implant in fibrinogen and platelets. The encapsulation of the implant can lead to further complications, since the thick layers of fibrous encapsulation may prevent the implant from performing the desired functions. Bacteria may attack the fibrous encapsulation and become embedded into the fibers. Since the layers of fibers are thick, antibiotics may not be able to reach the bacteria and the bacteria may grow and infect the surrounding tissue. In order to remove the bacteria, the implant would have to be removed. Lastly, the immune system may accept the presence of the implant and repair and remodel the surrounding tissue. Similar responses occur when the body initiates an allergic foreign body response. In the case of an allergic foreign body response, the implant would have to be removed. [36]

Failures

The many examples of implant failure include rupture of silicone breast implants, hip replacement joints, and artificial heart valves, such as the Bjork–Shiley valve, all of which have caused FDA intervention. The consequences of implant failure depend on the nature of the implant and its position in the body. Thus, heart valve failure is likely to threaten the life of the individual, while breast implant or hip joint failure is less likely to be life-threatening. [3] [36] [37]

Devices implanted directly in the grey matter of the brain produce the highest quality signals, but are prone to scar-tissue build-up, causing the signal to become weaker, or even non-existent, as the body reacts to a foreign object in the brain. [38]

In 2018, Implant files, an investigation made by ICIJ revealed that medical devices that are unsafe and have not been adequately tested were implanted in patients' bodies. In United Kingdom, Prof Derek Alderson, president of the Royal College of Surgeons, concludes: "All implantable devices should be registered and tracked to monitor efficacy and patient safety in the long-term." [39]

See also

Related Research Articles

<span class="mw-page-title-main">Dental implant</span> Surgical component that interfaces with the bone of the jaw

A dental implant is a prosthesis that interfaces with the bone of the jaw or skull to support a dental prosthesis such as a crown, bridge, denture, or facial prosthesis or to act as an orthodontic anchor. The basis for modern dental implants is a biological process called osseointegration, in which materials such as titanium or zirconia form an intimate bond to the bone. The implant fixture is first placed so that it is likely to osseointegrate, then a dental prosthetic is added. A variable amount of healing time is required for osseointegration before either the dental prosthetic is attached to the implant or an abutment is placed which will hold a dental prosthetic/crown.

<span class="mw-page-title-main">Hip replacement</span> Surgery replacing hip joint with prosthetic implant

Hip replacement is a surgical procedure in which the hip joint is replaced by a prosthetic implant, that is, a hip prosthesis. Hip replacement surgery can be performed as a total replacement or a hemi/semi(half) replacement. Such joint replacement orthopaedic surgery is generally conducted to relieve arthritis pain or in some hip fractures. A total hip replacement consists of replacing both the acetabulum and the femoral head while hemiarthroplasty generally only replaces the femoral head. Hip replacement is one of the most common orthopaedic operations, though patient satisfaction varies widely. Approximately 58% of total hip replacements are estimated to last 25 years. The average cost of a total hip replacement in 2012 was $40,364 in the United States, and about $7,700 to $12,000 in most European countries.

In modern Western body piercing, a wide variety of materials are used. Some cannot be autoclaved, and others may induce allergic reactions, or harbour bacteria. Certain countries, such as those belonging to the EU, have legal regulations specifying which materials can be used in new piercings.

Osseointegration is the direct structural and functional connection between living bone and the surface of a load-bearing artificial implant. A more recent definition defines osseointegration as "functional ankylosis ", where new bone is laid down directly on the implant surface and the implant exhibits mechanical stability. Osseointegration has enhanced the science of medical bone and joint replacement techniques as well as dental implants and improving prosthetics for amputees.

Chin augmentation using surgical implants can alter the underlying structure of the face, providing better balance to the facial features. The specific medical terms mentoplasty and genioplasty are used to refer to the reduction and addition of material to a patient's chin. This can take the form of chin height reduction or chin rounding by osteotomy, or chin augmentation using implants. Improving the facial balance is commonly performed by enhancing the chin using an implant inserted through the mouth. The goal is to provide a suitable projection of the chin as well as the correct height of the chin which is in balance with the other facial features.

