Engineering Management Report: Cost-Effective Spinal Biomaterials

This report provides a comprehensive analysis of the cost-effectiveness of various biomaterials used in spinal fusion surgery. It begins with an introduction to biomaterials and their applications, followed by a literature review covering autografts, allografts, bioactive glass, bone morphogenetic protein, demineralized bone matrix, hydroxyapatite, and calcium phosphate/calcium triphosphate. The report details the advantages and disadvantages of each material, along with considerations for their use. It outlines the data collection methodology used for the cost comparison, presents the results of the cost analysis between autografts and allografts, and discusses surgeons' opinions on different materials and their usage. The report concludes by identifying the most cost-effective material based on the evidence presented, utilizing charts and figures to support the findings. The report also includes a PowerPoint presentation summarizing the key findings, including a price comparison chart, and adheres to APA referencing style. Desklib provides this and other solved assignments to aid students in their studies.

ENGINEERING MANAGEMENT
[Author Name(s), First M. Last, Omit Titles and Degrees]
[Institutional Affiliation(s)]

Contents
CHAPTER 1: INTRODUCTION........................................................................................................................3
Background of the study..........................................................................................................................3
Introduction.............................................................................................................................................4
CHAPTER 2: LITERATURE REVIEW................................................................................................................7
Autografts................................................................................................................................................7
Advantages, disadvantages and Considerations of autograft..............................................................7
Allograft Bone in Cervical Spinal Fusion Surgery......................................................................................8
Uses of Allograft Bone.......................................................................................................................10
Considerations for Allograft...............................................................................................................10
Bioactive glass.......................................................................................................................................12
Features and Benefits of Bioactive glass............................................................................................15
Bone Morphogenetic Protein................................................................................................................16
Demineralized Bone Matrix...................................................................................................................17
Hydroxyapatite......................................................................................................................................18
Calcium Phosphate/Calcium triphosphate............................................................................................20
Surgeons opinion about different materials and how much materials are surgeon using per surgery. 23
CHAPTER 3: RESEARCH METHODLOGY......................................................................................................25
Data collection Method.........................................................................................................................25
CHAPTER 4: RESULTS AND DISCUSSION.....................................................................................................26
Cost Comparisons of the Various Biomaterials......................................................................................26
Autograft versus allograft......................................................................................................................26
Discussion..............................................................................................................................................29
References.................................................................................................................................................31

CHAPTER 1: INTRODUCTION
Background of the study
A surgical repair or replacement is necessitated by trauma, diseases or degeneration.
When an individual experiences pain in the joints, the main focus tends to relief of the pain
restoration of the health of the individual to a not only healthy but functional lifestyle. This
normally comes with the replacement of some of the skeletal parts including hips, finger joints,
elbows, teeth, knees, vertebrae or even repair of the mandibles. The value of biomedical
materials globally currently stands at approximately $24,000M with dental and orthopedic
applications accounting for about 55% of the total market for biomaterials. In the year 2000, the
value of orthopedic products in the market was more than $13 billion and an expansion in such
trends expected to continue citing a number of factors among them the ageing population,
advancements and improvements in technology and lifestyle, an increased taste and preference
by the younger to middle aged population to undertake surgery, desire for better function,
enhanced aesthetics as well as better comprehension of the functionality of the body.
The use and requirements for biomaterials in tissue engineering is strictly defined with
biocompatibility being the top of the agenda for the choice of any material for use for their
orthopedic or diagnostic purposes. For the case of biocompatibility, the scaffolds and bioreactors
have to attain qualities among them tissue friendly so as not to invoke an immune-response. At
best, biomaterials should be supportive of the cellular and tissue functions among the adhesion,
proliferation and differentiation through its special surface in chemistry. Another important
requirement for scaffolds is porosity which is supposed to be at least 90% so as to allow cells to
seed evenly and promote vascular growth after implantation. Controlled biodegradation gains
concern especially under circumstance that implanted materials are replaced by healthy tissues

and then biomaterial slowly degrades in the body of the host. Biomaterials are either natural or
synthetic.
Introduction
The science of biomaterials was in place more than a century ago when artificial devices
and objects were enhanced to the point where they could replace different components of the
human body. A biomaterial is a substance that can has been tailored to interact with the systems
of biology for the purposes of medical practice. These composites have the ability to be in
contact with the fluids of the body and tissues from relatively long periods of time without
invoking any significant if any adverse reactions with the body systems. Biomedical materials
are used either of therapeutic i.e. treatment, replacement or repair of a tissue that functions in the
body or they can be used for diagnostic purposes (Bandyopadhyay, 2013). They are non-viable
materials that have the capability to be implanted to replace or repair a tissue that is missing or
worn out. Biomaterial can either be synthesized in the laboratory or be of natural origin.
Biomaterials traces its roots as far back as the ancient Phoenicia during which gold wires
were used in binding together loose teeth by tying artificial teeth to the neighboring natural teeth.
Implementation of bone plates was successful in stabilization of bone fractures and thus
accelerating the process of healing in the 1900s. Artificial hip joints and heart valves were under
development and replacement of blood vessels was undergoing clinical trials in the 1950s and
60’s (Black, 2014).
Biomaterials are categorized into metals, ceramics, polymers and natural biomaterials.
Metals are the group of biomaterials that is most commonly used due to the ability to bear loads.
This load bearing ability makes metals ideal for such practices as knee implants and total hip
replacements. These metallic implants comes in various ranges of shapes and sizes and do vary

