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Sacral kyphoplasty for the treatment of painful sacral insufficiency fractures and metastases
The Spine Journal 12 (2012) 113–120
Clinical Study
Sacral kyphoplasty for the treatment of painful sacral insufficiency fractures and metastases Rinoo V. Shah, MD, MBA* Department of Anesthesiology, Guthrie Clinic-Big Flats, 31 Arnot Rd, Horseheads, NY 14845, USA Received 3 March 2011; revised 17 November 2011; accepted 22 January 2012
Abstract
BACKGROUND CONTEXT: Sacral insufficiency fractures and metastases are a source of severe intractable pain, with limited therapeutic options. Sacroplasty has demonstrable efficacy and safety; sacral kyphoplasty, however, is rarely reported. PURPOSE: To evaluate the safety and efficacy of sacral kyphoplasty for sacral insufficiency fractures and metastases. STUDY DESIGN: Retrospective, with long-term follow-up; rural community–based practice. PATIENT SAMPLE: Patients with sacral insufficiency fractures and metastases. OUTCOME MEASURES: Numerical pain rating scale, opioid equivalent usage. SELF-REPORT MEASURE: Numerical pain rating scale. FUNCTIONAL MEASURE: Opioid equivalent consumption. METHODS: Retrospective analysis. RESULTS: Statistically significant improvement in pain; overall, an improvement in opioid consumption. CONCLUSIONS: Sacral kyphoplasty appears to be a safe and efficacious procedure, comparable to sacroplasty, in the treatment of SIFs and sacral metastases. Ó 2012 Elsevier Inc. All rights reserved.
Keywords:
Sacroplasty; Sacral kyphoplasty; Kyphoplasty; Sacral insufficiency fracture; Osteoporosis
Introduction Sacral insufficiency fractures (SIFs) and sacral metastases are very painful, debilitating, often missed, and typically atraumatic sacral pathologies [1–6]. They are associated with significant morbidity, economic impact, and prolonged hospitalizations [2,3,7–9]. Computed tomography (CT), magnetic resonance imaging (MRI), and three-phase bone scans are used to make the diagnosis [3]. Conservative treatment consists of modified bed rest, limited physical therapy,
FDA device/drug status: This study uses KyhpExpress inflatable bone tamp and KyphX HV-R Bone Cement in an off-label manner. Author disclosures: RVS: Relationships Outside the One-Year Requirement: Stryker (C, paid in 2009 for consulting work completed in 2006). The disclosure key can be found on the Table of Contents and at www. TheSpineJournalOnline.com. * Corresponding author. Department of Anesthesiology, Guthrie Clinic-Big Flats, 31 Arnot Rd, Horseheads, NY 14845, USA. Tel.: (607) 795-5182; fax: (607) 795-5159. E-mail address: [email protected] (R.V. Shah) 1529-9430/$ - see front matter Ó 2012 Elsevier Inc. All rights reserved. doi:10.1016/j.spinee.2012.01.019
percutaneous interventions, and analgesics [10–12]. Comprehensive care, along with appropriate referrals for the origin of sacral pathology, for example, osteoporosis or malignancy, is warranted [10–13]. If early mobilization and optimal pain control are not achieved, patients are at risk for venous thromboembolic disease, urinary retention, reduced cardiac output, postural hypotension, pressure ulcers, depression, pneumonia, and catabolic energy states [10]. Even conservative treatment has attendant risks: delayed fracture healing (months), deconditioning, and adverse events secondary to analgesics [10–12]. Targeted options for sacral metastases include chemotherapy, radiotherapy, radiofrequency thermocoagulation, and excision, but these have associated morbidities. Chemotherapy causes systemic adverse events. Radiotherapy may damage collateral neurologic structures. Surgical excision and open stabilization have high mortality rates ranging from 19% to 48% [6,14]. Radiofrequency thermocoagulation palliates tumor-associated pain but not as rapidly as sacroplasty: a three- to four-point drop in the numerical pain score occurs over a 4- to 12-week period [5].
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Context Sacral insufficiency and pathological (ie, tumor) fractures can result in debilitating pain. Sacroplasty, and now sacral kyphoplasty, has been suggested as a treatment option. Contribution The author reports on a small series of patients undergoing sacral kyphoplasty who reported pain relief and less opioid use after the procedure. Implication This is a retrospective case series report. It is not a randomized control trial or comparative cohort study. Therefore, efficacy cannot be validly determined. Furthermore, the small number of patients precludes any real estimate of safety or generalizability. Readers are encouraged to read the ‘‘Caveat’’ section at the end of the paper. That said, common experience (such as that reflected by this case series) suggests that some well-selected patients might benefit from sacroplasty or kyphoplasty in experienced hands. —The Editors These concerns have prompted interest in a nascent therapy for painful SIFs and sacral metastases: sacroplasty [10–12]. Sacroplasty consists of percutaneously delivering cement into an SIF or sacral metastasis. Proposed mechanisms include neurolysis, thermal injury, and bone stabilization. Frey et al. [11,12] has demonstrated safety, early and durable pain relief, and functional restoration in patients with SIFs. In his group’s multicenter trial, there was a continuous improvement in visual analog scale: 7.7 preprocedure, 3.2 immediately postprocedure, and 0.7 one-year postprocedure. Sacroplasty has been used to treat sacral metastases [6,15–19]. These are case reports but not formal clinical studies [6,14–19]. Osteoplasty (pubic rami and ischial tuberosity) demonstrated pain relief, in patients with pelvic metastases [20]. With this precedent, sacroplasty has emerged as a promising treatment for this unfortunate patient population [11,12,21]. Sacral kyphoplasty is a modification of sacroplasty, involving the use of a distensible balloon to create a bone void before cement delivery; this has been formally reported in four patients and informally reported in one patient [22–25]. My study evaluates the technical feasibility, safety, and efficacy of sacral kyphoplasty.
