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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_6011_Библиотеки_им_академика_М_И_Перельмана.pdf
C H A P T E R 3 7 Structural Osteoplasty
Height loss (cm)
180
Repair data/intact data (%)
235
This study found no mechanical difference for any of the mechanical
variables among the kyphoplasty type repair, the OsseoFix with cement
repair, and the OsseoFix repair without cement (Table 37-2). Thus an
OsseoFix implant alone (without cement) provides biomechanical strength
that is equivalent to the other repair techniques evaluated. Whereas the
definitive explanation remains unclear, it may be related to the compliance
or elasticity of the commercially pure titanium expandable region deforming
beneath the superior endplate when loaded. When using the cement, the
bolus underneath the superior endplate may not be as elastic and thus causes
more directed loading to the endplate and lower stability. Further visualization studies are needed to understand the deformation of the implant in
real-time while being loaded. It also may be possible to use alternative injectable materials within the OsseoFix implant, because the implant provides
0
0.10
0.20
0.30
0.40
=1.0mm
0.50
F IG UR E 3 7 -5 Collapse of repaired vertebral bodies following testing.
160
140
120
100
80
60
40
20
0
F IG UR E 3 7- 6 Ability of repair to return to intact data.
Kyphoplasty
OsseoFix
Initial
repaired
height
Kyphoplasty
OsseoFix
stability and structural support that is not required from the injectable
material. Again, further studies are warranted to understand the fracture
stabilization provided in this scenario.
CONCLUSION
Several in vitro biomechanical investigations have found that the OsseoFix
implant provides equivalent biomechanical strength compared to standard
kyphoplasty type of technique. However, greater height maintenance and
lower cement injection volumes were key results in the initial study. The
subsequent study found that a stand-alone OsseoFix implant provided
strength equivalent to the other repair techniques. From these investigations
it can be concluded that the OsseoFix repair technique provides a viable
biomechanical alternative to the standard kyphoplasty repair techniques.
CLINICAL DATA
The first case of vertebral compression fracture reduction and internal fixation using OsseoFix fracture reduction system was done by Dr. Rudolf
Bertagnoli on July 21, 2008, at Bogen center in Germany. Several hundred
patients have received this treatment since then. The first patient was suffering from acute T12 vertebral compression fracture (Figure 37-7). The
surgeon was able to achieve considerable height (Figure 37-8). The patient
got immediate pain relief and did not require any external bracing or support. Two such cases have been done to date with good clinical outcomes,
and no complications have been reported so far.
OPERATIVE TECHNIQUE
Step 1: Positioning. e patient is carefully placed prone on a Jackson
table with all the bony prominences well padded. Fluoroscopic views are
taken in the anteroposterior (AP) and lateral projections such that vertebral
bodies are clearly visualized. e spinous process should be equidistant from
the medial pedicle edges on AP view. e endplates should be superimposed
on lateral view. e level of surgical interest is identified and marked.
Step 2: Creating an access channel into the vertebral body
(Figure 37-9). e transpedicular approach is currently the most com-
monly used technique to access the vertebral body and is easy to master. An
extrapedicular approach may be preferable in the upper and mid thoracic
regions, where the size of the pedicle may limit the size of the OsseoFix
device that can be used via transpedicular approach.
A 1-cm incision is then made over the bony prominences at the marked
level. A targeting Jamshedi cannula with trocar is then placed into the vertebral body via transpedicular or extrapedicular approach. The trocar is then
replaced with a guide wire through the Jamshedi cannula. The position of
the guide wire must be verified using fluoroscopy at this stage. The Jamshedi cannula is then removed and replaced with a drill sleeve. A pathway
TA BL E 37 -2 No rmalize d Bio mech anical Data for E ach Treatment Gro up
Kyphoplasty
Mean 22.2 15.8 22.9 17.0 11.0 3.9
SD 17.0 9.4 16.7 9.8 10.3 2.8
Implant with Cement
Mean 23.0 16.8 23.9 18.8 11.5 4.9
SD 16.1 16.6 15.8 20.7 9.2 4.6
Implant without Cement
Mean 23.8 18.8 25.1 22.2 12.6 5.4
SD 15.5 16.1 15.5 16.9 11.3 3.4
N - Newtons, BMD- Bone Mineral Density, SD- Standard deviation.
Yield Load (N/BMD) Ultimate Load (N/BMD) Stiffness [(N/mm)/BMD]
Intact Repaired Intact Repaired Intact Repaired
236
P A R T V Osteoporotic Surgical Treatment Modalitites: Thoracic Spine
F IG UR E 3 7- 7 Osteoporotic vertebral compression fracture of the T12 vertebral body.
F IG UR E 3 7- 8 Reduction and internal fixation of T12 osteoporotic VCF using the OsseoFix fracture reduction system.
is created into the anterior one third of the vertebral body by drilling over
the guide wire through the drill sleeve (Figure 37-10). The pathway should
end a few mm posterior to the anterior cortex. Position is reconfirmed with
fluoroscopy, and the drill is removed, keeping the guide wire in place.
