Chapter 66 Osteoporosis, Vertebroplasty, and Kyphoplasty Flashcards
KEY POINTS 1. Osteoporosis and VCFs are a significant public health concern with high morbidity. 2. Vertebral augmentation is a safe and efficacious procedure for treatment of painful VCFs that fail conservative therapy. 3. Proper technique and vigilance can help avoid serious complications and the procedure should only be performed by those trained and experienced with the procedure. 4. Both kyphoplasty and vertebroplasty are efficacious for pain relief, but recent double-blind, placebo-
Vertebral compression fractures (VCFs) are caused by
the inability of the vertebra to sustain internal stresses applied from normal daily load or trauma. The inability of the vertebra to maintain
its structure is related to the constant change in its composition.
The primary structure of bone is distinguished
by
cortical, or compact bone, and trabecular bone,
otherwise known as cancellous and spongy bone.
Cortical bone is generally on
the surface and is characterized by its
dense composition without cavities
trabecular bone has many
interconnecting cavities consisting of red
blood cells and yellow bone marrow composed of fat cells
Trabecular bone
found in large supply in vertebral bodies, is largely responsible for the majority of the axial forces and
inherited extra-axial stress and strains. The extent of the two types of bone varies depending on its location.
Bone is also composed of
osteoprogenitor cells, osteoblasts, osteoclasts,
osteocytes, neurovascular progenitor cells of external origin, and an array of inorganic and organic constituents.
In multiple myeloma, there is an imbalance of
osteoclasts and osteoblasts (increased osteoclastic
activity) that can cause lytic lesions in the absence of
osteoporosis
The majority of vertebral compression fractures are
caused by
osteoporosis, but other causes include multiple
myeloma, metastatic tumor, and hemangiomas
Decrease in
height and vertebral deformities are indications of
vertebral fractures. Most VCFs are asymptomatic, and there is no associated origin of injury
Management of vertebral deformities
Most fractures will heal
within a few months, but some have pain and disability that fail to respond to conservative therapy. Conservative therapy includes the use of back bracing, bed rest, and
pain control with medications such as nonsteroidal antiinflammatory drugs (NSAIDs), calcitonin, and narcotics.
adverse consequences of conservative therapy
deep venous
thrombosis, pulmonary embolism, pneumonia, and accelerated
bone loss can occur with prolonged bed rest.
consequences of vertebral compression fractures
are
height loss and kyphosis.
Initial treatments for painful compression fractures that
failed conservative therapies
usually revolved around
surgery
technique for the treatment of osteoporotic compression fractures
Percutaneous vertebroplasty. injecting polymethylmethacrylate (PMMA) into the painful vertebral body provided significant pain relief
Kyphoplasty to address
the additional consequences with vertebral compression
fractures that came along with pain (height loss and kyphosis).
the addition of inserting and inflating a balloon in the vertebral body prior to cement to restore height and decrease kyphosis
Osteoporosis
marked by a reduction in bone mass per unit volume with normal bone chemical composition, decreased skeletal function, progressive spinal deformity, and vulnerability to fractures.
Osteoporosis aka
lso dubbed “porous bone
disease” or “brittle bone disease,” osteoporosis is a universal disease
Bone
a connective tissue that is responsible for hematopoiesis, mechanical and structural support, and mineral storage of inorganic salts and organic material. Bone is constantly broken down and architecturally rebuilt to provide optimal mechanical support for its various functions.
If bone turnover, the breakdown and formation of new bone, is unbalanced,
then progression of bone loss develops.
hallmarks of osteoporosis
an increase in bone
resorption and a decrease in new bone formation.
