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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_6011_Библиотеки_им_академика_М_И_Перельмана.pdf
Kyphoplasty
Eeric Truumees
34
k e y p o i n t s
Kyphoplasty, like vertebroplasty, is a cement augmentation procedure that is
used to restore vertebral body strength and stiffness.
e procedure involves percutaneous placement of balloon tamps that, when
inflated, partly restore lost vertebral height after osteoporotic compression
fracture. is percutaneous placement requires high-quality fluoroscopic
imaging in at least two planes.
After inflation, the balloons are removed and the cavities created are
backfilled with bone cement, typically polymethylmethacrylate.
e cavities created by the balloon tamps may also decrease the cement leak
risk.
Kyphoplasty is indicated in patients with intractable pain from a compression
fracture. Excellent outcomes and rapid pain relief can be seen in patients with
focal pain and tenderness over the involved level.
INTRODUCTION
Kyphoplasty, along with vertebroplasty and newer, related procedures, are
forms of vertebral body augmentation (VBA). The procedures employ percutaneous injection of polymethylmethacrylate (PMMA) acrylic cement
into a fractured vertebral body to restore strength and stiffness. Other indications, such as pathologic fractures from metastasis, are becoming more
common. High energy, bursting, and extension fracture patterns should be
avoided because of the increased PMMA extravasation risk.
In appropriately indicated patients, kyphoplasty yields excellent early
pain relief and return to activity. Potential disadvantages of kyphoplasty
include procedural risks, such as cement leakage and possible fracture of
adjacent segment.
BRIEF DESCRIPTION
Spinal osteoporosis alone is asymptomatic. If allowed to progress, however,
it confers increasing risk of fragility fracture. The principal manifestation
of osteoporotic vertebral compression fractures (VCFs) is back pain. Some
minimally symptomatic patients do not present for medical evaluation.1
Others require hospital admission for unrelenting pain. Typically, over 3
months, the fracture heals and the back pain subsides.2 Although the nonunion rate is low, not all VCFs heal.
Back pain can persist after fracture heali ng. From 33% to 75% of fractures precipitate chronic back pain.3 The chronic pain has been attributed
to hyperkyphosis, leading to excessive muscular strain. Excessive anterior
vertebral body loading engendered by this malalignment may propagate
stress fractures in the surrounding endplates.4 Late kyphosis is occasionally
associated with myelopathy.
5
INDICATIONS AND CONTRAINDICATIONS
The goal of kyphoplasty is to interrupt the cycle of pain and functional decline
associated with VCFs. Given the limited data comparing long-term impacts
of kyphoplasty relative to nonoperative management, injecting all fractures
cannot be justified. Because many patients improve quickly, most patients
should try nonoperative management before considering kyphoplasty.
The duration of this nonoperative trial is inversely related to the patient’s
pain level and functional limitations. Consider early intervention in patients
unable to return to ambulation after a few days. Protracted bed rest may be
riskier than procedural risks. At least 150,000 VCFs per year are refractory
to nonoperative measures and require hospitalization, with bed rest and IV
narcotics. Ambulatory patients should undergo 4 to 8 weeks of nonoperative care. In this group, treatment often includes limited contact thoracolumbar bracing, activity limitations, and sparing use of pain medications.
For fractures of L2 and above, a CASH or Jewett brace is recommended.
Low lumbar fractures may respond to a chairback brace. Fractures above T6
are more frequently related to metastasis than osteoporosis. Fractures less
likely to improve with standard medical management include those with
the following:
oracolumbar junction (T11-L2)
Bursting patterns
Fractures with >30 degrees of sagittal angulation
Vacuum shadow in fractured body (ischemic necrosis of bone)
Progressive collapse in office follow-up
6
Over time, kyphoplasty indications have gradually been expanded to
include conditions such as multiple myeloma and osteolytic metastases.
Moreover, kyphoplasty has been added to open decompression and internal
fixation procedures. Hybrid procedures may be indicated for more complex
fracture patterns, significant compression of the neural elements, and neoplastic lesions with cortical destruction.7 Another hybrid option combines
radiosurgery and kyphoplasty. Conventional radiotherapy remains the index
treatment in many patients with vertebral body metastasis.7 Used alone,
radiation is associated with delayed pain relief and further vertebral collapse due to both the previous bone erosion and the radiation itself. Newer
radiation therapy techniques allow more focused radiation to be applied via
intense treatments over a shorter time course.