<span class="mw-page-title-main">Biocompatibility</span> Biologically compatible substance

Biocompatibility is related to the behavior of biomaterials in various contexts. The term refers to the ability of a material to perform with an appropriate host response in a specific situation. The ambiguity of the term reflects the ongoing development of insights into how biomaterials interact with the human body and eventually how those interactions determine the clinical success of a medical device. Modern medical devices and prostheses are often made of more than one material so it might not always be sufficient to talk about the biocompatibility of a specific material. Even the same materials, such as diamond-like carbon coatings, may show different levels of biocompatibility based on the manufacturing conditions and characteristics.

<span class="mw-page-title-main">Bioglass 45S5</span>

Bioglass 45S5 or calcium sodium phosphosilicate, is a bioactive glass specifically composed of 45 wt% SiO2, 24.5 wt% CaO, 24.5 wt% Na2O, and 6.0 wt% P2O5. Typical applications of Bioglass 45S5 include: bone grafting biomaterials, repair of periodontal defects, cranial and maxillofacial repair, wound care, blood loss control, stimulation of vascular regeneration, and nerve repair.

<span class="mw-page-title-main">Bioactive glass</span>

Bioactive glasses are a group of surface reactive glass-ceramic biomaterials and include the original bioactive glass, Bioglass. The biocompatibility and bioactivity of these glasses has led them to be used as implant devices in the human body to repair and replace diseased or damaged bones. Most bioactive glasses are silicate-based glasses that are degradable in body fluids and can act as a vehicle for delivering ions beneficial for healing. Bioactive glass is differentiated from other synthetic bone grafting biomaterials, in that it is the only one with anti-infective and angiogenic properties.

<span class="mw-page-title-main">Joint replacement</span> Orthopedic surgery to replace a joint

Joint replacement is a procedure of orthopedic surgery known also as arthroplasty, in which an arthritic or dysfunctional joint surface is replaced with an orthopedic prosthesis. Joint replacement is considered as a treatment when severe joint pain or dysfunction is not alleviated by less-invasive therapies. Joint replacement surgery is often indicated from various joint diseases, including osteoarthritis and rheumatoid arthritis.

<span class="mw-page-title-main">Biomaterial</span> Any substance that has been engineered to interact with biological systems for a medical purpose

A biomaterial is a substance that has been engineered to interact with biological systems for a medical purpose, either a therapeutic or a diagnostic one. The corresponding field of study, called biomaterials science or biomaterials engineering, is about fifty years old. It has experienced steady and strong growth over its history, with many companies investing large amounts of money into the development of new products. Biomaterials science encompasses elements of medicine, biology, chemistry, tissue engineering and materials science.

Stress shielding is the reduction in bone density (osteopenia) as a result of removal of typical stress from the bone by an implant. This is because by Wolff's law, bone in a healthy person or animal remodels in response to the loads it is placed under. It is possible to mention the elastic modulus of magnesium compared to titanium, stainless steel, iron, or zinc, which makes it further analogous to the natural bone of the body and prevents stress shielding phenomena. Porous implantation is one typical alleviation method.

Nano-scaffolding or nanoscaffolding is a medical process used to regrow tissue and bone, including limbs and organs. The nano-scaffold is a three-dimensional structure composed of polymer fibers very small that are scaled from a Nanometer scale. Developed by the American military, the medical technology uses a microscopic apparatus made of fine polymer fibers called a scaffold. Damaged cells grip to the scaffold and begin to rebuild missing bone and tissue through tiny holes in the scaffold. As tissue grows, the scaffold is absorbed into the body and disappears completely.

<span class="mw-page-title-main">Bioceramic</span> Type of ceramic materials that are biocompatible

Bioceramics and bioglasses are ceramic materials that are biocompatible. Bioceramics are an important subset of biomaterials. Bioceramics range in biocompatibility from the ceramic oxides, which are inert in the body, to the other extreme of resorbable materials, which are eventually replaced by the body after they have assisted repair. Bioceramics are used in many types of medical procedures. Bioceramics are typically used as rigid materials in surgical implants, though some bioceramics are flexible. The ceramic materials used are not the same as porcelain type ceramic materials. Rather, bioceramics are closely related to either the body's own materials or are extremely durable metal oxides.

