porous tta. surgical technique. user guide
DESCRIPTION
User guide for surgical procedure of an alternative to traditional TTA using MMT (Modified Maquet Technique). POROUS TTA supplies a full honeycomb cage with several sizes able to be implanted even in 2 Kg weight dogs. Cage is free inside osteotomy region and osteotomy is fixed by a plate using only 2-3 screws: 1 in tibia and other one (it is possible to use 2) in the crista tibiae. Mechanical stimuli are allowed in this way so bone grows inside porous structure very quickly. We have developed this product during last two years and we had changed several items. We have more than 50 clinical cases and product is ready to be commercialized. What advantages does present POROUS TTA? - First of all it is price. At this moment, almost in countries where economic crisis is strong, cost of surgery could be decisive for taking decisions related to make surgical procedure. This technique only use 1 cage, 1 plate and only 2-3 screws. So price is very cheap. - Lesser number of screws. So surgery cost and time decrease. - Lesser damage in bone due to lesser amount of screws. Lesser risk of fracture in the crista tibiae. - More mechanical stimuli in order to increase bonegrowth. This is due cage is dynamically compressed by the plate. - Fewer amounts of cages needed in the stock tray. With lesser amount of cage (only 13 instead 21 of RAPID) are covered all requirements of the procedure. You can control height of implantation so you can get intermediate advancements. - It is very rapid and easy to implant too. It could be accomplished only by one person in the surgical theatre. We have clinical cases operating both stifles at the same moment. - Suitable for small dogs (less than 5 Kg). This is a great market.TRANSCRIPT
P O R O U S T T A S u r g i c a l T e c h n i q u e
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POROUS TTA
Developed by:
P O R O U S T T A S u r g i c a l T e c h n i q u e
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1. Introduction
One of the most common visits to a veterinary hospital is related to limb in the dog´s paws.
Controversy exists for explaining this although it is thought that first cause is stifle´s affection, even
over coxofemoral joint. Since the beginning of the 20th century Anterior Cruciate Ligament (ACL)
rupture in dogs has been widely studied including details related to its origin, how to diagnose it and
what treatment is the most efficient. Scientific discussion has not brought conclusive results. Why
do patients´ cruciate ligaments rupture? How should affection be diagnosed? And finally, if patient
suffers cruciate ligament affection ¿how should it be treated; conservative or surgical treatment?
And related to surgical treatment ¿what technique: intracapsular, extracapsular or osteotomy?
Consensus is established about what is the origin of cruciate ligament affection: most of evaluated
and treated patients with this affection did not shown a traumatic origin. Stifle is affected by
inflammatory/degenerative processes that accompanied by subsequent microtraumas generate
affection of ACL collagen ultrastructure and losing of functionality.
Diagnose of this pathology includes clinical examination following by radiographic examinations and
other current methods (Magnetic Resonance, CT scan, ultrasound scan, ….) allowing the surgeon to
view rupture of cruciate ligament and/or joint´s changes due to ACL affection.
Maybe question most repeated in last 40 years in Veterinary Science is what should be done after
diagnosing ACL pathology. Multiple techniques have emerged during these last years supported by
best achieved results. They argued better immediate results, retarding joint degenerative pathology.
These innovative techniques were fostered by several factors: emerging diagnosing methods,
development of new biomaterials and implants, news skills of surgeons, etc. But maybe main reason
is that none of these techniques provides successful results in all cases.
Tibial tuberosity advancement was first described by Dr. Maquet. This belgium surgeon argued
that advancing the tibial tuberosity would reduce femorotibial contact forces in extension
position as well as retropatellar pressures in patients with stifle arthrosis.
Montavón, Tepic et al. (2002) argued that this behavior is similar in the dog so tibial tuberosity
advancement (TTA) counteracts cranial shear femorotibial forces in stifles with defective anterior
cruciate ligament. TTA tries to achieve a patella tendon angle of 90 degrees to the tibial plateau
with the stifle in 135 degrees of extension. This was studied using a 3D finite elements model for
3D reconstruction corresponding to a human cadaver knee specimen. This study demonstrated
that TTA technique reduced non only femoropatellar contact forces but also femorotibial contact
forces in extension position.
