2. • Back pain is that the second most typical reason for medical
practitioner visits within the US, and affects up to 84 % of patients at
some purpose in their lives. For several patients, neck and back pain is
usually thanks to injury or spinal instability through trauma,
unwellness or degeneration. This will cause impingement of neural
structures leading to pain, numbness, or weakness
3 Joint Complex
3. Spinal Stability
Spinal stability refers to the power of the spine phase to limit
excessive displacement that may presumably lead to disabling
deformity or medicine symptoms because of impingement on
the neural structure and nerve roots. Factors that {may}
contribute to instability may have an effect on the bones, disc,
joints, or ligaments. These embrace trauma, tumors,
infections, inflammatory diseases, animal tissue disorders,
inherent disorders and chronic disorders
4. Vertebral instrumentation
Vertebral instrumentation is intended to stabilize the spine and
forestall excessive motion at the affected phase because the bones
fuse along. It provides immediate stability of the affected phase of
the spine and obviates the necessity for external fixation devices
like rigid collars, braces, and halo traction. This enables for a larger
quality of life for patients in real time following surgery. These
internal fixation devices like screws, plates, associate degreed rods
area unit mounted to the bone bodies and mix to make an
instrumentation construct
5. • Modern spinal fixation devices are manufactured from
biocompatible metallic alloys like chrome steel and metal. Whereas
these became standard because of their strength and fatigue
resistance, they possess radiographic challenges and biomechanical
limitations. First and foremost, metallic materials area unit radio
logically problematic. Artifacts created by metals in computerized
tomography (CT) and magnetic resonance (MR) imaging, also as
obfuscation of bone by metals in tabular x-rays, inhibit visual image
of latest bone growth so, creating it tough for physicians to assess
progression of arthrodesis. Second, implants that area unit stiffer
than natural bone area unit subject to alleged stress shielding. When
2 bones area unit coalesced along, the state of compressive forces
between them determines the extent of modeling or transforming
6. • According to Wolff’s law, bone apposition among a fusion graft is
ruled partially by the state of compressive stresses among it. Because
of this it's been projected that stiff metallic implants could protect the
graft from the strain needed for fusion, delaying or preventing the
method. This may induce induced effects like device-related
osteopenia, intervertebral device protrusion into a neighboring
vertebral body, and fracture or instability. Implants developed out of
less stiff materials could stop this stress shielding and foster higher
clinical outcomes compared to ancient devices
Planar X-ray of Patient Immediately after
Surgery with PEEK Cage and Titanium Rod
Construct Implanted in the Lumbar Spine
7. Intra-Vertebral Implants
• The purpose of this implant is to
support and stabilize the spinal
column in cases of total or partial
vertebroctomy. The adaptive
geometry of the implant will be
adjusted to varied anatomies. The
length of the implant will be
modified once the implant was set in
situ by a special tool permitting its
two parts to maneuver vertically with
relation to one another. The area
between the highest and also the
bottom plates will be full of
segments of bone which will grow
and fuse the highest and also the
bottom bone. One of the most
expected advantages from
customizing end plate geometry of
bone implants is that the reduced risk
and potential for subsidence into the
bone end plate Intra Vertebral Implants
8. • Coating of Metallic Implants with SCPC Bioactive
Ceramic:
• Coating orthopedic implants with bioactive ceramics has the potential
to boost material-tissue integration and supply higher fixation of the
device. SCPC has been coated on Ti-6Al-4V yet as Co-Cr alloys
exploitation action deposition (EPD) technique. SEM image of SCPC
coating on Ti-6Al-4V foam bone implant. (Left) SCPC Nano-particles
uniformly coated the outer surface as well because the entire thickness
of the porous implant. (Right)Cross-section analysis showed that SCPC
coating forms an identical coating thickness 3-5 millimeter (arrow) over
the inner surfaces of the Ti alloy foam disc
SEM image of SCPC
coating
9. • First-ever 3D-printed vertebra implanted in 12-year-old cancer patient’s spine (A
Recent Invention at Peking University).