Step 3: Insertion and deployment of the implant (Figure 37-11).
e chosen implant size comes preassembled on the inserter. Make sure that
the implant is not torqued onto the shaft. e actuator is then positioned
perpendicular to and on top of the implant inserter handle. Rotate the fluted
metal shaft of the actuator clockwise until a click is heard, indicating locking
of the actuator onto the implant inserter handle. If the red band on the top
of the actuator is exposed, turn the actuator counterclockwise until it is no
longer visible. e color-matched actuation rod is then advanced through
the actuator into the implant inserter and is rotated until the end is firmly
threaded into the implant. e outer knob of the actuation rod is depressed
into the key feature of the actuator and is rotated clockwise until a positive
lock is achieved. e tip of the actuation rod should be seen protruding
through the distal end of the implant.
The assembled implant inserter instrument with the actuator setup is
then inserted over the guide wire. The position of the implant is confirmed
with AP and lateral fluoroscopy. The guide wire is then removed, and initial
deployment of the implant is performed by rotating the actuator clockwise
under direct visualization using fluoroscopy. If the surgeon is satisfied with
the initial deployment of the implant and reduction of the endplates, final
deployment of the implant is performed. There is a stop mechanism in the
actuator to prevent overdeployment of the implant. The actuator can be
turned 3.5 times before the stop mechanism is engaged. After satisfactory
deployment of the implant, the implant inserter assembly is disassembled
and the actuator rod is removed. The insertion cannula is left behind in the
vertebral body. The second implant can be placed in the same vertebral body
through the other pedicle, if clinically indicated.
Step 4: Cement delivery. e cement powder is mixed with the liquid
monomer in the mixing chamber at room temperature. e delivery gun
is then loaded with the desired amount of cement. A bone biopsy cannula
is inserted through the implant inserter into the most distal portion of the
implant. e cement delivery gun is connected to the extension tube. e
desired amount of cement is then injected through the bone biopsy cannula
into the vertebral body under live AP and lateral fluoroscopy. e cement
should never be inserted directly through the implant inserter tube. e
cement injection is stopped when a sufficient amount has been placed to
stabilize the fracture, if cement reaches cortex or an endplate, or leakage is
C H A P T E R 3 7 Structural Osteoplasty
237
noted. e bone biopsy and the insertion cannula are removed after the
cement delivery has been completed. Final fluoroscopic images are taken
and the skin is closed.
32
14
30
38
A B
F IG UR E 3 7 - 9 An access channel is created into the vertebral body. A,
Extrapedicular approach. B, Transpedicular approach.
F IG UR E 3 7 - 10 Creating the pathway in the pedicle and the vertebral
body by drilling over the guide wire.
34
42
10
40
36
PITFALLS AND COMPLICATIONS OF THE PROCEDURE
Besides the usual anesthetic complications that can occur with any procedure, there are certain procedural complications that can occur with
OsseoFix. The preoperative radiographs, MRI, and CT scans should be
carefully examined for any retropulsed fragments and break in the posterior
cortex. The retropulsed fragments may be pushed back into the canal during deployment of the device and can cause adverse neurological outcomes,
which may include radiculopathy, paresis, or paralysis. Cement may leak out
of the fracture or fissure in the posterior cortex and cause neurological damage. Embolism of fat, thrombus, or other materials can occur during reduction of fracture or delivery of cement and can cause catastrophic clinical
sequelae. It is possible, though highly unlikely, that the implant may break,
dislocate or get infected and may require revision surgery. Proper patient
selection, good fluoroscopic guidance with good quality images, patient
compliance, proper surgical training, good understanding of the spinal
anatomy to avoid the spinal cord and nerves at all times during insertion of
instruments, proper postoperative care and physiotherapy, and treatment of
osteoporosis all help to improve the surgical outcome.
TREATMENT ALTERNATIVES
Vertebroplasty, or augmentation of the vertebral body with cement, was first
used in the 1980s for the management of vertebral hemangioma, and later
its use was extended to the management of painful osteoporotic VCFs and
osteolytic metastasis of spine. The success rate of vertebroplasty for relief of
pain is very high as reported in various studies.
the trabecular bone of vertebra and thus strengthens the vertebra. However, vertebroplasty does not correct the sagittal alignment, which is important for better biomechanics and to prevent the progression of kyphosis.
Moreover, some studies have reported cement leakage and embolism with
vertebroplasty, possibly a result of cement injection under high pressure.
Kyphoplasty is a minimally invasive procedure involving the insertion of
a bone tamp “pump” via a small cortical window, allowing the low-pressure
injection of bone cement (PMMA) into a compression fracture to restore
vertebral body height. Kyphoplasty is supposed to correct the vertebral
deformity and thus improve the sagittal alignment of spine. It is also argued
that cement is injected under low pressure in kyphoplasty, because a cavity
is usually created with the bone tamp before the cement is injected. Recent
studies have shown that injection pressures depend on the size of the cannula and rate of injection rather than creation of intravertebral cavity. One
of the problems with kyphoplasty is that some of the restored height is lost
on removal of the balloon tamp before insertion of cement. Also, because
9
Cement interdigitates with
10
11
A
F IG UR E 3 7 - 11 A, Rotating the metal shaft of the actuator for the deployment of the device. B, Fluoroscopic image showing implant insertion in the ante-
rior one third of the vertebral body. C, Fluoroscopic images showing deployment of the implant.