from modest wires to screw to plates for fixation of fractures and to as complicated as total joint
prostheses. artificial joint implantation have been successful on joints including ankles, shoulder,
hops and knees with different metals currently being used in various medical applications to
meet different surgical needs. Cobalt-base alloys, stainless steel, titanium alloys and pure
titanium are among the most commonly used metals as biomaterials (Dobke, 2013).
A good biomaterial of metallic nature should have the same values of Young’s modulus
as the bone or the tissues for which it is replacing. The surrounding tissues may degenerate as a
result of lack of mechanical loading in cases where the biomaterial is carrying too much loading.
On the other hand, a biomaterial that cannot carry adequate load cannot make an adequate
replacement (DiMasi, 2014).
Ceramics and composites: these biomaterials are mostly used on dental applications
including fillings, crowns and dentures. The application and utilization of ceramics is limited to
the cats that they have poor toughness to fracture due to their brittle property. Ceramics cannot
be applied in implantations that required high tolerance of loads. Despite the shortcomings,
calcium phosphates have been applied in augmentation and bone repair while alumina and
zirconia have formed fundamental materials in joint replacement (Black, 2014).
Composites widely find their applications in dentistry. PMMA-glass filter and BIS-
GMA-quartz-silica filler are the two most commonly used composites and are mostly used for
dental filling and restoration. Other applications of composts include prostheses which are
favored by heir light weight and high loading capability.
Polymers are grouped as one of the most versatile biomaterials and have the widest range
of applications from scaffolds used in tissue engineering to the PLGA that is used in drug

delivery. It is possible to mold polymers into any desirable shapes or size. Collagen or synthetic
fibre is used in making scaffolds that are used in tissue engineering (Bronzino, 2016). Scaffolds
are very important as they offer both the molecular and physical cues that control development
of the donor cells. The extra cellular matrix is normally used in the provision of these cues.
Nevertheless, the polymers also have the capability to provide protection to the donor cells from
the different immune systems that are available as a result of the transplant. Lastly, the three
dimensional space offers a convenient way of package to the cells thereby prompting growth
after transplantation has been done. It is possible to design the pores in the polymers in such a
way that they are large enough to allow the growth of endothelial cells and blood vessels into the
scaffold.

CHAPTER 2: LITERATURE REVIEW
Autografts
Autograft, also known as autologous bone or autogenous bone graft is harvesting of the bone
from a patient and transferring it to the part of the spine that is to be fused. A separate spinal
fusion procedure is carried out during spinal fusion surgery to extract a bone from another part of
the body of the patent and place it in the region of the spine that is to undergo fusion. This is a
surgical process and is termed as harvesting of the bone graft (Bronzino, 2016). The procedure is
normally carried out through a separate incision on anterior fusions and through a same incision
in the posterior fusions.
Harvesting of the bone is normally done from one of the bones of the patient in the iliac
crest also known as the pelvis. Under other circumstances, this can also be extracted from the rib
or another region of the spine. Very few spine procedures include autograft harvesting. This is
attributed to the morbid nature of the bone graft harvest procedure as well as an ever increasing
number of better and more reasonable alternatives to autograft.
Advantages, disadvantages and Considerations of autograft
As a result of bearing all the features that are required for a solid bridge to grown, autograft is
perceived to be the gold standard in the achievement of a successful and solid spine fusion.
Among those characteristics include:
 It is composed of osteophytes which are the bone growing cells as well as bone-growing
portions also called bone morphogenic proteins which are all used in facilitating the
growth of new bone in the patient.
 It offers the spinal fusion with calcium scaffolding which forms a base on to which the
new bone grows (Williams, 2014)

There are two main benefits or advantages that are associated with autograft:
 There is no risk of transmission of disease
 There are higher chances of success of fusion versus allograft (cadaver bone) as well as
some types of substitutes for bone graft
Risks and chances of complications that are associated with carrying out any surgical
procedure is the main disadvantage of autograft. Among such risks include bleeding, injury to
the nerves as well as surgical wound problems for example infection (Guda, 2017).
Still, there is a risk of chronic pain associated with autograft procedures at the site of harvest
of the bone. The incidence of ongoing pain is a factor of the technique adopted in the harvesting
for the case of posterior incisions. The incidences of such pain are usually very low in actual
practice. Research has established that site pain of ongoing graft is relatively higher in separate
incision rather than using the same incision. The pain is worse in cases where the graft requires
three cortical surfaces for example a structural bone graft that is to be use on an interbody fusion
(Gunzburg, 2012).
Limitation in the supply of this type of bone graft is as well a disadvantage. Under some
circumstances, bone graft may need to be supplemented with some bone graft substitute form in
order to meet the required expectations.
Allograft Bone in Cervical Spinal Fusion Surgery
Allograft is a bone that has been extracted from a cadaver by a tissue bank for the purposes of
medical procedures. Allograft can be prepared in a number of various forms among them chips
for use in a spine fusion. In as much as allograft bone only offers a calcium scaffolding, has not
any bone growing cells or proteins that grow bones needed to ignite growth of a new bone and

