Musculoskeletal Disoders 2 Flashcards
devices or tissues that are placed inside or on the surface of the body
Implants
it is the resistance of a structure to deformation
STIFFNESS
it is used in context of fracture fixation describes an implant or of a bone- implant construct physical property of resisting deformation under load.
RIGIDITY
it is the ability of a material to recover its original shape after deformation
ELASTICITY
– the ability of a material to be formed to a new shape without fracture and retain that shape after load removal
PLASTICITY
the ability of solid material is to be deformed under tensile stress and to be stretched into a wire without fracture
DUCTILITY
many surgeons were using hooks , pins and wires made of various metals –
gold ,silver ,platinum or iron
in animal experiment found platinum was the most inert metal
LAVERT
introduced pins for
fixation of “small fragments” at the intra articular level.
VON BAYER in 1908
stressed the value of rigid fixation and showed that movement at the fracture site
EARNEST HEY GROVES
because of its total inertness(chemically inactive) in the body.
TITANIUM
have the fabrication(invention)versatility and strength of stainless steel and excellent compatibilty in the body.
TITANIUM,VITALLIUM
Implants can be tested under following categories:
PCSB
- Physical
- Chemical
- Structural
- Biological.
Physical Tests
Appearance
Weight
Magnetism
Hardness
Impact test
Spark test
A drop of the electrolyte is placed on the stainless steel under test, and the electrodes are placed against the electrolyte solution
Molybdenum Detection Test
contains hydrochloric acid and nitric acid in the proportion of 3:1, and it is a strong solvent.
Corrosion Test (Aqua Regia)
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acronym for nickel titanium naval ordnance laboratory, where the alloy’s remarkable properties were discovered
Nitinol
Biomaterials can be defined as being
“natural or synthetic substances, capable of being tolerated permanently or temporarily by the human body
Non metallic implants
These have a characteristic of osteoconduction and the capability of chemical bonding with living bone tissue in accordance with the pattern of “bonding osteogenesis
Bioactive Ceramics
These are gradually absorbed in vivo and replaced by bone in the bone tissue.
Bioresorbable Ceramics
are chemically inert, have good biotolerance, and high hydrophobic capacity
Polymers Silicones
provided in two parts, liquid monomer which helps methacrylate powder to polymerize
Polyacrylics
have allowed a paradigm shift away from bionic (mechanical replacement) engineering toward true biologic solutions in orthopaedics reconstruction.
Biodegradable implants
reduction in bone density (osteopenia)
as a result of removal of typical stress from the bone by an implant ), pain, local irritation
stress shielding
phenomeno