Absolute contraindications to kyphoplasty include the following:
Coexisting infection
Pregnancy
Young patients
Nonpainful fractures
Uncontrolled coagulopathy
High-velocity fractures
Fractures with retropulsed bone
Medical conditions precluding anesthesia or operative intervention
6,8,9
In this setting, “young” suggests patients younger than 65 years. The
stronger the host bone, the less effectively polymethylmethacrylate restores
stiffness. Patients with good bone stock fracture only after high energy loading. In this setting, PMMA leakage is more common. Calcium phosphate
kyphoplasty (and other resorbable materials) is under study for this indication. Though isolated reports suggest pain improvement with kyphoplasty
for sacral fractures, this indication is not widely accepted.
While less common than VCF, osteoporotic burst fractures (senile burst
fractures) are not rare. Any fracture precipitating more than 50% height loss
207
208
P A R T V Osteoporotic Surgical Treatment Modalities: Thoracic Spine
will have associated posterior cortical compromise. In many cases, this compromise takes the form of cortical buckling. When the canal occlusion is less
than 33%, kyphoplasty can be considered. On the other hand, in the face
of cortical comminution, avoid percutaneous kyphoplasty because of the
increased risk of cement extravasation. In patients with neurologic injury,
open surgery may be required.
Open surgery is indicated in patients with osteoporotic bones who also
have prog ressive neurologic deficit. Unfortunately, in this frail population,
operative intervention confers high risk. Similarly, spinal instrumentation
systems often fail in osteoporotic bone. PMMA augmentation increases
screw pull-out strength. Combination of kyphoplasty with open decompression restores anterior column load bearing and limits the scope of the
reconstruction necessary.
DESCRIPTION OF THE DEVICE
Kyphoplasty requires one or two high quality fluoroscopes and a kyphoplasty kit. The traditional set begins with a modified Jamshidi needle and
a guide wire. Other systems remove the guide wire step (“express” and “one
step”). Ultimately, each system is used to safely place two working cannulae through which KyphX balloon tamps can be inserted into the vertebral body. Smaller cannulae are available for upper thoracic vertebrae. The
balloon tamps are modified ang ioplasty balloons. Currently, three sizes are
available and are selected based on the size of the fractured vertebral body:
10, 15, and 20 mm. The balloons attach to a syringe with an integral pressure gauge. In the operating room, the balloons are prepped at the back table
by instilling 10 ml of radiopaque contrast media. As volume is added to
the balloon, the balloon pressure (measured in psi) increases. As the tamp
displaces bone, the pressure gradually decays.
Kyphon (Sunnyvale, CA) manufactures several specific balloon products
thought to assist in challenging clinical scenarios. For example, a bidirectional
balloon (KyphX Elevate) emphasizes craniocaudal expansion and limits
mediolateral enlargement. Another single-direction balloon (KyphX Exact)
is deployed through a metal housing, which is thought to control balloon
direction. These tamps confer additional cost to the procedure. There are no
data demonstrating improved outcomes or decreased risk with these devices.
The system also includes bone void fillers, each of which holds 1.5 ml of
PMMA. The bone void fillers are cannulae with plungers that allow gradual
backfilling of the void created by the tamp. A modified bone void filler, the
biopsy d evice, has sharper tips and can be deployed through the working
cannula. PMMA with added barium to enhance fluoroscopic visibility and
a mixing system are also available in a separate kit.
BACKGROUND OF SCIENTIFIC TESTING AND CLINICAL OUTCOMES
The source of pain relief after kyphoplasty remains unclear. Currently, most
authors suggest that restoration of strength and stiffness to the fractured
vertebral body relieves pain. Both cement volume and percentage of the vertebral body filled can predict postaugmentation bone strength and stiffness.
Overall, the more PMMA inserted, the higher the postinsertion vertebral
strength and stiffness.
Outcomes data include a number of retrospective studies. Very recently
prospective data have been reported from the FREE trial.10 This trial
included 21 sites in 8 countries that enrolled 300 patients with acute VCF
and randomized them to either kyphoplasty (149) or nonoperative care
(151). As of this writing, the complete paper has not been published, but
early pain relief seems to be a clear advantage of kyphoplasty. Whether that
advantage persists is more difficult. The primary outcome was the difference in the Short Form (SF-36) physical component summary at 1 month.
