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Current Perspectives on Percutaneous Vertebroplasty: Current Evidence/Controversies, Patient Selection and Assessment, and Technique and Complications

Current Perspectives on Percutaneous Vertebroplasty: Current Evidence/Controversies, Patient... Hindawi Publishing Corporation Radiology Research and Practice Volume 2011, Article ID 175079, 10 pages doi:10.1155/2011/175079 Review Article Current Perspectives on Percutaneous Vertebroplasty: Current Evidence/Controversies, Patient Selection and Assessment, and Technique and Complications Robert James Nairn, Shagran Binkhamis, and Adnan Sheikh Musculoskeletal Division, Department of Diagnostic Imaging, The Ottawa Hospital, General Campus, 501 Smyth Road, Ottawa, ON, Canada K1H 8L6 Correspondence should be addressed to Adnan Sheikh, asheikh@ottawahospital.on.ca Received 30 December 2010; Revised 22 March 2011; Accepted 23 March 2011 Academic Editor: Ali Guermazi Copyright © 2011 Robert James Nairn et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Osteoporotic-associated vertebral compression fractures are a major public health concern, dwarfing even hip fractures in incidence in the United States. These fractures carry a significant morbidity and mortality burden and also represent a major growing source of consumption of scarce heath resources. Percutaneous vertebroplasty remains a commonly used and safe technique for the symptomatic treatment of vertebral compression fractures, both osteoporotic- and neoplastic-induced. By carefully selecting appropriate patients who are referred promptly, vertebroplasty can provide significant and durable pain relief over traditional conservative therapy. Recent controversies surrounding the evidence for vertebroplasty in osteoporotic-associated vertebral compression fractures are reviewed. A comprehensive step-by-step practical guide to performing vertebroplasty is then described. A brief description of patient selection, workup, as well as complications is also provided. 1. Introduction vertebral fractures are secondary to osteoporosis. Gradual pain resolution following these fractures is the expected Two related interventional procedures are performed for natural history, but pain can persist and or resolve slowly the treatment of painful vertebral compression fractures [5]. Pain in these patients is also frequently refractory to (VCF), percutaneous vertebroplasty (PV), and kyphoplasty. conservative therapy. VCFs can be complicated by defor- Both involve the fluoroscopically or CT-guided percutaneous mity, loss of stature, impairment of pulmonary function placement of wide-bored cannulae into the fractured ver- and the attendant risks of poor mobility/immobilisation tebral body which is subsequently cemented with synthetic in the elderly, such as venous thrombo-embolism [6–8]. bone cement, typically polymethylmethacrylate (PMMA). Immobilisation is also associated with increased bone density PV was first described for the treatment of an aggressive loss and enduring difficulty with activities of daily living [9]. haemangioma of C2 in 1987 [1, 2], but in subsequent years An increase in mortality after VCF has been noted. One large has been performed mainly for the symptomatic treatment of prospective cohort study of elderly patients with low-trauma painful osteoporotic-induced VCF. The palliative treatment osteoporotic VCFs calculated an increased standardized of tumour-induced VCF (typically myeloma or metastatic mortality ratio for women of 1.82 (95% CI 1.52–2.17) and disease) remains an important further indication for PV. for men of 2.12 (95% CI 1.66–2.72) [10]. VCF is a major public health concern, with an estimated Traditional treatment of uncomplicated VCF consists of 1.4 million patients presenting with such a fracture each analgesia, bracing, and rehabilitation. Pain often necessitates year [3]. The incidence of VCF in the US alone is estimated bed rest or other restrictions on mobility. Open reduction to be 750,000 [4], a figure that makes VCF more common and internal fixation is theoretically possible, but rarely than osteoporotic-related hip fractures. The majority of these performed due to poor bone stock and multiple underlying 2 Radiology Research and Practice co-morbidities. PV offers a less invasive therapeutic option old [24]. The NEJM trials have also been criticised on the for generally elderly patients with multiple comorbidities basis of the proportion of eligible patients who declined enrolment, 70% for Kallmes and 64% for Buchbinder. Bono which allows for early immobilisation. et al. [25] suggested this raised the spectre of selection bias. However, these figures are not remarkable when compared 2. Evidence and Controversies with previous experience in blinded randomised controlled trials. Prior to 2009, evidence for the effectiveness of PV in osteo- The expected natural history of VCF is of gradual healing porotic VCF was based on anecdotal experience, multiple and pain relief [26, 27]. Some evidence from observational prospective and retrospective case series, and prospective studies of PV have shown decreased pain relief and less comparative cohort studies [11]. Multiple observational improvement in mobility in fractures >12 months when studies had shown almost uniformly excellent results with treated with PV [28]. Based on the patient selection criteria PV, with moderated to marked pain relief experienced by 75– of both NEJM studies, patients with painful fractures up to 95% of patients [12–14]. Similar results in the treatment of one year of age were included in the trials. Most patients metastatic fractures have also been reported [15]. However, had pain of >3 months duration. This would have inevitably a bias towards overestimation of treatment benefits is resulted in the enrolment of patients with delayed union and possible when relying on this form of evidence [16, 17]. non union, altering the homogeneity of the disease process Well-designed, randomised, prospective trials comparing PV studied. The average reduction in pain as assessed on a visual versus conservative therapy were lacking. In 2009, NEJM analogue scale (VAS) was smaller in the active arms of both published the results of the first two randomised blinded trials than would have been expected from prior observa- trials comparing PV with a sham intervention, namely, tional studies, raising doubt about the ability to extrapolate local anaesthetic infiltration of skin, subcutaneous and these results to patients with severe pain post-VCF who have periosteum [18, 19]. failed conservative treatment. Bono et al. also criticised the Buchbinder et al. [18] enrolled and randomised 78 design of the sham procedure, labelling it an alternative patients with one or two painful osteoporotic vertebral intervention (the injection of long acting local anaesthetic fractures (as defined on imaging, predominately MRI) to onto periosteum) rather than a true sham procedure. It is either PV or a sham procedure, with followup reported up difficult to imagine, however, how participants in the NEJM to six months. Kallmes et al. [19] enrolled and randomised could have been truly