Bone cements are widely used for various orthopedic and trauma surgery

1. SPINAL FIXATION
&
BONE CEMENT

2. SPINAL FIXATION
It is an orthopaedic surgical
procedure in which two or more vertebrae are
anchored to each other through a synthetic
vertebral fixation device , with the aim of
reducing vertebral mobility and damage to
spinal cord / spinal root.

3. REASON FOR SPINAL FIXATION
 Pressure on the spinal cord / nerves
 Disc herniation : rubbery disc between spinal bones
 Spinal stenosis : abnormal narrowing of the spinal
canal
 Trauma : injury or damage caused by physical harm
 Spinal tumours

4. VERTEBRAL FIXATION DEVICES
 The device used to achieve a vertebral fixation is a
permanent rigid or semi-rigid prosthesis made of
titanium . Eg; rods, plates, screws and various
combinations.
 It stabilises the area of posterior spine limiting the
compression of the affected vertebrae .
 Device consist of two or more arm assemblies
connected by one or more telescopic assemblies.
 Left and right arms are connected to the corresponding
side of central portion of the arm assembly.

6. SPINAL FUSION
 Also called spondylodesis or spondylosyndesis is
a neurosurgical or orthopaedic surgical
technique that joins two or more vertebrae.
 It can be performed at any levels in the spine
(cervical ,thoracic or lumbar ).
 Bone grafts ( autograft ,allograft or artificial
bone substitutes ) are used.

7.  Additional hardware ( screws , plates, or cages
) are used to hold the bone while the graft fuses
two vertebrae together.

8.  It may be done as a follow up after surgery to
treat spinal stenosis , injuries , infection ,
tumours , herniated discs etc
 The risk of the surgery depends on age , health
and the type of surgery procedure. The risks
include :
 Pain at the graft site
Failure of the fusion , breakage of implants
Nerve injury
Graft rejection

10. SURGICAL INSTUMENTS USED

12. BONE CEMENT

13. BONE CEMENT
The successful & long-term performance of orthopedic
implants depends on
 implant material
 prosthesis design
 biocompatibility of the component
 wear of the articular surfaces,
 quality of the bone
 stability of fixation.

14.  Long-term stability of fixation in bone can be achieved
by either biological or cemented anchorage.
 Biological anchorage is achieved by ingrowth of bone,
thus inducing an intimate contact of the tissue to the
implant surfaces.
 Cemented anchorage achieves fixation with the help of
a form-fitting cement that fills the gaps between the
implant and the inner surface of the trabecular bone.
 The word cement is used to describe a substance that
bonds two things together.

15.  Cementing with self-curing substances was the
first, and initially the only, technique to achieve
a stable fixation of the implants
 Today, polymethylmethacrylate (PMMA) bone
cement is a widely used method of implant
fixation.
 Cement fixation remains the gold standard,
against which all forms of implant fixation
techniques are assessed.

16. PMMA AS BONE CEMENT
 First bone cement was used in orthopaedics by
Dr. John Charnley (1958) for total hip
arthroplasty.
 PMMA is formed by liquid MMA monomer and
powdered MMA - styrene co-polymer.
 In order to make it radiopaque a contrast agent
is added . Commercially available cement use
either zirconium dioxide or barium sulphate.

18.  Bone cements are usually supplied as two
component systems , made up of liquid and powder
 The powder mainly consists of bead-shaped
particles (dia 40 microns)
 These particles contain, homopolymer PMMA
and/or methyl methacrylate copolymers.
 one of the three activators of the polymerization
process, benzoyl peroxide or ZrO2, or (BaSO4) to
provide radiodensity

19.  And antibiotic, which is, in most cases,
aminoglycoside gentamicin.
 The liquid as the second component mainly
contains the monomer MMA but also the
second activator of the polymerization process,
N,N-Dimethyl para-toluidine
 hydroquinone as a stabilizer to prevent self-
curing of the monomer in the liquid during
storage.

20. PROPERTIES OF BONE
CEMENT
 Biocompatible
 Compressive strength is 70 MPa
 Bending modulus is 50 MPa
 Porosity
 Tensile strength is 35.3 MPa
 Shear strength is 42.2 MPa

23. ADVERSE REACTIONS ASSOCIATES
WITH ACRYLIC BONE CEMENTS
 Transitory fall in blood pressure.
 Elevated serum gamma-glutamyl-transpeptidase
(GGTP) upto 10 days post-operation.
 Thrombophlebitis.
 Loosening or displacement of the prosthesis.

24.  Superficial or deep wound infection.
 Trochanteric bursitis.
 Short-term cardiac conduction irregularities.
 Heterotopic new bone formation.
 Trochanteric separation.

25. DRAW BACKS OF BONE
CEMENT
 The main drawbacks of bone cement in joint
replacement is cement fragmentation and foreign body
reaction to wear debris, results in prosthetic loosening
and periprosthetic osteolysis.
 The production of wear particles from roughened
metallic surfaces and from the PMMA cement promotes
local inflammatory activity, resulting in chronic
complications to hip replacements.

26.  Bone cement generates heat as it cures and
contracts and later expands due to water
absorption. It is neither osteoinductive nor
osteoconductive and does not remodel.
 The monomer is toxic and there is a potential
for allergic reactions to cement constituents.