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ALLOFITACETABULARHIP SYSTEM
SurgicalTechnique
Unique ridgelocksurface designed foreasy implantationand stability
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ALLOFIT ACETABULARSYSTEM
Developed in conjunction with:
Nikolaus Boehler, MD
University Professor of Orthopedic Surgery
General Hospital
Linz, Austria
Wolfgang Schwaegerl, MD
University Professor of Orthopedic SurgeryVienna, Austria
CONTENTS
INTRODUCTION ................................................................... 2
PREOPERATIVE PLANNING ............................................ 3EXPOSURE OF THE ACETABULUM ............................. 3
REAMING THE ACETABULUM ....................................... 4
SELECTION OF IMPLANT SIZE .....................................5
IMPLANTING THE TITANIUM SHELL WITHOUT
SCREWHOLES ....................................................................... 6
IMPLANTING THE TITANIUM SHELL WITH
SCREWHOLES ....................................................................... 7
INSERTION OF SCREWS...................................................8
FITTING OF THE TRIAL INSERT ....................................9FITTING OF THE CUP INSERT ......................................10
REMOVING THE LINER ...................................................10
ORDERING INFORMATION ........................................... 11
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ALLOFIT ACETABULAR
SYSTEMSince its first use in 1993, the Allofit Acetabular
Cup System has gained popularity among
hundreds of orthopedic surgeons. It provides the
surgeon with a reliable prosthesis that is easy
to handle. The surgeon can individually select
the acetabular components most suitable in an
economical and practical framework.
Its unique geometry assures minimal bone
resection and aims to reestablish a secure and
physiological load transfer through the periphery
of the cup. The Allofit Acetabular Cup System
features a patented Ridgelock macro structure
that greatly supports primary stability of the
3mm titanium shell. Permanent secondary
fixation is achieved by the choice of a grit-blasted
commercially pure titanium surface.
To prevent failure due to incomplete metal
backing of the insert, the Allofit System offers
sufficient polyethylene wall thickness for inserts.All screwholes in the titanium shell are designed
so they can be sealed. The congruent insert
is seated and secured in the shell by a snap
mechanism that firmly holds the insert in place.
Allofit offers an industry-leading set of alternative
bearing options, addressing the most dominant
complications in THAlate loosening and
dislocation.
Durasul highly crosslinked polyethylene, which has shown nomeasurable wear on a physiological hip simulator. Available instandard and hooded options and 28 and 32mm articulating
diameters.
Metasul metal-on-metal inserts used for over 15 years in morethan 200,000 patients worldwide. Available in standard andhooded options and 28mm articulating diameter.
Sulene conventional polyethylene with increased crosslinkingand improved long-term stability due to gamma sterilizationunder nitrogen gas atmosphere. Available in 28 and 32mmarticulating diameters.
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Preoperative PlanningPreoperative planning is undertaken using the
X-ray templates and a current X-ray of the pelvis,
in which the inferior edge of the symphysis liesin the center of the picture. The object of the
planning is to determine the most favorable
position of the implant and its approximate
size, as well as to anticipate possible operative
difficulties. A stable acetabular floor capable of
bearing loads and a sol id lateral bony cover are
desirable. The prerequisite for the implantation of
a primary stable cup is an extensively maintained
bony circumference of the acetabulum.
In dysplasia cases, the pre-operative planning
helps in deciding whether the implant position
must be strengthened by bone graft material.
The axis of the artificial joint should approximate
physiological conditions as closely as possible.
The opening plane of the cup should form an
angle of 40-45 to the pelvis horizontal line.
The subchondral sclerosis line between oriel
and lacrimal figure serves as a reference point
for estimating the cup diameter. The cup will
receive an anteversion of 10-15 intraoperatively.
It is also to be kept in mind that the correct
cup orientation depends on the position of the
femoral implant.
ApproachAny usual approach is possible.
Exposure of theAcetabulumThe capsule is preferably excised in its entire
circumference to the extent that an easy
introduction of reamers is possible. Remove
fibrous, cartilaginous and bone structures
preventing the preparation of the acetabulum.
Fig. 1
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Fig. 2
Reaming the AcetabulumThe next stage is preparation of the
acetabulum with the spherical reamers until
the predetermined size has been reached. The
desired objective is based upon the following
conditions:
anatomically formed implant support
preservation of bone stock to assure a solid
support of the implant
certainty of anchoring the cup shell in good
vascular bone
The objective is the creation of the geometrical
and physiological requirements for a primary and
permanently stable implantation of the titanium
shell.