Characteristics of osteoporosis
l It affects more women than men, as women possess 10% to 25% less total bone mass at maturity.
l Caucasian and Asian women are at highest risk of developing an osteoporotic fracture due to low bone mineral density.
l In the US, 35% of women over age 65 years and 15% of Caucasian postmenopausal women are osteoporotic.
l In the U.S, this debilitating disease causes fractures in 1 million individuals per year with $14 billion spent for treatment.
l Hip and vertebral fractures occur in women at a rate of 250,000 and 500,000 cases annually, respectively,
and an additional 250,000 fractures are experienced
by men every year.16,17
l Vertebral fractures in women increase as menopause approaches and old age, with a ratio of 2:1 compared to men.
Iatrogenic osteoporosis is
caused by
prolonged corticosteroid administration, furosemide,
thyroid supplements that suppress TSH production,
anticonvulstants, heparin, lithium (by causing hyperparathyroidism),
and cytotoxic agents.
Type I of Osteoporosis
Postmenopausal Primarily trabecular bone 6:1 female to male ages 51–65 No calcium deficiency Estrogen deficiency Vertebral and Colles’ fractures prevalent Risk factors: low calcium intake, low weight-bearing regimen, cigarette smoking, and excessive alcohol consumption
Type II of Osteoporosis
Senile
Primarily cortical bone
2:1 females to males of age> 75 years
Calcium deficiency, decreased vitamin D, and increased PTH activity
No estrogen deficiency
Pelvic, hip, proximal tibia, and proximal humerus prevalent
Related to low calcium intake
Secondary Causes of Osteoporosis
Paget’s disease Malabsorption syndrome Hyperparathyroidism Multiple myeloma Hyperthyroidism Prolonged drug therapy Osteomalacia hypogonadism
DIAGNOSIS AND INITIAL EVALUATION
l Medical evaluation requires thorough investigation of family and medical history as well as physical and gynecologic
assessment.
l A complete blood cell count, serum chemistry group, and a urinalysis including a pH count should be carried out.
l Consider thyrotropin, a 24-hour urinary calcium excretion, erythrocyte sedimentation rate, parathyroid hormone and 25-hydroxyvitamin D concentrations,
dexamethasone suppression, acid–base studies, serum or urine protein electrophoresis, bone biopsy and/or
bone marrow examination, and an undecalcified iliac
bone biopsy if suspected as the underlying cause.
l Dual-energy x-ray absorptiometry (DXA) to evaluate bone mineral density. Plain radiographs are an option, but changes are usually seen after 30% loss of bone mass.
following categories receive routing screening by DXA
l All women 65 years and older
l Any adult with a history of fracture not caused by severe
trauma
l Younger postmenopausal women with clinical risk
factors for fracture
diagnostic criteria to designate the presence of
osteoporosis based on DXA measurements
Normal individuals possess a bone mineral density of one standard deviation (SD) of the mean of young adults. If bone mineral density is measured
2.5 or more SDs below the mean of a young adult population, then osteoporosis is present.
Osteopenia
indicated if the SD of bone mineral density is between 1.0 and 2.5 below the mean of a young adult population.
severe osteoporosis is denoted when
one or more accompanying
fragility fractures is present.
Bone Mass Density in women
Women lose 3% to 7% of BMD around the onset of menopause followed by a 1% to 2% decline yearly in the postmenopausal period
appropriate regimen of preventive
and therapeutic measures to combat osteoporosis
l Calcium and vitamin D l Bisphosphonates l Calcitonin l Selective estrogen receptor modulators l Parathyroid hormone l Sodium fluoride l Exercise l Modifiable risk factors such as cigarette smoking, excessive alcohol consumption, and treatment of potential secondary causes
Osteoporotic fractures are more prone to occur at the
hip, ribs, wrists, and vertebrae.
contribute to the complications of an
osteoporotic hip fracture.
pneumonia, blood clots in the lungs, and heart failure
Vertebral compression fractures (VCFs) can decrease height by up to
15 cm and result in the
kyphotic deformity called “dowager’s hump.”
Vertebral compression fractures occur due to the
inability of the osteoporotic vertebra to sustain internal stresses applied by the vertebral load from daily life or from minor or major traumatic events.
