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