Bone cement,Cementing Generations, Complications & Recent advances

Bone cement,
Cementing Generations,
Complications & Recent
Advances
Dr Sameer Ashar
AssistantProfessor
OrthopaedicsDepartment
Shri M.P.Shah govtmedicalcollege
Jamnagar

HISTORY
 1933- Otto Rohm put PMMA in the market.
Initially it was used to make dentures
and used in cranioplasty
 1943- German chemists discovered that
addition of dimethyle-para-toludine
(DMPT ) along with benzoyl peroxide
(BPO)polymerization can take place at
room temperature
2

HISTORY
 The success of PMMA in
orthopaedics is attributed
to Sir John Chrnley, son of a
Dentist.
 He did research in judet
prostheses
 He is well known for his low
friction arthroplasty
3

 While Charnley credited Kiar and Jansen for first use
of methyl methacrylate in 1951 ,they used very small
amount and did not created secure fixation
 Charnel first used methyl methacrylate to “cement”
femoral and acetabular components in place in 1958
which was a turning point in total hip replacement.
HISTORY
4

PROPERTIES OF BONE CEMENT
 Bone acts as “grout” and not as “glue” ,fixation is
achieved with interdigitations not with adhesion
 It is viscoelastic and Behaves like both fluid and
solid so it has four characteristics:
(1) Creep (2) stress relaxation (3)Damping (4)
Strain rate dependence of its mechanical
properties.
 It undergoes volumetric shrinkage after
polymerization.
5

CREEP
 In materials science, creep (sometimes
called cold flow) is the tendency of a
solid material to move slowly or deform
permanently under the influence of
mechanical stresses.
 Small amount of creep is desirable in early post
operative period but excessive amount is
undesirable.
6

 At the implant level the trend towards
polished tapered stem designs has been
facilitated by the visco-elastic properties of
PMMA. Robust evidence from both finite
element analysis and laboratory studies
indicates that the subsidence of a stem within
the cement mantle by the process of creep
protects the vital bone/cement interface and
hence the replacement overall.
JCJ Webb :J Bone Joint Surg Br July 2007 vol. 89-B no. 7 851-857
7

STRESS RELAXATION
 Stress relaxation is defined
as the change in stress with
time under constant strain
(deformation) . Just as with
creep, stress relaxation is
important for polymers at
body temperature, not
important for metals.
The Well-Cemented Total Hip Arthroplasty:
Theory and Practice 8

COMPOSITIONS OF BONE CEMENT
 Most bone cements have three similarities:
1) They based mainly on the same chemistry-PMMA
2) They are two part products-one part powder
polymer and other one liquid monomer
3) In term of constituents in most brand powder has
polymerised PMMA, an initiator of polymerization –
BPO and a radiopacifier similarly in liquid they have
MMA, an accelerator of polymerization-DMPT, and a
stabilizer-hydroquinone
9

COMPOSITIONS OF BONE CEMENT
10

POLYMERIZATION PROCESS
IT IS AN EXOTHERMIC PROCESS
11

PHASES
• On the use of bone cements different phases are distinguished:
mixing phase, waiting phase, application phase and setting
phase:
▬ MIXING PHASE: (up to 1 minute)
wetting and polymerization, cement relatively
liquid (low viscous), few chains, very movable;
At the end mixture is homogenous sticky mass
▬ WAITING PHASE: ( variable up to several minutes )
chain propagation, cement less liquid, more chains,
less movable; cement is neither “sticky” nor ‘hairy”.
▬ WORKING PHASE: ( 2-4 minutes )
chain propagation, reduced movability, increase
of viscosity heat generation;
▬ SETTING PHASE:
chain growth finished, no movability, cement
hardened, high temperature gradually settles and
undergoes volumetric shrinkage 12

VISCOSITY OF THE BONE CEMENT
• Low. These have a long waiting phase of three minutes, also known
as a sticky phase. The viscosity rapidly increases during the
working phase and the hardening phase is one to two minutes
long.
• Medium. There is a long waiting phase of three minutes, but during
the working phase, the viscosity only increases slowly.
Hardening takes between one minute 30 seconds, and
two minutes 30 seconds.
• High. A short waiting/sticky phase is followed by a long working
phase. The viscosity remains constant until the end of the
working phase. The hardening phase lasts between one
minute 30 seconds and two minutes.
13

PMMA polymer powder
60 sec-nitrogen freeze
specimen ,monomer on the
surface of polymer
2 min specimen
Draenert k,Draenert y, properties of bone cement. In
Breusch S,Malchau H The well cemented total hip
arthroplasty. Sturtz, Wurzburg, Germany: Springer
:2005. p. 93-102 14

FACTORS AFFECTING BONE CEMENT
 The ambient temperature - higher the temperature,
the shorter the phase and the colder the temperature,
the longer the phases.
 The mixing process - Mixing cement too quickly or too
aggressively can hasten the polymerization reaction
resulting in a reduced setting time.
 The powder to liquid ratio
If more liquid, or less powder, than required is
used, setting time will be prolonged; on the
other hand, if less liquid,ormore powder is used,
setting time will be shortened

EVOLUTION OF CEMENTING
TECHNIQUE
4TH GENERATION- Proximal and distal stem centralizers
16

VACCUM MIXING
VARIOUS VACCUM SYSTEMS
ADVANTAGE OF VACCUM MIXING IS –Reduction in micropores, better homogeneity and
thus prolonged life of implant
--Vertical paddles are better than horizontal
-- vacuum level of 0.25 to 0.05 is optimal for various
cements
-- cement collection under vacuum is an essential
part of porosity reduction
18