Methods An institutional review board at my institution approved the study. All patients at the institution undergoing sacral
kyphoplasty were retrospectively identified. A tracking system and prospective data collection were in place for quality assurance when the procedure was initiated at the institution. This facilitated identifying patients, but this study cannot be considered prospective. The study protocol was developed after all kyphoplasty procedures were finished. All patients undergoing sacral kyphoplasty were diagnosed with painful SIFs or sacral metastases; these patients underwent the procedure between 2007 and 2010. Data were extracted from these records: age, sex, etiology, fall before fracture, onset of pain, laterality (bilateral or unilateral), number of hospitalizations for pain before surgery, associated vertebral fractures, surgical date, surgical procedure time, presence of a confounding (alternate) diagnosis for sacral pain, presence of a comorbidities, preoperative imaging, preoperative treatment, procedure description, total cement volume per side, complications, postoperative CT scanning, bone biopsy, duration of pain before surgery, preoperative pain rating at rest, preoperative pain rating with mechanical loading (pre-op pain), postoperative pain rating on postanesthesia care unit (PACU) discharge pain, postoperative pain rating at 24 to 48 hours after surgery (24–48 hours pain), pain rating at the patient’s last follow-up (last follow-up pain), period to last followup, factors confounding interpretation of outcomes, surgery disposition (skilled nursing facility, home), and functional status before and after discharge. Pain scores at 24 to 48 hours after surgery were gleaned from the nursing records. Sometimes the nurses did not write the pain score. For this reason, the 24- to 48-hour pain was the pain at 24-, 48-, or an average of 24- and 48-hour scores. Intraoperative planning All patients underwent the procedure at a community hospital serving a rural catchment area. All patients signed witness informed consent after notification about the off-label use of this procedure. General anesthesia and prophylactic intravenous antibiotics (cefazolin 1,000 mg or clindamycin 600 mg) were administered in the operating room. Each patient was placed in a prone position, with ocular, truncal, and limb pressure relief. Sterile preparation with chlorhexidine was performed. C-arm fluoroscopy was used to visualize the sacral foramina, using an anteroposterior (AP) view. Cephalocaudad positioning and landmark identification were used to optimize visualization of the foramina. For instance, the sacral foramina lay along an imaginary line connecting the lateral margin of the base of the superior articular process of sacrum (S1) and the sacral cornua. The S3 sacral foramina were typically located at a horizontal imaginary line connecting the inferior pole of the sacroiliac (SI) joints. In the setting of poor foraminal visibility, Smith and Dix [26] have suggested fluoroscopic landmarks to approximate the lateral margins of the dorsal sacral foramina: an imaginary line connecting the center of the S5 (sacral cornua) and geometric center of the L5–S1
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facet joint. Preoperative trajectories were planned using a PACS imaging system. The PACS software has a triangulation tool for CT and MRI scans. By dragging this triangulation tool along a simulated path (mimicking trocar/ cannula trajectories), one can simultaneously visualize the structures encountered in a sagittal, coronal, and axial planes. A PACS measurement tool was used to measure distances (sacral depth, distance from skin, and distance from foramina to SI joint) on CT/MRI. This virtual information was used in conjunction with surface anatomy and fluoroscopy: an indelible marker can be used on the skin to demarcate the location of the median crest (residual sacral spinous processes), sacral foramina, SI joints, and trocar entry points. Technique description The skin entry point was typically at the lateral margin of the sacral foramina (vertical perimeter, y-axis) and halfway in between the sacral foramina (horizontal perimeter, x-axis). The trocars were styletted Kyphon cannulas, usually KyphExpress cannulas (11 gauge, 3.8-mm diameter tip; Kyphon Inc., Medtronic Spine, LLC, Sunnyvale, CA, USA). A skin wheal with lidocaine with 1:100,000 epinephrine was raised. A stab incision was made. A diamondtipped stylet was used to penetrate the sacrum; this was subsequently exchanged for a beveled stylet to allow directional control. The trocars were initially advanced to the center of a line connecting the 9-o’clock positions of the left S1þS2 and left S2þS3 foramina, respectively; on the contralateral side, the trocars were advanced to the center of a line connecting the 3-o’clock positions of the right S1þS2 and S2þS3 foramina (Fig. 1), respectively. The trocars were advanced perpendicularly through the skin, lateral to the foramina, until bone was contacted. This avoided traversing the foramen and gauged skin posterior sacral cortex depth. This bone contact point is a bone bridge, horizontally interposed between the sacral foramina. This bone bridge is anatomically congruous to fused inferior and superior articular processes. (Fig. 1); annotated with sacral kyphoplasty target entry points lateral to the bone bridges between S1þS2 and S2þS3). The rationale for entering at this location was to divert medially extravasating cement into the bone bridge away from the foramen. This added a margin of safety. The orientation of the trocar was angled in a medial to lateral direction. The handle of the trocar was pushed toward the floor for a shallow (tangential) trajectory. The handle was pulled upward to the ceiling for a steeper (perpendicular) trajectory. An angle of 45 relative to the skin surface is the ideal trajectory [11,12]. Intermittent fluoroscopy was used to advance the trocar on AP and lateral views (Fig. 2A). A mallet was not necessary in most patients; hand pressure sufficed. The trocar was slowly advanced toward the SI joint (the lateral articulating surface of the sacrum). Serial AP views were used to ensure that the SI joint was
Fig. 1. Oblique view of sacrum; annotated with trocar entry points (circular discs) lateral to the bone bridges between S1þS2 and S2þS3; (copyright release and courtesy of Dr David B. Fankhauser, University of Cincinnati Clermont College, http://biology.clc.uc.edu/fankhauser/).
not violated. Serial lateral views were used to ensure that the anterior sacral cortex was not violated (Fig. 2A). Once situated, the stylet was removed. A KyphExpress 10/2 inflatable balloon tamp (10-mm length, max volume 4 mL, 300 psi maximal inflation pressure; Kyphon Inc., Medtronic Spine, LLC) was inserted. The outer cannula was then pulled back to expose the proximal and distal balloon markers. The balloon was then inflated to approximately 1 to 1.5 mL, with nonionic iodinated contrast. Balloon pressure never exceeded 250 psi. The balloon margins were carefully monitored to ensure confinement within the cortical margins (Fig. 2B). The balloons were deflated and removed. Polymethylmethacrylate bone cement (KyphX HV-R bone cement; Kyphon Inc., Medtronic Spine, LLC) was mixed. The radiopaque cement slowly thickened and solidified. When a toothpaste consistency was reached, cement was slowly delivered down the cannula into the sacral balloon void. Real-time fluoroscopy (AP and lateral views) was used to monitor cement spread and detect extravasation (Fig. 2C, D). Small aliquots of cement, on the order of 0.1 to 0.2 mL, were delivered. With adequate cement viscosity, this slow delivery was useful in preventing extravasation. Typically, 1 to 3 mL of cement was delivered on each side. If the cement reached the SI joint or the lateral margin of the sacral foramina, cement delivery was stopped (Figs. 2C and 3 Left). On a lateral projection, cement was allowed to advance to the ventral margin of the sacral corpus. The
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Fig. 2. Metastatic vulvar carcinoma and sacral kyphoplasty fluoroscopic images: (A) trocar; (B) balloon; (C) lateral view; (D) coronal view.
ventral surface of the sacrum is slightly concave. On an axial view, the anterior boundary of the sacral corpus is actually posterior to the anterior margin of the sacral ala and SI joint (Fig. 3 Right). Hence, cement anterior to the sacral corpus (on lateral fluoroscopy) does not represent extravasation or leakage (Figs. 2D, 3 Left, and 3 Right). Monofilament nylon stitches and pressure dressings were applied. Patients were extubated and transferred to the recovery room. Statistical analysis Mean differences in pain scores were calculated: (Pre-op pain)(PACU pain); (Pre-op pain)(24–48 hour pain);
(Pre-op pain)(last follow-up pain); (PACU pain)(24– 48 hour pain); and (PACU pain)(last follow-up pain). Specifically, the difference in pain scores evaluated at different points in time was analyzed using a repeatedmeasures analysis of variance and Tukey-Kramer multiple comparisons test. The Wilcoxon signed-rank test was used to compare opioid consumption preoperative and at last follow-up, with and without one patient. This latter patient required very high doses of opioids, as compared with the remaining patient population: 1,856 mg2,160þmg opioid equivalents. The significance level for all tests was set at a 5%. The remainder of the data is presented in a descriptive statistical format. SigmaPlot 11.0 Systat Software Corp.