https://www.youtube.com/watch?v=83ytVGxcWl8
• - Review:
• BEIJING – A 12-year-old cancer patient in China underwent a first-of-its-kind operation
to implant a 3D-printed vertebra into his spine, Reuters reported
• During the 5-hour procedure, surgeons at Peking University Hospital in Beijing removed
a tumor from Qin Minglin’s spine before implanting the 3D-printed vertebra. The novel
device was made from titanium powder and included a series of tiny pores which will
allow the bone to grow and bond to the structure as it heals.
10. Currently, the standard procedure
for this kind of operation involves
removing the bone and inserting a
titanium tube held in place by
screws and surgical cement.
However, the tube can become
detached over time. For this
surgical procedure, doctors used a
combination of scans and
specialized engineering software to
create a perfect replica of the piece
of the patient’s spine that needed to
be replaced.
We can use iconographic tests on
patients such as a computed
[tomography], or CT scans, and
convert the CT data into 3D-
printing data in order to produce an
internal fixation with exactly the
same structure as the patient's bone
structure
3D Vertebra
11. Material Considerations
• Generally, biomaterials used in vertebral Implant can be classified in three groups:
Metals, ceramics and polymers. Ideally, material properties of the implants should
have a low elastic modulus close to cortical bone, high wear resistance, high
corrosion resistance, high fracture toughness and high ductility.
• In the last century, Vertebral Implants were mainly manufactured of metal alloys
such as stainless steel, pure Titanium and Titanium-aluminum-vanadium. In recent
years, developments in the field of non-metallic biomaterials lead to the application
of new materials such as PEEK and composite materials. Before Implanting, the
physical characteristics of the material must be observed.
Resorbable Plate
and Screw System
beside
Nonresorbable
titanium system
12. Physical Characteristics of the Implants
Strength:
• The ability of the Material to withstand an applied stress is called strength. Yield strength
refers to the point in the stress strain curve after which plastic deformation occurs. Strength of
a material may vary with the stress (compressive, tensile or shear) applied. For most vertebral
Implants fatigue strength is the most relevant criteria, as it refers material ability to withstand
alternating stresses under cyclic loading. This is especially important during the daily routine
of the patient. Strength of a metallic material is depending on its microstructure and can be
altered in the fabrication process (Casting, Forging, Annealing etc.)
Flexibility: Elastic Modulus
• The Elastic modulus describes the magnitude at which a material deforms when subjected to
stress. It is determined from the linear slope of a stress-versus-strain curve. In order to
minimize stress shielding, the elastic modulus of implants should be in the range of cortical
bone.
13. • Corrosion Resistance:
Degradation of materials into its constituent atoms caused by electrochemical
reactions with its surroundings is called Corrosion. The human body fluids
present a very hostile environment to metals making corrosion resistance an
important aspect in the biocompatibility of a material. The occurrence of small
holes in the surface due to break-up of the corrosion resistant oxide film is
called Pitting Corrosion. Crevice corrosion can occur in rod/screw or
plate/screw connections of vertebral instrumentation through development of
corrosion, while galvanic corrosion results from two different metals with
different electrode potentials and body fluid forming a voltage cell.
• Wear Resistance:
Relative motion between surfaces in contact causes erosion of the material
called wear. In contrast to Corrosion, wear is produced by a mechanical action
in form of contact and motion causing the removal of small particles from a
surface. Wear debris can induce inflammatory reaction causing local bone loss
and threatening implant fixation. Generally, the amount of wear increases with
the applied load and decreases with the hardness of the worn surface.
• Biocompatibility:
Generally, biocompatibility is defined as the ability of a material to perform
with an appropriate host response in a specific application. For Implants, this
can be interpreted as the property of being biologically compatible by not
producing a toxic, injurious or immunological response in the human body.