blinded without recourse to such a 131 patients with one to three fractures to PV or a similar procedure. Some authors, including the current authors, sham procedure; followup was to three months. Both advocate fluoroscopic-guided palpation and percussion of trials reported no statistically significant benefit of PV over PV candidates, in an attempt to correlate imaging findings placebo. with symptoms. This was not performed in either study. Both The NEJM trials have been criticised on several fronts, trials also did not examine the role of PV in nonosteoporotic with Buchbinder in particular strongly defending the validity vertebral fractures, or examine the role of PV in the inpatient of the trials in ensuing correspondence [20, 21]. Kallmes et al. setting. [19] allowed cross-over between the two arms at one month. More recently, the results of VERTOS II [29]have For those receiving the sham procedure, 42% opted to receive become available. This multicenter study was randomised, PV at three months, compared with 12% for the other but participants, physicians and outcome assessors were not arm. This higher rate of cross-over could be interpreted as blinded. Over 200 patients with a VCF and pain of less than reflecting dissatisfaction with the sham procedure compared 6 weeks duration were randomised to conservative treatment with PV, or possibly flaws in the blinding of the sham or PV. No sham procedure was performed. At one month and procedure such that patients were able to “guess” their one year, a statistically significant reduction in pain in the PV intervention. arm was evident. Alvarez et al. [11] concluded that PV is safe and able to be performed at an acceptable cost. Furthermore Mathis [22] and Munk et al. [23]criticised the low patient enrolment number compared with length of the the pain relief following PV is immediate, lasts for at least a enrolment period. Conceivably, patients with the most severe year, and is significantly greater than conservative treatment. Rousing et al. [30] also recently reported 12-month pain would be less likely to agree to undergo randomisation, and the studied population would therefore exclude those followup from an open-label, randomised study (n = 50, patients with the most severe pain. These authors also point fracture age <8 weeks) comparing PV with conservative management. Immediate and significant pain relief following out that Kallmes was close to proving a “clinically meaningful improvement in pain for PV compared to sham therapy” PV was evident. At one-month following discharge, the with a P value of .06. If the Kallmes trial had enrolled PV arm had a statistically significantly reduction in pain 19 more participants who experienced similar results, P compared with the conservative therapy arm. However, no would have been <.05 and thus regarded as statistically difference in pain scores was found between the groups at 3 and 12 months. These authors suggest that the role of significant. Mathis concluded that Kallmes therefore did not enrol enough patients to disprove the effectiveness of PV may therefore be as a short-term invasive method of PV. The number of patients enrolled in Buchbinder was pain control in those who fail conservative treatment or for those whom conservative treatment and the accompanying also insufficient to power a subgroup analysis to assess PV effectiveness in those with fractures less than six weeks immobilisation carry serious risks. Radiology Research and Practice 3 T8 (a) (b) Right prone T8 (c) Figure 1: Painful haemangioma of right-hand aspect of T8 (arrowed) in a 56-year-old man treated with unipedicular vertebroplasty. Sagittal (a) and axial (b) TSE T2-weighted images. (c): Vertebroplasty spot fluoroscopy image, AP projection. Postprocedure, the patient reported complete resolution of pain. 3. Conclusions on Available Evidence for PV 4. Performing Percutaneous Vertebroplasty It can beconcluded from the availableliteraturethat 4.1. Patient Selection. Ideally, patients with painful VCF who long-term effectiveness and complication data from PV is are failing conservative treatment should be referred for currently lacking. Performing a true blinded randomised- PV as early as practicable once it has become clear that controlled trial between conservative therapy and PV is im- conservative measures are failing, or in cases of severe pain possible. Despite the seemingly conflicting available data, it requiring hospitalisation. Patients with pain of greater than is the authors’ opinion that there is some evidence available three months duration are less likely to benefit from PV that in the acute to subacute period, in those who are failing [29]. conservative treatment or at are at increased risk from immo- There are few absolute contraindications to PV. Coag- bilisation, PV can provide good pain relief compared with ulation profile must be normal or near normal, and anti- conservative treatment, though as yet no durable long-term coagulants must be ceased prior to the procedure. PV is benefit has been demonstrated. When patients are carefully contraindicated in those with severe cardiac or respiratory screened by history, examination, and imaging prior to the failure precluding safe conscious sedation or general anaes- procedure, it is the authors’ opinions that a group highly thesia. These patients are considered high risk for clinically likely to significantly benefit from PV can routinely be iden- significant procedure-related fat embolism [31]. Infection tified and then offered PV. PV remains an important inter- or fever is also an absolute contraindication. Severe loss of vention for the treatment of intractable pain associated with vertebral body height is a relative contraindication, but good neoplasm-induced VCF (Figure 1), and for those hospitalised results can often be obtained in even severely compressed due to severe pain following osteoporotic-induced VCF. vertebrae [32]. 4 Radiology Research and Practice T8 120 mm 120 mm (a) (b) Figure 2: Sagittal TSE T2-weighted (a) and sagittal STIR (b) of the thoracolumbar spine in a 56-year-old man referred for PV for severe back pain following a fall. VCFs are noted at T8 (white dashed arrow) and T12 (continuous white arrow). There is prominent STIR hyperintensity at T12 without significant marrow edema at T8. The patient was symptomatic over T12 on palpation. This level was cemented with complete resolution of symptoms. Formal prevertebroplasty assessment is performed by the considered a relative contraindication to PV and prompt careful reassessment of the patient’s symptoms. interventionist one to two weeks before the procedure is scheduled. At this time, all of the imaging is reviewed. It is An assessment of the likely fluoroscopic approach to PV vital to ensure that a recent MRI dating from the time of is made to ensure the procedure is technically feasible. Severe symptom onset is available to assess marrow edema in the kyphosis and scoliosis are a relative contraindication. Poor target levels. PV is contraindicated if bone marrow edema pedicle visualisation and or aberrant anatomy may require is absent on STIR (short-tau inversion recovery) images CT-guided