thus has lower chances of fusion in comparison to using the patient’s own bone, it has been
proved to be comparable in some studies to autograft when it comes to generating successful
fusions (Ramalingam, 2012).
Allograft bone also known as donor bone or bank bone from a cadaver does away with the need
to harvest the bone of the patient. Instead, the donor graft serves as bone scaffolding that offers
the platform for the growth of the patient’s bone and finally replaces it over years. Chances of
rejection of the graft are very minimal as there are no living cells in the bone graft just contrary
to the case of organ transplant (Patel, 2013).
This notwithstanding, healing of bone graft still remains an issue of concern as there is higher
likelihood that the bone graft may fail with the allograft bone in comparison with autograft. This
has then generated studies that have been able to make comparison between allograft and
autograft with regard to production of successful fusions (Peterson, 2012). The rate of healing in
allografts is relatively slower as compared to a fusion involving an autograft bone. Still,
 Allograft produces almost equivalent rates of fusion as autograft bone in one level spinal
fusion
 More significance is continuously being attached to the differences in the rates of fusion
between autograft and allograft as a result of the ever increasing number of levels that are
to be fused or grafted (Nakai, 2015)
 To increase the rates of fusion, anterior cervical instrumentation such as plates and
screws are used.

A theoretical risk of transmission of disease from a donor exists and such a risk has been
established to be between 1 in 200,000 and 1 in 1 million for the cases if HIV and hepatitis. This
risk has been reduced even further with modern procurement and sterilization methods.
Uses of Allograft Bone
Allograft bone is usable either on its own or as a supplement to the patient’s own bone. It
is used on its own in the lumbar spine in which its use is restricted to PLIF or ALIF procedures.
In either of these procures, the bone graft is put in compression between the vertebrae and as the
compression continues, a better healing process is achieved for the bone. The use of allograft
bone by itself in spinal fusion of a posterolateral gutter where the bone is put in tension may not
yield a solid fusion (Kaur, 2017). In the case of using allograft bone as a supplement to the
patient’s own bone, the chips of allograft are used in augmenting the bone of the patient in a
posterolateral gutter fusion. This is also applicable in cases where more bone graft is required in
fusion procedures that are more extensive for example spin fusion for adolescent scoliosis.
Considerations for Allograft
Any surgical risk associated with harvesting of the patient’s own bone is eliminated when
allograft bone is used. The main drawbacks of allograft include:
 Risks of disease transmission: In as much as there are strict rules and regulations with
regard to processing and procedures of human tissue for tissue banks, a small potential
risk for disease transmission still exists from using cadaver bone (Manbachi, 2016)
 Low chances of fusion: This is probable due to the fact that allograft bone is not
composed of living bone cells which reduces the effectiveness of stimulation of fusion as
the own bone of the patient.

Bone banks also called tissue banks are the main source of allograft bone that is used in spine
fusion procedures. The tissue bank is controlled and regulated by the US Food and Drug
Administration so as to reduce the risk of contamination of tissue as well as transmission of
diseases. Demineralized bone matrix, (DBM) is one of the forms of allograft that is commonly
used. Demineralized bone matrix is a commercialized form of the bone morphogenic protein that
is a derivative of processing cadaver bone from various donors (Nakai, 2015). The quantity of
BPM available in the material varies from one manufacturer to another but is far less available
through the use of synthetic recombinant BPM. The stem cell technology is a recent form of
cadaver-donated tissue that makes use of stem cells from a donor to aid in the creation of a bone.
Biomaterials are classified depending on the responses of tissues into three categories:
bioactive, bio inert and bioresorbable. Bio inert biomaterials are devices that do not have any
interactions with the surrounding body tissues once they are placed in the human body. Among
such materials include stainless steel, polyethene, alumina, stabilized zirconia, titanium among
other materials (Benzel, 2012). It is possible that a fibrous capsule forms a bio inert implant
making the functionality of the implant be a factor of tissue integration through the implant
made. Bioactive biomaterials on the other hand refer to materials that interact with the
surrounding bones of the bone upon as soon as they are placed with the human body. In some
cases, these materials react with the soft tissues as well. The reaction takes place through a
kinematic modification of the surface that depends on time and is invoked by the implantation
within the living tissue or bone.
The interaction results into a reaction of exchange of cations between the nearby body
fluids and the bioactive implant which leads to the formation of a carbonate apatite layer which
is biologically active. This layer is formed on the implant and is equivalent to the mineral phase