<span class="mw-page-title-main">Titanium biocompatibility</span>

Titanium was first introduced into surgeries in the 1950s after having been used in dentistry for a decade prior. It is now the metal of choice for prosthetics, internal fixation, inner body devices, and instrumentation. Titanium is used from head to toe in biomedical implants. One can find titanium in neurosurgery, bone conduction hearing aids, false eye implants, spinal fusion cages, pacemakers, toe implants, and shoulder/elbow/hip/knee replacements along with many more. The main reason why titanium is often used in the body is due to titanium's biocompatibility and, with surface modifications, bioactive surface. The surface characteristics that affect biocompatibility are surface texture, steric hindrance, binding sites, and hydrophobicity (wetting). These characteristics are optimized to create an ideal cellular response. Some medical implants, as well as parts of surgical instruments are coated with titanium nitride (TiN).

<span class="mw-page-title-main">Surgical mesh</span> Material used in surgery

Surgical mesh is a medical implant made of loosely woven mesh, which is used in surgery as either a permanent or temporary structural support for organs and other tissues. Surgical mesh can be made from both inorganic and biological materials and is used in a variety of surgeries, although hernia repair is the most common application. It can also be used for reconstructive work, such as in pelvic organ prolapse or to repair physical defects created by extensive resections or traumatic tissue loss.

Materials that are used for biomedical or clinical applications are known as biomaterials. The following article deals with fifth generation biomaterials that are used for bone structure replacement. For any material to be classified for biomedical applications, three requirements must be met. The first requirement is that the material must be biocompatible; it means that the organism should not treat it as a foreign object. Secondly, the material should be biodegradable ; the material should harmlessly degrade or dissolve in the body of the organism to allow it to resume natural functioning. Thirdly, the material should be mechanically sound; for the replacement of load-bearing structures, the material should possess equivalent or greater mechanical stability to ensure high reliability of the graft.

Implant failure refers to the failure of any medical implant to meet the claims of its manufacturer or the health care provider involved in its installation. Implant failure can have any number of causes. The rates of failure vary for different implants.

<span class="mw-page-title-main">Surface chemistry of neural implants</span>

As with any material implanted in the body, it is important to minimize or eliminate foreign body response and maximize effectual integration. Neural implants have the potential to increase the quality of life for patients with such disabilities as Alzheimer's, Parkinson's, epilepsy, depression, and migraines. With the complexity of interfaces between a neural implant and brain tissue, adverse reactions such as fibrous tissue encapsulation that hinder the functionality, occur. Surface modifications to these implants can help improve the tissue-implant interface, increasing the lifetime and effectiveness of the implant.

Titanium foams exhibit high specific strength, high energy absorption, excellent corrosion resistance and biocompatibility. These materials are ideally suited for applications within the aerospace industry. An inherent resistance to corrosion allows the foam to be a desirable candidate for various filtering applications. Further, titanium's physiological inertness makes its porous form a promising candidate for biomedical implantation devices. The largest advantage in fabricating titanium foams is that the mechanical and functional properties can be adjusted through manufacturing manipulations that vary porosity and cell morphology. The high appeal of titanium foams is directly correlated to a multi-industry demand for advancement in this technology.

Alloplasty is a surgical procedure performed to substitute and repair defects within the body with the use of synthetic material. It can also be performed in order to bridge wounds. The process of undergoing alloplasty involves the construction of an alloplastic graft through the use of computed tomography (CT), rapid prototyping and "the use of computer-assisted virtual model surgery." Each alloplastic graft is individually constructed and customised according to the patient's defect to address their personal health issue. Alloplasty can be applied in the form of reconstructive surgery. An example where alloplasty is applied in reconstructive surgery is in aiding cranial defects. The insertion and fixation of alloplastic implants can also be applied in cosmetic enhancement and augmentation. Since the inception of alloplasty, it has been proposed that it could be a viable alternative to other forms of transplants. The biocompatibility and customisation of alloplastic implants and grafts provides a method that may be suitable for both minor and major medical cases that may have more limitations in surgical approach. Although there has been evidence that alloplasty is a viable method for repairing and substituting defects, there are disadvantages including suitability of patient bone quality and quantity for long term implant stability, possibility of rejection of the alloplastic implant, injuring surrounding nerves, cost of procedure and long recovery times. Complications can also occur from inadequate engineering of alloplastic implants and grafts, and poor implant fixation to bone. These include infection, inflammatory reactions, the fracture of alloplastic implants and prostheses, loosening of implants or reduced or complete loss of osseointegration.