B
C
238
P A R T V Osteoporotic Surgical Treatment Modalitites: Thoracic Spine
the cement bolus does not interdigitate with the cancellous bone in kyphoplasty, it compresses the adjacent cancellous bone with progressive loading
and leads to some loss of regained height.
Bed rest, analgesics, bracing, and treatment of osteoporosis remain the
mainstay of treatment for stable VCFs. Open decompression, reduction, and
fixation by anterior, posterior, or combined approach is warranted whenever
there is mechanical compression of the spinal cord or cauda equina with or
without neurological deficit.
DISCUSSION AND CONCLUSION
Early clinical and biomechanical results indicate that the OsseoFix device
is successfully able to correct the vertebral deformity and restore the spinal
alignment, provide rapid pain relief with dramatic improvement in the quality of life, and also prevent subsequent fractures and progressive kyphosis.
Unlike kyphoplasty, OsseoFix allows interdigitation of the cement with
the cancellous bone and thus has load-bearing properties. It also uses less
cement than kyphoplasty. Moreover, it allows for controlled deployment of
the device and reduction of vertebral fracture before injection of cement,
delivering predictable and reproducible results. Therefore, positive patient
outcomes, improved clinical results, and fewer complications may be
expected when using the OsseoFix implant in properly selected patients.
References
1. D.M. Kado, W.S. Browner, L. Palermo, et al., Vertebral fractures and mortality in older
women: a prospective study. Study of Osteoporotic Fractures Research Group, Arch. Intern.
Med. 159 (11) (1999) 1215–1220.
2. S.R. Garfin, R.A. Buckley, J. Ledlie, Balloon kyphoplasty for symptomatic vertebral body
compression fractures results in rapid, significant, and sustained improvements in back pain,
function, and quality of life for elderly patients, Spine 31 (19) (2006) 2213–2220.
3. C. Schlaich, H.W. Minne, T. Bruckner, et al., Reduced pulmonary function in patients with
spinal osteoporotic fractures, Osteoporos. Int. 8 (3) (1998) 261–267.
4. S.L. Silverman, M.E. Minshall, W. Shen, et al., The relationship of health-related quality of
life to prevalent and incident vertebral fractures in postmenopausal women with osteoporosis: results from the Multiple Outcomes of Raloxifene Evaluation Study, Arthe. Rheum. 44
(11) (2001) 2611–2619.
5. C. Kim, A. Mahar, A. Perry, et al., Biomechanical evaluation of an injectable radiopaque polypropylene fumarate cement for kyphoplasty in a cadaveric osteoporotic vertebral compression
fracture model, J. Spinal. Disord. Tech. 20 (8) (2007) 604–609.
6. A. Perry, A. Mahar, J. Massie, et al., Biomechanical evaluation of kyphoplasty with calcium
sulfate cement in a cadaveric osteoporotic vertebral compression fracture model, Spine J. 5 (5)
(2005) 489–493.
7. V. Upasani, C. Robertson, D. Lee, et al. Biomechanical comparison of kyphoplasty versus a
titanium mesh implant for stabilization of vertebral compression fractures. Spine (Accepted,
In Press).
8. H. Ghofrani, T. Nunn, C. Robertson, et al., Biomechanical evaluation of a titanium mesh
implant compared to kyphoplasty: is bone cement necessary for vertebral body fracture stabilization? Presented: at meeting of North American Spine Society, San Francisco, Calif., 2009.
9. S.R. Garfin, H.A. Yuan, M.A. Reiley, New technologies in spine: kyphoplasty and vertebroplasty for the treatment of painful osteoporotic compression fractures, Spine 26 (14) (2001)
1511–1515.
10. C. Kasperk, J. Hillmeier, G. Noldge, et al., Treatment of painful vertebral fractures by kyphoplasty in patients with primary osteoporosis: a prospective nonrandomized controlled study,
J. Bone Miner. Res. 20 (4) (2005) 604–612.
11. M.E. Majd, S. Farley, R .T. Holt, Preliminary outcomes and efficacy of the first 360
consecutive kyphoplasties for the treatment of painful osteoporotic vertebral compression
fractures, Spine J. 5 (3) (2005) 244–255.
Kiva System in the Treatment
of Vertebral Osteoporotic
Compression Fractures
Luis M. Rosales
38
k e y p o i n t s
e Kiva system is useful for the reduction and the treatment of pathologic
compression fractures of the vertebral body that may result from
osteoporosis, in segments T10 to L5 of the spine.
e Kiva system device preserves cancellous architecture using a
percutaneously introduced PEEK (Poliether etherKetone) implant in a
continuous loop to form a nesting, cylindrical column.
e implant is delivered over a removable guide wire to provide structural
support to the vertebral body. A vertical displacement of the column results
in endplate re-elevation and fracture reduction.
Bone cement is delivered through the lumen of the implant, which provides
contained interdigitation into the cancellous bone, thus stabilizing the
fracture and minimizing the risk of extravasation.
e Kiva system achieves an improvement in analog pain scales and
Oswestry Disability Index (ODI) and has no adverse effects from
components.
INTRODUCTION
Vertebral compression fractures (VCFs) have a high incidence in the elderly
population and are the most common fractures in osteoporotic bones. The
majority present without a history of major trauma.
is increased in patients with a prior vertebral compression fracture, with
studies indicating that nearly 20% of patients who have an osteoporotic
VCF will develop a second fracture within a year of the first.
these fractures cause significant morbidity in terms of pain, loss of mobility,
and kyphosis, but the relative risk of death after a vertebral fracture is nearly
nine times greater than in people without a vertebral fracture.