14. Materials used in Vertebral Implants:
• The bulk of Orthopedic implants used for skeletal reconstructions (E.g., plates, screws, rods and
joint replacements) are manufactured of metallic biomaterials. This is due to their ability to
withstand high and also dynamic loads. In order to improve implant fixation and/or cell ingrowth,
the anchoring surfaces can be roughened, precoated or refined with porous coatings.
• An excerpt of material properties of commonly used Implant materials and its comparision to
cortical bone is listed in the below table.
15. Metals and their usage as Implants
1. Metals:
• The majority of Implants used in vertebral Instrumentation (screws,
rods, hooks, vertebral body replacements,etc.) are manufactured of
metallic materials. They provide high tensile, compressive, shear
and fatigue strength, biocompatibility, corrosion and wear resistance
required in the application of load bearing implants in orthopedic
surgery. Flexibility and strength of a metallic alloy also depends on
the fabrication processes (casting, cold and hot forging). After
fabrication, the material properties can be enhanced by heat
treatment (annealing). Wear resistance can be further improved by
processes such as nitriding and Ion Implantation.
16. Contd..
1.1 Stainless steel:
• The most commonly used Stainless steel is 316L
(ASTM F138, F139). It is composed of iron, carbon,
chromium, nickel and molybdenum .while the carbon
content is kept low, the alloying additions improve the
corrosion resistance. While stainless steel has been and
is used in fracture plates, pedicle instrumentation and
screws, a trend towards Titanium (Ti)-based implants
due to the superior biocompatibility was seen in recent
years. However, stainless steel implants still gain a
worldwide popularity due its cost-effectiveness
compared to Ti-based alloys.
17. 1.2 Cobalt Chromium Alloys:
• The most commonly used cobalt-chromium alloys are cobalt-nickel-chromium-molybdenum
• (CoNiCrMo, ASTM F562) and cobalt-chromium-molybdenum (CoCrMo, ASTM F75). While Chromium
improves the corrosion resistance, molybdenum increases the strength and make it strong, hard,
biocompatible and corrosion resistant. Due to these characteristics, it is used in joint replacements and
fracture stabilisations requiring a long service life. However, the high percentage of nickel in CoNiCrMo
raises concerns of possible toxicity by wear particles.
1.3 Titanium Alloys:
• The increased biocompatibility and corrosion resistance of titanium-alloys compared to stainless steel
and CoCr alloys is attributed to a stable oxide film protecting it from corrosion. The elastic modulus of
titanium alloys is closer to bone and approximately half of stainless steel and CoCr alloys, while their
strength generally exceeds that of stainless steel. Due to the lower resistance to wear compared to CoCr
alloys, Ti-alloys are hardly applied as bearing material.
• An advantage of Ti-based alloys is their feature to produce fewer artefacts in computer tomography (CT)
and magnetic resonance imaging (MRI) scans.
2. Ceramics:
• Ceramics are characterized by a high wear resistance, low friction and good compatibility, but also
reduced fracture toughness. Therefore, they are mainly used for bearing surfaces in joint replacements.
The most commonly used ceramics are hydroxyapatite and glass ceramics, zirconia (ZrO2) and Alumina
(Al2O3) in the form of implant coatings.
3. Polymers:
• Generally, considering all types of medical applications, polymers from the largest group of biomaterials.
For polymers used in orthopaedic implants, the most important characteristics for choosing a specific
polymer are yield stress, wear rate and creep resistance.
3.1 Polyethylene (PE):
• Low friction coefficient, low wear rate and resistance to creep of PE in the form ultra-high molecular
weight polyethylene (UHMWPE) are the reasons for PE being the most common bearing material in total
joint anthroplasty (TJA).
19. Results
• Individuals suffering from spinal fractures—caused by osteoporosis or
weakened bones—now have another option to reduce pain, restore
function and improve quality of life, according to a study of 300 patients
treated with a new type of vertebral augmentation.