References

  1. ↑ Kong, L.; Heydari, Z.; Lami, G.H.; Saberi, A.; Baltatu, M.S.; Vizureanu, P. A Comprehensive Review of the Current Research Status of Biodegradable Zinc Alloys and Composites for Biomedical Applications. Materials 2023, 16, 4797. https://doi.org/10.3390/ma16134797 PMID: 37445111
  2. ↑ Zhao, J.; Haowei, M.; Saberi, A.; Heydari, Z.; Baltatu, M.S. Carbon Nanotube (CNT) Encapsulated Magnesium-Based Nanocomposites to Improve Mechanical, Degradation and Antibacterial Performances for Biomedical Device Applications. Coatings 2022, 12, 1589. https://doi.org/10.3390/coatings12101589
  3. 1 2 3 4 5 6 7 8 Wong, J.Y.; Bronzino, J.D.; Peterson, D.R., eds. (2012). Biomaterials: Principles and Practices. Boca Raton, Florida: CRC Press. p. 281. ISBN   9781439872512 . Retrieved 12 March 2016.
  4. ↑ "Medical Devices". American Elements. Retrieved 20 December 2023.
  5. 1 2 3 4 5 6 7 "Download Product Code Classification Files". FDA.org/medicaldevices. Food and Drug Administration. 4 November 2014. Retrieved 12 March 2016. Relevant info in the foiclass.zip file.
  6. 1 2 3 4 5 6 McLatchie, G.; Borley, N.; Chikwe, J., eds. (2013). Oxford Handbook of Clinical Surgery. Oxford, UK: OUP Oxford. p. 794. ISBN   9780199699476 . Retrieved 12 March 2016.
  7. ↑ Thomas, Daniel; Singh, Deepti (June 2017). "3D printing in surgery - The evolving paradigm-shift in surgical implants on demand". International Journal of Surgery (London, England). 42: 58–59. doi: 10.1016/j.ijsu.2017.04.027 . ISSN   1743-9159. PMID   28435025.
  8. ↑ Ibrahim, H.; Esfahani, S. N.; Poorganji, B.; Dean, D.; Elahinia, M. (January 2017). "Resorbable bone fixation alloys, forming, and post-fabrication treatments". Materials Science and Engineering: C. 70 (1): 870–888. doi: 10.1016/j.msec.2016.09.069 . PMID   27770965.
  9. ↑ Nowosielski R., Cesarz-Andraczke K., Sakiewicz P., Maciej A., Jakóbik-Kolon A., Babilas R., Corrosion of biocompatible Mg66+XZn30-XCa4 (X=0.2) bulk metallic glasses, Arch. Metall. Mater. 2016 vol. 61 iss. 2, s. 807-810
  10. ↑ Ritabh, Kumar; Richard, A Lerski; Stephen, Gandy; Benedict, A Clift; Rami, J Abboud (12 July 2006). "Safety of orthopedic implants in magnetic resonance imaging: An experimental verification". Journal of Orthopaedic Research. 24 (9): 1799–1802. doi:10.1002/jor.20213. PMID   16838376. S2CID   2991113.
  11. ↑ David, X Feng; Joseph, P McCauley (9 November 2015). "Evaluation of 39 medical implants at 7.0 T". British Journal of Radiology. 88 (1056): 20150633. doi:10.1259/bjr.20150633. PMC   4984944 . PMID   26481696.
  12. ↑ "With Bioelectronic Medicine, SetPoint Medical Wants To Revolutionize Autoimmune Disease Treatment". Forbes Magazine. 29 March 2019. Retrieved 19 November 2019.
  13. ↑ "Arthritis sufferers offered hope after electrical implants leave". The Independent. 23 December 2014. Retrieved 1 February 2019.
  14. ↑ Peeples, Lynne (3 December 2019). "Core Concept: The rise of bioelectric medicine sparks interest among researchers, patients, and industry". Proceedings of the National Academy of Sciences. 116 (49): 24379–24382. doi: 10.1073/pnas.1919040116 . PMC   6900593 . PMID   31796581.
