Surgical Technique

Patients can be treated in either the operating room or the radiology procedure suite. Although access to biplanar fluoroscopy can greatly facilitate the procedure, it is not essential. Some have advocated combined CT and fluoroscopic guidance ; however, the majority of patients reported to date have been treated with fluoroscopy alone with excellent results. CT guidance is best reserved for upper thoracic (above T4) lesions where the patient’s shoulder may obscure visualization or in patients with significant cortical disruption. However, upper thoracic level procedures can be safely performed with anteroposterior (AP) and lateral fluoroscopy as well.

Patients are placed in the prone position and made as comfortable as possible. Patients should be screened before the procedure to ensure that they will be able to remain prone for duration of the procedure. Blood pressure, electrocardiogram, and pulse oximetry are continuously monitored. Intravenous midazolam, fentanyl, and cefazolin are administered, and the area is prepped and draped. If multiple levels are to be treated, general anesthesia should be considered to minimize patient discomfort.

Under fluoroscopic guidance, the entry point is visualized approximately one centimeter lateral and half a centimeter rostral to the superior lateral edge of the pedicle ( Fig. 173-1 ). The skin and soft tissue are infiltrated with local anesthetic down to the periosteum. A #15 blade can then be used to make a stab incision at the planned entry site. Then, an 11-guage Jamshidi needle (Lee Medical, Ltd., Minneapolis, MN) is advanced under fluoroscopic guidance to the superior lateral aspect of the pedicle; anterior-posterior fluoroscopy is used to ensure that the medial wall of the pedicle is not violated. This method is termed the transpedicular approach . Alternatively, the parapedicular approach can be used, particularly in upper thoracic vertebral fractures, to access the vertebral body with the needle lateral to the pedicle. Once the base of the pedicle is reached and the vertebral body entered, the Jamshidi needle can be directed in a more medial location within the vertebral body. To ensure proper needle placement, the anteroposterior fluoroscopic view of the vertebral body must be aligned so that the end plate of the vertebral body is aligned flat and the spinal process of the targeted vertebral body is midline. The Jamshidi needle is then advanced into final position in the anterior portion of the middle of the vertebral body.

A, Anteroposterior view of spine with docking of Jamshidi needle on the lateral boarder of the pedicle. B, Passing Jamshidi needle through core of the pedicle to the junction of the pedicle and vertebral body without passing through the medial border of the pedicle. C, Passing the Jamshidi needle through the vertebral body for deployment of cement for vertebra augmentation.

Historically, vertebral body venography was performed at this stage using 5 ml of Hexabrix Omnipaque 300 (Nycomed, Princeton, NJ) to evaluate the venous drainage and filling characteristics of the vertebral body. Rapid flow of contrast medium into the epidural space, inferior vena cava, or azygous system is cause for concern for potential cement extravasation into these spaces creating embolisms. If this is encountered, the needle can be withdrawn or advanced approximately 5 mm and repeat venography is performed. If this fails to alter the appearance of the venogram, then Gelfoam pledgets or a suspension of Avitene can be injected.

Authors have called into question the necessity of performing preprocedural venography. Arguments put forth in these papers include increased contrast and radiation for the patient while lengthening procedure times. Others have countered that venography provides important information that can help predict PMMA distribution during injection and should be performed, particularly when less experienced operators are performing the vertebroplasty. Still others have described alternative methods for venography that use less contrast agent or alternative contrast agents that can lower the incidence of some of these unwanted occurrences while still providing valuable information to the clinician.

In the modern era, and with improvements in the consistency of the injectable cement, this step is rarely performed. It can be avoided by simply paying careful attention to the pattern of cement flow during vertebroplasty. If the outflow tracts begin to opacify, the procedure can be temporarily halted for 20 to 30 seconds until the cement consistency has thickened slightly. This may stop further leakage, in part, because the thicker cement is less likely to leak and also because the cement that has already leaked may effectively create occlusion of the veins, sealing off these channels and preventing further leakage. Ultimately, it is the individual physician who must take these factors into account and decide whether or not venography is a necessary step for their patient.

PMMA (Codman cranioplastic type 1; CMN laboratories, Blackpool, England) is prepared by mixing with 7 to 8 g of sterile barium sulfate powder (E-Z-EM, Westbury, NY); the powder mixture is then divided in half. A small amount of powder from each half is set aside for the purpose of adjusting the consistency if necessary. For patients with neoplastic disease, who are or will soon be immune compromised as a result of radiation therapy and chemotherapy, 1.2 g of tobramycin may be added to the powder. This may also potentially be used in patients with osteomyelitis of the vertebral body who are not candidates for definitive surgical management. Approximately 7 to 8 ml of liquid monomer is mixed with one half of the powder mixture until a toothpaste-like consistency is achieved. Additional powder can be added as necessary. The mixture is then placed into multiple aliquots in 1-ml syringes.

