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Kyphoplasty—A Treatment Option for Vertebral Compression Fractures
By Henry Ty, M.D.
Division of Neurological Surgery
Up until recently, patients with painfulcompression fractures have had limited treatment options. For Patient A, narcotic analgesics work intermittently but have been causing constipation and too much drowsiness. Patient B was treated for pneumonia recently and presents with sudden back pain that is not relieved by medications. Patient C had a car accident a few months ago and is now having worsening back pain that affects daily activities. All three patients have pain as the only symptom. They also have osteoporosis. MRI of their thoracic or lumbar spines showed vertebral compression fractures with bone marrow edema. In the past, further treatment would have consisted of dose adjustments, trials with other analgesics, or using various modalities for pain control. Recently, kyphoplasty has become available as a treatment option.
What is Kyphoplasty?
Kyphoplasty is a percutaneous procedure that introduces a pair of balloon-tipped catheters into the fractured vertebral body. Each catheter is connected to a syringe filled with a radio-opaque solution that allows fluoroscopic visualization of the balloon as it is inflated or deflated. A digital gauge measures the pressure within the balloon. Balloon inflation compacts the bone, creates a cavity within the vertebral body, and restores some of the vertebral height. After the balloons are deflated and removed, high-viscosity polymethylmethacrylate (PMMA) bone cement is injected into the cavity. The PMMA hardens and stabilizes the fracture. This usually provides significant pain relief, shortens the duration of pain, and prevents the progression of kyphosis.
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Figure 1. T11 and L1 compression fracture before balloon inflation
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Figure 2. Partial restoration of body height after balloon inflation.
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Kyphoplasty is a modification of vertebroplasty, a percutaneous procedure first performed in France in 1984. Vertebroplasty has been in the U.S. since 1995. It uses a catheter to deliver low-viscosity PMMA into the fractured vertebral body. Kyphoplasty is essentially a balloon-assisted vertebroplasty. This innovation allows possible vertebral height restoration prior to the injection of the PMMA. The cavity that is created allows the PMMA to be delivered with lower pressure than in vertebroplasty, thus decreasing the risk of cement leakage.
The Kyphoplasty Procedure
Kyphoplasty is done under general anesthesia and with biplane fluoroscopy. The patient is placed in a prone position. The fractures are localized with anterior-posterior and lateral views simultaneously. The entry points are marked and small incisions are made. Two tubes are positioned within the vertebral body, one on each side, through the pedicles in lumbar fractures or lateral to the pedicles in thoracic fractures. These serve as working channels for the balloon-tipped catheters. A bone biopsy is usually done to rule out metastasis, multiple myeloma, or other neoplasms. Up to three fractured segments may be done in a single procedure. Blood loss is minimal. The hospital stay is usually one or two days.
Indications for Kyphoplasty
The main indication for kyphoplasty is intractable pain due to compression fractures. The more commonly seen fractures are associated with osteoporosis, and they usually present as sudden onset of back pain with little or no trauma. Even minor stresses such as coughing or bending may result in a fracture. The elderly are especially at risk. The risk of subsequent compression fractures is increased five-fold after first fracture and up to twelve-fold after two or more fractures. Although the majority of compression fractures are minimally symptomatic, those that are painful may become quite debilitating. Elderly osteoporotic patients who present with severe pain can be difficult to treat. They often do not tolerate external bracing or the side effects of analgesics. Prolonged bed rest may worsen osteoporosis. When pain is severe enough to require hospitalization, kyphoplasty for pain relief should be considered.
Kyphoplasty is also indicated in painful compression fractures resulting from osteolytic metastasis, multiple myeloma, aggressive hemangioma, lymphoma, or eosinophilic granuloma. It is used in conjunction with radiotherapy to complement pain relief and to provide support for the tumor-ridden vertebral body. In the radiosensitive multiple myeloma, for example, pain relief may be delayed by as much as two weeks after initial radiotherapy, and spine strengthening takes about two to four months.
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Figure 3. Fracture (arrow) seen on plain radiograph.
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Figure 4. MRI STIR image showing the fracture to be old (with no bone edema—upper arrow) and a recent fracture below it (with bone edema—lower arrow) not apparent on the plain radiograph.
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Diagnosis of Compression Fractures
A clinical suspicion of a fracture in those at risk is important for its diagnosis. Serial radiographs will show progressive loss of vertebral body height. A patient who presents with pain and a normal-looking radiograph may return later with worsening back pain and a collapsed bone. These compression fractures are easily missed initially, especially when no vertebral body collapse was seen. When symptoms are apparently more severe than what would be expected in the plain radiographs, other imaging studies will be helpful. Subacute fractures are usually diagnosed by their high signals in the short-tau inversion-recovery (STIR) MRI images. A seemingly normal vertebral body on radiographs may appear white on STIR images, consistent with marrow edema seen in subacute fractures. Determining the age of fractures seen on radiographs is difficult. STIR images will differentiate old fractures from acute ones. Old compression fractures do not have marrow edema and appear dark on STIR images.
Contraindications
Kyphoplasty is contraindicated when there is spinal instability, infection, uncorrectable coagulopathy, severe cardiopulmonary disease, or neurologic deficit resulting from the fracture. However, it may be combined with a decompressive laminectomy in certain cases.
Risks
As in other surgical procedures, certain adverse events are associated with kyphoplasty. These include infection, cerebrovascular accident, myocardial infarction, and pulmonary embolism. Other reported complications include hematoma, fistula, radiculopathy, transient hypotension, allergy to PMMA, leakage of PMMA into surrounding tissues and spaces, fracture of pedicle, rib or transverse process, puncture of aorta or vena cava, and pneumothorax. Among 155 prospectively enrolled patients in a Kyphon U.S. study, only one complication was related to general anesthesia. The adverse event rate is estimated at 1% per fracture.
Conclusion
Kyphoplasty is available as a treatment option performed by NENA neurosurgeons at several hospitals in the Merrimack Valley. A multidisciplinary approach to patient selection and management is essential. Our local experience has erased any initial skepticism about the procedure. We have seen a significant reduction in pain intensity and duration in almost all of our treated patients. Patient mobility improves with earlier return to ambulation. Kyphoplasty provides one important benefit to the patients who need it most—a better quality of life.
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