Introduction

It is estimated that 1.4 million vertebral compression fractures (VCFs) occur annually, causing pain and disability in patients worldwide.¹ The lifetime risk of a vertebral compression fracture in White women is 16%; in men, it is 5%. Historically, treatment of these fractures has been limited to analgesics, bed rest, and bracing. However, recently the development of vertebroplasty and kyphoplasty has provided physicians with additional treatment options for select vertebral compression fractures.

History of Vertebroplasty

Vertebroplasty was initially developed as an open procedure designed to augment the purchase of pedicle screws and to fill large voids from tumor resection. In 1984, however, at the University Hospital of Amiens, France, Galibert and Deramond performed the first documented percutaneous vertebroplasty.² The patient presented with severe cervical pain, and imaging demonstrated a large vertebral hemangioma encompassing the entire vertebral body of C2 with extension into the epidural space. After performing a C2 laminectomy to excise the epidural component of the lesion, a 15-gauge needle was inserted into the C2 vertebral body via an anterolateral approach, allowing injection of cement for structural reinforcement. The document of this case, as published in 1987, reports complete pain relief in this patient. Physicians at University Hospital Lyon continued to refine the percutaneous vertebroplasty technique as well as to expand its indications, using 18-gauge needles to inject polymethylmethacrylate(PMMA) into four patients with compression fractures. Since then, its popularity has spread dramatically.

Patient Selection/Indications

As with any procedure, the success of vertebroplasty relies heavily on the selection of appropriate patients and the skill of the operating physician. It is essential to identify patients with pain related to VCF, and exclude the other common sources of back pain in this population, including degenerative disk disease, spinal stenosis, facet arthropathy, or SI joint dysfunction. This process begins, of course, by taking a thorough history of the patient. It is particularly important to ascertain details regarding the timing of the onset of back pain, any known precipitating events, and those activities that worsen and alleviate the pain. Additionally, patients should be questioned regarding previous episodes of similar back pain, and the time until resolution of those symptoms. It is vital to understand the premorbid condition of the patient, as well as the impact of the back pain on activities of daily living. Finally, an assessment for allergies, anticoagulants, and medical problems, especially respiratory compromise, is essential to anticipate potential complications during the procedure. A thorough physical examination seeks to identify pain and tenderness to palpation at the level of radiographic abnormality. During the examination, the operator must pay attention to symptoms that may suggest pain from alternative sources.

Radiographic imaging plays an important role in the screening of patients for vertebroplasty. X-rays are often the first mode of imaging employed, due to their cost-effectiveness and ease of availability. In patients with a VCF, diffuse osteopenia and evidence of one or more compression fractures may be present. With neoplastic compression fractures, it may be possible to see focal lytic lesions or destruction of the bony trabeculae. A CT scan may be obtained for improved visualization of bony details. Used most often with pathologic fractures, CT may demonstrate expansion of the bony contours of the vertebrae and multilevel disease, both of which suggest an underlying malignancy. Preprocedure CT scanning also allows the operator to assess the integrity of the posterior wall of the vertebral body and pedicles, which if destroyed may be a source for significant complication.

MRI is particularly useful in the screening of patients with osteoporotic VCF due to its reported ability to discern the relative age of the fracture. Acute or subacute osteoporotic fractures up to 30 days old typically show evidence of bone marrow edema, with hypointense signal on T1-weighted and hyperintensity on T2-weighted and STIR sequences. At approximately 1 month after fracture, VCFs variably become isointense to normal bone marrow on T1- and T2-weighted sequences. Fully healed fractures are isointense to normal bone elements, or hypointense on T1 and T2 due to significant sclerosis. Recent studies have found a positive correlation between the MRI findings suggestive of a fracture less than 30 days old and clinical pain relief after vertebroplasty.

Interpretation of MRI findings in a patient with a malignant VCF is more challenging. While STIR sequences with fat suppression may be helpful to show edema, there may be heterogeneous or diffuse areas of hyperintensity on STIR or T2-weighted imaging. Some authors have suggested a pattern of hypointensity or isointensity on diffusion-weighted sequences. In any case, evidence of abnormal signal in the posterior elements, an expansion of the contour of the vertebral body or posterior elements, or any associated epidural/extravertebral soft tissue mass suggests an underlying malignancy.

Bone scintigraphy may be employed to detect a relatively recent fracture in patients who cannot tolerate an MRI. Increased radiotracer uptake has been correlated with positive clinical response to vertebroplasty. However, this technique is limited by the fact that the bone scan may show increased tracer uptake for up to 12 months after fracture. Thus this method must be correlated with corresponding anatomic imaging.

After a careful history, physical examination, and assessment of radiographic imaging, the physician must then determine not only that the source of the patient’s pain is indeed a VCF, but also that this fracture is amenable to vertebroplasty. The primary indication for vertebroplasty is the alleviation of pain associated with a VCF due to osteoporosis or tumor. Repeated studies have demonstrated superior pain relief with treatment of acute or subacute fractures. Perhaps most notable is the non–industry-sponsored, double-cohort by Alvarez et al³, which compared vertebroplasty to nonoperative treatment for VCFs. He found statistically significant differences at 3 months follow-up. Wardlaw et al⁴ published a randomized controlled trial comparing balloon kyphoplasty with nonsurgical care for VCFs. He too demonstrated a significant improvement in the intervention group at 1 month. Some now advocate the treatment of VCF within days of injury if the pain is so severe as to require parenteral narcotics and hospitalization. Late treatment, 6 months to years after the initial injury, is less likely to completely relieve pain, but symptomatic improvement has been noted in some studies.