Important: Extreme caution must be used when
reaming in order to prevent excessive removal
of bone and not to alter the morphology of the
acetabulum.
The central acetabular floor is first reamed
with a relatively small reamer and deepenedaccording to the preoperative planning. The use
of centering pins is optional. When the necessary
depth has been reached, the reamer is moved to
an inclination of about 40 and a hemispherical
support is formed with the use of larger reamers.
This cranial reamer direction is maintained until:
1. the necessary depth has been attained; and
2. 50-60% of the acetabular roof has been
reamed to bleeding bone.
The anterior and posterior acetabular roof must
remain stable and solid. The reaming process
has ended when these conditions have been
achieved.
To obtain optimal implant support and to avoid
thermal necrosis, the final reamer should be
operated by hand. In normal cases, it will be
introduced to a depth such that its equator
is entirely covered by bone. Dysplastic hipsrepresent an exception because it is necessary to
create an additional abutment.
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Selection of the ImplantSizeIt is possible to test whether a cup of a given
diameter can be implanted in the optimumposition with the aid of the trial shell. The size
indication of the trial shell corresponds to the
reamer last used. After attachment to the cup
setting instrument, the trial shell is tapped in
up to the bony acetabular floor at the desired
abduction and anteversion. It should show stable
seating under pulling, rotating and careful tilting
loads. The contact between acetabular floor and
trial shell can be tested with the measurement
hook, after the setting instrument has been
unscrewed.
If the trial shell does not have a sufficiently firm
seat, it must be checked as to whether the edge
of the trial implant is anchored in bone. If this is
not the case, the acetabulum must be suitably
deepened with the reamer last used. If the trial
shell is not seated firmly enough in spite of a
sufficient bony enclosure, the next largest trial
shell is selected. In case of soft bone, additional
primary anchoring with at least two cancellous
bone screws should be performed.
Caution: To protect the acetabulum, the trial shell
is about 1mm smaller than the implant of the same
size designation. This is because the definitive
prosthesis has a surface macro structure that is not
present on the trial shell. The implant will thus have
a firmer seat compared to the trial.
The trial shell is then removed by tipping out.
Fig. 3
SELECTION OF THE IMPLANT SIZE
Size marked onreamer, shell,
implant
Actualtrial shell (mm)
Actual sizeimplant (mm)
Correspondingliner size
46 47 48 FF
48 49 50 GG
50 51 52 HH
52 53 54 II
54 55 56 JJ
56 57 58 KK
58 59 60 LL
60 61 62 MM
62 63 64 NN
64 65 66 OO
66* 67 68 PP
68* 69 70 QU
*sizes not available without screwholes
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Implanting the TitaniumShell without ScrewholesThe titanium shell is completely screwed to the
setting instrument and tapped in with the desiredabduction and anteversion. The anteversion
depends on the selected operative approach, the
anatomical conditions and the femoral implant.
It is absolutely necessary to align the cup before
final impaction and to maintain the selected
setting direction.
The measurement hook is used to check whether
the implant was driven to the acetabular floor. As
can be seen in Figure 7, because of the specificgeometry of the cup, a small gap of about 1mm
might be present at the dome area even if the cup
is completely seated. The shell must maintain its
stable seating under pulling, rotational and tilting
loads.
A threaded dome hole plug is supplied with every
implant. The hole at the pole of the titanium shell
must be seated with it, otherwise the cup insert
cannot be mounted correctly. The dome holeplug is placed on the corresponding placement
instrument and screwed into the borehole.
If a trial reduction with a trial insert is planned,
do not insert the dome hole plug (see page 9).
Fig. 4
Fig. 5
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Implanting the TitaniumShell with ScrewholesThe titanium shell is completely screwed to the
shell setting instrument and is tapped in withthe desired abduction and anteversion. The
anteversion depends on the operative approach
selected, the anatomical conditions, and the
femoral implant. It is absolutely necessary to
correctly align the shell before final impaction,
since its position can no longer be altered
afterwards.
A notch in the equator of the shell indicates the
main direction of the screwholes. The holesmust be placed correctly in the direction of
the resulting hip forces. No other orientation is
suitable biomechanically and such an orientation
may moreover entail the danger of vascular and
nerve lesions by the screws.