Percutaneous vertebroplasty (PVP) was introduced in France in 1984
by Galibert and Deramond as a treatment for a malignant aggressive hemangioma.
haps to stabilize vertebral lesions. Subsequently PVP was used to treat
painful lesions such as hemangiomas, metastasis, multiple myeloma, and
osteoporotic fractures. Today most patients undergoing PVP suffer from
vertebral osteoporotic compression fractures. PVP is generally seen as a
safe and efficient procedure for treatment of painful osteoporotic fractures.
is traditionally performed with polymethyl methacrylate (PMMA) cement.
Clinical studies have demonstrated the efficacy of both methods in reducing
fracture-related pain.
tions: extrusion of cement into surrounding tissue, vascular embolism in the
corresponding vascular system, adverse systemic reactions to unpolymerized
toxic monomers, and thermal damage to adjacent structures. The two latter
complications are specific to PMMA. For this reason, and because PMMA
does not become osseointegrated, attempts have been increasingly made in
1
It is a therapeutic procedure performed to reduce pain and per-
Vertebral augmentation using balloon kyphoplasty and vertebroplasty
2,4
However, there have also been reports of complica-
1
The incidence of VCF
2
Not only do
2
recent years to explore the possibilities of alternative cements by looking
into biomaterials based on calcium phosphate (CaP). The properties of such
bone cements, however, would have to fit a specific profile that takes into
account the following parameters: setting behavior, mechanical fitness, and
biological behavior.
There is a new vertebral augmentation device, the Kiva VCF Treatment System (Benvenue Medical, Santa Clara, Calif.), that can be used in
the treatment of patients sustaining painful VCFs. Unlike the traditional
balloon kyphoplasty procedure that pushes cancellous bone peripherally
to form a repository for bone cement, the Kiva device preserves cancellous architecture using a percutaneously introduced Poliether etherKetone
implant in a continuous loop to form a nesting, cylindrical column. The
implant is delivered over a removable guide wire to provide structural support to the vertebral body, and it is a conduit for bone void filler placement.
Vertical displacement by the column results in endplate re-elevation and
fracture reduction. Bone cement is delivered through the lumen of the
implant, which provides contained interdigitation into the cancellous bone
thus stabilizing the fracture and minimizing the risk of extravasation.
INDICATIONS
The Kiva system is indicated for the management of pathological compression fractures of the vertebral body that may result from osteoporosis, in
segments T10 to L5 of the spine. It can also used to treat benign or malignant lesions, by creating a transpedicular channel through which a PEEK
implant is inserted into the vertebral body.
CONTRAINDICATIONS
Contraindications include the following:
Infection, systemic or local, at the surgical site
Any medical condition that would preclude the patient from having
surgery or would impede the benefit of surgery
Pathology at the index level(s) (e.g., cancer)
Neurologic signs or symptoms related to the compression fracture
Previous surgical treatment for a vertebral body compression fracture
Index level(s) vertebral body collapse to the degree that access to the ver-
tebral body is not feasible
3
PRECAUTIONS
Precautions that should be taken include the following:
Failure to observe recommendations may contribute to serious patient
injuries.
Avoid contact with the sharp distal tip of the Osteo Coil wire.
239
240
P A R T V Osteoporotic Surgical Treatment Modalities: Thoracic Spine
If the device appears damaged, do not use. Discard or return to the manu-
facturer. is device is intended for single use only.
is device must be deployed under fluoroscopic guidance. Failure to use
fluoroscopic guidance could result in serious patient injuries.
DESCRIPTION OF THE DEVICE
The Kiva system is packaged as a single-use, sterile device incorporat-
ing an implantable PEEK distraction sleeve. It is a surgical instrument
designed to provide percutaneous access and channel creation in the
cancellous bone of the spine followed by delivery of a PEEK distraction
sleeve implant into that channel. The Kiva system consists of five primary
components:
1. Nitinol Kiva coil track. (Kiva coil track is a guide wire made of nitinol).
2. Stainless steel deployment with a PEEK liner
3. Polycarbonate deployment handle (Figure 38-1)
4. PEEK distraction sleeve implant made of PEEK-OPTIMA with 15%
BaSO
4
5. PMMA bone cement delivery needle
The “shape memory” nitinol coil track is preset into a loop shape and it
can be temporarily straightened into a cannula for deployment into cancellous bone. Once the cannula is positioned in the cancellous bone, the Kiva
coil track is then advanced forward out of the cannula. The surgeon controls
the amount of coil track wire deployment with the use of the handle, which
allows for 2-mm increments per quarter turn of the coil track deployment
knob. Upon exiting the cannula, the coil track regains its loop shape as it
channels through the cancellous bone. Once channel creation is complete,
the radiopaque PEEK-OPTIMA implant is advanced over the nitinol Kiva
coil track and into the channel using the implant deployment knob on the
deployment handle.