Fig. 3. Metastatic vulvar carcinoma: (Left) postoperative computed tomography (CT) coronal view; (Right) postoperative CT axial view.
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statistical software (Systat Software, Inc., Chicago, IL, USA) was used for all data analysis and graphics.
Results
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was successfully treated with a caudal epidural steroid injection with a catheter steered to S1 nerve root. An S1 transforaminal epidural steroid injection was not attempted because of the impaired visualization of the foramen, secondary to the cement radiopacity.
Patients Eleven patients were identified; all were women. The average age was 81.4 years (69–87 years). Six patients had bilateral SIFs, and five had metastatic involvement. There were no significant differences (p value more than .05) in median age between SIF and metastatic carcinoma patients. The sacral ala were involved in all patients, and in one patient, the sacral corpus was involved. Average duration of pain before sacral kyphoplasty was 203.5 days (1– 875 days). Five patients had a mistaken diagnosis before evaluation for sacral kyphoplasty: lumbar compression fractures, lumbar spinal stenosis, coccygodynia, and myofascial pain. None of the patients were diagnosed with SI joint disease or pain. Treatment before sacral kyphoplasty consisted of bed rest (seven patients), analgesics (nine patients), musculoskeletal injections (one patient), and nothing specific (two patients). Average number of hospitalizations for sacral pain was 1.1 (0–4). Six of 11 patients fell before developing pain. Seven of 11 patients had additional fractures: thoracic compression fracture, pubic rami, and lumbar compression fractures. On physical examination, the neurologic examination was nonfocal, and pain was concordantly provoked in all patients. Presurgical imaging consisted of plain films (five patients), CT scan (nine patients), MRI (two patients), and bone scan (three patients). The functional status of the patients before sacral kyphoplasty was bedbound (five patients); wheelchair bound (one patient); and ambulatory (five patients). Surgery and perioperative period Sacral kyphoplasty was performed bilaterally on 11 patients. General, combined with local anesthesia, was used on all 11 patients. The modified (angular) short-axis approach [8,9] was used on nine patients. The long axis [24,26] was used on two patients. In one long-axis patient, the right side required repeat treatment with the modified short-axis approach. Adjunct procedures included thoracic and lumbar kyphoplasties (six patients) and biopsies (eight patients). Biopsy results were benign in six patients and malignant in two patients (metastatic neuroendocrine carcinoma and metastatic small-cell lung carcinoma). Average total cement volume per patient (not per side) was 4.76 mL (range, 2–7 mL). The average surgical time was 45.36 minutes (range, 27–65 minutes). Postoperative CT scans were obtained in eight of 11 patients. Mild cement extravasation occurred in three patients: SI joint, ilium, and S1 foramen. Complications related to the procedure occurred in only one patient, wherein cement extravasated into the S1 foramen. This resulted in S1 radiculitis and
Pain scores The average numerical pain rating score with mechanical loading, before surgery (pre-op pain), was 9.64 (range58–10, standard deviation (SD)50.67, and median510). The pain rating in the PACU (PACU Pain) was 2.55 (range50–5, SD52.70, and median53). The pain rating at 24 to 48 hours postoperative (24–48 hours pain) was 1.19 (range50–5, SD51.94, and median50). The average pain rating at the last follow-up (last follow-up pain) was 0.73 (range50–5, SD51.62, and median50). The average length of time to last follow-up was 302.34 days (range579–669 and SD5202.04). There was no statistically significant difference in average length of time to last follow-up, between patients with an SIF or metastasis. The mean differences in pre-op pain versus PACU pain (7.091, 95% confidence interval (CI): 5.61–8.57) was statistically significant, p value less than .001. Mean difference in pre-op pain versus 24–48 hour pain (8.45, 95% CI: 7.31– 9.57) was statistically significant, p value less than .001. Mean difference in pre-op pain versus last follow-up pain (8.91, 95% CI: 7.98–9.84) was statistically significant, p value less than .001. Mean difference in PACU pain versus 24- to 48-hour pain (1.35, 95% CI: 0.51 to 3.22) was not statistically significant, p value more than .05. Mean difference in PACU pain versus last follow-up pain was (1.82, 95% CI: 0.04–3.68) was not statistically significant, p value more than .05. The average pain scores (pre-op, PACU, 24–48 hours, and last follow-up) were comparable in patients with an SIF or metastasis. Opioid consumption Seven of 11 patients were taking opioid analgesics preoperatively (pre-op). Only four of the seven patients continued to use opioids, at the last follow-up (last follow-up). Three patients were able to discontinue all opioids. Three patients reduced total daily opioid usage. Only one patient required higher doses of opioids (from 1,856 mg to 2,160 mg) because of progression of her underlying metastatic disease. Hence, 63.6% required opioids preoperatively and 36.3% required opioids postoperatively. The average opioid consumption in morphine equivalents was 268.82 mg (SD5566.8) pre-op and 202.27 mg (SD5649.55) at last follow-up. If we exclude this one patient with severe progression of underlying metastatic disease, average opioid consumption (morphine equivalent) among the remaining 10 was 110.1 mg (SD5221.5) pre-op and 6.5 mg (SD518.86) at last follow-up. There was no significant difference in opioid consumption between pre-op and last
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follow-up, p5.0625. If we exclude the one patient consuming very large doses of opioids, the sample size is too small, and significance could not be reached. From a descriptive standpoint, mean opioid consumption doses among patients drop from pre-op to last follow-up. One caveat is that morphine equivalency calculators (Global Rph Calculator) [27] may not be accurate. However, use of the same calculator for each patient at specified time periods allows one to follow a change in opioid equivalency consumption [27]. Postoperative period Six patients were discharged home. Three patients were transferred to a skilled nursing facility. Two patients were transferred to an inpatient rehabilitation facility. The functional status after the procedure, on discharge from the hospital, was improved in most patients: bedbound (zero patients), wheelchair bound (three patients), ambulatory with rolling walker (four patients), and ambulatory (four patients). Two of the patients remained wheelchair bound because of frailty (metastatic cancer) and Parkinson disease. Immediate postoperative complications, as discussed above, occurred in one patient: S1 radiculitis. Five patients developed medical issues, unrelated to the kyphoplasty, during their extended follow-up: death because of metastatic carcinoma; femoral fracture; progressive dementia, aspiration pneumonia, and associated sepsis; severe pain because of metastatic carcinoma; and Parkinson disease. There were no surgical sites, deep tissues, or bone infections. Two patients required SI joint injections within 4 months of the procedure; the SI joint pain in these patients was distinct from the SIF pain; the SI joint pain was less severe and caused no functional impairment, as compared with SIF pain. This improvement in function parallels improvement in pain and reduction in opioid consumption.