placement of bone cannulae. If the patient is (Figure 2). If MRI is contraindicated or unavailable, imaging unable to lie prone, general anaesthesia may be indicated. If assessment can be performed with a combination of CT and theprocedureis technically feasible and the imaging findings scintigraphic bone scan. CT may also be useful for assessing correlate with the examination findings, the patient is then pedicle bone stock and the integrity of the posterior vertebral educated about the procedure and possible complications, body cortex in selected patients, particularly in patients with and informed consent is obtained. malignant VCF. Severe loss of bone stock of the pedicle and posterior vertebral body cortex is a relative contraindication 4.2. Procedure. PV entails the percutaneous injection of bone to PV due to increased risk of symptomatic cement leak. cement, typically PMMA, into the collapsed vertebral body. A comprehensive history is obtained and a thorough In our institution, PV is generally performed under general examination is performed. The examination is performed, anaesthesia, although the procedure can be safely performed in part, in the fluoroscopic suite with the patient prone. under conscious sedation. After prone positioning, the X- Useful clinical information can be obtained prior to this stage ray tube and image-intensifier is centered over the relevant by observing the pain induced by patient mobilising and vertebral body such that the superior and inferior endplates climbing onto the fluoroscopy table. It is important to careful are aligned/not obliqued and the spinous process is midline. correlate the region of marrow edema on cross-sectional The pedicle to be cannulated is then centred in the vertebral imaging with the fluoroscopic image of the vertebra. The body image via cephalo-caudal tube angulation. Right and patient is then palpated and or gently percussed in the region left anterior oblique tube positioning is performed to of fracture in an attempt to correlate symptoms with imaging visualise the relevant pedicle “en-face.” If biplane is available, findings. If there is a clear disparity between the imaging and the true lateral projection of the vertebral body is obtained the examination findings, PV is contraindicated. Signs and by ensuring that the posterior vertebral cortex is visualised symptoms of concurrent facet or sacroiliac joint dysfunction, in profile without obliquity, the left and right ribs at the radiculopathy, or sacral insufficiency fracturing should be target level (if visible) completely overlap each other and Radiology Research and Practice 5 Prone Lateral (a) (b) Figure 3: Spot fluoroscopic images from two separate patients obtained during PV. (a) demonstrates left bone cannula insitu. The right pedicle has been cannulated, and is advanced in the AP plane staying clear of the pedicle medial cortical margin. Arrow indicates the medial pedicle cortex. (b) Lateral projection demonstrates tip of needle anterior to posterior vertebral cortex (dashed white line). Once this landmark is reached, the cannula can be safely advanced to 1 cm posterior to the anterior vertebral cortex under lateral projection fluoroscopic guidance. Cementing is also performed in this projection. the target vertebral body is centered in the image. PV can be progression should only be performed in the oblique AP pro- safely performed without access to biplane fluoroscopy but is jection, staying clear of the medial pedicle cortical margin. The tip of the cannula is advanced to a point approx- significantly more time consuming. imately 1 cm posterior to the anterior vertebral body as With aseptic technique and following local anaesthesia, assessed laterally. Because the vertebral body is not rectan- an 11 G or 13 G bone needle is inserted down onto the per- gular but rather curved, leaving a safe gap between these two iosteum overlying the pedicle, aiming for the lateral cortical points is needed to ensure the anterior cortex is not breached. margin of the pedicle at the 10:00 position on the left and The contralateral pedicle is cannulated in a similar fashion. the 2:00 position on the right. A transpedicular approach Bilateral cannulation is favoured due to increased chance of is the technique of choice. This approach ensures that risk adequate and safe cement injection. If there is doubt about of damage to adjacent structures is minimised, is easily the diagnosis, bone biopsy is performed at this stage. learnt, and conveniently positions the cannula tip at maximal The PMMA cement is prepared by mixing polymer pow- distance from bone entry for cement injection, helping to der with liquid monomer. Mixing of the powder and liquid minimise leaks. Occasionally, a parapedicular approach may leads to exothermic polymerisation and then progressively be necessary due to difficult/distorted anatomy. Cannula ad- thickening of the paste, which subsequently hardens. Once vancement is then performed. Typically, the periosteum is the cement has a toothpaste-like consistency, injections com- breached and the cannula advanced with hand pressure and mence via a 1 mL syringe. Continuous screening for cement screwing. Soft osteoporotic bone means that a soft bone extravasation during injection is performed. In particular, mallet is only occasionally needed for cannula advancement. close attention is made to the posterior margin of the verte- An attempt to stay initially lateral to the midline of the bral body. If cement extends posteriorly within 5 mm of this pedicle on the oblique AP projection is made to minimise the landmark, injection is ceased to minimise the risk of epidural chances of breaching the medial cortex of the pedicle, and space cement leak. One needle only at a time is injected. Any thus entering the spinal canal, during cannula positioning leak or extravasation is an indication to stop injection. Gen- (Figure 3(a)). After complete cannula engagement of bone, erally, a small waiting period for the cement to solidify is all the true lateral projection is checked for cannula trajectory that is required prior to resuming injection. Large leaks may in the cephalo-caudal plane. Once the needle is anterior to require the procedure be abandoned. At the end of the proce- the posterior margin of the vertebral body on the lateral dure when the cannulae are removed, it is advisable to rein- projection, the pedicle has been successfully traversed and sert the introducing stylet to push any residual cement into further needle progression can be monitored via the lateral the needle tract within the bone. A cast of cement deposited projection (Figure 3(b)). Prior to this landmark, cannula into soft tissues is irritant and can cause significant pain. 6 Radiology Research and Practice 4.3. Volume of PMMA to Inject. The volume of cement to be injected at each level for maximal efficacy has not been accurately determined [33]. In ex vivo studies, Belkoff et al. [33] demonstrated that vertebral body strength can be restored with 2 mL of cement, whilst restoration of preinjury stiffness required 4–8 mL. Regardless of exact measurements, visual filling of the body on the AP projection from the inner margins of the endplates along the lateral 1/3 on each side is ideal, though this is not always technically feasible (Figure 4) [31]. The current authors have often found this result to T8 be achievable with 3–5 mL of cement. As pain relief does not correlate with volume of injected cement [12], visual inspection of the amount of cement injected to the residual volume of the compressed vertebra is recommended when ascertaining total volume of cement to be injected. 