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Musculoskeletal Imaging |
1 From Barnes-Jewish Hospital (A.K.S.) and Washington University School of Medicine (T.K.P., L.A.G.), Mallinckrodt Institute of Radiology, 510 S Kingshighway Blvd, St Louis, MO 63110. Received December 8, 2004; revision requested January 25, 2005; revision received April 8; accepted May 2; final version accepted June 24. Address correspondence to L.A.G. (e-mail: gilulal{at}mir.wustl.edu).
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ABSTRACT |
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 TOP ABSTRACT INTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONReferences |
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Materials and Methods: Institutional review board approval and informed consent were obtained, and the study was HIPAA compliant. One hundred seventy-three patients (mean age at treatment, 73.8 years ± 11.9 [standard deviation]) with 422 symptomatic osteoporotic VCFs underwent 204 treatment sessions for over 4 years. Pain immediately before and after PV was measured by using a visual analogue scale (VAS). Pain degree, activity level, and analgesic use were assessed at 2 weeks and 1, 3, 6, 12, and 24 months after PV by using telephone interview questionnaires. Data were analyzed by using a combination of paired t tests, analysis of variance, contingency tables, and 
2 tests.
Results: Findings of 172 PV treatment sessions for 149 patients (mean age at treatment, 73.4 years ± 12), 110 (74%) of whom were women, were assessed; 32 treatment cases were lost to follow-up or lost owing to death. A single fracture level was treated at 65 sessions; two fracture levels, at 52 sessions; and three or more fracture levels, at 55 sessions. The mean VAS pain score decreased significantly (P < .001), from 76 ± 21 before to 19 ± 27 immediately after PV. Of the outcomes reported at 24 months, 82% (64 of 78 treatment sessions) were marked to complete resolution of the initial pain, 51% were complete cessation of analgesic use, and 51% were increased activity levels. These results did not differ greatly over time or when stratified into groups according to the number of fracture levels treated.
Conclusion: PV performed at a single fracture level and that performed at multiple fracture levels were equally effective in facilitating long-term pain relief, increased activity level, and decreased analgesic use in patients with osteoporotic VCFs.
© RSNA, 2006
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INTRODUCTION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONReferences |
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Percutaneous vertebroplasty (PV) with polymethylmethacrylate (PMMA) is a radiologically guided technique that can be used in patients in whom conservative therapy has been nonsuccessful (2–9). PV with PMMA has been used to treat a variety of lesions, including neoplastic and osteoporotic VCFs. In the United States, PV is used primarily for treatment of osteoporotic VCFs (9). Study (2,3,5–10) results have shown substantial pain relief and increased mobility during the first 72 hours after vertebroplasty in up to 90% of patients.
The practice of treating multiple fracture levels in a single patient by using PV appears to be commonly reported in the medical literature. This is because the likelihood of having additional fractures increases once a patient has a fracture compared with this likelihood in age-matched control subjects who have had previous fractures but have not undergone PV (11). The risk of having a second fracture is fivefold; in individuals with two fractures, the risk increases to 12-fold (11). Given the prevalence of osteoporosis, the number of patients with multiple osteoporotic VCFs is expected to be high. Investigators in many studies of PV have based their conclusions regarding the effectiveness of PV on data from multiple-level vertebroplasty that were grouped with data from single-level vertebroplasty (5–7,10,12–18).
Some investigators (10) have suggested that better outcomes are achieved in patients treated at a single fracture level than in those treated at multiple levels. The purpose of this study was to compare single- and multiple-level PV in terms of pain relief, activity level, and analgesic use in patients with osteoporotic VCFs.
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MATERIALS AND METHODS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONReferences |
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Patients with back pain believed to be secondary to osteoporotic compression fractures had been fully examined by their primary clinician. The patients had undergone conservative treatment for the fracture(s) that consisted of bed rest, analgesic use, and physical therapy before vertebroplasty was considered. Those in whom conservative therapy had failed underwent a formal examination for possible PV. Their medical histories, physical examination findings, and coagulation parameters were reviewed. Examination of all available radiographs, bone scintigrams, and magnetic resonance (MR) images was performed. In each case, the senior author (L.A.G.), who had more than 15 years of experience interpreting such images, compared fracture levels with pain symptoms. The degree and character of the vertebral compression, the visibility of the pedicles, the presence of cortical destruction, the edema on MR images, and the increased uptake on bone scintigrams were assessed. Indications for PV included focal, severe, intractable pain at the level of a known compression fracture without definite radicular signs or symptoms of bone impinging on the spinal cord or nerves. Contraindications to PV included infection, pain not related to a fracture, true radicular symptoms of bone compressing the spinal cord or nerves, and/or unstable fractures involving the posterior columns (19).
