artificial bones

8/16/2019 Artificial Bones

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Artificial BonesJulio Correa


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How bones work

•

Bone is a composite material, consisting of crystals of mineral boto protein.

• This provides both strength and resilience so that the skeleton caabsorb impact without breaking.

• A structure made only of mineral would be more brittle and bremore easily, while a structure made only of protein would be sofbend too easily.

• The mineral phase of bone consists of small crystals containingcalcium and phosphate, called hydroxyapatite.


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• Cortical bone accounts for 80% of the mbone in the human body, it has a muchsurface area than cancellous bone due lower porosity.

• Cancellous (or trabecular) bone is locat

ends of long bones, accounts for roughthe total mass of the skeleton.


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Formation and remodeling of bone

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OsteoblastsBone-forming cells found near the surface of bones.

• OsteocytesTheir main role is homeostasis – maintaining the correct oxymineral levels in the bone.

• OsteoclastsResponsible for bone resorption.


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Important functions

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Bone is a dynamic, highly vascularized tissue with the uniquto heal and remodel without leaving a scar .

• Provide mechanical stability to the skeleton that is needed fbearing, locomotion and protection of internal organs.

• Bone serves as a mineral reservoir and has the capacity to r

mobilize mineral stores if needed for homeostasis of the calblood level.


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• Due to the ageing world population, techniques to replace, restoregenerate bone have become a major clinical need in the fields orthopedic, spinal, dental, cranial, and maxillofacial surgery.

• Genetic abnormalities can produce weak, thin bones, or bones thdense.

• Nutritional deficiencies, particularly of vitamin D, calcium, and phcan result in the formation of weak, poorly mineralized bone.

• Abnormalities in remodeling are the primary cause of bone disea


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These bits of disconnected bone may be mea

but contribute nothing to bone strength.


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Bone replacement

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Bone replacement materials can be needed for a variety of rThey are sometimes required when a section of bone is misthe gap needs to be filled in, for example following an accidafter the removal of a tumor.

• Allografts / Xenografts

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Autografts• Artificial bone (Synthetic materials)

• DBM (Demineralized Bone Matrix)

• Ceramics


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Autografts

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Autografts have the advantages of no adverse immunologicresponse.

• Their availability is qualitatively limited by the anatomy andphysiological conditions of the donor site.

• They have no mechanical strength and shape which can pre

duplicate the bone being replaced.


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Allografts

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Allograft bone can either be collected from cadavers or livin• Available in considerable quantity, can be strong mechanica

• Inherent risk of disease transmission and immune reactions

• With such critical arguments on applications of naturally degrafts, development of artificial bone substitution materialsfrom metals, ceramics, polymers, and composites are of a gimportance.


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Bone graft fills in space between two vertebrae after disc

hasbeen removed


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•

Ideal artificial bone- Biocompatible….


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Applications

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Artificial bones are useful for tissue augmentation in patientfacial deformities or defects. Custom-made artificial bones, by mirroring the bone structure on the healthy side using coaided design, have been used.


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• 3D simulation models with special wax


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The artificial jaw was made from titanium powder, heated

and built-up in layers in a 3D printer to create a working

lower jaw which was then finished with a bioceramiccoating.

Bone Metastases in


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Bone Metastases inthe Upper Extremity

Artificial replacement of the upper arm bone.

The humerus has been stabilized with an intramedullary

rod inserted down the center of the bone.

Segmental spacer replacing a

bone.


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• Clinical application of CHACC used for bone augmentation after skeletal tumour resection.

• Before surgery, the tumour had invaded deep into the bone cavity and occupied nearly half thehumerus

• With CHACC (Coralline hydroxyapatite / calcium carbonate) implantation, two years and seven msurgery, the bone was completely healed, with normal function.


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• Stapedectomy (stapes is replaced with a small plastic tubesurrounding a short length of stainless steel wire)

• Due to Otosclerosis (Abnormal, microscopic growth ofbone in the walls of the inner ear which causes the stapes bone tobecome frozen in place or fixed)


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• B.D. Ratner, A.S. Hoffman, Biomaterials Science: An Introduction to Materials in Me

Elsevier Science & Technology, 2004.

• Handbook of Porous Solids, Wiley-VCH, Weinheim, 2002, 2923pp.

• L.L. Hench, Biomaterials 19 (1998).

Otosclerosis | University of Maryland Medical Center http://umm.edu/programs/hearing/services/otosclerosi

s#ixzz3ohXkadFs

University of Maryland Medical Center
http://umm.edu/programs/hearing/services/otosclerosis#ixzz3ohXkadFshttp://umm.edu/programs/hearing/services/otosclerosis#ixzz3ohXkadFshttp://umm.edu/programs/hearing/services/otosclerosis#ixzz3ohXkadFshttp://umm.edu/programs/hearing/services/otosclerosis#ixzz3ohXkadFshttp://umm.edu/programs/hearing/services/otosclerosis#ixzz3ohXkadFs

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