in the bone in terms of the chemical and crystallographic composition (Ong, 2017). The most
common examples of these materials include bio glass, hydroxyapatite as well as glass ceramic
A-W.
Bioresorbable materials on the other hand are biomaterials that dissolve and are gradually
replaced by advancing tissues such as bones when they are placed within the human body.
Tricalcium phosphate and polylactic-polyglycolic acid copolymers are the most commonly
examples of bioresorbable biomaterials.
Bioactive glass
These are inorganic materials that have clear bonding of bones and osteoinductive
properties. The characteristics of the surface of bio active glass have an impact in the facilitation
of rapid colonization and bonding of the cells that form bones. Cells that form bone differentiate
due to the release of ions when the material comes into contact with the body fluids. Among the
ions release includes zinc, copper and strontium (Kalaskar, 2016). Bioactive glass materials are
effective in the treatment of osteomyelitis in which they are associated with the production of
antigenic factors. They influence degradation and bioactivity through changing the chemical
composition and structure.
Clinical evidence in the application of bio active materials in bone replacement is limited
even though the mechanical and surface characteristic properties of the material are favorable for
the said application. A recent clinical trial and study was conducted in tibia plateau fractured and
the findings illustrated that the material is comparable to autologous bone.
A promising material has been identified in bioactive glass which is differentiated from
the ancient synthetics such as calcium phosphates since the material has the potential of

stimulating and attracting cells to the environment that is to be grafted. Bioactive glass has the
ability through its interaction with the surrounding environment to stimulate and attract
osteoblast to the site that needs healing (Patel, 2013). On itself, bioactive glass is a structure that
is quite challenging to handle and does not possess any porosity properties. Superior handling is
enabled through the transformation of the material to micro and nano fibers. This transformation
also enhances direct connections of the cells as well as engineered porosity.
Proprietary bioactive material is a product of micro and nano fibers which are able to
drawn cells to stick and communicate with one another directly. This is illustrated in how the
human body heals through connective tissue be it a cartilage or a tendon. The first step in the
healing process is the production of fibrin clot which when magnified is a mesh of fibers that are
micro and nano in size. Bioactive glass graft technology is a reproduction of the fists healing of
fiber network that is made using synthetic bioactive material. Bioactive glass is naturally
antimicrobial (Benzel, 2012).
Bioactive glasses are a collection of bioactive materials that have been made using silica
and bear bone bonding properties. In comparison to other synthetic bioresorbable bioactive
ceramics, bioactive glasses have very unique properties. They have various rates of bioactivity
relates of resoprtion that is influenced by their chemical composition. The content of SiO2 which
is less than 60% in weight is the critical characteristic that determines the rate of bioactivity.
Bioactive glasses are highly osteoconductive in vivo and tend to facilitate the growth of new
bones on its surfaces (Poitout, 2016). A recent study found out that the activeity of bioactive
glass can even overshadow the impacts of BMP-2 gene therapy. A dynamic balance is normally
created between resoprtion of bioactive glass and intramedullary bone formation.

Bioactive glasses have the capability to induce a high local turn over for resoprtion and
bone formation. Numerous patients of osteoporotic fractures have been found to be potential
individuals for concurrent treatment bone graft substitutes made using phosphates and bio
ceramic bone. The process of this treatment may be affected by adjunct agents of antisorptive
due to the fact that osteopromotive bioactive glasses that are based on silica can initiate an
accelerated turnover of the bones (Ramalingam, 2012). Through research it has however been
established that an adjunct antisorptive therapy in other words zoledronic acid is even biter when
it comes to incorporation of bioactive glass in bones. Following these finding and observations, it
is worth concluding that bioactive glass materials are groups of special biomaterials that can
serve as substitutes for bone graft.
Introduction of bioactive glass into the body leads to the stimulation of specific biological
activities which facilities the production of soluble ionic species. This makes the glass to be coats
using a substance that resembles hydroxyapatite. After the formation of the layer, a strong
bonding of the bioactive glass is formed with both the hard and soft tissues on the surface that is
to be grafted. Bioactive glasses can as well be developed for use in the release of nutrients that
are required for the process of bone regeneration (Williams, 2014).
Due to its porosity and brittleness nature, bioactive glass falls short of the requirements of
a suitable substitute for graft. That notwithstanding, bioactive glass is still usable in facilitating
the efficacy of the existing substitute materials for the bones. Research has illustrated that a
damaged bone quickly regains its strength when the repair is done using a combination of
bioactive glass and composite relative to using composite alone in the repair (Webster, 2018).
The efficiency achieved in such a combination can be compared to that achieved in autologous
bone grafting.

A recent study was conducted in which a mineralized collagen bone substitutes one
having added bioactive glass and the other not added was used for the purposes of making
comparison in spine fusion in rabbits. Results indicated that the composite of bioactive glass and
collagen had a close resemblance with autograft repair in terms of the quality and the quantity of
new bone. It was also observed that the fusion took place relatively earlier for the case of
collagen that was augmented using bioactive glass (Thakker, 2012).
Features and Benefits of Bioactive glass
Stimulations of osteogenesis
Bioactive glass has high levels of bioactivity. One of the major factors for implant
osteointegration is remodeling of natural bone. Through bioactivity of bioactive glass, natural
bone remodeling proceeds in two important stages (Kaur, 2017). The first stage involves the
formation of a calcium sulphate mineral layer which the second phase involves the stimulation of
osteogenesis.
Dissolution of bioactive glass results in exchange of ions with the biological fluids that lead to
the formation of a mineral layer of calcium phosphate. The layer aids in the formation of a
binding between the bone and the granules of biomaterials on the grafting environment. These
form the main components of osteogenesis and the process is called osteostimulation.
Through the intrinsic properties of bioactive glass, the natural process of regeneration of new
bones is promoted and this is attributed to the production of mineral ions. This is an innovative
technology that provides one of the safest and most reliable solutions in dental surgery (Poitout,
2016).