PV Technique
All PVs were performed either by or under the supervision of the senior author (L.A.G.), who has extensive experience with the technique, having began treating patients with PV in 1998. A similar PV technique was used in all patients and at all treated levels. Patients were placed in the prone position on the C-arm fluoroscopic table. The patients' vital signs were constantly monitored while conscious sedation was induced by a nurse trained in conscious sedation. Sedation was induced with neuroleptic analgesics such as fentanyl citrate (Sublimaze; Abbott Laboratories, North Chicago, Ill) and midazolam (Versed; Hoffmann-LaRoche Pharmaceuticals, Manati, Puerto Rico). Patients were kept alert enough to state whether or not they were experiencing pain during the procedure.
With fluoroscopic guidance, the vertebra(e) in question was localized for visualization of the pedicle(s) at the level(s) to be treated. The skin overlying the area was prepared and draped in sterile fashion. The skin and periosteum overlying the pedicle were anesthetized with a 1:1 solution of lidocaine 1% (Astra-Zeneca, Wilmington, Del) and bupivacaine hydrochloride 0.25% (Abbott Laboratories). After the skin incision, an 11- or 13-gauge Jamshidi-type bone biopsy trocar was advanced with fluoroscopic control until its tip reached the lamina posterior to the pedicle. Once this position was confirmed, the trocar was advanced centrally into the vertebral body with lateral and frontal fluoroscopic guidance.
Intraosseous "blush" venography was then performed by using 0.5–1.0 mL of iohexol (Omnipaque 180; Nycomed, Princeton, NJ), which was injected through the trocar to prevent the trocar from being placed in the main venous structures and to plan the subsequent injection of PMMA (20). PMMA powder—Osteobond Copolymer Bone Cement (Zimmer, Warsaw, Ind) or, in earlier cases, Cranioplastic (Plastics One, Roanoke, Va)—was mixed with 7 g of barium sulfate powder, which had been sterilized with dry heat to increase opacity (21). Cranioplastic was used in the 16 early treatment sessions, and Osteobond Copolymer Bone Cement was used in the remaining sessions. The barium sulfate powder was broken into fine particles and then combined with the PMMA powder. In the earlier cases only, tobramycin (Nebcin; Eli Lilly, Indianapolis, Ind) (1.2 g) was then added to the mixture. The entire combination of materials was then mixed to form a toothpaste-like substance.
The PMMA mixture was then placed through the back of a 20-mL syringe and backfilled into a 10-mL syringe, with care taken to expel air from the mixture. The 10-mL syringe was then mounted onto a screw flange–type injector with a hub adaptor modeled after the LeVeen screw-type syringe (Boston Scientific, Boston, Mass) (22), and the remainder of the PMMA mixture was placed into a cold water bath for later use. The PMMA mixture was injected with lateral fluoroscopic guidance through the trocar (Figure). The injection was terminated when PMMA entered the posterior quarter of the vertebral body or when there was leakage outside the vertebral body into the paravertebral space or intervertebral disks. If leakage was noted, either the injection was halted for 1–2 minutes to allow the PMMA to harden and plug the leak or the needle was repositioned. Minor extension of PMMA into the intervertebral disk space, paravertebral soft tissues, or paravertebral veins was not considered to represent clinically important sequelae (8,23).
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Data Collection
The patient and procedural characteristics of each PV were recorded by using a standard form that was completed at the time of the procedure and on which the patient's age and sex and the number and location of fractures treated were documented. Fracture age and fracture levels were measured in a way similar to the way in which they were measured in the study of Evans et al (12), who defined acute (<2 weeks), subacute (2 weeks to 2 months), early chronic (>2 months to 1 year), and late chronic (>1 year) fractures.