Decreasing of retropatellar pressure in dog after TTA has been experimentally demonstrated
recently (Hoffmann et al 2009). This reduction should protect patellar and femoral articular cartilage
avoiding ulterior injures.
P O R O U S T T A S u r g i c a l T e c h n i q u e
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2. Adventages
1. Simplify the surgical technique: partial osteotomy of crista tibiae enhances fixation stability in
such a way that fixation plate has a smaller size and lesser amount of screws is needed.
2. Shorten the convalescence: bone defect created after crista tibiae advancement is refilled by a
porous titanium cage providing an excellent fixation removing the need to place graft/bone
substitutes or similar.
3. POROUS TTA cage´s porosity fosters osteconduction accelerating bone ingrowth and
stabilization.
4. It is a minimally invasive surgical technique due to smaller size of the implant. This osteotomy
allows a shorter skin incision providing higher posterior comfort for patient (Artiles 2012).
5. Resources optimization: surgical procedure requires common used instruments in a veterinary
hospital avoiding spending money in specific instruments. It is an excellent solution and its price
is very interesting.
6. Technique is rapid, simple and reproductible. No bending of any implant.
3. Implants
The POROUS TTA procedure was developed by Instituto Tecnologico de Canarias through iterations
during clinical testing to best meet the exacting demands of the procedure.
• POROUS TTA Cages
Porous cages are made of Ti6Al4V ELI (ISO 5832-3). Several tibial tuberosity advancements are
provided (5 sizes: 12, 9, 6.5, 4.5 and 3 mm) and several widths for each advancement: 3 different
widths for advancements of 12, 9 and 6.5 mm; and 2 different widths for lesser advancements of 4.5
and 3 mm.
Multiple sizes of cages are disposable so surgeon has enough options during surgical procedure. In
order to decide which cage must be used it is important to understand nomenclature of cage´s
codification. Code includes three geometric measures of the cage: thickness (A), coinciding with
value of required tibial tuberosity advancement; width (B) and length (H).
Cage´s Code: A x B x H
• A: Advancement
• B: Width
• H: Length
P O R O U S T T A S u r g i c a l T e c h n i q u e
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12X23X30 12X20X30 12X17X30
9X20X26 9X17X26 9X14X26
6.5X17X20 6.5X14X20 6.5X11X20
4.5X11X13 4.5X8X13
3X7X8 3X5x8
• Plates
Plates are made of Titanium (Ti CP Grade 4, ISO 5832-2) so they are able to bent. It allows best
adjustment to dog anatomy although in most cases bending is not needed.
There are 6 sizes of plates distinguishing two groups according to their width: 7 mm or 4 mm. Wider
plates will be used in biggest dogs so they provide greater holes for using screws with greater
diameter.
Plates are non-straight excluding smaller one (4R). This fact provides polyvalence and best
adjustment to crista tibiae.
P O R O U S T T A S u r g i c a l T e c h n i q u e
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Plates dispose of two holes for cortex screws in crista tibiae (color code shown in the following
image: holes with diameter of 2.9 mm, red; holes with diameter of 2.2 mm, green) excluding smaller
one with has only one hole.
They have only one greater hole for tibial screw (color code shown in the following image: holes
with diameter of 3.7 mm, blue; holes with diameter of 2.9 mm, red; and holes with diameter of 2.2
mm, green)
Related to plate code, width (not confuse with thickness which is 1 mm in all plates) is linked with
the number on its name. The following letter is linked to its size: large (L), medium (M) and small (S).
The letter R is an exception for the only one straight plate.