Bone Morphogenetic Protein
Bone morphogenetic protein, BPM is a naturally occurring protein within the human
body and simulates the formation of bones. The protein is important in the healing of broken
bones as it initiates a sophisticated multistage cascade of events that promote vivo formation of
bones. BPM initiates the primitive cells found in the bloodstream to form bone cells. These
biomaterials are the only proteins that are able to initiate the formation of a new bone. The BPM
is placed on a sponge during fusion surgery on the surgical site to result into fusion of the bones
together (Söderback, 2014). Among the benefits of BPM is that it eliminates the need of the
procedure used in harvesting graft that is always painful thereby resulting into an increases rate
of success of fusion.
Bone morphogenetic protein is product applicable in spinal fusion procedures and is
formally known as recombinant bone morphogenic protein-2 abbreviated as rhBPM-2. It is
naturally occurring and is regenerated as a result of research on cutting edge human gene.
Studies have established that Bone morphogenetic protein could be a safe and effective option to
autograft. Scholar agree and accept that Bone morphogenetic protein enables fusion at the same
rate or even greater than the conventional bone grafts such as the use of the patient’s own
autograft bone (Ong, 2017).
This means that Bone morphogenetic protein gives the surgeons an opportunity to
conduct surgery at relatively improved rates as well as escape potential risks and health
complications brought about by the harvests of iliac crest autograft. By avoiding the iliac crest
autograft, the amount of time spent on surgery is greatly reduced and the rates of complication
developments checked. It also permits more rapid and less painful time of recovery (Razavi,
2017).

Recombinant bone morphogenic protein-2 molecule is specifically used in the lumbar spine
during a fusion surgery involving the anterior lumbar. Currently, the use of recombinant bone
morphogenic protein-2 has been expanded to numerous off level applications among them
posterior lateral spinal fusions, thoracic fusions, posterior lumbar interbody fusions, cervical
surgeries and even transforaminal lumbar interbody fusions.
Demineralized Bone Matrix
Demineralized bone is prepared through exposing a bone to a dilute acid. The acid slowly
dissolves the minerals in the bone and thus subjecting its protein scaffold. The exposed protein
scaffolds bold is mainly composed of collagen and has very little amount of non-collagenous
proteins. These are what make a group of actors called bone morphogenetic proteins. Bone
morphogenetic proteins are able to initiate the formation of new bones through facilitating
migration and differentiation of the stems cells into the cells which form the bones. These
processes are thought to begin from osteogenesis and thereafter become integrated into the
mineralizing matrix of the new bone that is to be formed. The inducement of the formation of a
new bone is high influenced by the combination of the factors of growth of osteoconductive
scaffold and osteoinductive growth (Patel, 2013).
Demineralized bone matrix is prepared from a cortical bone that is extracted from long
bones. The initial step in the preparing of the biomaterial is the cleaning of the bone of adherent
soft tissue components as well as marrow components. The bone is then ground to powder with
the aid of a custom-designed grinder. This process is achieved without the generation of excess
heat. The generated powder is then seized to particles of the desired size range, then
demineralized using hydrochloric acid solution and rinsed in a solution of buffered saline to
eliminate any residual acid. The product is then freeze-dried (Peterson, 2012).

In a bid to enhance handling, some of the demineralized bone matrix preparations are
thereafter mixed with fluid carrier. It can be prepared as a flowable gel or moldable putty which
is dependent on the ration with which the powder and carrier is mixed. The main advantages of
demineralized bone matrix
On autograft include the absence of a limit in the quantity; it does not have an accompanying
surgical procedure as well as no morbidity at the site of donor. When it comes to BMPs,
demineralized bone matrix provides an association of numerous factor of growth when
administered at physiological doses which is a natural on-site release that has no need for a
carrier. Still, in comparison to BPM, demineralized bone matrix is cost effective and is
completely reimbursed by the social security system across some countries (Suzuki, 2011).
Possible fluctuation in the osteoinductive properties between the various vials as well as for the
industrial composite side effects that result from the introduction of additional carriers is the
main disadvantage of demineralized bone matrix.
Hydroxyapatite
Hydroxyapatite, Hap, is a calcium phosphate that is similar to the hard tissues in human
beings and terms of its composition and morphology. This is with particular regard to its
hexagonal structure as well as the stoichiometric Ca/P ratio which is 1.67 that is identical to bone
appetite. Stability is one of the most important characteristics of hydroxyapatite in comparison to
other calcium phosphates. With regards to thermodynamics, hydroxyapatite has been found to be
the most stable of the calcium compounds when tested under physiological conditions including
pH, temperature and composition of the body fluids (DiMasi, 2014). Nano- hydroxyapatite has
gained special interest as a biomaterial that is used in numerous prosthetic applications. This is