Before undergoing PV, the patients rated their pain level by using a standard visual analogue scale (VAS), on which a score of 0 indicated no pain and a score of 100 indicated maximal pain (5,12,13,15–17). They repeated this rating approximately 1 hour after the procedure. Then, a research assistant trained to conduct telephone interviews contacted the patients by telephone at fixed intervals after their treatment sessions—at 2 weeks and 1, 3, 6, 12, and 24 months—and using an institutional review board–approved questionnaire designed specifically for this study recorded their responses to treatment in terms of a variety of factors, including pain degree, activity level, and analgesic use.
As stated earlier, some treatment sessions were performed before we decided to follow up patients prospectively for this study. The imperfect overlap of starting the study with the procedure dates meant that there were missing follow-up data on the earliest treatment sessions for some of the early time periods and on the latest sessions for some of the later time periods. However, follow-ups of more than 50% of the sessions were conducted at four or more time periods.
During each telephone interview, the patient rated his or her pain as gone or as better than, the same as, or worse than it was before the PV. In the past, many of our elderly patients had had difficulty reporting a reliable VAS pain score over the telephone. Because of this, a telephone questionnaire that addressed the described pain relief categories was developed. To allow adequate time for the treatment effect to occur, at each time interval except 2 weeks, the patients rated their activity level as follows: more active than, the same as, or less active than before the procedure. For assessment of analgesic use, the patients were asked whether or not they were currently taking any pain medicine, because the entire cohort had been taking some form of analgesic medication before undergoing PV.
Statistical Analyses
All data were collected and stored in a common database by using computerized spreadsheets (Microsoft Excel; Microsoft, Seattle, Wash). Treatment sessions were divided into three groups for analysis: one fracture level, two fracture levels, and three or more fracture levels treated. Measures of treatment success included reported pain degree, activity level, and analgesic use after PV. Pretreatment and immediate posttreatment pain was analyzed by using VAS pain scores. Mean scores of pre- and posttreatment pain and of change in pain level were calculated. The change in VAS pain scores was tested for statistical significance within each group by using paired t tests. Group differences in the change in VAS pain score according to number of fracture levels treated were tested by using analysis of variance. Longer-term changes in pain degree, activity level, and analgesic use were examined according to treatment group at each follow-up time period by using contingency tables.
For statistical testing of long-term change, treatment sessions were categorized into two groups: single fracture level and multiple fracture levels treated. Outcomes also were categorized into two groups: improved and unimproved. The combining of categories was designed to increase statistical power, and the 2 tests had 80% power for the detection of a 25% difference (eg, 65% vs 90% improved) at an 
of .05. For all statistical testing, results were reported to be significant at P < .05. All statistical analyses were performed by using JMP 4.0 software (SAS Institute, Cary, NC).
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RESULTS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONReferences |
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Pain Relief
The mean VAS pain score for all treatments was 76 ± 21 before and 19 ± 27 after treatment (P < .001, paired t test) (Table 2). The decrease in pain following treatment was similar among all treatment groups (P = .50, analysis of variance). Longer-term pain relief was recorded by using categorical evaluations. Pain was reported as gone or better by 77%–85% of all the respondents throughout the follow-up period (Table 3). At most time periods, a greater proportion of the respondents in whom multiple fracture levels were treated reported improvement compared with the proportion of respondents in whom one fracture level was treated; however, the difference never exceeded 6% and was not significant (P > .40 for all cases, 2 test). A minority (2%–5%) of the respondents reported having worse pain after the PV. The only exception to this finding was the proportion of respondents who reported having worse pain among those patients who had two fracture levels treated and were followed up at 24 months.
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2 test). A minority of respondents (5%–9%) had decreased activity levels throughout the follow-up period, with exceptions observed in only a few subgroups: in patients who had one and two fracture levels treated and were followed up at 1 month, in patients who had two fracture levels treated and were followed up at 3 months, in patients who had three fracture levels treated and were followed up at 6 months, and in patients who had two fracture levels treated and were followed up at 24 months.
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.39, 2 test).