• Self-tapping Cortex screws
Screws are made of Titanium alloy (Ti6Al4V, ISO 5832-3). Screws are self-tapping and Hex Head. Set
has four different measures of diameter (3.5, 2.7, 2 and 1.5 mm). Each diameter offers several
lengths showed in the following table:
Ø 1.5 mm Ø 2 mm Ø 2.7 mm Ø 3.5 mm
Ø 1.5 x 6 mm Ø 2 x 6 mm Ø 2,7 x 14 mm Ø 3,5 x 16 mm
Ø 1.5 x 8 mm Ø 2 x 8 mm Ø 2,7 x 16 mm Ø 3,5 x 18 mm
Ø 1.5 x 10 mm Ø 2 x 10 mm Ø 2,7 x 18 mm Ø 3,5 x 20 mm
Ø 1.5 x 12 mm Ø 2 x 12 mm Ø 2,7 x 20 mm Ø 3,5 x 22 mm
Ø 1.5 x 14 mm Ø 2 x 14 mm Ø 2,7 x 22 mm Ø 3,5 x 24 mm
Ø 2 x 16 mm Ø 2,7 x 24 mm Ø 3,5 x 26 mm
Ø 2,7 x 26 mm Ø 3,5 x 28 mm
Ø 3,5 x 30 mm
Width: 7 mm Width: 4 mm
P O R O U S T T A S u r g i c a l T e c h n i q u e
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4. Surgical procedure
Surgical procedure is explained step by step:
Patient´s placement: patient is placed in dorsal
recumbency over side of the limb to be
surgically treated. The other limb is tied to a
stand in the opposite side. Surgical approach is
located on medial aspect of tibia positioned
such that lateral side is in contact with the
tabletop. If patient presents bilateral ruptures
of both ACL, it is possible to accomplish
surgical procedure of both stifles by
positioning dog in supine recumbent position.
Modified Maquet Procedure is going to be
carried out so crista tibiae osteotomy is partial
in distal direction. A skin incision is made on
the medial aspect separated 1 cm to cranial
edge and starting from 1 cm proximal to
insertion of ACL to 1 cm distal to end of crista
tibiae. If patellar dislocation must be treated
too, then approach will be enlarged.
Incision is developed at the crural fascia,
proper retracting of the tibia. Vascular damage
must be minimized. Musculature of the lateral
aspect must not be unaltered. Incision must
be deeper in the caudal zone to patellar
ligament because spreader will be inserted in
this zone.
Location of the hole at the distal end of the
osteotomy for controlling crack propagation
(Maquet hole). This point must be in the distal
zone of the crista tibiae, nearly to 4 m of
cranial border on average (in a large dog the
cortex is approximately 5mm thick and in a
small dog approximately 3mm). Location is
shown in the image (hole accomplished).
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After location, Maquet hole will be drilled by
using a drill with diameter of 2, 2.5 or 2.9 mm
depending on patient. Avoiding bone and
surrounding tissues damage by using enough
irrigation.
Spreaders must be used in order to achieve a
wide surgical vision. A specific one spreader
(provided by POROUS TTA technique) has to
protect the patellar tendon allowing saw guide
will be inserted through it at the same time.
Most dorsal zone of the patellar tendon must
be located in order to protect the tendon.
Spreader will be used with this purpose.
The saw guide is provided for ensuring
osteotomy standardization. The saw is slotted
in order to insert saw blade presenting a hole
that must coincide with Maquet Point in its
proper location. For location, guide must be
placed inside the spreader. Afterwards, drill
used previously for drilling Maquet hole must
be placed new again in the distal hole of the
saw guide such guide maintains optimal
positioning during bone sawing. Guide must
be placed guaranteeing proper osteotomy´s
angle by turning around Maquet hole. In the
case of medium- big patients, saw guide must
be positioned just caudal to patellar ligament.
After guide´s positioning, osteotomy must be
executed by using an oscillating saw. A saw
blade with a thickness of approximately
0.7mm should be used. Osteotomy must be
distally extended ending in the Maquet hole,
protected by the drill. Abundant irrigation
must be used during bone sawing.
Saw guide is removed and surgeon must check
if small bony bridge persists. In this case,
osteotomy must be gently completed
removing the small bony bridge using the
same oscillating saw. Spreader must be
located in the same position in order to
preserve patellar ligament. Copious irrigation
should be used.
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On completion of the osteotomy, crista tibiae
advancement will start. Spreader has been
simply used for patellar ligament protection
but now it will be used for spreading and
holding open the osteotomy. In the
preoperative planning, the advancement was
calculated (using whatever of several existing
methods). It is suggested to open the
advancement (value of selected cage)
increased in one additional millimeter.