The cement is then injected under fluoroscopic guidance. The injection is continued until the vertebra is sufficiently opacified. As the cement starts to fill the posterior aspect of the vertebra, the injection rate is slowed or stopped to prevent canal violation. The cement then undergoes an exothermic polymerization reaction thought to be part of its therapeutic effect. The temperature in animal studies have been shown to range at the cranial end plate (mean, 42.4 +/− 8.8° C) and in the center of the vertebral body (mean, 43.3 +/− 6.9° C). Temperatures stayed above 40° C for approximately 2.5 minutes. Peak temperatures in the discs and at the dorsal wall of the vertebral body did not exceed 41° C and 47° C and stayed above 40° C for approximately 1.5 minutes.

At the completion of the procedure, the stylette is inserted and left in place for a few minutes to allow the cement to begin to harden. After this the needle is rotated several times before removal to prevent extension of cement into the needle tract.

Typically, a unilateral approach is sufficient to treat a vertebra completely. If individual anatomy prevents adequate filling from a unilateral approach, then a second procedure can be performed on the opposite side. However, bilateral Jamshidi needle placement is performed before cement is injected to allow for adequate visualization of needle placement. Studies have shown that the volume of injected cement does not correlate with success rates. but correlates with the incidence of extravertebral cement leakage. In fact, pain relief can occur with as little as 2 mL of cement.

Outcomes

The literature regarding the efficacy of vertebroplasty is hotly debated. Numerous studies have demonstrated a positive rapid symptomatic improvement across numerous patient subgroups. Using objective pain rating scales as well as subjective patient responses, these studies have shown improvement in up to 97% of patients treated with osteoporotic compression fracture and in 50% to 97% of patient treated for neoplastic disease. However, these studies are often not blinded and not controlled against a sham procedure. The scarcity of these gold standard studies has led to criticism stating that vertebroplasty is not within the practice of evidence-based medicine. Claims include the belief that the studies are confounded by natural progression of the disease, regression to the mean, and a powerful placebo effect. To demonstrate the varying views between medical professionals, the National Institute for Health and Care Excellence (NICE), a body charged with establishing guidelines for the United Kingdom’s National Health Service (NHS), places kyphoplasty and vertebroplasty under its “Major Recommendations” category for symptomatic osteoporotic VCFs resistant to medical management. In 2010, the American Academy of Orthopaedic Surgeons (AAOS) recommended strongly against vertebroplasty for osteoporotic compression fractures. The following literature highlights the source of this fierce controversy.

Diamond and colleagues published a prospective, nonrandomized, intention-to-treat study that involved 126 patients, aged 51 to 95 years, consisting of 39 men and 87 women, with acute osteoporotic compression fractures not relieved by analgesics sorted into percutaneous vertebroplasty (88 patients) or conservative medical management (38 patients). Outcomes were assessed using visual analog scale (VAS) for pain and the Barthel Index for level of function. At 1 day postoperation, pain scores demonstrated a 60% reduction when compared to preoperative assessment (P < 0.001). Physical functioning was improved 29% as well (P < 0.001). The conservative management group saw no difference after 24 hours (P > 0.01). Greater pain reduction remained at 6 weeks (P < 0.01), but there were no significant differences between conservative management and vertebroplasty at 6, 12, and 24 months. Both groups demonstrated an almost complete return of functionality per the Barthel Score index by 6 weeks with the vertebroplasty group improving sooner. Length of hospital stay was also shown to be associated with a 43% reduction in the vertebroplasty group compared with conservative management (P < 0.001).

Alvarez and colleagues put forth a double cohort prospective trial studying the effects of percutaneous vertebroplasty as a treatment modality for osteoporotic compression fractures versus conservative medical management. The study population consisted of patients that had at least 6 weeks of less than satisfactory response to conventional therapy; 101 patients chose to undergo vertebroplasty, whereas 27 sorted themselves into the conservative management cohort. Clinical outcomes were assessed using VAS, analgesic dosage, Oswestry function test, and the Short Form-36 (SF-36) health survey. The vertebroplasty group was significantly older (P = 0.033) and in more pain at the time of the procedure (P < 0.001) than the conservative cohort. At 3 months and 6 month, the vertebroplasty patients had significantly less pain (P < 0.001, P = 0.033) when compared with the conservative group. There was no significant difference at 1 year. Analgesic use went from 71% pretreatment to 26% during follow-up (P < 0.001) in the vertebroplasty group as well. Although the treatment group required significantly more analgesics preoperatively, they had a greater reduction in analgesic dosage than those in the conservative group at postoperative month 3, requiring even less medication. The mean functional scores in all postoperative periods were improved compared with the preoperative mean values ( P < 0.001). There was also a significant difference at the postoperative third month ( P = 0.001) when compared with the conservative treatment group. However, at 6 months ( P = 0.006) and 12 months ( P < 0.001) after the operation, the mean values of the conservative treatment group were significantly better than those of the percutaneous vertebroplasty (PV) group. There was significant and rapid improvement in SF-36 of the vertebroplasty group at 3 months, 6 months, and 1 year (P < 0.001) that was not observed in the conservative group until 6 months after treatment began. The authors recognize the limitations of the study as having lack of randomization and blinding. Alvarez and colleagues also noted that comparisons between groups could not be made due to significant differences between groups despite controlling demographics.