  15. ↑ "New arthritis implant hailed as 'magic'". The Guardian. Press Association. 23 December 2014. ISSN   0261-3077 . Retrieved 1 February 2019.
  16. ↑ Duke, J.; Barhan, S. (2007). "Chapter 27: Modern Concepts in Intrauterine Devices". In Falcone, T.; Hurd, W. (eds.). Clinical Reproductive Medicine and Surgery. Elsevier Health Sciences. pp. 405–416. ISBN   9780323076593 . Retrieved 12 March 2016.
  17. ↑ "Upper G.I. Surgery - Gastroesophageal Reflux Disease (GERD)". Keck School of Medicine of USC. Archived from the original on 9 May 2018. Retrieved 12 March 2016.
  18. ↑ "Gastric Electrical Stimulation". The Regents of The University of California. Archived from the original on 30 July 2019. Retrieved 12 March 2016.
  19. ↑ "Chapter 1, Part 2, Section 160.19: Phrenic Nerve Stimulator" (PDF). Medicare National Coverage Determinations Manual. Centers for Medicare and Medicaid Services. 27 March 2015. Retrieved 19 February 2016.
  20. ↑ Simmons M, Montague D (2008). "Penile prosthesis implantation: past, present, and future". International Journal of Impotence Research. 20 (5): 437–444. doi:10.1038/ijir.2008.11. PMID   18385678. S2CID   35545391.
  21. ↑ Hjort, H; Mathisen, T; Alves, A; Clermont, G; Boutrand, JP (April 2012). "Three-year results from a preclinical implantation study of a long-term resorbable surgical mesh with time-dependent mechanical characteristics". Hernia. 16 (2): 191–7. doi:10.1007/s10029-011-0885-y. PMC   3895198 . PMID   21972049.
  22. ↑ Syring, G. (6 May 2003). "Overview: FDA Regulation of Medical Devices". Quality and Regulatory Associates, LLC. Retrieved 12 March 2016.
  23. ↑ "Classify Your Medical Device". FDA.gov/MedicalDevices. Food and Drug Administration. 29 July 2014. Retrieved 12 March 2016.
  24. ↑ Gotman, I. (December 1997). "Characteristics of metals used in implants". Journal of Endourology. 11 (6): 383–389. doi:10.1089/end.1997.11.383. PMID   9440845.
  25. ↑ van den Brink, Wimar; Lamerigts, Nancy (26 November 2020). "Complete Osseointegration of a Retrieved 3-D Printed Porous Titanium Cervical Cage". Frontiers in Surgery. 7: 526020. doi: 10.3389/fsurg.2020.526020 . ISSN   2296-875X. PMC   7732662 . PMID   33330602.
  26. 1 2 Spoerke, Erik D.; Murray, Naomi G.; Li, Huanlong; Brinson, L. Catherine; Dunand, David C.; Stupp, Samuel I. (September 2005). "A bioactive titanium foam scaffold for bone repair". Acta Biomaterialia. 1 (5): 523–533. doi:10.1016/j.actbio.2005.04.005. ISSN   1742-7061. PMID   16701832.
  27. ↑ Kováčik, J. (1 July 1999). "Correlation between Young's modulus and porosity in porous materials". Journal of Materials Science Letters. 18 (13): 1007–1010. doi:10.1023/A:1006669914946. ISSN   1573-4811. S2CID   134497468.
  28. ↑ Morrissey, Liam S.; Nakhla, Sam (24 April 2018). "A Finite Element Model to Predict the Effect of Porosity on Elastic Modulus in Low-Porosity Materials". Metallurgical and Materials Transactions A. 49 (7): 2622–2630. Bibcode:2018MMTA...49.2622M. doi:10.1007/s11661-018-4623-2. hdl: 10315/35416 . ISSN   1073-5623. S2CID   140090946.
