Rigid internal fixation is a surgical procedure that precisely reduces and immobilizes bone fractures with metal implants to allow healing. It relies on two-point fixation with a stabilizing unit like a bone plate and a tension band like a miniplate. Rigid fixation prevents interfragmentary movement and allows direct bone healing. Non-rigid fixation allows some movement between bone fragments. Various plate types, screw designs, and materials are used depending on the situation. The goals of fixation are anatomic reduction, stability, and early function to promote healing.

1. RIGID INTERNAL FIXATION
Presented by-
Dr.Shibani Sarangi
M.D.S . II year

2. 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 osteosynthesis ?
Osteosynthesis is the reduction and internal fixation of a bone fracture with implantable
devices that are usually made of metal. It is a surgical procedure with an open or percutaneous
approach to the fractured bone. It aims to bring the fractured bone ends together and
immobilize the fracture site while healing takes place. In a fracture that is rigidly immobilized
the fracture heals by the process of intramembranous ossification.

3. Rigid fixation
• It can be definesd as any type of directly applied bone fixation that prevents the
interfragmentary movements between the fracture segments, when the bone is
under active load.
• It rely on two point fixation- a stabilising unit & a tension band.
Non rigid fixation
• In this method of fixation :interfragmentary movements across the fracture lines
is allowed.
• This technique has been termed as functionally stable as it allows activation of
Mandible during healing ,even with interfragmentary motions.

4. • INDICATIONS-
• Trauma- facial bone fracture
• Orthognathic surgery
• Reconstruction of craniofacial deformities
• Reconstruction of bony defects secondary to ablative tumour surgery.
• Augmentation of atrophic mandible in the elderly
• Iatrogenic secondary to anterior/ lateral mandibulotomy.

5. History of Fracture Treatment and Development Of Modern Osteosynthesis
• In the Preantibiotic era, closed reduction of fractures was understandably the rule for
most fractures. However, when closed reduction was insufficient, external fixation
appliances served to maintain skeletal units in position, frequently without the need for
MMF (Maxillo-mandibular fixation) .Following the development of antibiotics, the open
treatment of fractures began to be used on a more frequent basis.

6. -Bone fractures have been treated with various conservative techniques for centuries and
it was not until the eighteenth century that internal fixation was first documented. -
 Icart, a French surgeon in Castres, performed ligature fixation with brass wire on a young
man with a humeral fracture.
 Lambotte developed and manufactured a variety of bone plates and screws and much of
his armamentarim remained in use until the 1950s.
 1970s-titanium ERA
 Luhr helped advance the principles of compression and dynamic compression, but it
wasn’t until 1977 that he developed these techniques to the maxillofacial skeleton.
 Spiessl later popularized dynamic compression bone plating of the mandible using
Arbeitsgemeinschaft für Osteosynthesefragen-Association for the Study of Internal
Fixation (AO-ASIF) techniques.

7. BIOLOGY OF BONE HEALING

10. BIOPHYSICS OF THE FACIAL SKELETON
• Although complex, the facial skeleton does not consist
of many moving parts. The major axis of bony motion
in the face is around the mandibular condyles, or TMJ.
The muscles of facial expression originate on various
bones of the craniomaxillofacial skeleton, are invested
in the superficial musculoaponeurotic system, and
insert on each other and the facial skin. These have
little effect on forces exerted on facial bones.
• The muscles of mastication and suprahyoid muscles,
however, produce significant forces on the jaws and
surrounding osseous structures. Bite force is generated
by contracture of the masseters, temporalis, & medial
pterygoids; the sum of these vectors allows for
occlusion of the teeth via movement of the mandible.
• Due to its dynamic nature, the mandible bears most of
the forces applied by facial musculature to the skeleton.

11. Beam mechanics dictates that the mandible is a class III lever, with the condyle being the
fulcrum, the muscles of mastication acting as the applied force, and bite load acting as the
resistance This rationale applies to one side of the mandible at a time, but as a horseshoe
shaped bone, the mandible is more than a simple class III lever.

12. Mechanical Stress on mandible under Function
• The force of the masseter, medial pterygoid, and temporalis muscle results in upward
and forward vector of force on the posterior aspect of the mandible.
• The suprahyoid musculature places a downward and posterior force on the anterior
portion of the mandible.
• With the pterygomasseteric sling functioning as a point of fulcrum, the superior border of
the angle/posterior mandible is placed under tension while the inferior border is placed
under compression.