Discussion Technique review Sacroplasty is performed with different imaging methods (fluoroscopy [11,12]; CT [28]; CT-fluoroscopy [29]), and approaches (short axis, modified (angular) short axis, or long axis [11,12,24,26,28,30]). Proponents of CT guidance raise concerns about adequately visualizing foramina in an osteoporotic sacrum, breaching the anterior cortex, and monitoring cement leakage [28,31,32]. Cement leakage, however, can even occur with CT guidance [24,32,33]. A modified (angular) short-axis approach [11,12] has been safely used for the largest sacroplasty series. I used the long axis for two patients and then switched to the modified short axis. I found the long axis to be cumbersome, whereas the modified short axis was simpler to adopt. The modified short axis allows greater directional control and targeted cement placement.
Fluoroscopy alone may be safely used for sacroplasty based on cadaveric dissection, fluoroscopic landmarks, and clinical outcome studies [11,12,34,35]. Technical vigilance, image quality, multiplanar views, and cannula placement in Denis Zone 1 are emphasized [11,12,24,26,36]. Denis Zone 3 lesions have been rarely accessed: hemangioma [22], tumor [6], and fracture [37]. Fluoroscopy has several additional advantages over CT guidance: reduced cost, reduced radiation exposure, real-time imaging, and accessibility in the hospital/clinic. Balloon kyphoplasty creates a cavitary void in trabecular bone. Cavity creation, along with use of landmarks, may help avoid an anterior cortical breach and facilitate cement containment [35,37]. The feasibility and safety, of sacral kyphoplasty, have been demonstrated in cadavers and in case reports: SIFs, hemangioma, pelvic fracture [22,23,25,35,37,38]. This author noted several advantages with kyphoplasty, despite cost and additional fluoroscopy time. The balloon is a three-dimensional, radiopaque, and roughly spherical structure with a measurable volume and diameter. This helps gauge depth, width, and volume under fluoroscopy. The outer boundaries of the inflated balloon delimit the size of the bone void. This is necessary to predict cement spread and volume. With slow insufflation, one can visualize the balloon perimeter expanding toward the cortex. This may help predict and prevent a Denis Zone 2 [36], anterior cortex, or SI joint breach. Attention to several factors will help enhance safety, with fluoroscopically guided sacral kyphoplasty: preprocedural CT or MRI; instrument trajectory planning with PACS software tools; modified (angular) short-axis technique; cannula placement lateral to the bone bridges (fused articular pillars); cannula placement in Zone 1, with a sufficiently steep angle to avoid the foramina and anterior cortex; real-time fluoroscopic monitoring of cement delivery, in multiple planes; adequate cement viscosity; use of low cement volumes; early recognition of cement extravasation; postoperative CT scanning in the event of extravasation; and practitioner experience. Data review Recent articles indicate that patients with chronic vertebral compression fractures or acute metastases may have similar levels of pain; both groups, however, may benefit from vertebral augmentation [39–42]. Sacral kyphoplasty addresses a similar need. My sacral kyphoplasty outcomes are comparable to the sacroplasty results presented in two multicenter prospective trials [11,12]. My patients demonstrated early and rapid pain reduction. The pain relief was sustained for almost 1 year (mean5302 days, range: 79–669 days). Patients demonstrated functional improvement. Most patients advanced to an ambulatory status with or without a walking aid (rolling walker).
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Opioid consumption was reduced in almost all patients. One exception was a patient with progressive metastatic carcinoma; this patient skewed the opioid consumption results for the entire series. Frey et al. demonstrated drop in opioid utilization from 71.2% to 21.2%, at 52 weeks [11]. My series demonstrates a similar reduction in opioid consumption from 63.6% of patients to 36.3% of patients. Four patients continued to use opioids: two had metastatic carcinoma; one suffered a femoral fracture; and one had a prior history of chronic low back pain treated with opioids. This patient’s opioid consumption was reduced but not eliminated. Persistency of low back and pelvic pain after vertebroplasty exists. Georgy [43] noted a 23.6% rate of persistent residual pain in patients undergoing vertebral or sacral augmentation. Sacral kyphoplasty may have to be complemented with ongoing multimodal spinal pain care and analgesic usage in some patients [44]. A recent literature review, assessing 108 patients from 15 studies, demonstrated a significant VAS reduction from 8.9 to 2.6 [30]. My series results are comparable to those in this pooled data set and multicenter prospective trials [11,12,21].
Caveats Irrespective of the robust improvements in pain in this series, there are several caveats that readers must acknowledge. Publication in a peer-reviewed journal has the potential to rapidly influence physician, patient, and commercial enterprise behavior, irrespective of the quality of evidence. Retrospective studies are arguably easier to conduct than randomized controlled trials. A retrospective study with positive results can influence practitioner judgment. There may be a time gap between the publication of positive results in a retrospective study and the publication of a confirmatory or refutatory randomized controlled trial. This time gap can be exploited, and interventional procedures can be carried out on numerous patients, before a randomized clinical trial demonstrates lack of effect [45,46]. Dr Eugene Carragee [47] raised concerns about this with respect to vertebroplasty: What seems most impressive in this whole affair has been the relentless shrinking of the apparent vertebroplasty effect size and duration. With each increase in the quality of evidence, the apparent quantity of effect has diminished and diminished until we are searching for any traces of it at all. Like King Lear’s retinue dwindling with each successive scene, we have to wonder, ‘‘now comes it truly as scant a size as this?’’ We have gone from 1998, when 90% of a large cohort had immediate and complete relief of symptoms, perhaps lasting a year or longer—completely attributed to the procedure—to arguing whether even the modest improvement now reported is a totally nonspecific effect, at even 6 weeks after
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treatment. From our editorial prospective, we worry about the decade or so lost, without systematically evaluating this intervention. If there is that subset of patients, miserable with persistent fracture pain, who will have great relief from vertebroplasty, we have not begun to identify them. Just as troubling, there are clearly some patients for whom the procedure is nearly all risk and no benefit—and who are they? So, what is the answer to the mysterious case of the disappearing effect size?’’ At a minimum, I hope practitioners understand that SIFs and metastases are very debilitating pathological syndromes in an often-neglected patient population. Sacral insufficiency fractures and metastases, if left alone, will most likely reach specified end points within a 3- to 6-month period: pain relief and death, respectively. The question is whether sacral kyphoplasty will improve pain relief and function, within this period of time. I have provided a detailed description of this technique. If a physician considers using this technique on their patients, outcome data should be systematically collected and quality assurance should be monitored. Another factor worthy of consideration is to perform this procedure after review by an institutional review board or credentialing committee to monitor the efficacy and safety of this procedure.
Conclusion Sacral kyphoplasty appears to be a safe, useful, and efficacious procedure. Consideration should be given to several technical factors (use of PACS software for targeting, trocar placement between the foramina-bone bridge, radiopaque balloon to create and delimit shape of void) to optimize procedural safety.