• Made of medical polymer, the implant is designed to treat painful and
debilitating vertebral compression fractures, which cause the bones in the
spine to collapse and, left untreated, can lead to pain and a condition called
kyphosis (or a curvature of the spine). Recently cleared by the U.S. Food
and Drug Administration (FDA), the implant provides a new treatment
alternative to vertebroplasty and kyphoplasty, the current standards of
care.
• Kiva System as a Vertebral Augmentation Treatment—A Safety and
Effectiveness Trial (KAST) was a study conducted with FDA approval in
which 153 patients with one or two painful osteoporotic vertebral
compression fractures received the new implant and 147 had balloon
kyphoplasty.
20. Contd…
• Patients were treated at one of 21 centers in the United
States, Canada, Belgium, France and Germany and were
followed for one year. Results of the study confirmed that
the implant provided essentially the same amount of pain
relief and improvement in daily function based on accepted
measures for pain and function (visual analogue score, VAS;
Oswestry Disability Index, ODI) and safety.
• Researchers also found patients who had the implant were
more likely to benefit from a reduction in the angle of the
kyphosis and less likely to have the bone cement leak.
• Moreover, the study showed a clinically important trend in
that the implant patients were less likely to suffer a fracture
in adjacent vertebra.
21. Advantages to Vertebral Stimulation Treatment
• There are many advantages to spinal cord or peripheral nerve field stimulation for
the treatment of chronic back pain
• A trial can test patient response before the patient commits to a permanent
implant.
• It has few side effects and is easily reversible; if it doesn’t work or is no longer
needed it can be removed.
• Implantation of the system is minimally invasive, requiring a relatively minor
surgical procedure on an outpatient basis.
• Leads are inserted just under the skin, and patients can travel anywhere, and
participate in any recreational activities, including swimming.
• Achieving pain relief with spinal cord stimulation or peripheral nerve field
stimulation can allow patients to reduce or eliminate their use of narcotic drugs.
• Ongoing advances in neurostimulator technology give patients more control to
adjust the stimulation if their pain changes in location or severity.
• Continual improvements in the design of electrodes and longer lasting,
rechargeable batteries mean that implantable systems can be placed in locations to
give optimal and more efficient pain control than other modalities.
22. Disadvantages of Spinal Cord Stimulation
• As with any chronic pain treatment, there are also a number of
potential disadvantages with spinal cord stimulation, including:
• Spinal cord stimulation does not work for everyone. Most studies
show that 50% to 60% of people find meaningful pain relief with
spinal cord stimulation.
• It does not eliminate the pain. A successful outcome of spinal
cord stimulation is considered to be pain relief of 50% or more.
• Spinal cord stimulation does not address the source of the pain.
The system is designed to interrupt pain signals being sent to the
brain, but it does not correct any underlying anatomical problem.
For many people with chronic pain, this is the right approach to
treatment. However, for those with a correctable anatomic lesion,
treatments to address the source of the pain should be tried first.
• The treatment involves an implant and surgery. As with any
surgical procedure and implant, there are certain risks and
potential complications associated with spinal cord stimulation
and peripheral nerve field stimulation, discussed below.
23. Future Work (A study from Journal)
• This biocompatible composite
material, with endless fiber
content over 60% of volume,
distinguishes itself with its
excellence mechanical strength
and its fatigue resistance.
• The well-known spinal expert,
Professor Friedrich Magrel,
developed both implants through
extensive research at icotec.
• He used the first composite
implants to execute his ideas and
obtain the assumed product
standards that are developing as
orthopedic and neurosurgeons
discover the main advantages of
composites. Standard Titanium
plants that are tend to fatigue
problems are still being replaced
in some areas by biocompatible
thermoplastic composites..
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• WEBSITES
• http://www.foxnews.com/health/2014/08/28/first-ever-3d-printed-vertebra-implanted-in-12-year-old-cancer-
patients-spine/
• http://www.jeccomposites.com/news/composites-news/new-generation-spinal-implants-launched
• http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2200680/