4.4. Postprocedure Care. The patient remains supine or sem- R irecumbent for one hour, with monitoring of neurovascular Prone status and wound inspection every 15 and 30 minutes respec- tively. The patient is then gently mobilised. If the status of the patient is stable, they can be discharged home after two (a) hours. Occasionally, patients may experience an increase in pain following PV. This is usually of benign aetiology and self-limiting [22]. Good pain relief is usually obtained with oral or parenteral narcotics. Ongoing severe pain, radicular pain or signs/symptoms of spinal stenosis should prompt early imaging with CT. Followup for treatment of the pa- tient’s underlying osteoporosis is mandatory. 4.5. Complications. In general, PV is a safe procedure which is well tolerated. The overall complication rate in PV for T8 VCF reported in the literature is low, ranging from 1% to 10% [13, 34–36]. Complications are considerably more common in the acute peri-and postoperative period. The complication rate for malignant tumours is higher than for benign VCF [36–41], with one review by Murphy and Deramond [41] estimating the complication rate for OP to be 1.3% for osteoporotic VCFs, 2.5% for haemangiomata- associated VCF, and 10% for malignant VCF. The commonest complication of PV is cement extravasa- tion, occurring 26–97% of the time [42]. The vast majority of leaks are asymptomatic. However, cement leaks can (b) narrow and/or impinge neural structures, either within the neural foramina or the epidural space (Figures 5 and Figure 4: Spot AP (a) and lateral (b) fluoroscopic images following 6). [43, 44]. Radiculopathy related to cement leakage is T8 PV in a 62-year-old man with an osteoporotic VCF. A bi- usually transient and responds well to systemic analgesia pedicular approach was used. There is satisfactory filling of the and or transforaminal nerve block, although occasional cases vertebral body in the lateral and AP projections without evident leak (arrows). The patient’s symptoms had resolved on awakening from requiring of surgical decompression have been reported [43, the procedure. 44]. Failure to respond promptly to transforaminal nerve block for radiculopathy or any symptoms referable to central canal stenosis is an indication for urgent neurosurgical consultation and decompression. Systemic cement embolisation is rare, with one study complication [46]. As risk of marrow embolisation may be estimated as much as 5% of patients may undergo cement proportional to volume of displaced marrow during cement pulmonary embolism [45]. These are rarely clinically sig- injection, the authors favour performing PV at up to three nificant [46]. Displaced marrow from the cemented ver- levels only at one sitting. Venography prior to cementing tebra may also result in fat embolism. Patients with poor has fallen out of favour [47, 48]as noclinicalbenefit cardiorespiratory function may be at increased risk of this referable to venography has been demonstrated [28]. Other Radiology Research and Practice 7 T6 T6 (a) (b) Figure 5: 86-year-old woman with known multiple myeloma and pathological fracture of T6. During PV, posterior cement leak was noted soon after injection commenced; the procedure was abandoned. (a): Axial CT demonstrates permeative bone destruction of T6 (black arrows). Cement has extravasated posteriorly into the epidural space. (b) Sagittal CT demonstrates a thin collection of epidural cement anterior to the thecal sac (dashed white arrow). The patient remained asymptomatic initially and at followup and decompression was not required. L1 (a) (b) Figure 6: Modern biplane fluoroscopy allows on-table CT to be performed, with multiplanar reformats. Although the images acquired are susceptible to quantum mottle, the technique is invaluable in PV to quickly assess and confirm cement position and to assess for complications. Sagittal (a) and coronal (b) reconstructions (Siemens Axiom Artis biplane fluoroscopic unit) are shown in a 78-year-old man with recent VCF of L1 treated successfully with PV. An old VCF is noted at L2 (white arrow). A trace of lateral cement leak is noted to the left (dashed black arrow). This was asymptomatic. complications of PV include bleeding, haematoma, infec- and there is no evidence to support routine antibiotic tion, pneumothorax, pedicle fracture, thecal sac puncture, impregnation into the cement or intravenous antibiotics at and CSF leak. Patients with severely lowered bone mineral the time of the procedure [35]. density may experience fractured ribs or sternum whilst PMMA used during arthroplasty has been associated theprocedureisperformed [49]. Infection is uncommon, with transient hypotension, though a link between PV with 8 Radiology Research and Practice PMMA and cardiovascular effects has not been demon- [6] G. P.Lyritis,B.Mayasis, N.Tsakalakos et al., “The natu- ral history of the osteoporotic vertebral fracture,” Clinical strated on retrospective review [50]. The exothermic process Rheumatology, vol. 8, supplement 2, pp. 66–69, 1989. of PMMA polymerisation has led to some concern about [7] C. Schlaich, H. W. Minne, T. 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Kallmes, “Relevance of in patients with severe vertebral compression fractures: a technical report,” American Journal of Neuroradiology, vol. 21, antecedent venography in percutaneous vertebroplasty for the treatment of osteoporotic compression fractures,” American no. 8, pp. 1555–1558, 2000. Journal of Neuroradiology, vol. 23, no. 4, pp. 594–600, 2002. [33] S. M. Belkoff, J.M.Mathis, L. E. Jasper,and H. Deramond, “The biomechanics of vertebroplasty: the effect of cement [48] C. Vasconcelos, P. Gailloud, N. J. Beauchamp, D. V. Heck, and K. J. Murphy, “Is percutaneous vertebroplasty without volume on mechanical behavior,” Spine, vol. 26, no. 14, pp. 1537–1541, 2001. pretreatment venography safe? Evaluation of 205 consecutives procedures,” American Journal of Neuroradiology, vol. 23, no. 6, [34] M. E. Jensen,A. J.Evans,J.M. Mathis, D. F. Kallmes,H. J. pp. 913–917, 2002. Cloft, and J. E. 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Current Perspectives on Percutaneous Vertebroplasty: Current Evidence/Controversies, Patient Selection and Assessment, and Technique and Complications

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Hindawi Publishing Corporation
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Copyright © 2011 Robert James Nairn et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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10.1155/2011/175079