Acknowledgment The author thanks Robert Bienkowski, PhD, Erik Dickson, RT, and Mary Hatch, NP.
References [1] Lourie H. Spontaneous osteoporotic fracture of the sacrum. An unrecognized syndrome of the elderly. JAMA 1982;248:715–7. [2] Depalma MJ, Ketchum JM, Saullo T. What is the source of chronic low back pain and does age play a role? Pain Med 2011;12:224–33. [3] Tsiridis E, Upadhyay N, Giannoudis PV. Sacral insufficiency fractures: current concepts of management. Osteoporos Int 2006;17: 1716–25. [4] Finiels H, Finiels PJ, Jacquot JM, et al. [Fractures of the sacrum caused by bony insufficiency. Meta-analysis 508 cases]. [in French]. Presse Med 1997;26:1568–73. [5] Goetz MP, Callstrom MR, Charboneau JW, et al. Percutaneous image-guided radiofrequency ablation of painful metastases involving bone: a multicenter study. J Clin Oncol 2004;22:300–6.
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[6] Zhang J, Wu CG, Gu YF, et al. Percutaneous sacroplasty for sacral metastatic tumors under fluoroscopic guidance only. Korean J Radiol 2008;9:572–6. [7] Weber M, Hasler P, Gerber H. Insufficiency fractures of the sacrum. Twenty cases and review of the literature. Spine 1993;16: 2507–12. [8] Kannus P, Palvanen M, Niemi S, et al. Epidemiology of osteroporotic pelvic fractures in elderly people in Finland: sharp increase 19701997 and alarming projections. Osteoporos Int 2000;11:443–8. [9] Dasgupta B, Shah N, Brown H. Sacral insufficiency fractures: an unsuspected cause of back pain. Br J Rheumatol 1998;37:789–93. [10] Lin JT, Lane JM. Sacral stress fractures. J Womens Health (Larchmt) 2003;12:879–88. [11] Frey ME, Depalma MJ, Cifu DX, et al. Percutaneous sacroplasty for osteoporotic sacral insufficiency fractures: a prospective, multicenter, observational pilot study. Spine J 2008;8:367–73. [12] Frey ME, DePalma MJ, Cifu DX, et al. Efficacy and safety of percutaneous sacroplasty for painful osteoporotic sacral insufficiency fractures: a prospective, multicenter trial. Spine 2007;32:1635–40. [13] Dipaola C, Bible J, Biswas D, et al. Survey of spine surgeons on attitudes regarding osteoporosis and osteomalacia screening and treatment for fractures, fusion surgery, and pseudoarthrosis. Spine J 2009;9:537–44. [14] Pascal-Moussellard H, Broc G, Pointillart V, et al. Complications of vertebral metastasis surgery. Eur Spine J 1998;7:438–44. [15] Nebreda C, Vallejo R, Aliaga L, et al. Percutaneous sacroplasty and sacroiliac joint cementation under fluoroscopic guidance for lower back pain related to sacral metastatic tumors with sacroiliac joint invasion. Pain Pract 2011;11:564–9. [16] Toro A, Pulvirenti E, Manfre L, et al. Sacroplasty in a patient with bone metastases from hepatocellular carcinoma. A case report. Tumori 2010;96:172–4. [17] Valencia-Anguita J, Julia-Narvaez M, Rodrıguez-Burgos F, et al. [Percutaneous sacroplasty for relieving pain caused by sacral metastases]. [in Spanish]. Neurocirugia (Astur) 2007;18:247–9. [18] Masala S, Konda D, Massari F, et al. Sacroplasty and iliac osteoplasty under combined CT and fluoroscopic guidance. Spine 2006;31: E667–9. [19] Uemura A, Matsusako M, Numaguchi Y, et al. Percutaneous sacroplasty for hemorrhagic metastases from hepatocellular carcinoma. AJNR Am J Neuroradiol 2005;26:493–5. [20] Kelekis A, Lovblad KO, Mehdizade A, et al. Pelvic osteoplasty in osteolytic metastases: technical approach under fluoroscopic guidance and early clinical results. J Vasc Interv Radiol 2005;16:81–8. [21] Bayley E, Srinivas S, Boszczyk BM. Clinical outcomes of sacroplasty in sacral insufficiency fractures: a review of the literature. Eur Spine J 2009;18:1266–71. [22] Atalay B, Caner H, Yilmaz C, et al. Sacral kyphoplasty for relieving pain caused by sacral hemangioma. Spinal Cord 2006;44:196–9. [23] Deen HG, Nottmeier EW. Balloon kyphoplasty for treatment of sacral insufficiency fractures. Report of three cases. Neurosurg Focus 2005;18:e7. [24] Lyders EM, Whitlow CT, Baker MD, et al. Imaging and treatment of sacral insufficiency fractures. AJNR Am J Neuroradiol 2010;31:201–10. [25] Briem D, Grossterlinden L, Begemann PG, et al. [CT-guided balloonassisted sacroplasty. Preliminary results of a feasibility study]. [in German]. Unfallchirurg 2008;111:381–6. [26] Smith DK, Dix JE. Percutaneous sacroplasty: long-axis injection technique. AJR Am J Roentgenol 2006;186:1252–5. [27] Opioid (Narcotic) analgesic converter: an opioid conversion calculator. Available at: http://www.globalrph.com/narcotic.cgi. Accessed February 15, 2011.