Trabecular bone
largely responsible
for the majority of the axial forces and inherited
extra-axial stress and strains. With the cascade of osteoporotic effects and aging, the architecture of trabecular bone becomes altered, characterized with increased spaces, thinness,
disorientation, and weakened connectivity
compromise the vertebra’s mechanical prowess, integrity, and spinal column stability, predisposing
it to trabecular buckling
a decrease in density and loss of structural strength
Multiple VCFs develop a
hyperkyphotic or “dowager’s hump” at the thoracic level with a stooped posture decreasing
abdominal and thoracic cavities. Multiple lumbar VCFs further increase lordosis, creating a protruding abdomen.
A decrease in axial height is a result of reduction of
intervertebral and vertebral loss of height. Also, developed stooped
posture progresses to the point where ribs rest on the iliac crest with circumferential pachydermal skin folds developing at the pelvis and ribs.
The cauda equina or spinal cord related symptoms
are uncommon and are secondary to other conditions, such as
Paget’s disease, lymphoma, primary or metastatic
bone tumors, myeloma, and infection
Effects of VCF on life
When awakening, the abdomen appears normal, only to distend throughout
the day. Nonrestorative sleep or trouble getting to sleep is often the case with patients. Lifestyle changes occur, such as difficulty driving a car, getting dressed, fear of large crowds, and depression. Self-esteem is also compromised as a result
of a socially unacceptable body image.
the most common primary malignant tumors of the bony spine that rarely affect the posterior elements.
Multiple myelomas
Diffuse multiple
myeloma presents
reoccurring lesions at previously radiated levels and offers a poor prognosis
Management of multiple
myeloma
Initially, patients
report severe pain and disability and are unresponsive to drug treatment. The disease is usually multifocal in nature and surgical consolidation is not advantageous. In spite of this, single-level lesions are treated with vertebrectomy and strut grafting with some success. radiation therapy alone or as an adjunct to surgery to address the painful manifestation of malignant lesion offers partial or
complete pain relief.
Vertebral augmentation for Multiple Myeloma
Vertebral augmentation offers an alternative route for immediate pain relief, bone strengthening,
and mobility. Although vertebral augmentation goes some way to restoring the mechanical integrity of the vertebral
body and provides a degree of pain relief, tumor growth is not prevented. Therefore radiotherapy accompanying
augmentation is appropriate because it does not affect the
properties of the bone cement, affects tumor growth, complements
pain relief, and effects spine strengthening
Hemangiomas
benign bony spine lesions. Often, hemangiomas are detected during evaluation of back pain and subsequent routine plain radiographs. Soft tissue
extension of the lesion may compress the spinal cord and nerve roots producing neurologic symptoms and even produce epidural hemorrhage.
If extensive growth of the
hemangioma transpires,
vertebral integrity may be compensated, resulting in fracture with associated pain at the level of the lesion.
signs of the aggressive nature of hemangiomas and their candidacy for vertebral augmentation
Vertebral collapse, neural arch invasion, and soft tissue mass extensions
metastatic tumor
develop malignant lesions in the spine common location
thoracic spine but all levels can be affected and usually more than one level is involved
The most important aspect of patient evaluation of VCF begins with
good clinical history and physical exam
Patients with symptomatic VCF typically present with
acute or subacute back pain with no associated major trauma or precipitating event. The sudden onset of pain is
usually described as a moderate to severe, deep ache, at midline location, and exacerbated by any motion. More specifically, pain is experienced when standing from a seated position, bending, lifting, and prolonged sitting
and/or standing. Walk is sluggish, but gait is normal.
Coughing, sneezing, and bowel exertion exacerbate pain.
Pain of VCF may be relieved by
recumbent positioning and bed rest
In VCF Physical examination will usually find a patient in
mild to severe distress depending on the the general conditioning
of the patient as well as the location and type of fracture. There is usually tenderness at the site of fracture in the midline, but its absence does not rule out the presence
of an unhealed fracture.
