Compression fractures that are a result of osteoporosis are not
benign. Besides the pain and disability that occur, morbidity and age-adjusted
mortality rates are also higher in these patients. Specifically, there is as much
as a 15% to 30% increase in mortality rate in patients with osteoporotic
vertebral compression fractures (VCFs). A comparison of a prospective cohort of
9,575 women over the age of 65 years also confirmed an increased age-adjusted
mortality rate, that increased with number of fractured levels, whether
symptomatic or not.[1] Each
subsequent vertebral fracture also causes diminishing forced vital capacity.[2] This seems to
affect morbidity, since many of these patients eventually die as a result of
pulmonary disease or cancer.[3] Is this a
cause or an effect? Certainly, many of these patients are debilitated with
pulmonary disease and are steroid-dependent. This question may not be answered
any time soon.
Until
recently, VCFs have been treated mainly with bed rest, analgesics, braces, and
variable modes of physical therapy. Operative intervention has been reserved
for cases of neurologic compromise, which are exceedingly rare in these
low-energy fractures. Poor bone quality usually necessitates long constructs,
segmental fixation, anterior and posterior surgery, and polymethylmethacrylate
(PMMA) augmentation. The massive undertaking of such surgical procedures is
often not possible for medical reasons, or simply not desired by the patient.
The advent of awareness of osteoporosis and early preventative regimens has
helped to lessen fracture risk by as much as 50%. Nonetheless, despite maximal
medical therapy, many fractures are still going to occur. What can be done for
the elderly patient who has an acute or chronically painful VCF?
In 1984, the use of PMMA for the percutaneous treatment of vertebral hemangiomas was first described.[4,5] Since then, a natural progression has occurred in the application of this technology to VCFs resulting from osteoporosis. Successful results have dominated the literature, with few complications noted.[6-12] The complications that have occurred have typically been related to the common event of cement extrusion from the vertebral body through nutrient blood-vessel foramina that pierce the structural cortical shell. Despite a high rate of cement extrusion (30% to 73%), neurologic sequelae are uncommon, and thermal injury to the neural structures does not appear to occur.[6,9,11,13] Pulmonary embolism of cement has rarely been reported, resulting in mortality.[14]
Advantages of
vertebroplasty include its relative simplicity, with the procedure often being
performed under a local anesthetic. This allows conversation with the patient
and a dynamic neurologic evaluation to help prevent cement extrusions. This
minimally painful procedure can be done either unilaterally or bilaterally, as
anatomy allows.[15] There are several
disadvantages of vertebroplasty, predominantly the result of high-pressure
injection of a low-viscosity cement. This technique has the potential for
cement extravasation and complications. Additionally, no attempt is made to
reduce the vertebral deformity, so normal anatomy may or may not be restored
with this technique.
Kyphoplasty is
a relatively new procedure that has evolved from the technique of
vertebroplasty. It was developed in 1997 and has gained popularity as an option
for the treatment of osteoporotic VCFs. This technique involves the placement
of inflatable bone tamps into the fractured vertebra, with subsequent expansion
of these balloons to create a bone void and also to restore vertebral height.
The premise of the procedure is that a more viscous
bone cement is injected into the bone under low pressure, and a known volume of
void is filled after variable height restoration. Few device-related
complications have occurred in the first several years kyphoplasty has been
used. Disadvantages of the procedure mainly relate to the relatively more
complicated instruments and proper placement of the bone tamps. Instrumentation
for kyphoplasty is also expensive, and this may be a consideration in the
managed care arena.
Indications for percutaneous vertebral augmentation procedures are patient-dependent. The natural history of osteoporotic VCFs is symptomatic improvement, though a third of the patients will have chronic pain. Theoretically, increased kyphosis may also propagate adjacent compression fractures. If that holds true with further study, then acute intervention would be indicated in the presence of kyphosis. It is imperative that the treating physician fully evaluate the patient, including prefracture function and morbidity, and assess the risks of prolonged recumbency, narcotic medications, and braces. With these patient-specific factors in mind, several relative indications for vertebroplasty and kyphoplasty have been outlined in the literature. Acuity of treatment is truly dependent on the amount of pain, medical condition of the patient, and efficacy of nonsurgical treatments. Results have been excellent with both procedures, with few clinically significant complications. Kyphoplasty seems to show some promise in early studies with fewer complications, less frequent cement extrusion, and a similar efficacy to vertebroplasty.[16,17]
Preoperative
evaluation requires the patient to tolerate the prone position for 1 to 2
hours. General anesthesia is necessary for patients unable to lie prone or needing treatment to multiple levels, versus
sedation and a local anesthetic for patients needing treatment to 1 or 2
levels. There should be no evidence of coagulopathy, and platelet inhibitors or
anticoagulants should be stopped before the surgery to allow for normal
clotting. Additional workup before either procedure should include standing
anteroposterior and lateral radiographs, if possible, magnetic resonance
imaging (MRI) with short tau inversion recovery (STIR) sequences, and
occasionally bone scan and/or computed tomography (CT). Radiographs taken with
the patient standing will often show more deformity or collapse than films done
with the patient supine. This allows identification of some fractures that
otherwise may not be easily visualized. Magnetic resonance imaging will show
hypointensity or isointensity on the T1-weighted images, and a hyperintensity best
seen on the STIR sequences (Fig. 1). This appearance is characteristic of an
acute fracture, especially when a linear hyperintense zone underlies the
depressed endplate. It is necessary to exclude malignant pathology, if
possible. Computed tomography is helpful when patients are unable to tolerate
MRI. Sagittal reconstructions will often show a vacuum phenomenon within the
vertebral body, consistent with avascular necrosis or K¸mmell's disease. These
latter fractures respond well to kyphoplasty or vertebroplasty. Bone scan is of
limited value, however, and may be positive in only 20% of patients with height
loss >15%; it is more often positive in fractures with height loss of
>25%.[18] Knowing the
limitations of radiographic studies is necessary to determine the best
evaluation of the patient while limiting the number of unnecessary tests.