The measurement hook is used to test whether
the implant was driven to the acetabular floor. As
can be seen in Figure 7, because of the specific
geometry of the cup, a small gap of about 1mmmight be present at the dome area even if the cup
is completely seated. The shell must maintain
its stable position under pulling, rotational and
tilting loads.
A threaded dome hole plug is supplied with every
implant. The hole at the pole of the titanium shell
must be sealed with it, otherwise the cup insert
cannot be mounted correctly. The dome hole
plug is placed on the corresponding placement
instrument and screwed into the borehole.
If a trial reduction with a trial insert is planned,
the dome hole must not yet be closed (see page
9).
Fig. 6
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Insertion of ScrewsFlat-head cancellous bone screws ( 6.5 mm,
reference #4301-07-015/070) must be used.
To simplify the initial insertion of the screws,
3.2mm holes are drilled through the subchondral
bone. The use of an angular drill gear with a drill
guide is recommended because it facilitates the
correct orientation of the holes in the center of
the screw funnel and vertically to the shell and
off-center insertion of the screws can lead to
damage of the screw or the screwhole and to a
possible dislodgement of the shell.
Tapping of the drill holes is only recommended in
cases of especially hard bone.
Since the screws are only to be anchored in
cancellous bone, lengths of up to 30mm are
normally sufficient. The screws must not
penetrate the opposite cortex. The geometry
of the screw funnel permits the screws to be
oriented within a range of 30 degrees.
Caution: The specified Ti-6Al-4V screws have a
lower shearing resistance than screws made of
steel or CoCrMo alloys.
It is recommended to check whether all screws
are completely seated before impacting the
insert. Projecting screw heads would make the
fitting of the cup insert impossible.
Screwholes in the titanium shell that are not
used can each be sealed with a screw plug.
The plug is placed on the appropriate setting
instrument and fixed in the screw funnel of thetitanium shell with a light tap. These screw plugs
are intended for one-time use only, and cannot
be removed any more once inserted.
Fig. 7
Fig. 8
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Fitting of the Trial InsertWash the operative site thoroughly and carefully
clean the titanium shell.
It is recommended to manually place the trialinsert into the implanted shell.
The trial insert can be fixed into the titanium
shell by screwing in the attachment screw into
the dome hole of the implant. If the dome hole
plug has already been placed into the shell, it
must temporarily be removed.
Femoral ComponentIf alternative bearing surfaces are used, caremust be taken to select the appropriate femoral
head.
After implanting the femoral component, a trial
reduction is made to determine the correct size
of acetabular insert to be implanted. The trial
insert is then removed.
Fig. 9
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Removing the LinerIf the disassembly of an already firmly seated
insert becomes necessary, the following
procedure is often successful: A cancellous
bone screw is inserted into the polyethylene
insert after making a small pilot drill hole. This
is done centrally in the case of polyethylene
inserts and decentrally between articulating
surface and shell edge with Metasul inserts, ifthe polyethylene body is sufficiently strong for
the purpose. It is also possible to attempt to
lever out the insert at the edge with one or two
osteotomes.
The inside edge of the shell, where the locking
mechanism for the insert is located, must be
protected if a new insert is to be fitted.
If a new insert can no longer be reliably anchored
in the old shell, the shell must be replaced.
Follow-up TreatmentA partial loading of the operated hip during the
first 6 weeks is advisable.
Fitting of the Cup InsertInterposed tissues in the titanium shell or at the
shell edge must be avoided since they prevent
the insert from snapping in. The shell edge must
be free from any tissue and particular attention
must be paid to the posterior-inferior bony edge
of the acetabulum.
Caution: The dome hole plug must be properly
inserted before impaction of the insert. It is
important that the dome hole plug is in place as it
plays a vital role in the alignment of the insert.
The size of cup inserts is indicated with a
letter code. This code corresponds to the size
indicated on the corresponding titanium shell
(see table on page 5) The appropriate modular
liner attachment is screwed onto the liner
impactor.
The insert is then attached to the setting
instrument, introduced into the cleaned shell,
and is carefully centered. The polyethylene guide
nipple must be centered in the hole of the dome
hole plug before impaction.
A couple of firm hammer blows on the setting
instrument are sufficient to snap the insert into
the shell. Once fully impacted, the phase of the
liner will be approximately 2mm above the rim of
the titanium shell. If the insert was not properly
aligned, deformation of the guiding nipple might
occurthe insert can not be impacted and a new
insert must be used.
In order to avoid any scratching of the delicate
surface, Metasul liners must be handled with
care.