CLINICAL PRESENTATION AND EVALUATION
Material and Methods
Twenty-two patients with radiologically confirmed VCFs between T10
and L5 underwent treatment with the Kiva device for persistent back pain
symptoms. Study eligibility required a back pain visual notestyle scale
(VAS) score of 5, fracture age less than 6 months, and Oswestry Disability
Index (ODI) score of 30%. Patient-reported outcomes (VAS, ODI) were
repeated at 3 and 12 months.
to sedation according to the ACR Standard for sedation and analgesia in
adults. Conscious sedation is induced by intravenous administration of
fentanyl and midazolam (Versed) or other medications (e.g., propofol) in
accordance with the preference of the treating physician. The patient’s vital
signs must be monitored during the procedure. If needed, oxygen can be
administered by nasal cannula, controlling the breath. Standard fluoroscopy
is used to locate the body or the vertebral bodies to be treated and to place
the needle to correctly. A 1-inch, 25-gauge needle is used to create a blister
to administer subcutaneous bupivacaine 0.25%. Then a 2-inch, 25-gauge
needle under fluoroscopic guidance is inserted at the site of the blister and
introduced to the periosteum of the pedicle. The periosteum is then infiltrated with 6 to 7 ml bupivacaine 0.25%. A small incision is made in the
skin over the pedicle, and the access needle is placed for a transpedicular
approach.
The vertebral body is accessed with a cannula, using a standard transpedicular vertebral access technique, always through the right pedicle of
the vertebra. With the Kiva handle in the vertebral body, the coil track is
advanced using the coil track deployment knob, located on the right hand
side of the deployment handle.
1. Using imaging guidance, insert the deployment cannula into the access
site and through the cancellous bone. Position the cannula to deploy the
Kiva coil track centrally in the anterior column.
2. Rotate the coil track deployment knob on the deployment handle for-
ward slowly to incrementally control to the deployment of the Kiva coil
track in the cancellous bone. After one-half turn, check fluoroscopic
image for proper orientation of the Kiva coil track exiting the cannula
(Figure 38-2).
3. If the Kiva coil track is not oriented in the proper plane or at to the
proper position, retract the coil track back into the cannula and reposition the cannula to achieve a more optimal orientation.
4. Repeat steps 2 and 3 until the Kiva coil track is oriented at an optimum
plane and position.
5. Using imaging guidance, continue to deploy the Kiva coil track making
sure to check the fluoroscope image often (Figure 38-3).
6. Using imaging guidance, continue to deploy the Kiva coil track until the
full length of the wire is reached or until the desired number of loops are
deployed into a symmetrical stacked toroidal shaped coil.
RESULTS
Patients in to the study group (n = 22) had a mean age of 70.4 years, and
95.5 % were women. Mean pain scores declined from 7.6 to 2.8 (p < .0001).
Mean ODI scores declined from 61.0% to 31.7% (p < .0001). There were
no device-related adverse events.
OPERATIVE TECHNIQUE
The procedure should be performed under strict aseptic conditions. The
treating physician can administer prophylactic antibiotics according to usual
practice. The patient is placed on the table in prone position and subjected
F IG UR E 3 8- 1 Kiva handle.
F IG UR E 3 8- 2 Percutaneously introduced nitinol Kiva coil (guide wire)
advanced through a deployment cannula.
F IG UR E 3 8 - 3 The nitinol Kiva coil is advanced fully coiled within the
cancellous portion of the fractured vertebral body.
F IG UR E 3 8 -4 Radiopaque PEEK-OPTIMA Implant is delivered progres-
sively over the removable Kiva coil.
C H A P T E R 3 8 Kiva System in the Treatment of Vertebral Osteoporotic Compression Fractures
241
DEPLOYMENT OF THE DISTRACTION SLEEVE
The radiopaque PEEK-OPTIMA implant is advanced using the distraction sleeve implant deployment knob located on the lefthand side of the
deployment handle. The radiopaque PEEK-OPTIMA implant can only be
advanced forward, and it may not be retracted once advanced.
1. Once the coil track has been adequately deployed into the cancellous bone, using imaging guidance, advance the radiopaque PEEKOPTIMA implant over the coil track and into the channel created by
the coil track (Figure 38-4).
2. Monitor advancement of the radiopaque PEEK-OPTIMA implant
using anteroposterior and lateral fluoroscopy to ensure proper advancement of the distraction sleeve implant.
3. Using imaging guidance, continue advancing the distraction radiopaque
PEEK-OPTIMA implant until it reaches the end of the coil track or
until resistance is encountered (Figure 38-5).
4. Using imaging guidance assess the position of both the coil and the
implant. If any loop of the coil track has opened up to a larger diameter
compared to the other coil loops, retract additional lengths of the coil in
quarter to half-turn increments until all the loops of the coil track have
a uniform diameter.
5. Using imaging guidance, slowly advance the coil in half-turn increments
until either the full length of the wire is reached or until or until one of
the wire loops begins to open up into a larger diameter than the other
loops.
6. Using imaging guidance, advance the distraction implant.
7. Continue to advance the distraction sleeve implant until resistance is
encountered or until one of the wire loops beginning to open up to a
larger diameter than the other coil track loops.
8. At this point, the implant deployment is complete (Figure 38-6).
Remove the coil track completely by rotating the coil track deployment
knob backward until the coil track is fully retracted in the deployment
handle (Figure 38-7).