[28] Strub WM, Hoffmann M, Ernst RJ, etal. Sacroplasty by CT and fluoroscopic guidance: is the procedure right for your patient? AJNR Am J Neuroradiol 2007;28:38–41. [29] Layton KF, Thielen KR, Wald JT. Percutaneous sacroplasty using CT fluoroscopy. AJNR Am J Neuroradiol 2006;27:356–8. [30] Binaghi S, Guntern D, Schnyder P, Theumann N. A new, easy, fast, and safe method for CT-guided sacroplasty. Eur Radiol 2006;16: 2875–8. [31] Butler CL, Given CA, Michel SJ, et al. Percutaneous sacroplasty for the treatment sacral insufficiency fractures. AJR AM J Roentgenol 2005;184:1956–9. [32] Pommersheim W, Huang-Hellinger F, Baker M, et al. Sacroplasty: a treatment for sacral insufficiency fractures. AJNR Am J Neuroradiol 2003;24:1003–7. [33] Given CA. Radiological case of the month. Appl Radiol 2006;5:38–41. [34] Betts A. Sacral vertebral augmentation: confirmation of fluoroscopic landmarks by open dissection. Pain Physician 2008;11:57–65. [35] Jayaraman MV, Chang H, Ahn SH. An easily identifiable anatomic landmark for fluoroscopically guided sacroplasty: anatomic description and validation with treatment in 13 patients. AJNR Am J Neuroradiol 2009;30:1070–3. [36] Denis F, Davis S, Comfort T. Sacral fractures: an important problem. Retrospective analysis of 236 cases. Clin Orthop Relat Res 1988;227: 67–81. [37] Betts A. Vertebroplasty of the first sacral vertebra. Pain Physician 2009;12:651–7. [38] Sedat J, Chau Y, Razafidratsiva C, et al. One-stage percutaneous treatment in a patient with pelvic and vertebral compression fractures. Cardiovasc Intervent Radiol 2010;33:219–22. [39] Depalma MJ, Ketchum JM, Frankel BM, et al. Percutaneous vertebroplasty for osteoporotic vertebral compression fractures in the nonagenarians: a prospective study evaluating pain reduction and new symptomatic fracture rate. Spine 2011;36:277–82. [40] Brown DB, Glaiberman CB, Gilula LA, Shimony JS. Correlation between preprocedural MRI findings and clinical outcomes in the treatment of chronic symptomatic vertebral compression fractures with percutaneous vertebroplasty. AJR Am J Roentgenol 2005;184: 1951–5. PMID: 15908560. [41] Brown DB, Gilula LA, Sehgal M, Shimony JS. Treatment of chronic symptomatic vertebral compression fractures with percutaneous vertebroplasty. AJR Am J Roentgenol 2004;182:319–22. PMID: 14736654. [42] Berenson J, Pflugmacher R, Jarzem P, et al. Balloon kyphoplasty versus non-surgical fracture management for treatment of painful vertebral body compression fractures in patients with cancer: a multicentre, randomised controlled trial. Lancet Oncol 2011;12: 225–35. [43] Georgy BA. Interventional techniques in managing persistent pain after vertebral augmentation procedures: a retrospective evaluation. Pain Physician 2007;10:673–6. [44] American Geriatrics Society Panel on Pharmacological Management of Persistent Pain in Older Persons, Ferrell B, Argoff CE, et al. Pharmacological management of persistent pain in older persons. J Am Geriatr Soc 2009;57:1331–46. [45] Buchbinder R, Osborne RH, Ebeling PR, et al. A randomized trial of vertebroplasty for painful osteoporotic vertebral fractures. N Engl J Med 2009;361:557–68. [46] Kallmes DF, Comstock BA, Heagerty PJ, et al. A randomized trial of vertebroplasty for osteoporotic spinal fractures. N Engl J Med 2009;361:569–79. [47] Carragee EJ. The vertebroplasty affair: the mysterious case of the disappearing effect size. Spine J 2010;10:191–2.
Clinical Study
Sacral kyphoplasty for the treatment of painful sacral insufficiency fractures and metastases Rinoo V. Shah, MD, MBA* Department of Anesthesiology, Guthrie Clinic-Big Flats, 31 Arnot Rd, Horseheads, NY 14845, USA Received 3 March 2011; revised 17 November 2011; accepted 22 January 2012
Abstract
BACKGROUND CONTEXT: Sacral insufficiency fractures and metastases are a source of severe intractable pain, with limited therapeutic options. Sacroplasty has demonstrable efficacy and safety; sacral kyphoplasty, however, is rarely reported. PURPOSE: To evaluate the safety and efficacy of sacral kyphoplasty for sacral insufficiency fractures and metastases. STUDY DESIGN: Retrospective, with long-term follow-up; rural community–based practice. PATIENT SAMPLE: Patients with sacral insufficiency fractures and metastases. OUTCOME MEASURES: Numerical pain rating scale, opioid equivalent usage. SELF-REPORT MEASURE: Numerical pain rating scale. FUNCTIONAL MEASURE: Opioid equivalent consumption. METHODS: Retrospective analysis. RESULTS: Statistically significant improvement in pain; overall, an improvement in opioid consumption. CONCLUSIONS: Sacral kyphoplasty appears to be a safe and efficacious procedure, comparable to sacroplasty, in the treatment of SIFs and sacral metastases. Ó 2012 Elsevier Inc. All rights reserved.
Keywords:
Sacroplasty; Sacral kyphoplasty; Kyphoplasty; Sacral insufficiency fracture; Osteoporosis
Introduction Sacral insufficiency fractures (SIFs) and sacral metastases are very painful, debilitating, often missed, and typically atraumatic sacral pathologies [1–6]. They are associated with significant morbidity, economic impact, and prolonged hospitalizations [2,3,7–9]. Computed tomography (CT), magnetic resonance imaging (MRI), and three-phase bone scans are used to make the diagnosis [3]. Conservative treatment consists of modified bed rest, limited physical therapy,
FDA device/drug status: This study uses KyhpExpress inflatable bone tamp and KyphX HV-R Bone Cement in an off-label manner. Author disclosures: RVS: Relationships Outside the One-Year Requirement: Stryker (C, paid in 2009 for consulting work completed in 2006). The disclosure key can be found on the Table of Contents and at www. TheSpineJournalOnline.com. * Corresponding author. Department of Anesthesiology, Guthrie Clinic-Big Flats, 31 Arnot Rd, Horseheads, NY 14845, USA. Tel.: (607) 795-5182; fax: (607) 795-5159. E-mail address: [email protected] (R.V. Shah) 1529-9430/$ - see front matter Ó 2012 Elsevier Inc. All rights reserved. doi:10.1016/j.spinee.2012.01.019
percutaneous interventions, and analgesics [10–12]. Comprehensive care, along with appropriate referrals for the origin of sacral pathology, for example, osteoporosis or malignancy, is warranted [10–13]. If early mobilization and optimal pain control are not achieved, patients are at risk for venous thromboembolic disease, urinary retention, reduced cardiac output, postural hypotension, pressure ulcers, depression, pneumonia, and catabolic energy states [10]. Even conservative treatment has attendant risks: delayed fracture healing (months), deconditioning, and adverse events secondary to analgesics [10–12]. Targeted options for sacral metastases include chemotherapy, radiotherapy, radiofrequency thermocoagulation, and excision, but these have associated morbidities. Chemotherapy causes systemic adverse events. Radiotherapy may damage collateral neurologic structures. Surgical excision and open stabilization have high mortality rates ranging from 19% to 48% [6,14]. Radiofrequency thermocoagulation palliates tumor-associated pain but not as rapidly as sacroplasty: a three- to four-point drop in the numerical pain score occurs over a 4- to 12-week period [5].