After
treatment by vertebroplasty or kyphoplasty, patients are allowed up after
recovery from anesthesia or sedation. Symptomatic relief is usually significant
within the first few days after the procedure. No procedure-specific
limitations on patient activity are required after either procedure. Physical
therapy is prescribed for patients with a significant muscular component to
their pain after surgery, which is common in chronic fractures. Additionally,
patients can be instructed regarding weight-bearing aerobic exercises for the
prevention of further bone loss. Braces are not used.
Adjacent-level compression fractures deserve
mention. Biomechanically, these procedures are augmenting a soft and fractured
vertebral body. As a result of the use of PMMA, over-stiffening of segments may
result in fracture of the untreated levels. This has been identified in as many
as 10% of patients having these procedures. Not all of these fractures are
symptomatic; however, the acute recurrence of pain after a pain-free
postoperative interval should arouse suspicion of a new compression fracture.
Treatment should proceed as for any acute fracture, though acute treatment with
augmentation may be desirable to the patient after the results of the index
procedure are realized. In my practice, this is especially problematic at the
site of chronic fractures. When these fractures are left alone, the poor
alignment increases the tendency for kyphosis and increases forces on the
adjacent segments. Couple this with the increased stiffness of an augmented
vertebral body after either of these procedures and there is a risk for
subsequent adjacent-level fractures. Decreased volume of cement or use of more
biologic materials may help reduce this tendency, but this problem needs to be
monitored.
In summary, there are presently excellent
options for the treatment of symptomatic VCFs in the osteoporotic patient.
Recognition of the problem, patient education, and early pharmacologic
treatment are preventive in many cases. Kyphoplasty and vertebroplasty are used
in cases when other treatment fails, but allow for quick improvement of
symptoms in most patients, with a minimum of complications. After augmentation
of VCF, all patients should be re-evaluated to determine if they have been
investigated for osteoporosis or if the present treatment regimen is adequate.
New directions in treatment will include the use of hydroxyapatite cements and
other osteoinductive agents for filling vertebral voids.
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Vertebroplasty and kyphoplasty indications[9] |
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Destabilizing painful lesions |
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Hemangiomas |
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Malignant tumors |
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Osteoporosis VCFs |
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Persistent and severe focal back pain related to 1-3 fractures lasting >3-4 weeks |
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Impending decubitus ulcers |
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Pain after 1-2 weeks in severely debilitated patients |
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Patients not responsive to conservative treatment |
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Vertebroplasty contraindications |
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Complete loss of vertebral height (vertebra plana) |
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Presence of osteoblastic metastasis |
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Tumor involvement with lysis of the posterior vertebral-body wall |
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Acute burst fracture or high-energy fractures |
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Kyphoplasty contraindications |
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Pregnancy |
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Bleeding disorders, warfarin, heparin, etc |
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Pain unrelated to vertebral collapse |
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Fractured pedicles |
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Solid tumors |
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Osteomyelitis |
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Contrast allergy (balloons are filled with contrast that can extravasate if they rupture) |
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Use caution in patients <40 years of age, due to unknown natural history of PMMA in younger patients |
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VCFs = Vertebral compression fractures, PMMA =
polymethylmethacrylate.
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Vertebroplasty results[6-11] |
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70%-90% have less pain |
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Complications in 10% with neoplasm |
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Complications in 1%-6% with osteoporotic VCFs |
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Radiculopathy (4%) |
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Femoral nerve/lumbar plexus palsy |
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Spinal stenosis (0.5%) |
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Rib fractures |
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Infection |
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Pulmonary embolus |
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Death |
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Cement extrusions 30%-73%6,[9,11,13] |
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Kyphoplasty results[16,17] |
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90% have less pain at 18 months postoperatively |
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Kyphosis decreased by 50% |
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Height restoration also noted |
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Average hospital stay 1-3 days |
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Complications (1.2%) |
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Paralysis |
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Epidural hematoma |
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Transient fever and hypoxia |
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Cement leaks (8.6%) |
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