Kyphosis
may also be an important
indicator of VCF as loss of more than 4 cm of height
is associated with 15 degrees of kyphosis
imperative to rule out other causes of symptoms, especially myelopathy,
radiculopathy, and spinal stenosis
Comprehensive
musculoskeletal and neurological exam
Diagnosis of VCF
Decrease in height and vertebral deformities are indications of vertebral fractures. VCFs maintain an axis of rotation at the middle column. As a
result, anterior column disruption is seen with intact middle and posterior columns.
Bioconcave VCFs manifest as a
central vertebral deformity
as a crush fracture involves anterior, posterior, and central aspects.
Wedge fractures
the most common VCFs, affecting anterior elements more often than posterior.
VCFs adopt, fractures
occur more often at the
thoracolumbar and midthoracic region
Once there is suspicion of VCF or new-onset, moderate to severe back pain not explained by any other cause
radiographic imaging should be ordered. The simplest, most cost-effective initial study is a plain AP and lateral x-ray of the suspected area of the spine. However, if there
is a high clinical index of suspicion, it is reasonable to proceed straight to magetic resonance imaging (MRI).
MRI is useful in determining
acute versus chronic fractures (edema on T2 weighted image) as well as determining any canal compromise or tumor presence. A hypointense T1 weighted image is also suggestive of edema
Short tau inversion recovery (STIR)
a type of MRI that is used to suppress the hyperintensive image readings of
substances such as fatty tissue and cerebrospinal fluid. STIR is the most sensitive imaging sequence for visualizing edema, and edema is highly predictive of success with vertebral augmentation
If MRI is contraindicated, then either
bone scan or computed
tomography (CT) scan may be useful in determining
the acuity of the fracture. Acute or unhealed fractures will take up the injected 99mTc-MDP tracer in higher concentrations on bone scan. Thin-section (< 3 mm) CT is often used in conjunction with MRI reconstructions in
order to derive the most accurate visualization of the target vertebral levels.
CT has been cited specifically as the best modality for
determining whether or not a fracture line has extended through the posterior wall of a vertebral body. CT can also see fracture cavities that should be the targets.
Comprehensive evaluation of the patient should also
include other causes of VCFs
Complete blood count Serum calcium Serum alkaline phosphatase Serum creatinine Urinary calcium excretion Serum 25-hydroxyvitaminD Serum protein electrophoresis Sex steroids Serum aminotransferase Serum TSH
Once a determination is made that VCF is the cause of the patient’s pain, steps should be taken to
manage and keep the patient weight bearing and prevent functional
decline.
Management of VCF
Initial modalities include walking aids and lumbar supports, but efficacy of
lumbar supports has limited evidence and my cause more harm if used chronically.
Exercise programs have demonstrated
decreased use of analgesics, improved quality of life and increased bone mineral density along with evidence that 1% of bone loss per year in the spine and hip is prevented or reversed.
Pharmacologic therapy for VCF
NSAIDs if tolerated, short- or long-acting opioids, and, possibly, calcitonin.
Acute pain from VCF can persist up to
12 weeks, while chronic pain is secondary to vertebral deformity, paraspinal muscle spasm, or degenerative arthritis in the region of the fracture.
At any time point, if
pain is uncontrolled to the extent that the patient cannot perform weight-bearing activities, or has side effects from analgesics
vertebral augmentation should be considered,
assuming that proper workup is completed and the VCF is the source of pain
VERTEBRAL AUGMENTATION
Minimum
requirements for the procedure include:
l IV access and sedation; possibly general anesthesia.
l Image guidance—usually fluoroscopy, possibly computed tomography or both. Some practitioners advocate using a biplanar fluoroscope to always have an AP and lateral image. This is convenient and saves time, but is not necessary.
l Informed consent.
l IV antibiotic prophylaxis—cefazolin 1 g or clindamycin 600 mg—within 60 min of incision.
l Appropriately padded table for prone positioning.
l Sterile precautions.
l Appropriate bone biopsy needles with opacified PMMA.