9. Retract the distraction sleeve implant pusher completely by rotating
the distraction sleeve implant deployment handle backward until the
pusher wire is completely retracted into the deployment handle.
10. Disconnect the flexible connector at the end of the deployment handle
from the deployment cannula by releasing the tab on the connector
switch.
POSTOPERATIVE CARE
No special postoperative care is needed. After the procedure, the patient can
stand up, either the same day or the day after.
COMPLICATIONS AND AVOIDANCE
This procedure, although performed percutaneously, has the risks of any
procedure of vertebroplasty, including infection, bleeding, and neurological
complications. With careful technique, these potential complications can be
avoided.
CONCLUSIONS AND DISCUSSION
These findings, albeit short-term, suggest robust and consistent clinical
improvement for pain and function outcomes, following this novel vertebral
augmentation procedure in patients with painful VCFs. Clinically relevant
gains were realized early postoperatively and maintained through follow-up.
The device could be deployed and implanted without adverse events, with
improvement in VAS pain scores (p = .0002) and ODI scores (p < .0001),
INJECTING PMMA BONE CEMENT
1. Insert the PMMA bone cement delivery needle through the deployment
cannula and advance the needle until the distal tip of the needle engages
the lumen of the distraction sleeve implant.
2. Once the tip of the needle has engaged the lumen of the implant, ensure
that the bone cement delivery needle is steadily inserted into the implant
by rotating the needle back and forth while it is applying gentle forward
pressure to the needle.
3. e distraction sleeve implant and vertebral body are now ready for
delivery of bone cement. Use bone cement approved for use in the spine
(Figure 38-8, A and B).
F IG UR E 3 8- 5 A continuous loop forms a nesting, cylindrical column,
providing vertical displacement that results in endplate elevation and fracture
reduction.
F IG UR E 38 - 6 Fluoroscopic image illustrating the deployment of the
implant over the removable Kiva coil in a continuous loop, properly positioned
within the vertebral body.
F IG UR E 3 8 -7 After removal of the Kiva coil, the implant is fully
deployed and it serves as a conduit for bone cement placement.
242
A
P A R T V Osteoporotic Surgical Treatment Modalities: Thoracic Spine
F I G UR ES 3 8- 8 AP and late-
ral fluoroscopic images show contained interdigitation of cement into
the adjacent cancellous bone, minimizing the risk of cement extravasation, and the fracture is fully stabilized
in situ. (A) Lateral and (B) AP view of
the fluoroscopic images, show the
PEEK implant filled with bone cement
in the center of the vertebral body.
B
with the following overall clinical success criteria: 2-point improvement in
VAS and 15-point improvement in ODI. Two cases of cement extravasations occurred without clinical manifestations.
Although the PMMA cement has proved useful in these procedures,
biodegradable vertebroplasty materials are being tested. Arecent report
showed for the first time that there is no difference in clinical and morphologic outcomes after kyphoplasty using either CaP cement (Calcibon)
or conventional PMMA material in patients with painful osteoporotic vertebral fractures for at least 3 years of follow-up. There was no significant
difference with regard to postoperative pain reduction or the improvement
of mobility between the CaP and PMMA groups. Furthermore, there was
a comparable height restoration of the fractured vertebral bodies, and no
significant difference in the number of vertebral follow-up fractures during
the 3-year study period. In daily routine, PMMA is used for the internal
stabilization of vertebral fractures by kyphoplasty. However, PMMA is
not biodegradable and heals with a fibrous tissue layer around the implant.
Therefore CaP cement materials have been developed, which are biodegradable by osteoclastic resorption and allow a direct osseous integration of the
entire surface of the implant, whereby a slow replacement by normal bone
tissue seems possible.
Vertebroplasty is widely accepted as an effective, minimally invasive
procedure, and is becoming the standard of care for the management of
painful osteoporotic VCFs. Significant pain relief has been reported in
78% to 95% of patients suffering from osteoporotic VCFs. However, very
few articles in the literature have focused on those patients who failed
to respond to the initial PV. Although one study reported that a repeat
PVP performed on previously treated vertebral levels for recurrent pain
might offer therapeutic benefits (these patients experienced pain relief for
8 to 167 days after the initial PV), we are not aware of any studies on the
5
use of repeat PVs in patients whose pain does not resolve after the initial
treatment.
5
References
1. R . Rousing, O. Andersen Mikkel, M. Jespersen Stig, K. Thomsen, J. Lauritsen, Percutaneous
vertebroplasty compared to conservative treatment in patients with painful acute or subacute
osteoporotic vertebral fractures: three-months follow-up in a clinical randomized study, Spine
34 (13) ( June 1, 2009) 1349–1354.
2. K. Becky Benz, M. John Gemery, J. John McIntyre, J. Clifford Eskey, Value of immediate preprocedure magnetic resonance imaging in patients scheduled to undergo vertebroplasty or
kyphoplasty, Spine 34 (6) (March 15, 2009) 609–612.
3. R . Blattert Thomas, L. Jestaedt, A. Weckbach, Suitability of a calcium phosphate cement in
osteoporotic vertebral body fracture augmentation: a controlled, randomized, clinical trial of
balloon kyphoplasty comparing calcium phosphate versus polymethylmethacrylate, Spine 34
(2) ( January 15, 2009) 108–114.