Quality of life measurements and spine radiographs were assessed through
12 months. Kyphoplasty subjects reported greater improvement than controls in their SF-36 physical component (5.2 point difference; p < 0001) at
one month). By 12 months, the difference declined to 1.5 points and was
no longer significant (p = .2). Kyphoplasty improved quality of life by the
1-point EuroQol questionnaire at 1 (0.18 points; 95% CI, 0.08–0.28; p <
.001) and 12 (0.12; 95% CI, 0.01–0.22; p = .025) months. Back function,
as measured by the 24-point Roland-Morris scale, was improved by 4.0
points by kyphoplasty at 1 month (p < .001) and 2.6 points at 12 months
(p = .001). Kyphoplasty patients reported fewer days with limited activity,
less back pain, and less use of analgesics and walking aids.
Of note, the FREE study was funded by the manufacturer and many of
its authors are Kyphon consultants. On the other hand , three other small
studies comparing kyphoplasty w ith conventional medical treatment also
found that kyphoplasty consistently improved pain and physical function,
with results sustained at 6 months.
11-13
In 2005, Hadjipavlou et al14 combined the available vertebroplasty and
kyphoplasty outcome reports in an effort to compare the procedures. Using
meta-regression techniques, the authors found that individual study design
had a considerable impact on subsequent analysis. For prospective studies,
the rates of success with vertebroplasty and kyphoplasty were not significantly different at 92% and 93% respectively. However, in retrospective studies, kyphoplasty was more successful (95% vs. 86%; p = .019)
Aside from pain relief, a major benefit of VBA lies in the restoration of
mobility. In one series of 11 wheelchair-bound cancer patients, 73% were
able to walk shortly after vertebroplasty.15 Other studies reported restoration of mobility after kyphoplasty in 84% to 100%.
8,16
In terms of other
types of physical functioning, a number of different outcome measures have
been used. In a retrospective analysis of patients with painful osteoporotic
VCF, 49 patients who were available for follow-up at a mean 9-month interval had an improvement in visual analogue pain scale score of seven points
(p < .05), and an improvement in Roland-Morris Disability Survey of 11
points (p < .05).
17
In a retrospective analysis of 52 patients with 82 painful osteoporotic
VCFs, kyphoplasty restored 4.6 mm and 3.9 mm to the heights of the anterior and medial columns, respectively.17 The mean Cobb angle increased by
14%. In a meta-analysis, Hadjipavlou et al concluded that, although postural
reduction can improve vertebral height following a compression fracture,
better reductions are obtained with kyphoplasty than with vertebroplasty.14
Better reductions may be achieved with earlier treatment.
CLINICAL PRESENTATION AND EVALUATION
Successful kyphoplasty hinges on d istinction of compression fracture pain
from other etiologies. Clinical assessment involves an evaluation of the
patient’s spinal alignment and gait, followed by palpation of the spine, ilium,
sacrum, and paravertebral tissues. The importance of local tenderness over
the involved spinous process as a principal sign of a painful VCF has been
analyzed in two studies. In the first, which comprised 10 patients, Gaughen
et al18 noted that local tenderness was not present despite imaging findings
suggestive of an acute fracture. Recently, Gaitanis and coworkers16 found
that spinous process tenderness corresponded to the level of pathology in
100% of osteolytic tumors and in 96% of VCFs when correlated with magnetic resonance imaging (MRI) findings of an acute fracture.
Several imagi ng techniques are employed in the evaluation of a painful
VCF. Recently, flexion and extension or standing and supine lateral radiographs have been used to assess fracture mobility. A number of studies have
examined the presence of intravertebral clefts. Although the exact cause of
these intraosseous nitrogen pockets has been d ebated, the so-called Kummel sign may characterize pseudarthrosis. A cone-down lateral view directly
perpendicular to the i nvolved level is required in the assessment, because
these clefts can easily be missed with standing lateral radiographs alone.
Magnetic resonance imaging is an important technique for detection of
osteoporotic compression fractures (Figure 34-1). It is more sensitive than
plain radiography, with a reported accuracy of 96%.19 Fracture acuity (or
failure of healing) is also best observed as intense signal on sagittal MRI
with short tau inversion recovery (STIR) sequences (Figures 34-2 and
34-3).20 For patients unable to undergo MRI, the combination of a tech-
netium bone scan with computed tomography (CT) of the scintigraphically active levels can provide useful information on relatively fresh vertebral
fractures (Figure 34-4).