Note: The modular liner attachment for Metasul
28mm liners can also be used for polyethylene
28mm liners.
Fig. 10
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Ordering InformationALLOFIT SHELLS
Catalog No. Description
4242 Allofit Shell 46/FF
4243 Allofit Shell 48/GG4244 Allofit Shell 50/HH
4245 Allofit Shell 52/II
4246 Allofit Shell 54/JJ
4247 Allofit Shell 56/KK
4248 Allofit Shell 58/LL
4249 Allofit Shell 60/MM
4250 Allofit Shell 62/NN
4251 Allofit Shell 64/OO
ALLOFIT-S SHELLS
Catalog No. Description
4262 Allofit-S Shell 46/FF4263 Allofit-S Shell 48/GG
4264 Allofit-S Shell 50/HH
4265 Allofit-S Shell 52/II
4266 Allofit-S Shell 54/JJ
4267 Allofit-S Shell 56/KK
4268 Allofit-S Shell 58/LL
4269 Allofit-S Shell 60/MM
4270 Allofit-S Shell 62/NN
4271 Allofit-S Shell 64/OO
4272 Allofit-S Shell 66/PP
4273 Allofit-S Shell 68/QU
ALLOFIT DOME HOLE PLUG
Catalog No. Description
001.00004.000 Dome Hole Plug
ALLOFIT SCREWHOLE SEALS
Catalog No. Description
001.00004.001 Screwhole Seals 7 pcs.
STANDARD METASUL INSERTS
Catalog No. Description
01.00010.407 Alpha Metasul 28 Standard GG/28
01.00010.408 Alpha Metasul 28 Standard HH/28
01.00010.409 Alpha Metasul 28 Standard II/28
01.00010.410 Alpha Metasul 28 Standard JJ/28
01.00010.411 Alpha Metasul 28 Standard KK/28
01.00010.412 Alpha Metasul 28 Standard LL/28
01.00010.413 Alpha Metasul 28 Standard MM/28
01.00010.414 Alpha Metasul 28 Standard NN/28
01.00010.415 Alpha Metasul 28 Standard OO/28
01.00010.416 Alpha Metasul 28 Standard PP/28
01.00010.417 Alpha Metasul 28 Standard QU/28
HOODED METASUL INSERTS
Catalog No. Description
01.00010.507 Alpha Metasul 28 Hooded GG/28
STANDARD DURASUL INSERTS
Catalog No. Description
01.00013.206 Alpha Durasul 28 Standard FF/28
01.00013.207 Alpha Durasul 28 Standard GG/28
01.00013.208 Alpha Durasul 28 Standard HH/28
01.00013.209 Alpha Durasul 28 Standard II/28
01.00013.210 Alpha Durasul 28 Standard JJ/28
01.00013.211 Alpha Durasul 28 Standard KK/28
01.00013.212 Alpha Durasul 28 Standard LL/28
01.00013.213 Alpha Durasul 28 Standard MM/28
01.00013.214 Alpha Durasul 28 Standard NN/28
01.00013.215 Alpha Durasul 28 Standard OO/28
01.00013.216 Alpha Durasul 28 Standard PP/28
01.00013.217 Alpha Durasul 28 Standard QU/28
HOODED DURASUL INSERTS
Catalog No. Description
01.00013.306 Alpha Durasul 28 Hooded FF/28
01.00013.307 Alpha Durasul 28 Hooded GG/28
01.00013.308 Alpha Durasul 28 Hooded HH/28
01.00013.309 Alpha Durasul 28 Hooded II /28
01.00013.310 Alpha Durasul 28 Hooded JJ/28
01.00013.311 Alpha Durasul 28 Hooded KK/28
01.00013.312 Alpha Durasul 28 Hooded LL/28
01.00013.313 Alpha Durasul 28 Hooded MM/2801.00013.314 Alpha Durasul 28 Hooded NN/28
01.00013.315 Alpha Durasul 28 Hooded OO/28
01.00013.316 Alpha Durasul 28 Hooded PP/28
01.00013.317 Alpha Durasul 28 Hooded QU/28
TRAY 1 (Sizes 46 to 58)
Catalog No. Description
8604 Instrument Case Size 48 to 56
7139 Instrument Tray Cover
REAMERS
Catalog No. Description
840.6002 Spherical Reamer 42
840.6003 Spherical Reamer 44
840.6004 Spherical Reamer 46
840.6005 Spherical Reamer 48
840.6006 Spherical Reamer 50
840.6007 Spherical Reamer 52
840.6008 Spherical Reamer 54
840.6009 Spherical Reamer 56
840.6010 Spherical Reamer 58
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GUARD FOR REAMER
Catalog No. Description