VERTEBRAL AUGMENTATION
There are two different techniques in placing the
11- or 13-gauge needles
transpedicular and parapedicular. In general, the augmentation of the lumbar and lower thoracic (below T10) spine is usually performed with a transpedicular approach,
while the upper thoracic spine (above T8) is done with either route, but usually parapedicular
VERTEBRAL AUGMENTATION
Technique
Intravenous antibiotics should be given within 60 min of incision. Once the patient is in position and pressure
points are padded, the C-arm is brought in to identify the proper level or levels to be augmented. This level is marked and the area is prepped and draped in usual sterile
fashion.
VERTEBRAL AUGMENTATION
For the transpedicular approach, there are two methods that can be utilized and can be simply defined as
the AP approach (maintaining visualization of the medial and lateral cortex of the pedicle) versus the en face approach (tunnel vision). Regardless of approach, an AP image is first obtained of the appropriate level.
VERTEBRAL AUGMENTATION
If utilizing the en face approach
the C-arm is then angulated ipsilateral oblique to place the pedicle in the middle of the vertebral body
VERTEBRAL AUGMENTATION
For the AP approach, the target needle site is the
superior
and lateral portion of the pedicle, sometimes described as the 10 o’clock or 2 o’clock for the left and right pedicle on AP view, respectively. If utilizing the oblique view, then
the needle should be placed in the center of the pedicle
VERTEBRAL AUGMENTATION
Technique
Local anesthetic is infiltrated intradermally and subcutaneously. A 22-gauge spinal needle is then advanced coaxially to the periosteum of the pedicle. Then 5 to 10 ml
of either 2% lidocaine or 0.5% marcaine is injected at the periosteum and during withdrawal of the spinal needle to anesthetize the tract of the larger needle. Then, a small incision is made with an 11-blade scalpel. The needle is
advanced to the pedicle in the tract of the spinal needle. After the needle is engaged into bone, either a screwdriver
technique or gentle tapping with an orthopedic hammer is used to drive the needle into the pedicle with frequent imaging to confirm that the needle is within the pedicle
VERTEBRAL AUGMENTATION
Technique
Once needle is properly engaged
an AP view is obtained to confirm that the medial cortex of the pedicle is not violated. A lateral image is then obtained to confirm that the needle is within the pedicle
and not cephalad or caudal, in which case a disc or nerve
foramen may be entered
VERTEBRAL AUGMENTATION
Technique
For vertebroplasty, the needle is advanced into the
anterior third of the vertebral body, while for kyphoplasty the needle is only advanced
into the posterior third
VERTEBRAL AUGMENTATION
Technique
The parapedicular approach involves
placing the needle
lateral to the edge of the pedicle and advancing along
the surface of the pedicle directly into the vertebral body.
Initial needle placement is lateral to the lateral cortex of
the pedicle. The vertebral body is entered the junction
of the pedicle which will appear more anterior on lateral
imaging. More medial placement of the needle in the vertebral body, and thus greater likelihood of a single needle placement, may occur with this approach. This approach may be preferred for treatment of compression fractures above T10 because
of the smaller pedicle size.
The goal of augmentation
is to
have filling of all of the fracture lines.
KYPHOPLASTY
initial needle placement
similar to
the vertebroplasty approach except that the needle is not
advanced past the posterior one-third of the vertebral body. Also, the introducer system is slightly larger than the vertebroplasty needles.
KYPHOPLASTY
Technique
The introducer has a beveled or diamond tip, which allows it to be gently hammered or manually pushed into the vertebral body. After entering the posterior aspect of the vertebral body, the introducer is removed
leaving the cannula in place. A hand-operated drill is advanced to the anterior aspect of the vertebral body taking care not to violate the anterior margin on lateral imaging.