21
There are patients in whom both MRI and CT imaging is useful. For
those with questionable endplate erosion, the greater bone–soft tissue contrast of the CT scan often demonstrates erosions more clearly (Figure 34-5).
Similarly, a fine-cut (2 mm) CT scan with sagittal reconstructions may
demonstrate small lytic lesions not otherwise seen in the fractured vertebral
body on MRI (Figure 34-6). Most commonly, however, the CT is ordered
as an adjunct to MRI in patients with canal compromise from their fracture.
19
C H A P T E R 3 4 Kyphoplasty
S162
F IG UR E 3 4- 3 The T1-weighted MRI gives better anatomic information
than the STIR. Look for evidence of metastatic change such as soft tissue extension or extension of the marrow signal through the pedicle.
209
F IG UR E 3 4 -1 In this sagittal MRI, a patient has gradually increased
collapse of superior endplate with stress injury to the pars and progressive
kyphosis and translation. This patient complained of both a chin on chest deformity and progressive myelopathy. Kyphoplasty is not indicated in this case.
S162
F IG UR E 3 4- 2 Sagittal T2-weighted or STIR MRIs are critical images in
the evaluation of a patient with suspected painful osteoporotic vertebral compression fractures. In this STIR image of a patient with a lumbar transitional
vertebral, multiple injuries are seen, especially acute L1 and L2 superior endplate
injuries. The acute injuries demonstrate marked marrow edema diffusely. In the
L1 lesion, a band of edema is seen from anterior to posterior along the fracture
line. These bands often reflect “reducible” fractures.
OPERATIVE TECHNIQUE
Kyphoplasty procedures may be performed in the operating room or in the
angiography suite. These procedures can be done under local anesthesia
with intravenous sedation or under general anesthesia. There are advantages
to both approaches. General anesthesia is associated with more comfortable
F IG UR E 3 4 -4 For patients unable to have an MRI, a bone scan can be
helpful in identifying acute or subacute fractures. In this case, note the marked
uptake at the T12 level.
prone positioning and less involuntary motion. On the other hand, rib
f ractures during positioning can occur.
Kyphoplasty patients are positioned prone on a radiolucent operating table or surgical frame. Lordotic positioning is maintained with bolsters. Lordosis allows a positional reduction. Later, when the balloons are
removed, the lordotically positioned patient will be less likely to lose the
reduction achieved. With this in mind, the radiolucent Wilson frame often
makes lordosis difficult to achieve. A Jackson frame may allow better lordotic placement, but may be less comfortable for awake patients.
Kyphoplasty begins with true anteroposterior (AP) and lateral fluoroscopic images (Figures 34-7 and 34-8). Ensure a true AP with the spinous
process in the midli ne between the pedicles. On the lateral view, the pedicles should line up and yield a clear view of the foramen and the posterior
210
F IG UR E 3 4- 5 CT scans are useful for anatomic detail in patients
unable to have an MRI. In patients with unusual fracture patterns or in those
in whom cortical compromise or metastasis is suspected, order a CT scan for
its excellent bone–soft tissue contrast. In this case of a prostate cancer metastasis, note the lytic lesion in the posterior aspect of the vertebral body with the
destruction of the posterior cortex. This patient would not be a good candidate
for percutaneous kyphoplasty, but mini-open or hybrid procedures could be
considered if needed.
P A R T V Osteoporotic Surgical Treatment Modalities: Thoracic Spine
border and aim medially. Once in bone, verify your trajectory on the lateral
image. If the AP and lateral images do not demonstrate a clearly intrapedicular position, an en face or oblique view is useful.
Under lateral fluoroscopic view, advance the Jamshidi to the midway
point of the pedicle. Return to the AP view and verify tip position. Until the
Jamshidi has passed through the posterior cortical margin of the vertebral
body, it must be lateral to the medial pedicle wall on the AP image. If the
needle has been medialized appropriately, return to lateral, and advance to
1 to 2 mm past the posterior vertebral body margin. Now the needle should
be just barely across the medial pedicle border on the AP. Remove the Jamshidi stylet and place a guide pin.