840.6043 Guard for Reamer 44
840.6044 Guard for Reamer 46
840.6045 Guard for Reamer 48
840.6046 Guard for Reamer 50
840.6047 Guard for Reamer 52
840.6048 Guard for Reamer 54
840.6049 Guard for Reamer 56
840.6050 Guard for Reamer 58
REAMER HANDLE
Catalog No. Description
MPF310034 Reamer Handle
CENTERING PINS
Catalog No. Description
840.6108 Centering Pin S
840.6109 Centering Pin M
840.6020 Centering Pin L
FIXATION SCREW
Catalog No. Description
8635 Fixation Screw M8
TRIAL SHELLS
Catalog No. Description
8609 Trial Shell Size 46
8610 Trial Shell Size 48
8611 Trial Shell Size 50
8612 Trial Shell Size 52
8613 Trial Shell Size 54
8614 Trial Shell Size 56
8615 Trial Shell Size 58
TRIAL INSERTS
Catalog No. Description
8623 Trial Insert Size FF/28
8624 Trial Insert Size GG/28
8625 Trial Insert Size HH/28
8626 Trial Insert Size II/28
8627 Trial Insert Size JJ/28
8628 Trial Insert Size KK/28
8629 Trial Insert Size LL/28
TRAY 2 (Sizes 60 to 68)
Catalog No. Description
8605 Instrument Case Size 60 to 68
7139 Instrument Tray Cover
REAMERS
Catalog No. Description
840.6011 Spherical Reamer 60
840.6012 Spherical Reamer 62
840.6013 Spherical Reamer 64
840.6014 Spherical Reamer 66
840.6015 Spherical Reamer 68
GUARD FOR REAMER
Catalog No. Description
840.6051 Guard for Reamer 60
840.6052 Guard for Reamer 62
840.6053 Guard for Reamer 64
840.6054 Guard for Reamer 66
840.6055 Guard for Reamer 68
TRIAL SHELLS
Catalog No. Description
8616 Trial Shell Size 60
8617 Trial Shell Size 62
8618 Trial Shell Size 64
8619 Trial Shell Size 66
8620 Trial Shell Size 68
TRIAL INSERTS
Catalog No. Description
8630 Trial Insert Size MM/28
8631 Trial Insert Size NN/28
8632 Trial Insert Size OO/28
8633 Trial Insert Size PP/28
8634 Trial Insert Size QU/28
TRAY 3 (Setting Instruments)
Catalog No. Description
8606 Instrument Setting Instruments Case
7139 Instrument Tray Cover
SETTING INSTRUMENTS
Catalog No. Description
7344 Impactor 28
8638 Impactor Straight for Titanium Shell
01.00019.005 Impactor Straight for Alpha Liner
01.00009.001 Dome Hole Plug Instrument
01.00019.004 Impactor Curved for Alpha Liner (optional)
8639 Setting Instrument for Screw Plug
5633 Control Hook
01.00019.107 Liner At tachment Standard 28
01.00019.109 Liner At tachment Hooded 28
01.00019.110 Liner At tachment Hooded 32
7843 Positioning Guide
75.12.00-10 Impactor Curved for Titanium Shell (optional)
8667 Adapter for Curved Impactor 75.12.00-10
(optional)
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TRAY 4 (INTER-OP INSTRUMENTATION FOR BONE SCREWS)
Catalog No. Description
9366-99-160 Inter-Op Acetabular System Screw
Instrument Case
9366-99-161 Inter-Op Acetabular System Screw
Instrument Tray #1
INSTRUMENTATION FOR BONE SCREWS
Catalog No. Description
9366-00-015 Straight Hex Head Screwdriver
9366-00-016 Universal Joint Hex Head Screwdriver
9366-00-017 Universal Joint Hex Head Shaft (Optional)
9366-00-040 Flexible Depth Gauge
9366-00-041 Inter-Op Acetabular System Drill Bit Size
3.2mm/35mm
9366-00-042 Inter-Op Acetabular System Drill Bit Size
3.2mm/50mm
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Please refer to package inserts for completeproduct information, including contraindications,warnings, precautions, and adverse effects.
Contact your Zimmer Representative or visit us atwww.zimmer.com.