ANTIBIOTIC LOADED CEMENT
 In 1970 Bucholz mixed Gentamicin in PMMA for treatment of
prosthetic joint infection
 In 2003, FDA has approved three commercial antibiotic loaded
cement for revision for prosthetic joint infection.
 In their guidelines, AAOS has advised it’s use as prophylactic
measure only in cases where patient has significant risk
factors for infection.
 Intensions to add antibiotic to PMMA are to prevent bacterial
colonization on implant or to control an established infection.
19

DESIRED PROPERTIES OF ANTIBIOTICS FOR BONE CEMENT
 PHYSICAL PROPERTIES
- Heat stable
- Water soluble
- Doesn’t affect
polymerization and
cement strength
- Good release from
cured cement
 CHEMICAL PROPERTIES
-Broad spectrum of action
- Bactericidal at low
concentration
- Non toxic to humans and
lower incidence of drug
resistance
- Low protein binding
20

 ABLC may be defined as “low dose”—containing less than 2 g
of antibiotic per 40 g cement—or “high dose,” with greater
than 3.6 g of antibiotic per 40 g of cement.
 Use high-dose ABLC—at least 3.6 g of antibiotic per 40 g of
cement—as a spacer in stage one of a two-stage
reconstruction.
.
Penner MJ, Duncan CP, Masri BA: bone cements. J Arthroplasty14:209, 1999
 Doses as high as 6 to 8 g of antibiotic per 40 g of cement have
also been proven safe and effective.
Springer BD, Lee BC, Osmon D,. Clin Relat Res427:47-51, 2004.
22

CONCERNS ABOUT ALAC
 Induction of antibiotic resistance
 Prolonged release of antibiotics :- potential for drug
resistance
 Unsuitable antibiotics :-
• Heat labile-penicilins ,Tetracycline
• Affecting bone cement-Rifampicin affects settling of
cement
 Hypersensitivity and toxic side effects
23

COMPLICATIONS OF CEMENTING
MOST SERIOUS REACTIONS
 Pulmonary embolism
 Cardiac arrest
 Myocardial infarction
 CVA
MOST FREQUENT REACTION
Transient fall in blood pressure
ATTRIBUTED TO
 Absorption of MMA
 Embolization of bone marrow
 Lysis of blood cell and
marrow during exothermic
reaction
 Conversion of methyl
methacrylate to methacrylate
acid
Joint replacement
arthroplasty;2011
•OTHER ADVERSE REACTIONS ARE
• Thrombophlebitis
• Surgical wound infection
• Trochenteric bursitis
• Short term irregularities in
cardiac conduction
24

 Hypotensive episodes occur more in-
Elevated or high normal blood pressure, Hypovolemia,
Pre existing cardio-vascular abnormaly
 Onset :- usually within 10-20 seconds
 Lasts for :- 30 secs to 5-6 mins
 Adequate hydration and maximizing inhalational oxygen will
minimize hypotension and hypoxemia following cementing
 Vigilance from an anaesthesiologist is of paramount
importance during this phase of procedure.
25

 PERI-OPERATIVE MORTALITY AND METHYLMETHACRYLATE
TOXICITY
 Potential direct toxic effect of absorbed liquid monomer methyl
methacrylate is investigated in great detail during previous years by
various workers including Wilert et al,Sir Charnley and homsey et al.
etc.
 However recent evidences suggest that only cement is not necessary
for all adverse reactions**
 Based on these and other similar studies focus is now on material
released and embolization to lungs as a result of preparation of bone
**
•Modig J, Busch C, Olerud S, et al:. Acta Anaesthesiol Scand 19:28,1975
•Byrick RJ, Forbes D, Waddell JP: . Anesthesiology 65:213, 1986.
•Fahrney NR, Chandler HP, Danychuk K, J Bone Joint Surg 72A:19, 1990.
•Breusch SJ, Reitzel T, Schneider U, Volkmann M, Ewerbeck V,
Lukoschek M: Cemented hip prosthesis. Orthopade29:578–86, 2000 26

RADIOLOGY
Gruen’s zone for femoral
components DeLee and Charnley zones
29

RADIOLOGY
 The thickness of the
cement mantle should
not drop below 2 mm at
anyplace if at all
possible. It also should
be complete, i.e., it
should not allow metal-
bone contact
“WHITE OUT”
30

RADIOLOGY
 Barrack et al. in 1992 emphasised the quality of cementing,
and described four grades in postoperative radiographs:
A: complete filling of the medullary canal by bone cement,a so-called
≫white out≪ at the bone-cement interface,
B: slight radiolucency at the bone-cement interface,
C: radiolucency involving 50–99% of the bone-cement interface or a
defective or incomplete cement mantle,
D: definite radiolucency at the cement-bone interface of 100% in any
projection, or a failure to fill the canal with cement such that the tip
of the stem is not covered.
31

 technical problems that contribute to stem loosening:
1. Failure to remove the soft cancellous bone from the medial
surface of the femoral neck;.
2. Failure to provide a cement mantle of adequate thickness around
the entire stem; a thin column cracks easily
3. Removal of all trabecular bone from the canal, leaving a smooth
surface with no capacity for cement intrusion or failure to roughen
areas of smooth neocortex that surrounded previous implants.
4. Inadequate quantity of cement and failure to keep the bolus of cement
intact to avoid lamination.
5. Failure to pressurize the cement, resulting in inadequate flow of cement
into the interstices of the bone.
6. Failure to prevent stem motion while the cement is hardening.
7. Failure to position the component in a neutral alignment or centralized
within the femoral canal.
8. The presence of voids in the cement as a result of poor mixing or injecting
technique or allowing blood or fragments of bone to be mixed in the cement
32
RADIOLOGY

VARIOUS RESTRICTORS
34
DePuy Implantcast Smith & Nephew Universal Stryker Biomet

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