Answer
In 1984, vertebroplasty was first successfully performed in France for the treatment of a cervical vertebral hemangioma (see image below). [1]
In a vertebral hemangioma, the fine trabeculae are replaced by venous channels, which predispose the patient to painful microfractures.
Since then, the application of vertebroplasty and kyphoplasty has expanded to include the treatment of the intense pain caused by vertebral compression fractures (see image below) that is refractory to conventional therapies such as analgesic use, bed rest, and bracing. Vertebroplasty may also be applied prophylactically to an at-risk vertebra between 2 other abnormal vertebra.
Vertebroplasty and kyphoplasty involve the injection of an acrylic cement under local anesthesia and either fluoroscopic guidance or, less commonly, CT guidance to control the pain of vertebral fractures associated with osteoporosis, tumors, and trauma (see image below). Typically, vertebroplasty is performed in an outpatient setting, while kyphoplasty typically requires hospital admission. Pain reduction or elimination is immediate, and the risk of complications is low. Neither vertebroplasty nor kyphoplasty is intended for the treatment of intervertebral disc disease or arthritis. [2]
Anterior wedge compression fracture after fusion of the fracture fragments with methylmethacrylate.
Vertebroplasty is a treatment for pain. Theoretically, 2 mechanisms may account for the pain reduction associated with the injection of methylmethacrylate. The first mechanism may be as a result of acrylic fusion of the fragments into a single block, preventing the painful motion of the individual fracture fragments against each other. The second mechanism of pain reduction may be related to the heat produced by the polymerization process as the acrylic hardens. An added benefit is that deposition of acrylic within the vertebra significantly strengthens osteoporotic bone, reducing the likelihood of repeat fracture.
Vertebroplasty does not restore the height of the compressed vertebral body. A related procedure, kyphoplasty, is intended to restore lost height by inflating a balloon tamp within and between the fracture fragments prior to the infusion of methylmethacrylate. The procedures result in similar relief of pain due to vertebral compression fractures.
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Anterior wedge compression fracture with intact posterior vertebral cortex.
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Transpedicular placement of a trocar in the anterior third of the fractured vertebral body.
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Anterior wedge compression fracture after fusion of the fracture fragments with methylmethacrylate.
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Lateral radiograph of fractured vertebra shows the initial placement of the trocar.
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Injection of methylmethacrylate through the trocar in anterior one third of the vertebral body.
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Compression fracture after vertebroplasty.
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In a vertebral hemangioma, the fine trabeculae are replaced by venous channels, which predispose the patient to painful microfractures.
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In a vertebral hemangioma after vertebroplasty, the venous channels are now filled with acrylic.
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Two adjacent vertebral hemangiomas causing continuous back pain as seen by MRI (A) and CT (B, C, D). Fluoroscopic appearance prevertebroplasty (E, F) and postvertebroplasty (G, H). The patient's pain had abated by the end of the procedure.
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A vertebral burst fracture is a fracture that cannot be treated safely by using vertebroplasty.
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Once an anterior wedge compression fracture has occurred, the physics of load bearing distribution are altered, creating abnormal stress points on the adjacent vertebra that can lead to a second fracture. This, however, is not the result of the vertebroplasty procedure; rather, it is a consequence of the wedge deformity of the original fracture exerting additional stresses on the adjacent weakened osteoporotic vertebra. A second fracture is likely to occur from this deformity, regardless of whether a vertebroplasty procedure is performed on the first fracture. Some authorities believe vertebroplasty stops the progression of a compression fracture, preventing further wedge deformity and likely reducing the chance of a second fracture.
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In kyphoplasty, a KyphX inflatable bone tamp is percutaneously advanced into the collapsed vertebral body (A). It is then inflated, (B) elevating the depressed endplate, creating a central cavity, and compacting the remaining trabeculae to the periphery. Once the balloon tamp is deflated and withdrawn, the cavity (C) is filled under low pressure with a viscous preparation of methylmethacrylate (D).
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Reduction in kyphotic angulation after kyphoplasty.
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This image was obtained in an 80-year-old man with a steroid-induced osteoporosis and a painful acute midthoracic vertebral compression fracture. Several additional chronic fractures are also present.
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After inflation of balloon tamp, the depressed superior endplate is elevated, and some height is restored. The cavity is then filled with methylmethacrylate. Pain is reduced, and the patient's posture is improved.