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Context Sacral insufficiency and pathological (ie, tumor) fractures can result in debilitating pain. Sacroplasty, and now sacral kyphoplasty, has been suggested as a treatment option. Contribution The author reports on a small series of patients undergoing sacral kyphoplasty who reported pain relief and less opioid use after the procedure. Implication This is a retrospective case series report. It is not a randomized control trial or comparative cohort study. Therefore, efficacy cannot be validly determined. Furthermore, the small number of patients precludes any real estimate of safety or generalizability. Readers are encouraged to read the ‘‘Caveat’’ section at the end of the paper. That said, common experience (such as that reflected by this case series) suggests that some well-selected patients might benefit from sacroplasty or kyphoplasty in experienced hands. —The Editors These concerns have prompted interest in a nascent therapy for painful SIFs and sacral metastases: sacroplasty [10–12]. Sacroplasty consists of percutaneously delivering cement into an SIF or sacral metastasis. Proposed mechanisms include neurolysis, thermal injury, and bone stabilization. Frey et al. [11,12] has demonstrated safety, early and durable pain relief, and functional restoration in patients with SIFs. In his group’s multicenter trial, there was a continuous improvement in visual analog scale: 7.7 preprocedure, 3.2 immediately postprocedure, and 0.7 one-year postprocedure. Sacroplasty has been used to treat sacral metastases [6,15–19]. These are case reports but not formal clinical studies [6,14–19]. Osteoplasty (pubic rami and ischial tuberosity) demonstrated pain relief, in patients with pelvic metastases [20]. With this precedent, sacroplasty has emerged as a promising treatment for this unfortunate patient population [11,12,21]. Sacral kyphoplasty is a modification of sacroplasty, involving the use of a distensible balloon to create a bone void before cement delivery; this has been formally reported in four patients and informally reported in one patient [22–25]. My study evaluates the technical feasibility, safety, and efficacy of sacral kyphoplasty.
Methods An institutional review board at my institution approved the study. All patients at the institution undergoing sacral
kyphoplasty were retrospectively identified. A tracking system and prospective data collection were in place for quality assurance when the procedure was initiated at the institution. This facilitated identifying patients, but this study cannot be considered prospective. The study protocol was developed after all kyphoplasty procedures were finished. All patients undergoing sacral kyphoplasty were diagnosed with painful SIFs or sacral metastases; these patients underwent the procedure between 2007 and 2010. Data were extracted from these records: age, sex, etiology, fall before fracture, onset of pain, laterality (bilateral or unilateral), number of hospitalizations for pain before surgery, associated vertebral fractures, surgical date, surgical procedure time, presence of a confounding (alternate) diagnosis for sacral pain, presence of a comorbidities, preoperative imaging, preoperative treatment, procedure description, total cement volume per side, complications, postoperative CT scanning, bone biopsy, duration of pain before surgery, preoperative pain rating at rest, preoperative pain rating with mechanical loading (pre-op pain), postoperative pain rating on postanesthesia care unit (PACU) discharge pain, postoperative pain rating at 24 to 48 hours after surgery (24–48 hours pain), pain rating at the patient’s last follow-up (last follow-up pain), period to last followup, factors confounding interpretation of outcomes, surgery disposition (skilled nursing facility, home), and functional status before and after discharge. Pain scores at 24 to 48 hours after surgery were gleaned from the nursing records. Sometimes the nurses did not write the pain score. For this reason, the 24- to 48-hour pain was the pain at 24-, 48-, or an average of 24- and 48-hour scores. Intraoperative planning All patients underwent the procedure at a community hospital serving a rural catchment area. All patients signed witness informed consent after notification about the off-label use of this procedure. General anesthesia and prophylactic intravenous antibiotics (cefazolin 1,000 mg or clindamycin 600 mg) were administered in the operating room. Each patient was placed in a prone position, with ocular, truncal, and limb pressure relief. Sterile preparation with chlorhexidine was performed. C-arm fluoroscopy was used to visualize the sacral foramina, using an anteroposterior (AP) view. Cephalocaudad positioning and landmark identification were used to optimize visualization of the foramina. For instance, the sacral foramina lay along an imaginary line connecting the lateral margin of the base of the superior articular process of sacrum (S1) and the sacral cornua. The S3 sacral foramina were typically located at a horizontal imaginary line connecting the inferior pole of the sacroiliac (SI) joints. In the setting of poor foraminal visibility, Smith and Dix [26] have suggested fluoroscopic landmarks to approximate the lateral margins of the dorsal sacral foramina: an imaginary line connecting the center of the S5 (sacral cornua) and geometric center of the L5–S1
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facet joint. Preoperative trajectories were planned using a PACS imaging system. The PACS software has a triangulation tool for CT and MRI scans. By dragging this triangulation tool along a simulated path (mimicking trocar/ cannula trajectories), one can simultaneously visualize the structures encountered in a sagittal, coronal, and axial planes. A PACS measurement tool was used to measure distances (sacral depth, distance from skin, and distance from foramina to SI joint) on CT/MRI. This virtual information was used in conjunction with surface anatomy and fluoroscopy: an indelible marker can be used on the skin to demarcate the location of the median crest (residual sacral spinous processes), sacral foramina, SI joints, and trocar entry points. Technique description The skin entry point was typically at the lateral margin of the sacral foramina (vertical perimeter, y-axis) and halfway in between the sacral foramina (horizontal perimeter, x-axis). The trocars were styletted Kyphon cannulas, usually KyphExpress cannulas (11 gauge, 3.8-mm diameter tip; Kyphon Inc., Medtronic Spine, LLC, Sunnyvale, CA, USA). A skin wheal with lidocaine with 1:100,000 epinephrine was raised. A stab incision was made. A diamondtipped stylet was used to penetrate the sacrum; this was subsequently exchanged for a beveled stylet to allow directional control. The trocars were initially advanced to the center of a line connecting the 9-o’clock positions of the left S1þS2 and left S2þS3 foramina, respectively; on the contralateral side, the trocars were advanced to the center of a line connecting the 3-o’clock positions of the right S1þS2 and S2þS3 foramina (Fig. 1), respectively. The trocars were advanced perpendicularly through the skin, lateral to the foramina, until bone was contacted. This avoided traversing the foramen and gauged skin posterior sacral cortex depth. This bone contact point is a bone bridge, horizontally interposed between the sacral foramina. This bone bridge is anatomically congruous to fused inferior and superior articular processes. (Fig. 1); annotated with sacral kyphoplasty target entry points lateral to the bone bridges between S1þS2 and S2þS3). The rationale for entering at this location was to divert medially extravasating cement into the bone bridge away from the foramen. This added a margin of safety. The orientation of the trocar was angled in a medial to lateral direction. The handle of the trocar was pushed toward the floor for a shallow (tangential) trajectory. The handle was pulled upward to the ceiling for a steeper (perpendicular) trajectory. An angle of 45 relative to the skin surface is the ideal trajectory [11,12]. Intermittent fluoroscopy was used to advance the trocar on AP and lateral views (Fig. 2A). A mallet was not necessary in most patients; hand pressure sufficed. The trocar was slowly advanced toward the SI joint (the lateral articulating surface of the sacrum). Serial AP views were used to ensure that the SI joint was
Fig. 1. Oblique view of sacrum; annotated with trocar entry points (circular discs) lateral to the bone bridges between S1þS2 and S2þS3; (copyright release and courtesy of Dr David B. Fankhauser, University of Cincinnati Clermont College, http://biology.clc.uc.edu/fankhauser/).
