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