13. INTERNAL FIXATION
• Internal fixation permits more precise anatomical bone reduction of the fracture site but
requires direct surgical exposure of fractures, especially for transosseous wiring or plate
fixation.
• Internal fixation of mandibles can be undertaken in the following ways-
 Circumferential wiring or nylon straps
 Transosseous wiring;upper and lower border
 Intramedullary pins; kirschners wire or Steinmann pin
 Rigid internal fixations

14. PRINCIPLES OF FIXATION
• AO-ASIF guidelines of rigid fixation follow four basic principles to ensure adequate
treatment of fractures:-
Bony segment reduction
Stable fixation
Immobilization of fragments
Maintaining blood supply &early function.

15. CLASSIFICATION
Fixation methods
Non rigid fixation
Direct Transosseous
wires
Rigid fixation
Static bone plates
Dynamic compression plates
Eccentric compression plates
Reconstruction plates
External pin fixation
Semirigid fixation
Lag screws
Miniplates/Microplates
Locking plates
3D plates
Resorbable plates

16. ADVANTAGES OF RIF
• Permits primary bone healing
• Increases 3D mechanical and functional stability
• Allows precise anatomic reduction and enhance bone healing
• Requires no distraction of the fracture cleft
• Requires no additional fixation
• Provides greater patient comfort- airway maintained and function is
immediately restored

17. Materials used for RIF
• Metallic and Resorbable(biodegradable) osteosynthetic devices.
• 1. Metallic
-Stainless steel
- Vitallium - trade name for alloy of chromium, cobalt & molybdenium
-Titanium
• 2. Resorbable materials
-Polylactic acid(PLA)
- Polyglycolic acid(PGA)
- Polydioxanone(PDA)
-Copoloymers e.g PLLA+PDLA; PLLA + PGA(Lacto Sorb)

18. Various concepts of Fixation
 Rigid internal fixation & Non rigid fixation
 Load-bearing & load-sharing fixation
 Compression & Non compression plates osteosynthesis
 Locking & Non locking plate-screw system

19. • Rigid internal fixation
• It rely on two point fixation—a
stabilizing unit, such as a bone plate
at the inferior border, and a tension
band, such as a miniplate or arch bar
superior to that.
• They have minimal gap
(>100microns) between the bone
segments allows for
primary bone healing
• Contact healing
•Non rigid internal fixation
• Allows interfragmentary movements.
• Depending on the magnitude of
movement across the fracture, nonrigid
fixation may result in nonunion or
malunion.
• Champy’s method for the fixation of
angle fractures-functionally stable

20. Load bearing Load sharing

21. Non locking plates
Requires precise adaptation of the plate to
underlying bone
Without intimate contact, tightening of the
screws will draw the bone segments towards
the plate,resulting alterations in position of
osseous segments & occlusal relationship
Compress the undersurface of the plate to
the cortical bone.
Increased incidence of inflammatory
complications from loosening of the
hardware
Unnecessary for the plate to intimately
contact the underlying bone in all areas.
As the screws are tightened, they "lock"
to the plate, thus stabilizing the segments
without the need to compress the bone
to the plate
Do not disrupt the underlying cortical
bone perfusion as much as conventional
plates
Unlikely to loosen from the plate
Non locking plates Locking plates

22. COMPRESSION PLATE OSTEOSYNTHESIS
• Goal of compression osteosynthesis is establishing absolute stability across a fracture .
• This is defined as zero movement occurring between bone across fracture ,as well as
complete immobility of hardware.
Regular EDCP

23. RETENTION HOLE
COMPRESSION HOLE

25. • Promotes contact healing
• Linear compression-counteracts
torsional forces
• Excellent stability
Advantages
• Technique sensitive
• -Distract the fracture segment
• -Creates gap
• - Malocclusion
• Thickness is more
Disadvantages

26. NONCOMPRESSION OSTEOSYNTHESIS
• Noncompression osteosynthesis is widely used in managing traumatic injuries to the
maxillofacial skeleton. This can be accomplished with a variety of methods
-Non-compression bone plates and reconstruction plates, both of which
are available with locking mechanisms.
MANDIBULAR FIXATION
LOCKING PLATES
MINIPLATES
RECONSTRUCTION PLATES

27. MANDIBULAR FIXATION
 Fixation must be sufficient to withstand masticatory forces during the healing period.
 Fracture plates are manufactured in various widths and universal fixation systems
generally allow interchangeable screw diameters to be used in multiple plates, depending
on the level of fixation desired.
 Other factors that should be taken into account when selecting the width of the fracture
plate are
- quantity and quality of overlying soft tissue,
- patient compliance, and
- risk of reinjury.
• Thicker plates provide more stability than thinner counterparts, but may be palpable
under soft tissue, may require more dissection, are more difficult to adapt, and have
higher rates of dehiscence.