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Hindawi Publishing Corporation Radiology Research and Practice Volume 2011, Article ID 175079, 10 pages doi:10.1155/2011/175079 Review Article Current Perspectives on Percutaneous Vertebroplasty: Current Evidence/Controversies, Patient Selection and Assessment, and Technique and Complications Robert James Nairn, Shagran Binkhamis, and Adnan Sheikh Musculoskeletal Division, Department of Diagnostic Imaging, The Ottawa Hospital, General Campus, 501 Smyth Road, Ottawa, ON, Canada K1H 8L6 Correspondence should be addressed to Adnan Sheikh, asheikh@ottawahospital.on.ca Received 30 December 2010; Revised 22 March 2011; Accepted 23 March 2011 Academic Editor: Ali Guermazi Copyright © 2011 Robert James Nairn et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Osteoporotic-associated vertebral compression fractures are a major public health concern, dwarfing even hip fractures in incidence in the United States. These fractures carry a significant morbidity and mortality burden and also represent a major growing source of consumption of scarce heath resources. Percutaneous vertebroplasty remains a commonly used and safe technique for the symptomatic treatment of vertebral compression fractures, both osteoporotic- and neoplastic-induced. By carefully selecting appropriate patients who are referred promptly, vertebroplasty can provide significant and durable pain relief over traditional conservative therapy. Recent controversies surrounding the evidence for vertebroplasty in osteoporotic-associated vertebral compression fractures are reviewed. A comprehensive step-by-step practical guide to performing vertebroplasty is then described. A brief description of patient selection, workup, as well as complications is also provided. 1. Introduction vertebral fractures are secondary to osteoporosis. Gradual pain resolution following these fractures is the expected Two related interventional procedures are performed for natural history, but pain can persist and or resolve slowly the treatment of painful vertebral compression fractures [5]. Pain in these patients is also frequently refractory to (VCF), percutaneous vertebroplasty (PV), and kyphoplasty. conservative therapy. VCFs can be complicated by defor- Both involve the fluoroscopically or CT-guided percutaneous mity, loss of stature, impairment of pulmonary function placement of wide-bored cannulae into the fractured ver- and the attendant risks of poor mobility/immobilisation tebral body which is subsequently cemented with synthetic in the elderly, such as venous thrombo-embolism [6–8]. bone cement, typically polymethylmethacrylate (PMMA). Immobilisation is also associated with increased bone density PV was first described for the treatment of an aggressive loss and enduring difficulty with activities of daily living [9]. haemangioma of C2 in 1987 [1, 2], but in subsequent years An increase in mortality after VCF has been noted. One large has been performed mainly for the symptomatic treatment of prospective cohort study of elderly patients with low-trauma painful osteoporotic-induced VCF. The palliative treatment osteoporotic VCFs calculated an increased standardized of tumour-induced VCF (typically myeloma or metastatic mortality ratio for women of 1.82 (95% CI 1.52–2.17) and disease) remains an important further indication for PV. for men of 2.12 (95% CI 1.66–2.72) [10]. VCF is a major public health concern, with an estimated Traditional treatment of uncomplicated VCF consists of 1.4 million patients presenting with such a fracture each analgesia, bracing, and rehabilitation. Pain often necessitates year [3]. The incidence of VCF in the US alone is estimated bed rest or other restrictions on mobility. Open reduction to be 750,000 [4], a figure that makes VCF more common and internal fixation is theoretically possible, but rarely than osteoporotic-related hip fractures. The majority of these performed due to poor bone stock and multiple underlying 2 Radiology Research and Practice co-morbidities. PV offers a less invasive therapeutic option old [24]. The NEJM trials have also been criticised on the for generally elderly patients with multiple comorbidities basis of the proportion of eligible patients who declined enrolment, 70% for Kallmes and 64% for Buchbinder. Bono which allows for early immobilisation. et al. [25] suggested this raised the spectre of selection bias. However, these figures are not remarkable when compared 2. Evidence and Controversies with previous experience in blinded randomised controlled trials. Prior to 2009, evidence for the effectiveness of PV in osteo- The expected natural history of VCF is of gradual healing porotic VCF was based on anecdotal experience, multiple and pain relief [26, 27]. Some evidence from observational prospective and retrospective case series, and prospective studies of PV have shown decreased pain relief and less comparative cohort studies [11]. Multiple observational improvement in mobility in fractures >12 months when studies had shown almost uniformly excellent results with treated with PV [28]. Based on the patient selection criteria PV, with moderated to marked pain relief experienced by 75– of both NEJM studies, patients with painful fractures up to 95% of patients [12–14]. Similar results in the treatment of one year of age were included in the trials. Most patients metastatic fractures have also been reported [15]. However, had pain of >3 months duration. This would have inevitably a bias towards overestimation of treatment benefits is resulted in the enrolment of patients with delayed union and possible when relying on this form of evidence [16, 17]. non union, altering the homogeneity of the disease process Well-designed, randomised, prospective trials comparing PV studied. The average reduction in pain as assessed on a visual versus conservative therapy were lacking. In 2009, NEJM analogue scale (VAS) was smaller in the active arms of both published the results of the first two randomised blinded trials than would have been expected from prior observa- trials comparing PV with a sham intervention, namely, tional studies, raising doubt about the ability to extrapolate local anaesthetic infiltration of skin, subcutaneous and these results to patients with severe pain post-VCF who have periosteum [18, 19]. failed conservative treatment. Bono et al. also criticised the Buchbinder et al. [18] enrolled and randomised 78 design of the sham procedure, labelling it an alternative patients with one or two painful osteoporotic vertebral intervention (the injection of long acting local anaesthetic fractures (as defined on imaging, predominately MRI) to onto periosteum) rather than a true sham procedure. It is either PV or a sham procedure, with followup reported up difficult to imagine, however, how participants in the NEJM to six months. Kallmes et al. [19] enrolled and randomised could have been truly blinded without recourse to such a 131 patients with one to three fractures to PV or a similar procedure. Some authors, including the current authors, sham procedure; followup was to three months. Both advocate fluoroscopic-guided palpation and percussion of trials reported no statistically significant benefit of PV over PV candidates, in an attempt to correlate imaging findings