The vertebroplasty versus conservative treatment in acute osteoporotic vertebral compression fractures (Vertos II) trial completed by Klazen and associates is the latest completed trial in the Vertos series that consists of five trials testing different clinical questions regarding vertebroplasty and osteoporotic compression fractures. This study involved 431 patients from the Netherlands and Belgium ages 50 or older. Patients were randomized who had x-ray confirmed vertebral compression fracture(s) and pain of 5 or greater on the VAS. Of these, 229 patients (53%) had spontaneous pain relief during assessment; the remaining 202 patients participated in the study. In this open label, prospective, randomized control trial, patients were randomized into a conservative treatment arm or a vertebroplasty arm. Primary outcomes from the study were measurements in pain reduction using the VAS scale at 1 month and 1 year. The study also assessed other quality of life surveys and cost analysis. Results from the trial showed that after vertebroplasty, VAS scores dropped 5.2 at 1 month. With conservative treatment, a 2.7 drop was noted. At 1 year, vertebroplasty and conservative treatment VAS scores dropped 5.7 and 3.7, respectively. Survival analysis demonstrated significant pain relief using vertebroplasty over conservative treatment (p < 0.0001). The authors concluded that treatment with vertebroplasty in subgroups of acute osteoporotic compression fractures is safe and effective.

The Investigational Vertebroplasty Efficacy and Safety trial (INVEST) by Kallmes and coworkers was a double blinded, randomized control trial testing the efficacy of percutaneous vertebroplasty against sham injection control. The study population consisted of patients at least 50 years of age who had a diagnosis of one to three painful osteoporotic vertebral compression fractures between vertebral levels T4 and L5, had inadequate pain relief with standard medical therapy, and rated their pain-intensity with a score of at least 3 on a scale from 0 to 10. Fractures were required to be less than 1 year old, as indicated by patient-reported duration of pain. Of the 131 patients enrolled, 68 patients randomized to vertebroplasty and 63 to control intervention. Outcomes were measured using a Roland-Morris Disability Questionnaire (RDQ) for functional disability appraisal and a 0 (no pain) to 10 (pain as bad as it could be) for measurement of pain status. The two study groups did not differ significantly with respect to primary outcomes at 1 month. The mean (±SD) RDQ score in the vertebroplasty group was 12.0 ± 6.3, as compared with 13.0 ± 6.4 in the control group (adjusted treatment effect, 0.7; 95% confidence interval [CI], −1.3 to 2.8; P = 0.49). The mean pain-intensity rating was 3.9 ± 2.9 in the vertebroplasty group and 4.6 ± 3.0 in the control group (adjusted treatment effect, 0.7; 95% CI, −0.3 to 1.7; P = 0.19). The two study groups had substantial improvement in back-related disability and pain immediately (3 days) after the procedure, with similar improvement in the two groups. The improvement in each group at 3 days was maintained at 1 month.

The study groups did not differ significantly on any of the secondary outcomes, including measures of pain and quality of life, at 1 month. Furthermore, the two groups did not differ in the postspecified proportion of patients who had clinically meaningful improvement in physical disability related to back pain at 1 month (40% of patients in the vertebroplasty group and 41% of patients in the control group, P = 0.99). There was a trend toward a higher rate of clinically meaningful improvement in pain in the vertebroplasty group than in the control group (64% versus 48%, P = 0.06).

Follow-up findings from the study at 1 year have shown pain improvements in the vertebroplasty group that are significant compared to the control group (mean difference, 1.02 points; 95% confidence interval [CI]: 0.04, 2.01; P = .042). The functional disability score did not demonstrate a difference between the groups (mean difference, 1.37 points; 95% CI, −0.88, 3.62; P = .231).

Buchbinder and associates released a randomized, parallel group, placebo-controlled trial aimed at determining the efficacy of vertebroplasty in regard to pain relief and restoration of function measured with RDQ. Numerous quality of life surveys were also included in this study and reported as secondary outcomes. The 78 patients included in the study were randomly sorted into percutaneous vertebroplasty (38 patients) and sham procedure (40 patients) groups. No significant differences between groups were seen in the primary outcome of overall pain at 3 months. Mean reductions in the score for overall pain in the vertebroplasty and placebo groups were 2.6 ± 2.9 and 1.9 ± 3.3, respectively (adjusted between-group difference, 0.6; 95% confidence interval, −0.7 to 1.8). No significant benefit was reported for vertebroplasty at 1 week, 1 month, 3 months, and 6 months. Overall scores on measures of pain improved modestly in both groups over time, as did scores for pain at rest and during the night, physical functioning, and quality of life, but the authors reported no significant between-group differences.