attributed to its similarity in size, chemical composition as well as crystallography with the hard
tissues in humans.
Among the main features of hydroxyapatite include biocompatibility, bioactivity, non-
toxicity, osteoconductivity and non-inflammatory nature. Hydroxyapatite is able to integrate
bone structures and promote ingrowth of bones without having the bone broken down or
dissolved. It is thermally unstable and decomposes at a temperature of between 800 and 1200⁰C
which is dependent on its stiochemistry. In general, dense hydroxyapatite does not possess the
mechanical strength to can allow it to be successful in the applications that call for long term
loading (Dobke, 2013).
Hydroxyapatite is formed through the precipitation of calcium nitrate and ammonium
hydrogen phosphate. Each of the pores in the compounds is about 100 to 140 um and has regular
interporous distance. Numerous studies have revealed that hydroxyapatite itself is not sufficient
in the formation of bones since it only has osteoconductive properties. It is for this reason that it
is mixed with autologous bone marrow or a graft so as to generate an osteoinductive stimulus.
An experiment was conducted to ascertain the applicability of hydroxyapatite as a bone
graft. In this study standard internal fixation was adopted for all the fractures since the ceramic
hydroxyapatite is very brittle and does not have sufficient tensile strength. The findings from the
study revealed that all the cancellous areas underwent successful healing and indicated signs of
union after about three months (Q. Ashton Acton, 2012). There were blurred outline of
hydroxyapatite after two years even though there was no lucent line that surrounded them, an
indication that they were incorporated into the surrounding bone. Hydroxyapatite is non-
degradable and has resoprtion rates of about 5% to 15% every year. Hydroxyapatite illustrates no

incorporation or growth inside them in cortical areas ad no incorporation or growth of bone on
histopathology at removal of the implant.
When autogenous bone graft is used in grafting, the usual healing process involves
resoprtion of osteons and revascularization. In this healing process, the interstitial bones remains
and act as a stromal frame work that allows the formation of new bone. The bony, matrix that s
achieved after this process has pores that are very large to allow the ingrowth of tissues. Due to
its unique porous nature, hydroxyapatite ceramic is osteoconductive and this permits intimate
growth of bones. The size of the pores of hydroxyapatite is similar to that of a normal osteon
bone size and also corresponds to the findings from research and study confirming that the
minimum size of pores is 100U and 150 to 200U is preferred for ingrowth of bones
(Ramalingam, 2012).
Owing to the mechanical and thermodynamic properties of hydroxyapatite, it is an
effective material for use in autogenous bone grafts that can be used in fractures a proper primary
mechanical stability as well as contact with the host bone have been established especially in
cases of cancellous area. It can be used in the supplementing of cancellous grafts when needed in
large quantities. The material is osteoconductive and not osteogenic and hence by mixing it with
the host marrow, it offers osteoinductive stimulus. It requires support from the techniques of
ideal internal fixation in order to achieve healing of the fracture. It is generally cost effective,
prevents morbidity of the graft site as well as being biocompatible (Prodromos, 2017).
Calcium Phosphate/Calcium triphosphate
Calcium phosphate materials for bone substitute are used instead of allograft or autograft
owing to their osseconductity, low cost as well as consistency in the properties of the material.
Besides, the use of Calcium phosphate helps in the elimination of morbidity of the donor site

those results from harvesting of autograft (Poitout, 2016). Calcium phosphate in besides
demineralized bone matrix is known for their ability to promote the formation of bones when
implanted. Calcium phosphate serves to promote the formation of bones through the functions of
calcium and phosphates are that are found within their structure during implantation. Calcium
phosphate is widely applied in orthopedics and in the reconstruction of maxillofacial surgery
where it is specifically used as a substitute for autograft or allograft bones that is set in spinal
fusion.
Calcium phosphate is the widest group of artificial substitutes for bone grafts and this is
attributed to their close resemblance to the minerals compositions of the human bone. There are
numerous forms, methods of application and compositions of these materials that are available.
Making an educated choice on Calcium phosphate is becoming a challenge as a result of the ever
increasing number of commercially available Calcium phosphate. A choice on a specific calcium
phosphate should be made based on its properties in conjunction with the desired indication and
intentions. One of such important properties of calcium phosphate is resoprtion rate which is
influenced in two varied ways: changes in the geometric properties and chemical composition
(Atala, 2011).
The geometrical properties of calcium phosphate revolve around their porosity as well as
the interconnectivity of their pores. The optimal size of pore required for ingrowth of new tissues
ranges between 15 and 500 um. This size of pores is integral in the facilitation of the ingrowth of
fibrous tissues as well as formation of vessels. The pore sizes are also important in the invasion
of cells that take part in the resoprtion of the material the interconnectivity of the pores also has
an influence on the ingrowth of the tissues (Peterson, 2012).

