Introduction
Back pain remains one of the most common complaints seen by primary care and pain treatment providers. Lifetime prevalence has been reported to be as high as 84%. Roughly 11% of the population is disabled due to low back pain. Back pain has many etiologies and can be difficult to treat. On the other hand, some forms of back pain can be readily diagnosed and can be treated successfully with proven therapeutic interventions. One proven intervention for some types of back pain is vertebral body augmentation, which includes both vertebroplasty and kyphoplasty. This chapter will focus specifically on kyphoplasty.
Kyphoplasty differs slightly from vertebroplasty. A report of treatment with vertebroplasty was first published in 1987. It involves filling a vertebral body with an acrylic cement, polymethyl methacrylate (PMMA). PMMA solidifies within the vertebral body to prevent further damage by providing structural support to the vertebral body. There is also a theory that the reaction of the cement solidifying within the vertebral body may damage local intrinsic pain fibers. This, in turn, shortens the duration of pain experienced and prevents worsening kyphosis. Kyphoplasty was developed as an evolution of vertebroplasty and was first performed in 1998. Kyphoplasty differs in that it involves inflating a balloon inside the vertebral body to create a cavity for the PMMA ( Fig. 5.1 ). The balloon allows for height restoration and improvement in focal kyphosis prior to filling.
The rest of the chapter will focus on specific aspects of kyphoplasty. It will cover indications, contraindications, diagnostic workup, and the procedure. Kyphoplasty can be safely performed as an outpatient procedure by a well-trained proceduralist.
Indications
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Severe pain or progressive collapse of a vertebral body in the setting of osteoporosis or osteopenia
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Osteoporotic compression fracture: A review found that physical disability, general health, and pain relief were improved with vertebroplasty and kyphoplasty compared with medical management within 3 months of intervention. Another review found improvements in pain, functionality, vertebral height, and kyphotic angle at least 3 years post-procedure comparing kyphoplasty with medical management. Another review comparing vertebroplasty, kyphoplasty, and nonsurgical management found that vertebroplasty and kyphoplasty provided significantly more pain reduction over nonsurgical management with no difference in pain reduction between vertebroplasty and kyphoplasty. They also found that subsequent fractures occurred more frequently in the nonsurgical group compared with surgical groups. Additionally, there was greater kyphosis reduction and less cement extravasation in patients in kyphoplasty groups over vertebroplasty groups. Another review comparing vertebroplasty and kyphoplasty found no significant difference in pain reduction or disability scores. However, they did find lower odds of new fractures, less extraosseous cement leakage, and greater reduction in kyphotic angle with kyphoplasty. A randomized controlled trial found a statistically significant improvement in mean SF-36 Pain Catastrophizing Scale (PCS) score between the kyphoplasty group and nonsurgical group.
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Osteonecrosis (Kümmell disease): A randomized controlled trial compared kyphoplasty with a bone-filling mesh container and found that both improved visual analog scale (VAS) scores, Oswestry Disability Index (ODI) scores, and Cobb angles. Another trial comparing kyphoplasty with vertebroplasty found both a decrease in VAS scores and ODI scores with no significant difference between techniques.
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Severe pain or progressive collapse of a vertebral body in the setting of neoplasm
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Vertebral metastasis: A review found that patients with spine metastasis treated with kyphoplasty had better scores for pain, disability, quality of life, and functional status. Another review found that pain scores decreased, often within 48 hours of the procedure, and analgesic use decreased along with noted improvement in mean pain-related disability scores. Finally, a randomized controlled trial found a statistically significant improvement in Roland-Morris disability questionnaire (RDQ) scores between kyphoplasty and control groups.
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Multiple myeloma: A systematic review found that vertebroplasty and kyphoplasty were equally effective at lowering pain scores in patients with multiple myeloma.
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Vertebral hemangioma: A small case series and review of the literature found kyphoplasty to be successful in the management of painful spine hemangiomas.
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Severe pain or progressive collapse of a vertebral body in the setting of trauma
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There are small studies that indicate improved pain and earlier mobilization without bracing after kyphoplasty for non-osteoporotic traumatic fractures.
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Contraindications
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Active infection at the target vertebral level
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Sepsis, blood-borne illness, systemic infection
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Burst fracture or disrupted posterior vertebral body wall
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Neurological deficit
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Spinal instability
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Nonpainful fracture, healed fracture
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Pain responding to conservative therapy
Complications
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PMMA leak
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Central canal
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Neural foramen
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Disc space
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Soft tissue
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Venous, with possible pulmonary embolism
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Radiculopathy, possibly from thermodynamics of cement hardening
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Hemo- or pneumothorax by anterior vertebral wall puncture
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New iatrogenic fracture: pedicle, transverse process, rib
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Hematoma from needle tract
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Future adjacent level fracture
Workup
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Standing upright X-ray (XR) anteroposterior (AP) and lateral views to evaluate height loss and angulation
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Computed tomography (CT) of the spine to evaluate posterior wall
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Magnetic resonance imaging to evaluate for acute fracture (short T1 inversion recovery [STIR])
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Dual-energy X-ray absorptiometry (DEXA) scan to evaluate for osteoporosis/osteopenia
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Bone scintigraphy in setting of multiple pathological levels because the most active level can correlate with the most successful intervention level
Procedure
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Setup. Various vendors provide the supplies for balloon augmentation. We will describe a generic approach to the procedure. The procedure requires fluoroscopy, which can be performed in an operating room, angiography suite, or procedure room. Some providers prefer using two C-arm machines in a “nested” technique to avoid switching one machine between AP and lateral images. The O-arm intraoperative CT scanner can also be used for rapid AP and lateral images using the scout XR function without performing a full CT. The procedure can be performed under general anesthesia, sedation, or local anesthesia.
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Positioning . The patient is positioned prone on a radiolucent table. For most thoracic and lumbar vertebral levels, the arms should be positioned with the shoulders abducted 90 degrees and elbows flexed 90 degrees in the “Superman” position and padded to prevent any brachial plexus or peripheral nerve palsies.
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Localization . The vertebral level is marked on the skin using lateral radiographs with a radio-opaque object. The radiographs must be exactly perpendicular to the intended level. We align the spinous process directly midway between pedicles on AP XR with a single radiodensity of the superior and inferior end plates of the target level. This will yield a clear view down the column of the pedicles ( Fig. 5.2 ). On the lateral XR, we overlie the pedicles and create a single radiodensity of the superior and inferior end plates of the target level (see Fig. 5.2 ). Obtaining the appropriate XR views in the AP and lateral orientations is one of the most critical steps to performing this procedure effectively and safely. We mark out bilateral stab incisions roughly 3 cm lateral to the midline at the target level using a lateral XR. If needed, AP radiographs can be used for additional confirmation.