The osteointroducer instruments are passed over the guide pin. The
blunt dissec tor of the osteointroducer and guide pin are removed, leaving
the working cannula in place just anterior to the posterior cortical margin
of the vertebral body. Better medialization allows for more aggressive anterior placement. For harder bone, use the provided drill to prepare the path
for the bone void filler. Live or pulsed fluoroscopy is recommended when
approaching the anterior cortex.
Insert IBT to within 4 mm of the anterior cortex. Inflate the balloon to
50 psi (pounds per square inch) pressure to maintain its position and tamponade the bone. Place instruments through the opposite pedicle in similar
fashion. Once the contralateral balloon has been placed, inflate both IBTs
in 0.5-ml increments. Once inserted into the vertebral body, the balloons
are gradually inflated using visual (radiographic), and volume and pressure
controls (via a digital manometer), to reduce the fracture deformity.
Monitor AP, lateral, and oblique images for IBT position in relation to
cortices. Sequentially inflate until the following inflation endpoint is reached:
Realignment of vertebral endplates
Maximum balloon pressure (>220 psi) without decay
Maximum balloon volume: 4 m l for the size 15 balloon and 6 ml for the
size 20 balloon
Cortical wall contact
A number of acrylic cements are available. Though the PMMA kits used
with total joint arthroplasty can be employed, cement formulations specifically designed for vertebral augmentation may have better handling and setting characteristics. VBA cements also have extra sterile barium added to
the polymer powder to increase its radiopacity.
With the balloons removed, bone filler devices are advanced into the distal
portion of the cavity. Retrograde fill with PMMA is then undertaken using
fluoroscopic monitoring. For kyphoplasty, the PMMA is placed into bone
filler devices (BFDs). Then it is left in the device until it reaches a toothpaste
consistency. Early implantation with runny PMMA increases leak risk. Operating room temperatures may affect PMMA polymerization times. Occasionally, warm saline solution is useful to accelerate setting of the PMMA.
Using the plunger, apply the PMMA under continuous fluoroscopy.
Inject slightly more PMMA than final IBT inflation volume to allow intercalation of the material into surrounding trabeculae. The wound may be
closed with a suture or Steri-Strip.
F IG UR E 3 4 - 6 This axial CT image obtained in a patient noted to have
a compression fracture without trauma was found to have both a hemangioma
(on the right) and a lytic metastasis (on the left).
vertebral cortex. Both images should show the endplates of the level selected
as a single line, not an oval.
When possible, biplanar fluoroscopy should be employed. This saves
considerable time when switching from AP to lateral. If only one machine
is available, mark the fluoroscope positions achieved, so they are easily reachieved. Most typically, a transpedicular route to the vertebra is selected. In
some thoracic cases, the narrow and straight pedicle precludes appropriate
medialization and an extrapedicular approach is required. Most authors recommend a bilateral approach.
Beginning with AP fluoroscopy, an 11-gauge Jamshidi needle is placed
at the 10 o’clock or 2 o’clock position on the pedicular ring. Unlike pedicle
screws, the goal is not to proceed “straight down the barrel,” but rather to
medialize through the cylinder of the pedicle. Therefore start at the lateral
POSTOPERATIVE CARE
No braces or particular postoperative precautions are needed after kyphoplasty. That said, osteoporotic patients should be restricted in terms of
heavy lifting and the carrying of heavy weight away from the body or above
shoulder level. Osteoporotic patients should avoid concurrent bending and
lifting. Ensure that the patient has been evaluated for and treated for their
underlying osteoporosis.
Other postoperative care is fairly straightforward. Many patients will
have remaining axial weakness. Consider physical therapy for patients who
are weak or have ongoing muscular pain. Wound issues are typically minimal except for those patients taking blood thinners. Address nutritional
issues when needed.
COMPLICATIONS AND AVOIDANCE
Kyphoplasty complications can be categorized: medical, anesthesia related,
instrument placement, and PMMA problems. In most cases, failure to
improve is due to inappropriate patient selection. The more diffuse the
C H A P T E R 3 4 Kyphoplasty
211
A
F IG UR E 3 4 -7 These images exhibit craniocaudal and lateral intraoperative views in the operating room during a two-level kyphoplasty. In this case, a single
fluoroscopy unit was used and positioning assessed in the AP (A) and lateral (B) planes. Four working cannulae have been placed. Through the cannulae are seen the
inflatable balloon tamps attached to pressure syringes containing contrast medium. Serial inflation is undertaken gradually to effect reduction.
