VERY BASIC IMPLANT

1. ORTHO
BASIC IMPLANT
(SCREWS &PLATES)
PRESENTED BY:
SN ABA BERIAK
SN LORNA SIDIN

2. SCREWS

3. Screws introduction
O An elementary machine to change the small
applied rotational force into a large compression
force
O Function
 -holds the plate or other prosthesis to the bone
 -fixes the fracture fragments (position screw)
 - Achieves compression between the fracture
fragments (Lag screw)

5. Screws
1. Head
• means for applying torque with a screwdriver
• act as a stop (the undersurface) i.e. countersunk
2. Recess type
• slotted
• Cruciate
• Philips
• Hex/Allen
• Torx (eg Stardrive of synthes)

6. Screws
3. Shaft/Shank
• Smooth link
• almost not present in standard cortex screw
• Present in cortical shaft screw or cancellous screw
• Run out – transition between shaft and thread,
- site of most stress riser, screw break when
- incorrectly centered hole
- hole not prependicular to the plate
4. Thread
• Invlined plane encircling the root
• Single thread
• May have two or more sets of thread
• V-thread profile: more stress at sharp corner
• Buttress thread profile: less stress at the rounded corner

7. Screws
5. Core Diameter
• Narrowest diameter across the base of threads
• Also the weakest part
• Smaller root –shear off
• Torsional strength varies with the cube of its root
diameter

8. Screws Thread
O Cortical screws

9. O Cancellous screws
Screws Thread

10. O Locking screws
Screws Thread

11. Screws

12. Screws

13. Screws

15. NAME MECHANISM
Plate screw Potential and friction applied to create force between the plate and the bone
Lag screw The glide hole allows compression between bone fragments
Position screw Holds anatomical parts in correct relation to each other without compression,
ie, thread hole only, no glide hole
Locking Head
screw
Used exclusively with LCP/LISS; thread in the screw head allow mechanical
coupling into a reciprocal thread in the plate and provide angular stability
Interlocking
screw
Couples an intramedullary nail to the bone to maintain length, alignment and
rotation
Anchor screw a point of fixation used to anchor a wire loop or strong suture
Push-pull screw A temporary point of fixation used to reduce a fracture by distraction and/or
compression
Reduction
screw
Conventional screw used through a plate to pull fracture fragments towards
the plate; the screw may be removed or exchanged once alignment is
obtained.
Poller screw Screw used as a fulcrum to redirect an intramedullary nail
Screws Function

16. PLATES

17. Plate
O Definition by Oxford Dictionary
A thin, flat sheet or strip metal or other material,
typically one used to join or strengthen things or
forming part of a machine.

18. O First record of plates for the long bones 1886 by
Hansmann, of Heidelberg University, Germany
Historical introduction

19. Historical introduction

20. O Since 1958, AO has
devised a family of plates
for long bone fractures,
starting with a round holed
plate.
O In 1969 the DCP was
developed.
O In 1994 LC DCP was
created.
O In 2011 LCP with
combination holes has
come into use
Historical introduction

21. Plates…
O Plates are now widely accepted with different
standard techniques of osteosynthesis,
throughout the skeleton.
O Different anatomical locations demand different
shapes and sizes of plates.

22. O Dynamic compression plates (DCP)
O Limited contact dynamic compression plates
(LCDCP)
O Locking compression plates (LCP)
O Reconstruction plates
O Tubular plates
O Anatomic plate
Plates Design

23. Plates Functions

24. O 1969 – DCP was developed
O Has a self-compressing hole design
O Experimental work showed that the flat
undersurface of the DCP interfered with blood
supply of the underlying cortex onto which it was
compressed by the screws.
O The concept of the ‘footprint” of plate emerged.
The “footprint” is the area of the undersurface of
the plate in contact with the underlying bony
cortex.
Dynamic Compression Plates (DCP)

25. DCP

26. O Unstable fixation leads to
fatigue and failure
O Strict adherence to
principles of compression
O Compromised blood
supply due to intimate
contact with underlying
cortex
O “refractures” after plate
removal
Problem with DCP

27. O Represents a design
change
O Overcome problems with
DCP
O Plate footprint reduced-
improved blood circulation
Limited Contact Dynamic Compression plates
(LC-DCP)

28. O Minimized kinking at screw holes, more
countourable and reduced plate fatigue at
hole
O Allow more inclination of screw in longitudinal
plane and transverse plane
Limited Contact Dynamic Compression plates
(LC-DCP)

29. O Since 2001 the LCP with
combination holes has
come into use.
O LCP has a combi hole
which permits the
insertion of standard head
screws and threaded
locking head screws.
O Angular-stability whereas
stability of conventional
plates is friction between
the plate and bone.
O Also designed with a
minimal footprint.
Locking Compression Plates (LCP)

33. O Have notched between the
holes to permit bending ‘on
the flat’ as well as
conventional bending.
O Very adaptable, using the
correct tools and are useful
in complex anatomical sites
such as the distal humerus,
the pelvis, the clavicle,
acetabulum, etc.
Reconstruction Plates

35. O 1mm thick
O Useful in areas with
minimal soft-tissue
covering such as
lateral malleolus,
olecranon, distal end
of the ulna.
Tubular Plates

37. O Fixed to the two
main fragments only,
leaving the fracture
zone untouched.
O Respect the biology
of a complex and to
minimize any
additional soft-tissue
injury
Bridge Plates

38. O Extramedullary splint
O Provide relative
stability
O Maintain length,
rotation, axis
O Healing with calus
formation
Bridge Plates

40. REFERENCES:
O References:
1. www.orthobullets.com/basic-
science/9063/orthopaedic
2. Aotrauma.aofoundation.org/plate-form
and function
3. www.slideshare.net/screws and plates
fixation/BaHuong