placebo. with symptoms. This was not performed in either study. Both The NEJM trials have been criticised on several fronts, trials also did not examine the role of PV in nonosteoporotic with Buchbinder in particular strongly defending the validity vertebral fractures, or examine the role of PV in the inpatient of the trials in ensuing correspondence [20, 21]. Kallmes et al. setting. [19] allowed cross-over between the two arms at one month. More recently, the results of VERTOS II [29]have For those receiving the sham procedure, 42% opted to receive become available. This multicenter study was randomised, PV at three months, compared with 12% for the other but participants, physicians and outcome assessors were not arm. This higher rate of cross-over could be interpreted as blinded. Over 200 patients with a VCF and pain of less than reflecting dissatisfaction with the sham procedure compared 6 weeks duration were randomised to conservative treatment with PV, or possibly flaws in the blinding of the sham or PV. No sham procedure was performed. At one month and procedure such that patients were able to “guess” their one year, a statistically significant reduction in pain in the PV intervention. arm was evident. Alvarez et al. [11] concluded that PV is safe and able to be performed at an acceptable cost. Furthermore Mathis [22] and Munk et al. [23]criticised the low patient enrolment number compared with length of the the pain relief following PV is immediate, lasts for at least a enrolment period. Conceivably, patients with the most severe year, and is significantly greater than conservative treatment. Rousing et al. [30] also recently reported 12-month pain would be less likely to agree to undergo randomisation, and the studied population would therefore exclude those followup from an open-label, randomised study (n = 50, patients with the most severe pain. These authors also point fracture age <8 weeks) comparing PV with conservative management. Immediate and significant pain relief following out that Kallmes was close to proving a “clinically meaningful improvement in pain for PV compared to sham therapy” PV was evident. At one-month following discharge, the with a P value of .06. If the Kallmes trial had enrolled PV arm had a statistically significantly reduction in pain 19 more participants who experienced similar results, P compared with the conservative therapy arm. However, no would have been <.05 and thus regarded as statistically difference in pain scores was found between the groups at 3 and 12 months. These authors suggest that the role of significant. Mathis concluded that Kallmes therefore did not enrol enough patients to disprove the effectiveness of PV may therefore be as a short-term invasive method of PV. The number of patients enrolled in Buchbinder was pain control in those who fail conservative treatment or for those whom conservative treatment and the accompanying also insufficient to power a subgroup analysis to assess PV effectiveness in those with fractures less than six weeks immobilisation carry serious risks. Radiology Research and Practice 3 T8 (a) (b) Right prone T8 (c) Figure 1: Painful haemangioma of right-hand aspect of T8 (arrowed) in a 56-year-old man treated with unipedicular vertebroplasty. Sagittal (a) and axial (b) TSE T2-weighted images. (c): Vertebroplasty spot fluoroscopy image, AP projection. Postprocedure, the patient reported complete resolution of pain. 3. Conclusions on Available Evidence for PV 4. Performing Percutaneous Vertebroplasty It can beconcluded from the availableliteraturethat 4.1. Patient Selection. Ideally, patients with painful VCF who long-term effectiveness and complication data from PV is are failing conservative treatment should be referred for currently lacking. Performing a true blinded randomised- PV as early as practicable once it has become clear that controlled trial between conservative therapy and PV is im- conservative measures are failing, or in cases of severe pain possible. Despite the seemingly conflicting available data, it requiring hospitalisation. Patients with pain of greater than is the authors’ opinion that there is some evidence available three months duration are less likely to benefit from PV that in the acute to subacute period, in those who are failing [29]. conservative treatment or at are at increased risk from immo- There are few absolute contraindications to PV. Coag- bilisation, PV can provide good pain relief compared with ulation profile must be normal or near normal, and anti- conservative treatment, though as yet no durable long-term coagulants must be ceased prior to the procedure. PV is benefit has been demonstrated. When patients are carefully contraindicated in those with severe cardiac or respiratory screened by history, examination, and imaging prior to the failure precluding safe conscious sedation or general anaes- procedure, it is the authors’ opinions that a group highly thesia. These patients are considered high risk for clinically likely to significantly benefit from PV can routinely be iden- significant procedure-related fat embolism [31]. Infection tified and then offered PV. PV remains an important inter- or fever is also an absolute contraindication. Severe loss of vention for the treatment of intractable pain associated with vertebral body height is a relative contraindication, but good neoplasm-induced VCF (Figure 1), and for those hospitalised results can often be obtained in even severely compressed due to severe pain following osteoporotic-induced VCF. vertebrae [32]. 4 Radiology Research and Practice T8 120 mm 120 mm (a) (b) Figure 2: Sagittal TSE T2-weighted (a) and sagittal STIR (b) of the thoracolumbar spine in a 56-year-old man referred for PV for severe back pain following a fall. VCFs are noted at T8 (white dashed arrow) and T12 (continuous white arrow). There is prominent STIR hyperintensity at T12 without significant marrow edema at T8. The patient was symptomatic over T12 on palpation. This level was cemented with complete resolution of symptoms. Formal prevertebroplasty assessment is performed by the considered a relative contraindication to PV and prompt careful reassessment of the patient’s symptoms. interventionist one to two weeks before the procedure is scheduled. At this time, all of the imaging is reviewed. It is An assessment of the likely fluoroscopic approach to PV vital to ensure that a recent MRI dating from the time of is made to ensure the procedure is technically feasible. Severe symptom onset is available to assess marrow edema in the kyphosis and scoliosis are a relative contraindication. Poor target levels. PV is contraindicated if bone marrow edema pedicle visualisation and or aberrant anatomy may require is absent on STIR (short-tau inversion recovery) images CT-guided placement of bone cannulae. If the patient is (Figure 2). If MRI is contraindicated or unavailable, imaging unable to lie prone, general anaesthesia may be indicated. If assessment can be performed with a combination of CT and theprocedureis technically feasible and the imaging findings scintigraphic bone scan. CT may also be useful for assessing correlate with the examination