This process must be carried out carefully and
slowly, allowing the bone time to adjust,
taking advantage of it elasticity. The spreader
should be used with great caution in order to
avoid crista tibiae´s fracture. Provided
spreader could be blocked so opening could
be controlled. If surgeon is not in possession
of this adjustable spreader, it is possible to use
spreaders with well-known common
measures.
Cage selection. Multiple sizes of cages are
disposable so surgeon has enough options
during surgical procedure: five tibial tuberosity
advancements (12, 9, 6.5, 4.5 and 3 mm) and
several widths for each advancement (more
details in this document, in 3. Implants). The
depth of the osteotomy should be measured
with a drill depth gauge for selecting proper
cage size.
After proper osteotomy opening, cage should
be inserted into space generated by the
spreader. Whole cage must be inserted into
the bone.
Medial side of the cage must be fully or
partially in contact with medial bone cortex.
The proximal end of the cage will lie below the
proximal extremity of the tibial tuberosity.
Ensure that there is no tendency for soft tissue
to be “dragged” in between the cage and the
bone.
Other important detail is location of proximal
tip of the cage. This RX picture shows a correct
implantation. It is possible to modify the tibial
tuberosity advancement by controlling this
location. Spreader should be removed once
cage is inserted.
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P O R O U S T T A S u r g i c a l T e c h n i q u e
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Selection of the plate. There are 6 sizes of
plates distinguishing two groups according to
their width: 7 mm or 4 mm. There are 3
models of each width with several lengths:
large (L), medium (M) and small (S). Plates are
non-straight excluding smaller one (4R). This
fact provides polyvalence and best adjustment
to crista tibiae. Plate should be selected
according to dog size.
Plates dispose of two holes for cortex screws
in crista tibiae and one greater hole for tibial
screw. It is possible to use cortex screws with
diameters of 3.5, 2.7, 2 and 1.5 mm.
Plates with 7 mm of width have one tibial hole
of diameter 3.7 mm and two holes of 2.9 mm
in crista tibiae. For plates with 4 mm of width,
crista holes are 2.2 mm whereas tibial hole is
2.9 mm in non-straight plates and 2.2 mm in
the straight one (4R).
Plate fixation for osteotomy stabilization. Plate
location influences on load transmission. It
must be first fixed tibial screw. Its location
must stay always at least 1 cm (in the direction
of axial axis) below distal tip of the osteotomy
(Maquet hole). Screw must not be fully
tightened (only until be in contact with the
plate).
Second screw to be inserted will be crista
tibiae proximal screw. A gentle compression
between cage and crista tibiae fragment
should be performed before proximal screw
implantation in order to enhance porous
cage´s stability.
Its location depends on crista tibiae´s
anatomy. Plate should be oriented such angle
between tibial axis and crista tibiae fragment
would be 40 degrees. Hole for screw must be
previously drilled by using the proper drill
according to screw´s diameter to be
implanted. Cortex self-tapping screws are
provided with diameters of 3.5, 2.7, 2 and 1.5
mm, with several lengths. So it is
recommended measuring for selection the
proper screw´s length.
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A different drill to previously used for tibial
hole should be used because plates have
greater holes for crista tibiae screws
(excepting 4R where holes have same
diameter). Proximal screw must be fully
tightened and later on tibial screw too
previously implanted. Only in very energetic
dogs should be necessary to implant crista
tibiae distal screw. Anyway it could be
implanted if surgeon desires to prevent
loosening of proximal screw.
Finally surgical skin must be closed. It is
minimally invasive procedure so scar is very
short.
5. Postoperative cares
It is required a period of controlled activity so it is essential that running, jumping, and general
“rough and tumble” with other pets is avoided for the first 6 weeks. It is advisable your pet be
encouraged to take frequent short leash walks.
For proper following of surgical procedure carried out, it is required radiograph exams almost taking
lateral views four and eight weeks after implantation.
6. Support
Do not hesitate to contact with this mail if you have any question related to this surgical procedure:
[email protected] (phone: 928189613)
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