Date post: | 09-Feb-2017 |
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Health & Medicine |
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RIGID INTERNAL FIXATION
MADE BYROSHALMARIA THOMASIV YEAR
What is fixation? Fixation in orthopedics is the process by which an injury is
rendered immobile. This may be accomplished by internal fixation, or by external fixation.
What is internal fixation? Internal fixation is an operation in orthopedics that involves
the surgical implementation of implants for the purpose of repairing a bone
Rigid internal fixation refers to the direct method of fracture fixation where the hardware or implant used for fixation provides sufficient rigidity for the jawbone to withstand masticatory stresses.
Avoids immobilization by MMF Does not allow micromotion of fracture segments
Internal fixation
Semirigid
Transosseous wiring
Noncompression miniplate
Rigid
Compression Fixation
DCP
EDCP
Lag screw
Fixation osteosynthesis
Locking plate
Reconstruction plate
THORP
Rigid Internal Fixation
Goals of AO/ASIF technique for rigid fixation
1. Anatomic reduction of bone fragments2. Functionally stable fixation of the
fragments3. Preserving the blood supply to the
fragments by atraumatic surgical procedures
4. Early, active and pain free mobilisation
Compression osteosynthesis
Based on AO/ASIF principles These plates included pear-shaped holes
at the extreme ends
Dynamic compression plate
Produce compression between bone fragments on activation
300kPa/cm2 Indication
Nonoblique fracture with good bony apposition after reduction
Contraindications Severely oblique fracture Comminuted fracture Fracture with bone loss
Properties of plate1. Plate has inclined plane in the hole proximal
to the fracture2. The highest portion of the inclined plane lies
on the outer aspect3. 2 types of screws- compression screw and
static screw4. Min two screws on each side5. Unfavourable fracture requires longer plates
with more screws6. Order of fixation 7. Plate bending8. Bicortical screws are used9. Fixation protocol
Disadvantages Require precise adaptation If used on oblique fractures, the fragments slide over
one another Maladapted plate in anterior mandiblecreates
widening of mandible Technique sensitive Ideally should be placed on tension zone, but due to
anatomic reasons the plate is placed on the inferior border
In fracture with good reduction and no bone loss, causes stripping of screws and bone splintering adjacent to fracture
Eccentric dynamic compression plate
Used in situations where tension band application is not possible Presence of impacted 8 with angle fracture Edentulous mandibular fracture Avulsion of bone from fracture site
Plate design
Advantage Even distribution of forces along length of
fracture Disadvantage
Technique sensitive Results not superior to other fixation
methods
Lag screw Oblique fracture in long bones Principle- a screw that glides through the
cortex of one fragment and engages the cortex of the opposite fragment with its thread, draws the fragments together and compresses them when tightened. Gliding holes and thread holes must be coaxial
- (Pics)
Fixation osteosynthesis This includes
Reconstruction plate THORP Locking plate
Indications Oblique fracture Comminuted fracture Loss of bone fragments in fracture Questionable post op compliance Non atrophic edentulous fracture
Reconstruction plate Thick rigid plates primarily used in
reconstruction of mandible following resection
Mandibular fracture involving multiple segments
THORP( titanium hollow osseointegrated reconstruction plate) Plate thickness 3 mm 4mm screw diameter Special locking screws are inserted into
each screw head to perform locking principle between bone anchored screw and corresponding plate hole
Aim- Stability to fractured bone segments without
applying pressure Prevents focal ischemia, bone necrosis, screw
loosening and plate mobility Components- reconstruction plate and
anchor screws Disadvantage- screw and plate
osseointegrate with the bone making removal difficult
Locking plate Locking plates 2.5 mm thickness Diameter of screws=2.4-3.0 mm Reduces plate mobility Reduces chances of infection and
nonunion Disadvantages of THORP has been
replaced by locking plate