findings, the patient is then pedicle bone stock and the integrity of the posterior vertebral educated about the procedure and possible complications, body cortex in selected patients, particularly in patients with and informed consent is obtained. malignant VCF. Severe loss of bone stock of the pedicle and posterior vertebral body cortex is a relative contraindication 4.2. Procedure. PV entails the percutaneous injection of bone to PV due to increased risk of symptomatic cement leak. cement, typically PMMA, into the collapsed vertebral body. A comprehensive history is obtained and a thorough In our institution, PV is generally performed under general examination is performed. The examination is performed, anaesthesia, although the procedure can be safely performed in part, in the fluoroscopic suite with the patient prone. under conscious sedation. After prone positioning, the X- Useful clinical information can be obtained prior to this stage ray tube and image-intensifier is centered over the relevant by observing the pain induced by patient mobilising and vertebral body such that the superior and inferior endplates climbing onto the fluoroscopy table. It is important to careful are aligned/not obliqued and the spinous process is midline. correlate the region of marrow edema on cross-sectional The pedicle to be cannulated is then centred in the vertebral imaging with the fluoroscopic image of the vertebra. The body image via cephalo-caudal tube angulation. Right and patient is then palpated and or gently percussed in the region left anterior oblique tube positioning is performed to of fracture in an attempt to correlate symptoms with imaging visualise the relevant pedicle “en-face.” If biplane is available, findings. If there is a clear disparity between the imaging and the true lateral projection of the vertebral body is obtained the examination findings, PV is contraindicated. Signs and by ensuring that the posterior vertebral cortex is visualised symptoms of concurrent facet or sacroiliac joint dysfunction, in profile without obliquity, the left and right ribs at the radiculopathy, or sacral insufficiency fracturing should be target level (if visible) completely overlap each other and Radiology Research and Practice 5 Prone Lateral (a) (b) Figure 3: Spot fluoroscopic images from two separate patients obtained during PV. (a) demonstrates left bone cannula insitu. The right pedicle has been cannulated, and is advanced in the AP plane staying clear of the pedicle medial cortical margin. Arrow indicates the medial pedicle cortex. (b) Lateral projection demonstrates tip of needle anterior to posterior vertebral cortex (dashed white line). Once this landmark is reached, the cannula can be safely advanced to 1 cm posterior to the anterior vertebral cortex under lateral projection fluoroscopic guidance. Cementing is also performed in this projection. the target vertebral body is centered in the image. PV can be progression should only be performed in the oblique AP pro- safely performed without access to biplane fluoroscopy but is jection, staying clear of the medial pedicle cortical margin. The tip of the cannula is advanced to a point approx- significantly more time consuming. imately 1 cm posterior to the anterior vertebral body as With aseptic technique and following local anaesthesia, assessed laterally. Because the vertebral body is not rectan- an 11 G or 13 G bone needle is inserted down onto the per- gular but rather curved, leaving a safe gap between these two iosteum overlying the pedicle, aiming for the lateral cortical points is needed to ensure the anterior cortex is not breached. margin of the pedicle at the 10:00 position on the left and The contralateral pedicle is cannulated in a similar fashion. the 2:00 position on the right. A transpedicular approach Bilateral cannulation is favoured due to increased chance of is the technique of choice. This approach ensures that risk adequate and safe cement injection. If there is doubt about of damage to adjacent structures is minimised, is easily the diagnosis, bone biopsy is performed at this stage. learnt, and conveniently positions the cannula tip at maximal The PMMA cement is prepared by mixing polymer pow- distance from bone entry for cement injection, helping to der with liquid monomer. Mixing of the powder and liquid minimise leaks. Occasionally, a parapedicular approach may leads to exothermic polymerisation and then progressively be necessary due to difficult/distorted anatomy. Cannula ad- thickening of the paste, which subsequently hardens. Once vancement is then performed. Typically, the periosteum is the cement has a toothpaste-like consistency, injections com- breached and the cannula advanced with hand pressure and mence via a 1 mL syringe. Continuous screening for cement screwing. Soft osteoporotic bone means that a soft bone extravasation during injection is performed. In particular, mallet is only occasionally needed for cannula advancement. close attention is made to the posterior margin of the verte- An attempt to stay initially lateral to the midline of the bral body. If cement extends posteriorly within 5 mm of this pedicle on the oblique AP projection is made to minimise the landmark, injection is ceased to minimise the risk of epidural chances of breaching the medial cortex of the pedicle, and space cement leak. One needle only at a time is injected. Any thus entering the spinal canal, during cannula positioning leak or extravasation is an indication to stop injection. Gen- (Figure 3(a)). After complete cannula engagement of bone, erally, a small waiting period for the cement to solidify is all the true lateral projection is checked for cannula trajectory that is required prior to resuming injection. Large leaks may in the cephalo-caudal plane. Once the needle is anterior to require the procedure be abandoned. At the end of the proce- the posterior margin of the vertebral body on the lateral dure when the cannulae are removed, it is advisable to rein- projection, the pedicle has been successfully traversed and sert the introducing stylet to push any residual cement into further needle progression can be monitored via the lateral the needle tract within the bone. A cast of cement deposited projection (Figure 3(b)). Prior to this landmark, cannula into soft tissues is irritant and can cause significant pain. 6 Radiology Research and Practice 4.3. Volume of PMMA to Inject. The volume of cement to be injected at each level for maximal efficacy has not been accurately determined [33]. In ex vivo studies, Belkoff et al. [33] demonstrated that vertebral body strength can be restored with 2 mL of cement, whilst restoration of preinjury stiffness required 4–8 mL. Regardless of exact measurements, visual filling of the body on the AP projection from the inner margins of the endplates along the lateral 1/3 on each side is ideal, though this is not always technically feasible (Figure 4) [31]. The current authors have often found this result to T8 be achievable with 3–5 mL of cement. As pain relief does not correlate with volume of injected cement [12], visual inspection of the amount of cement injected to the residual volume of the compressed vertebra is recommended when ascertaining total volume of cement to be injected. 