A
B
B
C
D
F IG UR E 3 4- 8 This series of fluoroscopic images demonstrates the kyphoplasty procedure beginning with a lateral scout image (A). Note that the pedicles
line up so that the foramen can be seen clearly. In this c ase, a biopsy was obtained through the cannula (B). The bone void filler or the special biopsy needle can
be used for this purpose. A syringe is attached to the needle and mild suction applied. An 8-gauge core is obtained. These cores may obviate open biopsy in
cases in which Tru-Cut and Jamshidi biopsies w ere not diagnostic. In C and D, balloons have been deployed and an excellent reduction of the superior endplate
is noted. On the AP view (D), note the m edialization of the balloons and the alignment of the spin ous process equidistant between the pedicle s. In E, from
another patient, the “air vertebrogr am” left when the balloons have been removed is noted. Note the backfilling of the void with PMMA. In the final lateral view
(F), excellent fill of the void is noted. Additional PMMA has been injected to fill the interstices around the void. Some of the reduction achieved with the balloons
was lost, however.
E
F
212
P A R T V Osteoporotic Surgical Treatment Modalities: Thoracic Spine
patient’s pain, the less likely they are to benefit from VBA. Placement of
PMMA into the spine may increase the risk of adjacent segment fracture.
Kyphoplasty patients are, by definition, frail. Medical and anesthesia
issues are not unusual in this elderly patient population. On the other hand,
VBA procedures are not significantly physiologically taxing. When medical
problems occur, they can be ascribed to the procedure itself or to preexisting
cardiac and pulmonary problems. In markedly functionally limited patients,
the risks of activity restriction in terms of deep vein thrombosis, pulmonary
embolus (PE), and opiate-related complications are likely underreported
and could be riskier than operative treatment.
Many patients in this age group take anticoagulant medications. When
possible, reverse these agents before kyphoplasty. In particular, patients with
multiple fractures, concomitant rib fractures, and osteoporotic bursting patterns are at higher risk for procedural and medical complications. Biopsies
should be performed with kyphoplasty in patients with a history of cancer
or an absence of concomitant trauma.
The most devastating technical complication of kyphoplasty arises
from PMMA extravasation. Leakage is clinically silent in the vast majority
of cases, with symptomatic leaks representing only a small portion of the
total.22 PMMA may extravasate into the vasc ular tree, disc space, anterior
and lateral soft tissues, and spinal canal. Extravasation is most common in
metastatic osteolytic tumors or myeloma.
15
Interestingly, leakage into the central canal is better tolerated in most
cases than intraforaminal leak; however, when symptomatic, central canal
extravasation leads to more devastating neurological symptoms, such as
paraplegia. In most cases, symptoms are transient and respond well to nerve
root blocks or oral medication; rarely do they require surgical decompres-
23
sion.
Along with the more viscous cement applied, void creation and bone
compacting effects may decrease extravasation rates compared with vertebroplasty. A cadaveric study by Belkoff et al24 reported reduced rates of
PMMA extravasation after kyphoplasty compared with vertebroplasty. In
a series of patients with metastatic disease, Fourney et al25 reported a 9%
extravasation rate after vertebroplasty, but no cases of extravasation following kyphoplasty.
Another serious complication of VBA procedures is postoperative
infection. Simple wound infections can be identified and treated easily,
but deep space infections including those of the cement mantle are serious and difficult to f ully eradicate without removal of the cement bolus.
Concurrent i nfection, even in distant organ systems, is a contraindication
to kyphoplasty
Improper instrumentation placement most frequently stems from difficulty delineating the bony anatomy in patients in whom poor bone quality coexists with spinal deformity, such as degenerative scoliosis or marked
spondylosis. Once the instruments are i n place, care must be taken not to
apply too much force, because leverage may lead to fractures. Pedicle and
transverse process fractures may lead to postoperative pain, irritate local
nerve roots, or destabilize the spine. Finally, these breaches create a path
for inadvertent leakage of cement i nto the spinal canal. In one multicenter
study, instrument placement problems led to postoperative hematoma in
two patients, and a direct injury to the spinal cord when an extrapedicular
approach was used on a vertebra with a fractured pedicle.
