Date post: | 20-Mar-2017 |
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Materials & Systems
OSTEOSYNTHESIS:
Dr Uzair LuqmanResident Oral and Maxillofacial
SurgeryArmed Forces Institute of Dentistry
Rawalpindi
Types of Internal Fixation
Rigid internal fixation
Non rigid internal fixation
Functionally stable fixation
Rigid Internal Fixation
“Any form of fixation which is strong enough to prevent interfragmentary motion across fracture when actively using the skeletal structure”
Non Rigid Fixation
“Any form of bone fixation that is not strong enough to prevent interfragmentary motion”
Example:
Transosseous wiring
Functionally Stable Fixation
“Forms of non rigid skeletal fixation that allow strong enough to allow active use of skeleton during healing phase but not strong enough to prevent interfragmentary fixation”
Example:
Single adaptation mini plate at angle
A walk through time
1886: Hansmann developed a retrievable bone plate
1932: Key employed crude compression plates for tuberculosis of tibia
Late 1960’s: Luhr, Mittelmeier introduced sliding hole concept
1970’s: Luhr, Spiessl and Champy’s introduction of compression plates for mandibular fractures
Late 1970’s: EDCP’s introduced, Mini and recon titanium plates
Early 80’s: Bioresorbable plates
Role of AO / ASIF
Arbeitsgermeinschaft fűr Osteosythenfragen Founded in Switzerland in 1958 AO-CMF A non profitable organization funded by its three
daughter companies Creates guidelines, new products and promotes
research on internal fixation Includes human as well as veterinary IF
Materials
Vanadium Stainless steel Vitallium Titanium
• Development of 18-8 SS for surgical implants
• Introduction of 316L SS in 1943
• Still in use, although available materials are limited
• Proprietary name of Co-Cr alloy
• Developed by Albert W. Merrick in 1932
• Use abandoned in mid 60’s
• Introduced by Sherman• soft, silvery gray,
ductile transition metal• Imparts aggressive soft
tissue reaction
Titanium CP-Ti used (commercially pure Titanium) Divided into grades I-IV depending upon oxygen contents Extremely insoluble, inert and biocompatible High corrosion resistance due to spontaneous formation of thin
oxide layers Anodized, electrolytically passivated Non ferromagnetic Titanium alloys available: only where special high strength
requirements (not in CMF)
Osteosynthesis Materials
Screws Plates
› Compression plates› Adaptation plates Mini, Micro› Universal plates› Reconstruction plates
Components of Screws
Head
Shank/ neck
Threads
Screw point
Head diameter
Thread pitch
Thread diameter
Core diameter
Types of Screws
Different diameters / lengths + Emergency screws
Manner of tapping Self tapping Non tapping Self drilling
Screw recess Cruciform Hexagonal
Manner of locking Locking Non locking
Craniofacial plates
Dynamic Compression Plates
Ability to compress fracture segments
Helps in direct bone union Little role in midface Variants:
› LC-DCP (Limited Contact)› E-DCP (Eccentric)
Adaptation Plates Adapt to the cortical surface of bone Friction between bone and plate
interface leads to functional stability Types:
› Mini plates (mandible + midface) 1.5 mm and 2.0 mm
› Micro plates (midface) 1.0 mm and 1.3 mm
Thickness 0.9 mm diameter 2.0 mm
Difference between Mandible and Midface Adaptation Plates
Mandible 2.0 mm adaptation
plate and screw
Midface 2.0 mm adaptation
plate and screw
Mid face
• Mini
• Micro
Micro Plates
Available in 1.3 and 1.0mm Thickness of plate 0.5 mm or below Less projection Suitable for paper thin bones of midface Provide limited stability
Universal plates
Universal Plates
Plate thickness 2.0 mm
Screw core dia 2.4 mm
Works like adaptation plate
Indicated where additional
stability is required
Reconstruction Plates
The “RECON” Concept
1. ≥ 2.5 mm plate thickness
2. ≥ 2.4 mm core diameter of screw
3. ≥ 3 screws on each side
4. Bicortical
Types Non locking recon plates
Uni lock recon plates
› Both available in 2.4mm and 2.7 mm systems, plate thickness 2.5 mm and 3.0 mm
THORP (Titanium HOllow screw Recon Plate)
› 4.0mm osteointegrated system, plate thickness 3.2mm
Unilock Recon
Difference between non locking and locking recon plates
Recon plate with condylar head Not approved by FDA, available in other countries
Resorbable Fixation System
Lag Screw Simple, quick and cheap Provides rigid fixation Concept lies in method not
the screw Gliding hole in one segment,
thread hole in other Always perpendicular to
fracture line
Orbital mesh, plate
Power tools
Drill Bits Contain 2-3 flutes Diameter corresponds to
core diameter Coupling varies, depending
upon system Can be with or without stop Care:
› No contact with metals during drilling
› No bending forces› Continuous irrigation
Depth Gauge
For bi-cortical screws Insert, pull, engage, measure
Screw tap
For non self tapping screws Useful in high corticated areas of bone
Plate cutting and bending instruments
Transbuccal Instruments
Synthes Vario set
Thank you
Thank you