4.4. Postprocedure Care. The patient remains supine or sem- R irecumbent for one hour, with monitoring of neurovascular Prone status and wound inspection every 15 and 30 minutes respec- tively. The patient is then gently mobilised. If the status of the patient is stable, they can be discharged home after two (a) hours. Occasionally, patients may experience an increase in pain following PV. This is usually of benign aetiology and self-limiting [22]. Good pain relief is usually obtained with oral or parenteral narcotics. Ongoing severe pain, radicular pain or signs/symptoms of spinal stenosis should prompt early imaging with CT. Followup for treatment of the pa- tient’s underlying osteoporosis is mandatory. 4.5. Complications. In general, PV is a safe procedure which is well tolerated. The overall complication rate in PV for T8 VCF reported in the literature is low, ranging from 1% to 10% [13, 34–36]. Complications are considerably more common in the acute peri-and postoperative period. The complication rate for malignant tumours is higher than for benign VCF [36–41], with one review by Murphy and Deramond [41] estimating the complication rate for OP to be 1.3% for osteoporotic VCFs, 2.5% for haemangiomata- associated VCF, and 10% for malignant VCF. The commonest complication of PV is cement extravasa- tion, occurring 26–97% of the time [42]. The vast majority of leaks are asymptomatic. However, cement leaks can (b) narrow and/or impinge neural structures, either within the neural foramina or the epidural space (Figures 5 and Figure 4: Spot AP (a) and lateral (b) fluoroscopic images following 6). [43, 44]. Radiculopathy related to cement leakage is T8 PV in a 62-year-old man with an osteoporotic VCF. A bi- usually transient and responds well to systemic analgesia pedicular approach was used. There is satisfactory filling of the and or transforaminal nerve block, although occasional cases vertebral body in the lateral and AP projections without evident leak (arrows). The patient’s symptoms had resolved on awakening from requiring of surgical decompression have been reported [43, the procedure. 44]. Failure to respond promptly to transforaminal nerve block for radiculopathy or any symptoms referable to central canal stenosis is an indication for urgent neurosurgical consultation and decompression. Systemic cement embolisation is rare, with one study complication [46]. As risk of marrow embolisation may be estimated as much as 5% of patients may undergo cement proportional to volume of displaced marrow during cement pulmonary embolism [45]. These are rarely clinically sig- injection, the authors favour performing PV at up to three nificant [46]. Displaced marrow from the cemented ver- levels only at one sitting. Venography prior to cementing tebra may also result in fat embolism. Patients with poor has fallen out of favour [47, 48]as noclinicalbenefit cardiorespiratory function may be at increased risk of this referable to venography has been demonstrated [28]. Other Radiology Research and Practice 7 T6 T6 (a) (b) Figure 5: 86-year-old woman with known multiple myeloma and pathological fracture of T6. During PV, posterior cement leak was noted soon after injection commenced; the procedure was abandoned. (a): Axial CT demonstrates permeative bone destruction of T6 (black arrows). Cement has extravasated posteriorly into the epidural space. (b) Sagittal CT demonstrates a thin collection of epidural cement anterior to the thecal sac (dashed white arrow). The patient remained asymptomatic initially and at followup and decompression was not required. L1 (a) (b) Figure 6: Modern biplane fluoroscopy allows on-table CT to be performed, with multiplanar reformats. Although the images acquired are susceptible to quantum mottle, the technique is invaluable in PV to quickly assess and confirm cement position and to assess for complications. Sagittal (a) and coronal (b) reconstructions (Siemens Axiom Artis biplane fluoroscopic unit) are shown in a 78-year-old man with recent VCF of L1 treated successfully with PV. An old VCF is noted at L2 (white arrow). A trace of lateral cement leak is noted to the left (dashed black arrow). This was asymptomatic. complications of PV include bleeding, haematoma, infec- and there is no evidence to support routine antibiotic tion, pneumothorax, pedicle fracture, thecal sac puncture, impregnation into the cement or intravenous antibiotics at and CSF leak. Patients with severely lowered bone mineral the time of the procedure [35]. density may experience fractured ribs or sternum whilst PMMA used during arthroplasty has been associated theprocedureisperformed [49]. Infection is uncommon, with transient hypotension, though a link between PV with 8 Radiology Research and Practice PMMA and cardiovascular effects has not been demon- [6] G. P.Lyritis,B.Mayasis, N.Tsakalakos et al., “The natu- ral history of the osteoporotic vertebral fracture,” Clinical strated on retrospective review [50]. The exothermic process Rheumatology, vol. 8, supplement 2, pp. 66–69, 1989. of PMMA polymerisation has led to some concern about [7] C. Schlaich, H. W. Minne, T. Bruckner et al., “Reduced pulmo- possible associated thermal injury, but in experimental nary function in patients with spinal osteoporotic fractures,” testing no thermal injury to neurological structures has been Osteoporosis International, vol. 8, no. 3, pp. 261–267, 1998. demonstrated [51, 52]. [8] K.W. Lyles, D.T.Gold, K. M. Shipp, C. F. Pieper,S. Martinez, and P. L. Mulhausen, “Association of osteoporotic 4.6. Risk of Subsequent Fracture at Adjacent Vertebrae. Some vertebral compression fractures with impaired functional reports in the literature have suggested that PV is associated status,” American Journal of Medicine, vol. 94, no. 6, pp. 595– 601, 1993. with a higher incidence of new VCF at adjacent levels, [9] S.L.Silverman, “The clinical consequences ofvertebral possibly reflecting a biomechanical consequence of the aug- compression fracture,” Bone, vol. 13, no. 2, pp. S27–S31, 1992. mented stiffness of the cemented level [53–56]. Recent data [10] D. Bliuc, N. D. Nguyen,V. E.Milch, T.V. Nguyen, J. A. Eisman, from the VERTOS II trial [57] randomising painful VCFs and J. R. Center, “Mortality risk associated with low-trauma to conservative treatment or PV showed the incidence of osteoporotic fracture and subsequent fracture in men and new VCF between the two groups was not different at 12 women,” Journal of the American Medical Association, vol. 301, months followup, and the only risk factor identified for new no. 5, pp. 513–521, 2009. VCF was the number of baseline VCFs. This adds weight to [11] L. Alvarez, M. Alcaraz, A. Per ´ ez-Higueras et al., “Percutaneous the theory that new VCF post-PV are manifestations of the vertebroplasty: functional improvement in patients with natural history of osteoporosis rather than reflecting a risk osteoporotic compression fractures,” Spine, vol. 25, pp. 1051– intrinsic to PV. 1052, 2000. [12] J. D. Barr,M.S. Barr, T. J. Lemley,and R. M. 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