  29. ↑ COBLE, R. L.; KINGERY, W. D. (November 1956). "Effect of Porosity on Physical Properties of Sintered Alumina". Journal of the American Ceramic Society. 39 (11): 377–385. doi:10.1111/j.1151-2916.1956.tb15608.x. ISSN   0002-7820.
  30. ↑ Fernandes, Matheus C.; Aizenberg, Joanna; Weaver, James C.; Bertoldi, Katia (February 2021). "Mechanically robust lattices inspired by deep-sea glass sponges". Nature Materials. 20 (2): 237–241. Bibcode:2021NatMa..20..237F. doi:10.1038/s41563-020-0798-1. ISSN   1476-4660. PMID   32958878. S2CID   221824575.
  31. ↑ Egan, Paul F.; Gonella, Veronica C.; Engensperger, Max; Ferguson, Stephen J.; Shea, Kristina (10 August 2017). "Computationally designed lattices with tuned properties for tissue engineering using 3D printing". PLOS ONE. 12 (8): e0182902. Bibcode:2017PLoSO..1282902E. doi: 10.1371/journal.pone.0182902 . ISSN   1932-6203. PMC   5552288 . PMID   28797066.
  32. ↑ Ibrahim, Mahmoud Z.; Sarhan, Ahmed A.D.; Yusuf, Farazila; Hamdi, M. (August 2017). "Biomedical materials and techniques to improve the tribological, mechanical and biomedical properties of orthopedic implants – A review article". Journal of Alloys and Compounds. 714: 636–667. doi:10.1016/j.jallcom.2017.04.231. ISSN   0925-8388.
  33. ↑ Carpenter, R. Dana; Klosterhoff, Brett S.; Torstrick, F. Brennan; Foley, Kevin T.; Burkus, J. Kenneth; Lee, Christopher S.D.; Gall, Ken; Guldberg, Robert E.; Safranski, David L. (April 2018). "Effect of porous orthopaedic implant material and structure on load sharing with simulated bone ingrowth: A finite element analysis comparing titanium and PEEK". Journal of the Mechanical Behavior of Biomedical Materials. 80: 68–76. doi:10.1016/j.jmbbm.2018.01.017. ISSN   1751-6161. PMC   7603939 . PMID   29414477.
  34. ↑ Apostu, Dragos; Lucaciu, Ondine; Berce, Cristian; Lucaciu, Dan; Cosma, Dan (3 November 2017). "Current methods of preventing aseptic loosening and improving osseointegration of titanium implants in cementless total hip arthroplasty: a review". Journal of International Medical Research. 46 (6): 2104–2119. doi:10.1177/0300060517732697. ISSN   0300-0605. PMC   6023061 . PMID   29098919.
  35. 1 2 Black, J. (2006). Biological Performance of Materials: Fundamentals of Biocompatibility. Boca Raton, Florida: CRC Press. p. 520. ISBN   9780849339592 . Retrieved 12 March 2016.
  36. 1 2 Dee, K.C.; Puleo, D.A.; Bizios, R. (2002). An Introduction to Tissue-Biomaterial Interactions. Hoboken, NJ: Wiley-Liss. p. 248. ISBN   9780471461128 . Retrieved 12 March 2016.
  37. ↑ Wagenberg, B.; Froum, S.J. (2006). "A retrospective study of 1925 consecutively placed immediate implants from 1988 to 2004". The International Journal of Oral & Maxillofacial Implants. 21 (1): 71–80. PMID   16519184.
  38. ↑ Polikov, Vadim S.; Patrick A. Tresco & William M. Reichert (2005). "Response of brain tissue to chronically implanted neural electrodes". Journal of Neuroscience Methods. 148 (1): 1–18. doi:10.1016/j.jneumeth.2005.08.015. PMID   16198003. S2CID   11248506.
  39. ↑ "Patients given unsafe medical implants". BBC. 25 November 2018. Retrieved 5 February 2019.
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