KYPHOPLASTY
Technique
Ideal placement on AP imaging is in the midline. The drill is then removed and the deflated balloon is advanced through the cannula into the cavity. created by the drill. A second introducer and balloon should be placed on the opposite side in a similar fashion. Each balloon is attached to a locking syringe that has a
digital manometer followed by slow inflation with iodinated
contrast. Both manometry and fluoroscopy are used
to monitor balloon inflation
KYPHOPLASTY
Continue
inflating the balloon until:
l Maximum pressure (up to 400 psi) or volume is reached.
l The balloon tamp reaches any cortical margin.
l Correction of the kyphotic deformity.
l The balloon is then deflated and removed.
POLYMETHYLMETHACRYLATE
the PMMA contains a sterile barium sulfate powder to provide radiographic opacity. There are various PMMA mixing and delivery
options for both vertebroplasty and kyphoplasty
PMMA
For vertebroplasty
a cannula from the cement mixer is
connected to the needle and the cement is slowly injected
under live fluoroscopy in the lateral position. Injection is stopped periodically with intermittent fluoroscopy during
“rest” periods to ensure proper control of cement spread
and avoid aberrant placement.
PMMA
Injection is stopped when the
posterior one-third or one-fourth or any other cortical margin is reached
PMMA
The stylet must be
placed into the needle to
complete the injection and not allow the cement in the lumen of the needle to track
back in the needle which could cause cement leakage into
neural foramen, spinal canal, or paraspinal muscles. The stylet is placed under live or intermittent fluoroscopy to visualize final spread of cement.
PMMA
For kyphoplasty
the cement has a slightly greater viscosity than the one used during vertebroplasty. PMMA is injected using a blunt cannula under live fluoroscopy. Injection is stopped
when the cavities are filled along with any potential fracture
line outside of the cavity.
PMMA
After the cement is injected, the delivery system
removed and pressure is maintained on the incision sites.
Contraindications to Vertebral Augmentation
Absolute
Uncorrectable coagulation disorders Allergy to PMMA or contrast Spinal instability Myelopathy Pregnancy Active site infection or sepsis Fractured pedicles Burst fractures Young age Pain unrelated to fracture Solid tissue or osteoblastic tumor
Contraindications to Vertebral Augmentation
Relative
Inability to lie prone Loss of vertebral height 66% (vertebroplasty) Posterior wall destruction 20% retropulsion with spinal stenosis Previous spinal stenosis Vertebra plana Gibbus H-shape Multiple previous surgeries Obesity Poor pulmonary status Greater than three compression fractures
complications of Vertebral Augmentation
l Osteomyelitis l Hematoma (paraspinal or epidural) l Rib fracture l Sternum fracture l Adjacent vertebral fracture l Pedicle fracture l Pulmonary embolus of PMMA l Hypotension l Cord compression l Epidural abscess l Neurologic complications l Allergic reaction to contrast or PMMA
required
if there is any postprocedural neurologic compromise
caused by bleeding or cement leakage into the epidural
or foraminal space
Surgical decompression
Adjacent vertebral fractures are a significant concern with
vertebral augmentation
A vertebral compression fracture
causes a focal kyphotic deformity that moves the center of
gravity forward, which increases the load onto adjacent
vertebrae
Vertebroplasty Advantages
Lower cost Shorter procedure Decreases pain Infrequent clinical sequelae due to cement extravasation Often done under local anesthesia Stabilize and strengthen vertebral body
Vertebroplasty
Disadvantages
42% cement extravasation
Limited correction of lost vertebral Body height
Cannot correct sagittal imbalance
Kyphoplasty Advantages
Lower cement extravasation Lower complication rate Equivalent pain relief Vertebral body height restoration Sagittal imbalance correction Stabilize and strengthen vertebral body
Kyphoplasty Disadvantages
Increased cost
Increased procedural time More likely to require general anesthesia
Usually requires overnight hospital stay
Kyphoplasty has been touted to restore
vertebral body
height and restore sagittal alignment.