4. Shi-Cheng He, Teng, Gao-Jun; Deng, Gang; Fang, Wen; Guo, Jin-He; Zhu, Guang-Yu; Li,
Guo-Zhao, Repeat vertebroplasty for unrelieved pain at previously treated vertebral levels
with osteoporotic vertebral compression fractures, Spine 33 (6) (March 15, 2008) 640–647.
5. A. Grafe Ingo, M. Baier, G. Nöldge, C. Weiss, K. Da Fonseca, J. Hillmeier, M. Libicher,
G. Rudofsky, C. Metzner, P. Nawroth, P.-J. Meeder, C. Kasperk, Calcium-phosphate and polymethylmethacrylate cement in long-term outcome after kyphoplasty of painful osteoporotic
vertebral fractures, Spine 33 (11) (May 15, 2008) 1284–1290.
Directed Cement Flow Kyphoplasty for
Treatment of Osteoporotic Vertebral
Compression Fractures
Kern Singh and Robert Pflugmacher
39
k e y p o i n t s
Osteoporotic compression fractures of the thoracic and lumbar spine can be
treated successfully from a unilateral approach using the Shield Kyphoplasty
System with medium viscosity bone cement.
Minimally invasive access to the center of the vertebral body is achieved
through the use of a novel, curved cavity creation instrument set inserted
through a single portal.
Symmetrical cement augmentation with a low incidence of leakage,
particularly in the posterior direction, is facilitated by a cement-directing
implant positioned in the center of the vertebral body, which guides cement
flow in the anterior, superior, and inferior directions.
Assessment of vertebral body strength and ability to withstand repeated
cyclic compressive loading demonstrates that adequate cement fill,
interdigitation, and biomechanical reinforcement is provided by the Shield
Kyphoplasty System.
Treatment of painful osteoporotic compression fractures using the Shield
Kyphoplasty System results in immediate pain relief, which is sustained long
term, as supported by patient follow-up for up to 2 years.
INTRODUCTION
Vertebroplasty is one of the most widely used image-guided minimally invasive vertebral augmentation procedures for treating painful vertebral compression fractures. A percutaneous bipedicular approach is typically used to
access the vertebral body. Polymethylmethacrylate (PMMA) bone cement is
injected directly into the cancellous bone, stabilizing the fracture and providing
virtually immediate pain relief. Relatively low viscosity cement is required for
this procedure to achieve adequate fill and interdigitation. The cement flow
is uncontrolled, however, and leakage into the vascular system, paravertebral
space, or disk is commonly reported. Although most cement leaks are asymptomatic, serious leakage-related clinical complications such as compression of
neurologic structures or formation of pulmonary embolus have been reported.
In an effort to achieve fracture reduction and restore sagittal balance,
balloon kyphoplasty was introduced. This procedure has proven to be safe
and efficacious, and its beneficial effects are sustained according to the most
recent clinical studies.
ture reduction has not been clearly demonstrated in these same studies.
The technique involves the use of inflatable bone tamps to create a cavity
through compaction of bone and marrow, followed by high viscosity cement
injection using bone filling cannulas. The cumulative volume required to
fill the large voids requires the use of multiple cannulas, but provides the
surgeon greater control of the cement injection rate and volume compared to
vertebroplasty. Cement flow and interdigitation are limited to some extent
by the compressed bone lining the cavity walls and by the cement viscosity.
This technique is generally reliable and safe, provided cement viscosity is
high and the operator includes careful fluoroscopic monitoring.
1
However, reproducible and clinically significant frac-
2,3
More recently, new devices and procedures have been designed to
achieve fracture reduction and reduce leakage rates. The Shield Kyphoplasty System (Soteira, Inc., Natick Mass.) was developed to better contain and control the flow of cement, reduce cement leakage rate and create
biomechanically optimized cement augmentation. In this chapter, the components of the Shield Kyphoplasty System and the associated surgical
technique will be described in detail. Mechanical testing of fractured osteoporotic vertebral bodies treated with this system under monotonic and
cyclic loading conditions will be discussed. Finally, the primary outcomes
from long-term clinical evaluations of this system will be presented, including a randomized multicenter study that compared pain relief and cement
leakage for the Shield Kyphoplasty System and conventional bipedicular
vertebroplasty.
SYSTEM OVERVIEW
The Shield system features a non–load-bearing, hollow, self-expanding
implant that is deployed into a cavity created within the center of the
fractured vertebral body. The function of the device is to initially contain
injected cement, then to regulate and direct the flow of the cement through
engineered openings in the anterior wall of the device. Cement injection into
the implant and through the openings creates a mantle of cement in the
anterior vertebral body, which spans the endplates and stabilizes the fracture by filling cracks and voids, interdigitating with viable trabecular bone.
Placement of the device in a central cavity helps to limit posterior flow of
cement via the basivertebral plexus and allows cement to permeate the entire
vertebral body using a unipedicular approach.
The Shield system includes a set of single patient use disposable instruments for unipedicular percutaneous access and specially designed instruments for cavity creation, implant deployment, and cement injection, as
shown in Figure 39-1. The unique curved design of the cavity creation
instrument allows the surgeon to drill a curved path from one pedicle, crossing the sagittal midline, and stopping within the contralateral anterior quadrant of the vertebral body. The cavity creation instrument then converts to
a reamer in situ, which is capable of creating a 10-mm diameter cylindrical
cavity in the retrograde (proximal) direction that is matched to the implant
size. The delivery system subsequently provides a means to insert and deploy
the cement directing device within the cavity and facilitates cement injection
with a high pressure injection system.