26
Methacrylate monomer is toxic. Some recommend that more than 30
ml PMMA be injected per session.27 The more viscous the cement, the less
likely it is that untoward blood pressure or blood gas effects will occur.
Several VBA reports suggest an increased risk of secondary fractures
adjacent to the augmented vertebra.
28,29
Two small studies suggest that
kyphoplasty decreases ad jacent fracture risk. Kasperk and colleagues
14
11,30
found that at 6-month follow-up, 30% (6 of 20) nonoperat ively treated
patients developed secondary fractures, whereas only 12.5% of 40 kyphoplasty patients had secondar y fractures. Similarly, Komp e t al12 reported
that 65% of 17 nonoperatively treated patients had new fractures, whereas
only 37% of 19 kyphoplasty patients had additional fractures. In the
FREE study, on the other hand, at 12 months, new vertebral fractures
were slightly higher but not statistically sign ificantly different between
the kyphoplasty (41.8%) and nonsurgical (37.8%) groups (p = .5).10 The
exact effects of VBA on adjacent levels probably vary with steroid exposure, spinal level, local spondylosis, and muscular factors; these require
further stu dy.
ADVANTAGES AND DISADVANTAGES
Advantages
Rapid pain relief
Percutaneous
Minimal medical impact
Ability to achieve partial reduction
Disadvantages
Achieving full reduction difficult
PMMA leakage is possible
Adjacent segment fractures possible
Extra cost and time of kyphoplasty has not yet proved advantageous over the
simpler, cheaper vertebroplasty
CONCLUSIONS AND DISCUSSION
Kyphoplasty has been widely available for roughly 10 years. During that
time, its popularity as a percutaneous means of stabilizing osteoporotic
compression fractures has skyrocketed. Vertebroplasty remains widely popular and highly successful as well. Use of balloon tamps appears to improve
fracture reduction and decreases cement leakage rates. But leakage remains
problematic in higher energy fractures and those associated with retropulsion. A number of newer procedures are evolving to compete with vertebroplasty and kyphoplasty.
Kyphoplasty should be considered in patients with persistent pain and
functional limitation after fracture despite a trial of nonoperative management. Markedly limited and bedridden patients should be offered earlier
treatment. In all cases, maximal management of the underlying osteoporosis
should be pursued.
A number of controversies remain. Reports conflict as to the degree of
reduction achieved and its impact on clinical outcomes. Kyphoplasty adds
significant cost, radiation exposure, and operative time over vertebroplasty.
So far, clear benefit has not been confirmed.
Though current data suggest that kyphoplasty patients experience
marked early pain reduction and return to activity, its impact on long-term
outcomes is unclear. As we study these fractures more closely, our ability to
predict which fractures are likely to collapse and which may heal uneventfully with observation should improve.
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Vertebroplasty
Elizabeth Gardner
35
k e y p o i n t s
Worldwide there are 1.4 million vertebral compression fractures (VCFs)
annually. e lifetime incidence in White women is 16%.
Vertebroplasty is indicated for the treatment of painful acute or subacute
vertebral compression fractures due to osteoporosis or neoplasm.
An acute or subacute osteoporotic VCF typically appears hypointense on
T1-weighted and hyperintense on T2-weighted and STIR MRI sequences.
Complications specifically associated with vertebroplasty include pain
localized to the injection site, cement extravasation, paralysis, pulmonary
cement/fat embolism, pneumothorax, and even death.
While a large number of studies have provided anecdotal evidence to support
use of vertebroplasty in the treatment of acute/subacute VCFs, Kallmes and
Buchbinder published two randomized controlled trials in 2009 doubting the
efficacy of the procedure. ough interesting, these studies are plagued with
numerous Shortcomings that leave their conclusions in doubt.
INTRODUCTION
It is estimated that 1.4 million vertebral compression fractures (VCFs)
occur annually, causing pain and disability in patients worldwide.
time risk of a vertebral compression fracture in White women is 16%; in
men, it is 5%. Historically, treatment of these fractures has been limited to
analgesics, bed rest, and bracing. However, recently the development of vertebroplasty and kyphoplasty has provided physicians with additional treatment options for select vertebral compression fractures.