Calcium phosphate has undergone tremendous changes in its chemical composition over
time. The initial calcium phosphate consisted of hydroxyapatite (HA) (CA10 (PO4) (OH) 2)
which is an inert material that was not resorbed for a long time. Since the introduction of β-
tricalciucm phosphate aming other compsitions such as α -TCP9, tricalcium phosphate and
octaclcium phosphate, the field of calcium phosphate has experienced tremendous changes. HA
is not resorbed whole the other compositions aforementioned are resorbable very quickly (Nakai,
2015).
The rate of resoprtion of a material can be altered through combining TCP and HA which
results into the formation of biphasic calcium phosphates as well as the other compositions of
calcium phosphate in order to come up with various rates of resoprtion. In a theoretical
perspective, the addition of TCP would lead to increased rate of resoprtion while adding more
HA slows down the rate of resoprtion. A recent study has introduced a combination of calcium
phosphate and HA, known as CeramentTM. This was a development aimed bringing together the
properties of HA and the high resoprtion rate of calcium phosphate. CeramentTM is an injectable
paste that has easy handling properties besides excellent biomechanical behavior upon
implantation (Razavi, 2017). It also has good osteointegration and hence an illustrated of the
most current generation of calcium phosphate.
Amorphous calcium phosphate, ACPs is yet another form of calcium phosphate and may
have a role to play in precipitation and well as initial assemblage of particles of HA that are more
structured. Amorphous calcium phosphate is thus considered to be a reliable source of initial
formation of bones. The applications of this type of calcium phosphate are limited owing to their
manufacturing process (Söderback, 2014). The injectable Biobon cement tends to be the only
calcium phosphate that is commercially available for use in orthopedic application which

contains ACP. Both the characteristics of the host and properties of the bone substitute play a
role in the difficulty in the rate or resoprtion. Among the properties of calcium phosphate used as
bone graft are as discussed:
Mechanical strength
The composition and the geometrical properties of calcium phosphates determine the
mechanical strength of these biomaterials. Bones have different mechanical properties from
calcium phosphate since bone illustrates some level of elasticity since they contain collagen.
Important to note as well is that various bones have different properties and os do different bone
tissues. Cortical bones for example have longitudinal compression strength of 205MPa while
human trabecular bones have strengths ranging from 0.1 to 30 MPa which are influenced by the
age of the patient as well as the site of implantation. This is a feature that is to be considered
when a choice is to be made on a material for a specific indication. An example is that the
compression strength of calcium phosphate should be the same as that of cancellous bone during
the implantation in a tibial plateau fracture (Benzel, 2012).
Surgeons opinion about different materials and how much materials are
surgeon using per surgery
There are numerous strategies that are used in the application of biomaterials in the
reconstruction of tissues be it for functional or cosmetics application. The type of tissue that is
being reconstructed forms the main focus of creating a biomaterial. Still, the intended function of
the biomaterial within a biological system deserves as much attention. This is quite important in
the treatments of defects in bones in reconstructive surgery (Prodromos, 2017). A perfect
scaffold used in bone tissue engineering must possess a number of features such as
biocompatibility, osteoinductive and osteoconductive. Other important characteristics include:

 The material must have a degradation rate that is similar to the rate of natural bone
production
 It must have mechanical properties that are similar to those in bones
 It must have a porous structure that offers the appropriate matrix for cell differentiation
and proliferation (Poitout, 2016)
 It must possess a proper structure that permits vascularization
Various clinical approaches are in place of use in the repair of nervous tissues including
nerve graft, nerve bridging, end-to-end suture as well as fascicular suture. Favorable
environment for the regeneration of nerves have been achieved through the use of various
biogenic matrices bearing the limited capacity available for the regeneration of long and severe
defects or lesions (Manbachi, 2016).
Biomaterials that in at tissue or skin repair must be able to bring back to grafted site to
function by initiating or facilitating healing of the wound, reduction of pain as well as assisting
in the achievement of the desired cure even as it permits for the repair of the correct tissue, at
least in anatomical terms. The main focus today in the design of biomaterials is bioactive and can
result to a regenerative process in the tissue on to which implantation is to be executed. This
called for the need of the type of scaffold and the circumstances to be sufficiently supportive of
the differentiation and proliferation process of the specific type of biomaterial used (Webster,
2018). The strategies focus on the creation of scaffolds that resemble the natural extracellular
matrix both in the biomechanical and structural aspects. This offers treatment options for both
acute and chronic wounds inclusive of burns.

CHAPTER 3: RESEARCH METHODLOGY
Data collection Method
There are various research methods and methodologies that are available in literature and
a choice on a method of research should be based on the intended achievements of the study as
well as the limiting factors in the study. Two types of research methods are broadly used:
qualitative research and qualitative research (Atala, 2011).
Whereas qualitative research is mainly exploratory in nature, quantitative research is
applied in the quantification of the problem through the generation of numerical data or any data
that can be changed into usable statistics. Qualitative research is used in providing insights into
the underlying motivations, reasons as well as opinions on a research problem. Through
qualitative research, an understanding into the research problems are provides as well as aiding
in the development of the hypotheses or ideas that are potential for use in quantitative research.
Qualitative research is also applicable in unfolding the trends in the opinions and thoughts and
provides a deeper sense into a problem (Prodromos, 2017). The common methods of qualitative
data collection include focus groups, observations or participation and individual interviews.
Following the nature of this study and the research question the most cost effective
biomaterial for use in spinal fusion surgery, quantitative research analysis will be used in making
the findings. Quantitative research is used in the quantification of behaviors, opinions, attitudes
and any other defined variables and the generalized result is provided form a large population
sample. This method makes use of measurable data in the formula of the facts and unfolding of
the patterns in the research (Ramalingam, 2012). Quantitative methods of data collection are
structured more than qualitative methods of data collection and come in various forms such as
surveys, longitudinal studies, systematic observations, website interceptor as well as interviews.