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DISCUSSION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONReferences |
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In this study, the pain relief reported by the total population of patients according to VAS scores was significant and similar across all treatment subgroups. This magnitude of relief has been replicated in several other studies (5,12,13,15–17) in which the same pain scale was used. Barr et al (10) achieved initial pain relief in 95% of patients treated for osteoporotic VCF and stable pain relief for 18 months in 94% of patients. Grados et al (16) found pain relief to be unchanged during a long-term follow-up period of 48 months in 25 patients. Perez-Higueras et al (15) observed large decreases in VAS pain scores, which were detected early (third day after PV) and preceded consistent pain relief for 5 years in a small patient cohort. Given these results, we believed that it was acceptable to measure the initial pain relief by using VAS scores and then to track patients on the basis of pain measurements by using simpler criteria that patients could readily understand and describe during the 24-month follow-up period. The suitability of this protocol was further validated by the 77%–85% of respondents who reported having partial to complete pain relief throughout the study, similar to the results observed in multiple other studies (2,7,10,12,13,17).
Vertebroplasty has been shown to provide early pain relief and increased ambulation (7,12,13,17). Ninety-one percent to 95% of the patients in our study had the same or increased activity levels after PV, and the majority (range, 54%–70%) of respondents had improved activity at all time intervals. This range of improved activity is consistent with results described in prior reports (7). McGraw et al (13) observed improved ambulation in 93% of patients after treatment. Evans et al (12) observed a similar substantial effect on ambulation and the ability to perform routine daily activities in a retrospective review of data for 245 treated patients with osteoporosis. Some study investigators (12,17) analyzed posttreatment activity by using formal outcome measures and found improved activity levels. In addition, each subgroup in our study maintained the benefits of PV in terms of activity level for 24 months, and these benefits did not differ according to the number of fracture levels treated. These findings are consistent with those observed by previous authors and show that vertebroplasty performed for treatment of a prospective cohort of osteoporotic VCFs can be expected to facilitate pain relief and the associated benefit of improved activity.
The percentages of patients with complete to partial posttreatment pain relief in our study population, as reflected by decreased analgesic use, were similar to findings described in prior reports. In most prior series, pain relief was substantial but not complete (2,7,10,12,13,17). This correlates with the number of patients who were able to completely cease using analgesics after PV in our study. Amar et al (7) observed large posttreatment decreases in analgesic use in 63% of their patient cohort. Evans et al (12) also observed a substantial decrease in pain medication use: Nearly 46% of patients claimed to have stopped using pain medication after the procedure; this percentage is similar to the percentages of patients in our study who made this claim at almost all follow-up time intervals. In our study, the percentage of patients who completely ceased using analgesics gradually increased for 3–6 months and then stabilized to a level in the range of values reported in the other described studies. The gradual increase in analgesic use cessation may have been due to progressive fracture healing and associated pain relief.
Some practitioners may expect patients who are treated at multiple fracture levels to have worse outcomes than patients who are treated at a single fracture level owing to factors such as increased thoracic kyphosis in patients with multiple fractures. Our treatment protocol involved the examination of each patient for focal pain at each fractured level and the correlation of these findings with MR imaging and/or scintigraphic findings. In this way, we were able to tailor each patient's treatment to his or her clinically relevant fractured levels. Very few patients returned for additional treatment of levels noted to be abnormal at radiologic and clinical evaluation. This is the likely explanation for the consistent results regarding pain relief, analgesic use, and activity level—regardless of the number of fracture levels treated—reported in our study.
A potential weakness of this study is that it was not completely longitudinal. However, it is not uncommon to have missing data when large cohorts of elderly patients are studied (7). Grados et al (16) collected data on only 60% of their original patients during follow-up, whereas Evans et al (12), in their large retrospective review, reported on only half of their original patient cohort. In our study, the patient recruitment period of almost 4 years, the follow-up interview period of more than 3 years, and the loss of follow-up in some patients yielded complete follow-up data (six follow-up reports) on just 27 (16%) treatment sessions. However, four or more follow-up reports were completed on the majority (n = 92 [53%]) of patients; the mean number of follow-ups conducted was 3.7. Neither the patient recruitment protocol nor the clinical examination procedure changed during the study period, however, so it is likely that the data collected at all follow-up times were comparable. The fact that the results as a whole were remarkably consistent also supports the credibility of the data.