1
The life-
HISTORY OF VERTEBROPLASTY
Vertebroplasty was initially developed as an open procedure designed to
augment the purchase of pedicle screws and to fill large voids from tumor
resection. In 1984, however, at the University Hospital of Amiens, France,
Galibert and Deramond performed the first documented percutaneous vertebroplasty.
demonstrated a large vertebral hemangioma encompassing the entire vertebral body of C2 with extension into the epidural space. After performing a
C2 laminectomy to excise the epidural component of the lesion, a 15-gauge
needle was inserted into the C2 vertebral body via an anterolateral approach,
allowing injection of cement for structural reinforcement. The document of
this case, as published in 1987, reports complete pain relief in this patient.
Physicians at University Hospital Lyon continued to refine the percutaneous
vertebroplasty technique as well as to expand its indications, using 18-gauge
needles to inject polymethylmethacrylate(PMMA) into four patients with
compression fractures. Since then, its popularity has spread dramatically.
2
The patient presented with severe cervical pain, and imaging
PATIENT SELECTION/INDICATIONS
As with any procedure, the success of vertebroplasty relies heavily on the
selection of appropriate patients and the skill of the operating physician. It
is essential to identify patients with pain related to VCF, and exclude the
214
other common sources of back pain in this population, including degenerative disk disease, spinal stenosis, facet arthropathy, or SI joint dysfunction.
This process begins, of course, by taking a thorough history of the patient.
It is particularly important to ascertain details regarding the timing of the
onset of back pain, any known precipitating events, and those activities that
worsen and alleviate the pain. Additionally, patients should be questioned
regarding previous episodes of similar back pain, and the time until resolution of those symptoms. It is vital to understand the premorbid condition of
the patient, as well as the impact of the back pain on activities of daily living.
Finally, an assessment for allergies, anticoagulants, and medical problems,
especially respiratory compromise, is essential to anticipate potential complications during the procedure. A thorough physical examination seeks to
identify pain and tenderness to palpation at the level of radiographic abnormality. During the examination, the operator must pay attention to symptoms that may suggest pain from alternative sources.
Radiographic imaging plays an important role in the screening of patients
for vertebroplasty. X-rays are often the first mode of imaging employed, due
to their cost-effectiveness and ease of availability. In patients with a VCF,
diffuse osteopenia and evidence of one or more compression fractures may
be present. With neoplastic compression fractures, it may be possible to see
focal lytic lesions or destruction of the bony trabeculae. A CT scan may be
obtained for improved visualization of bony details. Used most often with
pathologic fractures, CT may demonstrate expansion of the bony contours
of the vertebrae and multilevel disease, both of which suggest an underlying
malignancy. Preprocedure CT scanning also allows the operator to assess
the integrity of the posterior wall of the vertebral body and pedicles, which
if destroyed may be a source for significant complication.
MRI is particularly useful in the screening of patients with osteoporotic
VCF due to its reported ability to discern the relative age of the fracture.
Acute or subacute osteoporotic fractures up to 30 days old typically show
evidence of bone marrow edema, with hypointense signal on T1-weighted
and hyperintensity on T2-weighted and STIR sequences. At approximately 1 month after fracture, VCFs variably become isointense to normal
bone marrow on T1- and T2-weighted sequences. Fully healed fractures
are isointense to normal bone elements, or hypointense on T1 and T2 due
to significant sclerosis. Recent studies have found a positive correlation
between the MRI findings suggestive of a fracture less than 30 days old and
clinical pain relief after vertebroplasty.
Interpretation of MRI findings in a patient with a malignant VCF is
more challenging. While STIR sequences with fat suppression may be helpful to show edema, there may be heterogeneous or diffuse areas of hyperintensity on STIR or T2-weighted imaging. Some authors have suggested a
pattern of hypointensity or isointensity on diffusion-weighted sequences. In
any case, evidence of abnormal signal in the posterior elements, an expansion
of the contour of the vertebral body or posterior elements, or any associated
epidural/extravertebral soft tissue mass suggests an underlying malignancy.
Bone scintigraphy may be employed to detect a relatively recent fracture
in patients who cannot tolerate an MRI. Increased radiotracer uptake has
been correlated with positive clinical response to vertebroplasty. However,
this technique is limited by the fact that the bone scan may show increased
tracer uptake for up to 12 months after fracture. Thus this method must be
correlated with corresponding anatomic imaging.