The Shield cement director is an elongated 10-mm diameter hollow
structure fabricated from braided nitinol wire and other biocompatible textile and polymeric materials. The device is available in three lengths: 15 mm,
20 mm, and 25 mm, a range selected to approximate the anatomic distance
between the medial pedicle borders in the thoracic and lumbar spine in the
patient population with osteoporosis. The cylindrical wall of the implant
is impermeable to bone cement with the exception of small holes located
anteriorly-superiorly and anterior-inferiorly on the device, as shown in
Figure 39-2. The implant is supplied preloaded onto a delivery device and
243
244
12000
Load at failure (N)
F IG UR E 3 9- 1 Components of the Shield Kyphoplasty System. Shown
from left to right are the blunt tipped wire, working channel, curved drill/cavity
cutter, implant and cement delivery system, and tamp.
P A R T V Osteoporotic Surgical Treatment Modalities: Thoracic Spine
Shield
Vertebroplasty
10000
8000
6000
4000
2000
0
TreatedIntact
F IG UR E 3 9- 3 Comparison of failure loads for intact and treated ver-
tebral body specimens. The vertebral bodies were subjected to uniaxial compression until a 25% reduction in height was achieved. The failure load was
defined as the maximum load attained during compression. The mean failure
loads were equivalent for both treatments.
Vertebral bodies with less than adequate space to allow for the creation
of a 15-mm long cavity
Greater than three levels needing treatment
Inability to intraoperatively visualize anatomy under fluoroscopic
guidance
F IG UR E 39 -2 The Shield implant, shown in the expanded state. The
holes (3 of 6 holes shown, arrows) are positioned to direct cement flow in the
anterior, superior and inferior directions. There are no holes on the posterior
surface of the implant to prevent cement flow in this direction.
collapsed within a sheath to facilitate placement into the cavity through the
working channel. After placement, the sheath is retracted to deploy the selfexpanding implant in the prepared cavity.
INDICATIONS
The Shield Kyphoplasty System is intended for use in the treatment of
osteoporotic vertebral body compression fractures in the adult spine in levels T4-L5. It is intended to be used with a PMMA bone cement cleared
for use in vertebral body fixation. Up to three levels with osteoporotic compression fractures may be treated during one operative session regardless
of fracture age, excluding vertebral plana, unstable fractures, or suspected
infection.
CONTRAINDICATIONS
The Shield Kyphoplasty System should not be used when the following
conditions are present:
Previously resected or augmented vertebral body
Burst fractures
Spinal canal compromise
Uncorrectable coagulation disorder or bleeding disorders of any etiology
Active systemic or local infection
Pregnancy
Multiple myeloma
Vertebral bodies having less than adequate space between endplates for
10-mm cavity creation.
BIOMECHANICAL TESTING
The mechanical behavior of fractured osteoporotic vertebral bodies treated
with the Shield Kyphoplasty System has been studied under monotonic
and cyclic loading conditions. Controlled, reproducible compression fractures were created by applying a uniaxial compressive load until the vertebral body experienced a 25% loss in height. The fractured vertebral bodies
were subsequently treated with either the Shield Kyphoplasty System or
bipedicular vertebroplasty, which was used as a comparative control. The
failure strength of intact and treated vertebral bodies is shown in Figure
39-3. There were no statistically significant differences between the intact
failure strengths or the treated failure strengths for both groups (p = .146).
Treatment of vertebral compression fractures with Shield Kyphoplasty System, using a unipedicular approach, resulted in biomechanical performance
that was equivalent to conventional bipedicular vertebroplasty. Furthermore,
the presence of the cement director appears to have no detectable effect on
the ability of the bone cement to interdigitate and reinforce the fractured
vertebral body.
Cyclic loading tests were performed to assess the ability of fractured
vertebral bodies treated with the Shield Kyphoplasty System to withstand
repeated compressive loads and bending moments, as encountered during activities associated with daily living. Stryker SpinePlex PMMA bone
cement (Stryker Howmedica, Allendale, N.J.) was used to treat all specimens. Because fresh cadaveric vertebral bodies cannot be tested in a 37° C
saline bath for long periods of time without experiencing biological degradation, the cyclic loading tests were accelerated by increasing the compressive
load stepwise until the treated vertebral body failed.
Treated vertebral bodies either failed during cyclic loading at the first
load level (6 of 15 specimens), or they required multiple loading levels to
fail (9 of 15 specimens). A compilation of all of the results from the cyclic
testing of treated vertebral bodies is provided in Figure 39-4. For 6 of 8
specimen pairs, the specimen treated with the Shield Kyphoplasty System withstood a greater number of loading cycles and failed at a higher
load than the specimen treated with conventional vertebroplasty. These
results demonstrate that directed cement flow using the unipedicular
Shield Kyphoplasty System can provide biomechanical reinforcement
to fractured osteoporotic vertebral bodies that is equivalent to or better than conventional vertebroplasty, while reducing the risk of posterior
leakage.