The results obtained in this study represent data on only those patients in each treatment subgroup who were contacted by telephone at each time interval. Therefore, the patients within each subgroup who were contacted at one time point were not necessarily the exact same patients who were contacted at the next time point. It is possible that because the entire population was not sampled at every time point, measurement error in which a few patients with poor outcomes were not sampled could have occurred. However, the positive outcomes documented throughout the study were relatively stable across the treatment subgroups, despite the different combinations of patients whose data were sampled at each time interval; thus, this type of error was unlikely. Also, many of the outcome results generated, including percentages of patients with pain relief and percentages of patients who ceased using analgesics, were similar to those obtained in other studies.
Selection bias could have contributed to the treatment and examination of patients within certain subgroups who had less severe or fewer comorbidities and thus may have been expected to have better long-term results. However, the similar clinical makeups of the patients in our study population, regardless of the number of fractures, and the resultant positive outcomes seen in all groups independent of the number of levels treated made this bias less likely.
There was worsening pain and reduced activity level in some of the patient subgroups at various time intervals. Follow-up of our patient subgroups revealed the worsening conditions to be transient. In addition, results of studies in the literature suggest that patients treated with PV may have an increased relative risk of fracture at adjacent untreated levels (6). This is expected to result in worse pain in more patients in whom multiple fracture levels were treated; however, the reported worsening of these symptoms was not concentrated in any one subgroup in our study. The absolute numbers of patients with such results were small, and the percentages of these patients at some time points may have simply reflected a small sample size at that time.
It should be recognized that those patients who stated that they had worse symptoms usually had other comorbidities that were the source of their pain rather than failed vertebroplasty. In addition, the senior author of this article has encountered many patients who stated that their symptoms worsened after PV, only to find that they had developed a new fracture. The failure to follow up such patients after PV may be erroneously attributed to treatment failure, when in fact new fractures that may necessitate additional treatment may be present. Symptomatic worsening may be caused by a combination of comorbidities and new fractures. We believe that further studies to address this issue of persistent or worsening pain may be warranted for such patients.
Our data collection protocol, with the exception of the initial use of VAS pain scores, was based on elementary outcome measures. A research assistant trained in telephone follow-up interviewing found this format to be relatively easy to apply in this patient population, and the study questionnaire itself was created to minimize recall error. However, validated assessments of the global status of patients would have been preferable. Only formalized pain assessments have been performed reliably in many studies in which the VAS was used (5,12,13,15–17). Although this tool is more accurate when it is used with patients who are seen in person, many of our study patients lived several hours from our medical center, so a simpler, more reliable assessment tool that could be used over the telephone was needed. In addition, formal outcome measures of other parameters, such as mobility and analgesic use, which are used with small numbers of patients in some studies, may be difficult to assess in a large prospective patient cohort with long-term follow-up. Perhaps the use of an instrument such as the Roland scale proposed by Kallmes and Jensen (24) may be an option for future studies.
PV is a highly effective treatment in the hands of skilled personnel despite being invasive and the possible associated complications. However, a true measurement of its effectiveness cannot be performed until a randomized control trial in which some patients undergo PV while others participate in a sham procedure, with an emphasis on validated outcome measures and possible placebo effects, is undertaken. Some authors (24,25) have attempted to simulate this type of study on a small scale and achieved inconclusive results. Only until such a study is conducted will we be able to determine what, if any, true benefit patients attain after undergoing successful vertebroplasty.
We believe our study data are the first to demonstrate the equal effectiveness of PV performed at a single fracture level and PV performed at multiple fracture levels—in terms of pain relief, activity level, and analgesic cessation—in a large patient cohort. The results of the current study lend validity to the practice of treating multiple levels of osteoporotic VCF, with the expectation that many patients will have favorable treatment outcomes, improved qualities of life, and decreased morbidity and mortality.
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FOOTNOTES |
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Abbreviations: PMMA = polymethylmethacrylate • PV = percutaneous vertebroplasty • VAS = visual analogue scale • VCF = vertebral compression fracture
Authors stated no financial relationship to disclose.
Author contributions: Guarantors of integrity of entire study, A.K.S., L.A.G.; study concepts/study design or data acquisition or data analysis/interpretation, all authors; manuscript drafting or manuscript revision for important intellectual content, all authors; approval of final version of submitted manuscript, all authors; literature research, A.K.S.; clinical studies, A.K.S., L.A.G.; statistical analysis, A.K.S., T.K.P.; and manuscript editing, all authors
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONReferences |
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