28. Plate selection
fracture
exposed and
reduced
plate is
adapted to
buccal cortex
held in place
using plate
Holding forceps

29. Locking plates-
• Useful in securing plates that cannot be perfectly adapted to fractures or if bone quality
is poor.
-Locking screws are double-threaded;
- head of the screw has an additional larger diameter thread that secures into the
thread pattern of the plate hole.
• Locking plate and screw systems prevent loosening and extrusion of the screw from the
plate, even if it does not integrate to the mandible and resists mechanical yielding
under stress.

30. Miniplates
• Champy et al (1976,1978)popularized the treatment of mandible fracture with
miniplatyes fixation along the ideal lines of osteosynthesis .This is a form of looad-sharing
osteosynthesis too be applied in the simple fracture patterns having acceptable amount
of bone.
MONOCORTICAL tension banding osteosynthesis neutarilses
distraction and torsional during physiologic stress

32.  Reconstruction plates
 They are the thicker entity, designed for
load bearing purpose.
 Can be used to reconstruct mandible
with/without grafts
 Indications-
-Grossly comminuted fractures
-Atrophic Mandible
-Grossly unstable fracture
 Disadvantage- Higher degree of elastic
deformation
-

34. RECENT ADVANCES

35. UFP (Universal Fracture Plate) 2.4mm

36. LAG SCREWS(Brons and Boering)
• The premise of this technique is its ability to
engage and pull, or lag, the distal cortex
toward the proximal cortex across a
fracture.
• Lag screw osteosynthesis directly traverses
the fracture line, more evenly distributing
compressive forces between segments and
resulting in excellent stability and minimal
to no lingual splay.
• Lag screw osteosynthesis is a fracture compression technique that can be carried out
by using true lag screws or a lag technique with long bone screws fixation of transverse
mandibular symphysis and parasymphysis fractures or obliquely oriented body and angle
fractures.

38. Bioabsorbable plates
• First reported by Getter et al(1972) who reported plates made of polylactic acid.
• Polyglyolic acid plates were later on discoved by Vert et al (1984)
• Ewers & Forster (1985) used the polydioxane plates
• Work by Bos(1989),Rozema(1991) and Suuronen(1992) lead to invent to
Poly(L-lactide) plates

39. Resorption of Polyglycolic [plates]
PGA
GLYCOLIC ACID
URINE
GLYOXYLATE
GLYCIN
SERINE
PLA
LACTIC ACID
PYRUVATE
ACETYL CoA
CITRIC ACID CYCLE
H2O +CO2
•Excretion- urine,
faeces, expired air.
•Degradation time depends
on - temperature, pH,
presence of water,
mechanical strain on
implant,
polymer configuration

40. MIDFACE AND UPPER FACE FIXATION
 The zygoma is the only other bone that displays significant effects from the masticatory
musculature. Complex craniomaxillofacial trauma involving the frontal sinus, orbits, naso-orbito-
ethmoid (NOE) complex, zygomaticomaxillary complex, and maxilla-miniplate or microplate
fixation.
 Thin soft tissue and overlying skin encasing the orbital and nasal complexes requires low-profile
plates to prevent
- show-through,
- palpability, or
- dehiscence
 Compared with the mandible, midface and upper facial bones are thinner and more fragile. It is
important to take advantage of the facial buttresses in fixating fractures to achieve screw and
fracture stability
 Even with the pull of the masseter attachment at the zygoma, zygomaticomaxillary complex
fractures can be managed with miniplate or microplate fixation at multiple points, with stable
results.
 The contraction of the masseter muscle produces distracting forces at the zygomaticofrontal and
zygomaticomaxillary sutures, both of which are important points of fixation, with adequate bone
stock for screw stability.

42. Surgical Approaches
 Use of existing laceration/Extraoral
 Intraoral
-Makes use of a degloving vestibular incision
-With appropriate instruments and skill, can be used from symphysis
to condyle.
 Combined approach( Mitchel et al 1973)
-

43. Submental
Simple or extended
Submandibular Retromandibular
Preauricular Facelift/ Rhytidectomy Extraoral approach
using Trocar

44. COMPLICATIONS
 Dental injury
 Sensory nerve injury-
Inferior alveolar
Mental
Infraorbital
Supraorbital
 Motor nerve injury- Marginal mandibular branch
 Malocclusion
 Infections-
Minor-Not necessitating plate removal
Major-Neceissitating plate removal
 Metal allergy
 Hypertrohic scar formation

45. References
• Rowe and Williams-Maxillofacial injuries 2nd edtn
• Oral and Maxillofacial trauma,Fonseca 4th edtn Part-I
• Oral and Maxillofacial trauma,Fonseca 4th edtn Part-II
• Peterson’s oral and maxillofacial surgery,I

46. THANK YOU