CHAPTER 4: RESULTS AND DISCUSSION
Cost Comparisons of the Various Biomaterials
Autograft versus allograft
In this research, the surgical costs were reported inclusive of the costs of supply using the
invoice costs for every item that is used in a surgical procedure and the costs of personnel
calculate per minute (Ramalingam, 2012). The cost data for the procedure was retrieved from the
financial management database and then subdivided into various categories for the purpose of
making comparison. The findings were that the total mean cost per case for a group of patients in
the allograft group was higher than those in the autograft group. This is mostly evident in the
mean operating room time which is about 12 minutes greater than the case of autograft. This
means that autograft is more cost effective than allograft as substitute materials for grafting
taking into consideration the cost of supplies and the applicable professional charges.
Figure1: Baseline cost-effectiveness analyses of allograft versus autograft bone graft substitutes
The tables below illustrate the costs of the various biomaterials among other properties as have
been discussed previously in this report.

Autografts
Osteoconductive Osteoinductive osteogenic structural costs Disadvantages
Autograft
Cancellous + + + + + + + + + + $136/50ccc Donor site
morbidity,
increased OR
time, increased
loss of blood
Cortical + + + + + + $230-
1251/3-
20cme
Donor site
morbidity,
increased OR
time, increased
loss of blood
Vascularize
bone
+ + + + + + + - Donor site
morbidity,
increased OR
time, increased
loss of blood
Bone
marrow
aspirate
+/- + + + + + - Donor site
morbidity,
increased OR
time, increased
loss of blood
Platelet-
rich plasma
- + + + - - Unreliable
efficiency
Allograft
Osteoconductive osteoinductive osteogenic structural costs Disadvantages
Allograft
Cancellous + +/- - + $376/30ccc Potential
transmission of
infection, post
rejection by the
host, osteogenic
potential
Cortical + +/-d - + + + $530-
1681/3-
20cme
Potential
transmission of
infection, post
rejection by the
host, osteogenic
potential
DBM + + + - - $726- Potential

1225/10
mLf
rejection by the
host, no
structural
properties
Synthetic ceramics
Osteoconducti
ve
osteoinductiv
e
osteogeni
c
structural Costs Disadvantages
Synthetic
ceramics
Calcium
phosphate
+ +/- - + $655/10mL
g
Osteoconductiv
e properties
only
Tricalcium
phosphate
+ - - + + + $1520/10m
Lg
Osteoconductiv
e properties
only
Calcium
sulfate
+ - - - $655/10
mLg
Rapid
resoprtion(faste
r than bone
growth),
osteoconductive
properties only
Other biomaterials
Osteoconductive Osteoinductiv
e
osteogenic structural costs Disadvantages
Other
rhBMPs +/-e + + + $3500-
5000e
Costly, limited
indications,
limited FDA
approvals,
increasing
evidence of
neurovascular
complications
when used in
spine

Discussion
As can be observed from the comparison charts of the prices of the various biomaterials,
rhBMPs are the most expensive biomaterials which are even listed as one of its disadvantages
while autograft tends to the most cost effective biomaterial for use in spinal fusion surgery. The
cost of a biomaterial is determined by the technology that is needed in its design production and
application on the site of implantation. Autograft is one of the oldest bone graft substitutes to be
used in spinal fusion surgery (Ambrosio, 2012). The technology that was used in generation the
biomaterial is the ancient one even though it has adopted the technological advancements.
The technology used in manufacture of autograft bone substitutes is quite affordable
making the process of is application quite affordable as well. Important to remember as well is
that autograft, also known as autologous bone or autogenous bone graft is harvesting of the bone
from a patient and transferring it to the part of the spine that is to be fused (Grad, 2010). A
separate spinal fusion procedure is carried out during spinal fusion surgery to extract a bone from
another part of the body of the patent and place it in the region of the spine that is to undergo
fusion. From this information, a conclusion can be drawn to add on the list of the justifications
for autograft being affordable.
Since the bone graft is harvest from the same patient who is to undergo the spinal fusion
surgery procure, the cost of buying acquiring the bone graft is limited. In this regard, the patient
is left to only cater for the professional charges and the charges of supplying the equipment
required for harvesting the bone graft. Despite being a painful process and associated with
number other challenges, autograft tend to be an alternative when cost is one of the
considerations in performing a bone graft spinal surgical procedure (Bronzino, 2016). rhBMPs
tends to be the most expensive of all the bone grafts. The technology involved in the design,

production and application of rhBMPs is quite costly thereby leading to an increasing in the cost
of production. The end result is a transfer of the cost implication of the process to the final
consumer who is the patient (Ducheyne, 2015).

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