not violated. Serial lateral views were used to ensure that the anterior sacral cortex was not violated (Fig. 2A). Once situated, the stylet was removed. A KyphExpress 10/2 inflatable balloon tamp (10-mm length, max volume 4 mL, 300 psi maximal inflation pressure; Kyphon Inc., Medtronic Spine, LLC) was inserted. The outer cannula was then pulled back to expose the proximal and distal balloon markers. The balloon was then inflated to approximately 1 to 1.5 mL, with nonionic iodinated contrast. Balloon pressure never exceeded 250 psi. The balloon margins were carefully monitored to ensure confinement within the cortical margins (Fig. 2B). The balloons were deflated and removed. Polymethylmethacrylate bone cement (KyphX HV-R bone cement; Kyphon Inc., Medtronic Spine, LLC) was mixed. The radiopaque cement slowly thickened and solidified. When a toothpaste consistency was reached, cement was slowly delivered down the cannula into the sacral balloon void. Real-time fluoroscopy (AP and lateral views) was used to monitor cement spread and detect extravasation (Fig. 2C, D). Small aliquots of cement, on the order of 0.1 to 0.2 mL, were delivered. With adequate cement viscosity, this slow delivery was useful in preventing extravasation. Typically, 1 to 3 mL of cement was delivered on each side. If the cement reached the SI joint or the lateral margin of the sacral foramina, cement delivery was stopped (Figs. 2C and 3 Left). On a lateral projection, cement was allowed to advance to the ventral margin of the sacral corpus. The
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Fig. 2. Metastatic vulvar carcinoma and sacral kyphoplasty fluoroscopic images: (A) trocar; (B) balloon; (C) lateral view; (D) coronal view.
ventral surface of the sacrum is slightly concave. On an axial view, the anterior boundary of the sacral corpus is actually posterior to the anterior margin of the sacral ala and SI joint (Fig. 3 Right). Hence, cement anterior to the sacral corpus (on lateral fluoroscopy) does not represent extravasation or leakage (Figs. 2D, 3 Left, and 3 Right). Monofilament nylon stitches and pressure dressings were applied. Patients were extubated and transferred to the recovery room. Statistical analysis Mean differences in pain scores were calculated: (Pre-op pain)(PACU pain); (Pre-op pain)(24–48 hour pain);
(Pre-op pain)(last follow-up pain); (PACU pain)(24– 48 hour pain); and (PACU pain)(last follow-up pain). Specifically, the difference in pain scores evaluated at different points in time was analyzed using a repeatedmeasures analysis of variance and Tukey-Kramer multiple comparisons test. The Wilcoxon signed-rank test was used to compare opioid consumption preoperative and at last follow-up, with and without one patient. This latter patient required very high doses of opioids, as compared with the remaining patient population: 1,856 mg2,160þmg opioid equivalents. The significance level for all tests was set at a 5%. The remainder of the data is presented in a descriptive statistical format. SigmaPlot 11.0 Systat Software Corp.
Fig. 3. Metastatic vulvar carcinoma: (Left) postoperative computed tomography (CT) coronal view; (Right) postoperative CT axial view.
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statistical software (Systat Software, Inc., Chicago, IL, USA) was used for all data analysis and graphics.
Results
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was successfully treated with a caudal epidural steroid injection with a catheter steered to S1 nerve root. An S1 transforaminal epidural steroid injection was not attempted because of the impaired visualization of the foramen, secondary to the cement radiopacity.
Patients Eleven patients were identified; all were women. The average age was 81.4 years (69–87 years). Six patients had bilateral SIFs, and five had metastatic involvement. There were no significant differences (p value more than .05) in median age between SIF and metastatic carcinoma patients. The sacral ala were involved in all patients, and in one patient, the sacral corpus was involved. Average duration of pain before sacral kyphoplasty was 203.5 days (1– 875 days). Five patients had a mistaken diagnosis before evaluation for sacral kyphoplasty: lumbar compression fractures, lumbar spinal stenosis, coccygodynia, and myofascial pain. None of the patients were diagnosed with SI joint disease or pain. Treatment before sacral kyphoplasty consisted of bed rest (seven patients), analgesics (nine patients), musculoskeletal injections (one patient), and nothing specific (two patients). Average number of hospitalizations for sacral pain was 1.1 (0–4). Six of 11 patients fell before developing pain. Seven of 11 patients had additional fractures: thoracic compression fracture, pubic rami, and lumbar compression fractures. On physical examination, the neurologic examination was nonfocal, and pain was concordantly provoked in all patients. Presurgical imaging consisted of plain films (five patients), CT scan (nine patients), MRI (two patients), and bone scan (three patients). The functional status of the patients before sacral kyphoplasty was bedbound (five patients); wheelchair bound (one patient); and ambulatory (five patients). Surgery and perioperative period Sacral kyphoplasty was performed bilaterally on 11 patients. General, combined with local anesthesia, was used on all 11 patients. The modified (angular) short-axis approach [8,9] was used on nine patients. The long axis [24,26] was used on two patients. In one long-axis patient, the right side required repeat treatment with the modified short-axis approach. Adjunct procedures included thoracic and lumbar kyphoplasties (six patients) and biopsies (eight patients). Biopsy results were benign in six patients and malignant in two patients (metastatic neuroendocrine carcinoma and metastatic small-cell lung carcinoma). Average total cement volume per patient (not per side) was 4.76 mL (range, 2–7 mL). The average surgical time was 45.36 minutes (range, 27–65 minutes). Postoperative CT scans were obtained in eight of 11 patients. Mild cement extravasation occurred in three patients: SI joint, ilium, and S1 foramen. Complications related to the procedure occurred in only one patient, wherein cement extravasated into the S1 foramen. This resulted in S1 radiculitis and
Pain scores The average numerical pain rating score with mechanical loading, before surgery (pre-op pain), was 9.64 (range58–10, standard deviation (SD)50.67, and median510). The pain rating in the PACU (PACU Pain) was 2.55 (range50–5, SD52.70, and median53). The pain rating at 24 to 48 hours postoperative (24–48 hours pain) was 1.19 (range50–5, SD51.94, and median50). The average pain rating at the last follow-up (last follow-up pain) was 0.73 (range50–5, SD51.62, and median50). The average length of time to last follow-up was 302.34 days (range579–669 and SD5202.04). There was no statistically significant difference in average length of time to last follow-up, between patients with an SIF or metastasis. The mean differences in pre-op pain versus PACU pain (7.091, 95% confidence interval (CI): 5.61–8.57) was statistically significant, p value less than .001. Mean difference in pre-op pain versus 24–48 hour pain (8.45, 95% CI: 7.31– 9.57) was statistically significant, p value less than .001. Mean difference in pre-op pain versus last follow-up pain (8.91, 95% CI: 7.98–9.84) was statistically significant, p value less than .001. Mean difference in PACU pain versus 24- to 48-hour pain (1.35, 95% CI: 0.51 to 3.22) was not statistically significant, p value more than .05. Mean difference in PACU pain versus last follow-up pain was (1.82, 95% CI: 0.04–3.68) was not statistically significant, p value more than .05. The average pain scores (pre-op, PACU, 24–48 hours, and last follow-up) were comparable in patients with an SIF or metastasis. Opioid consumption Seven of 11 patients were taking opioid analgesics preoperatively (pre-op). Only four of the seven patients continued to use opioids, at the last follow-up (last follow-up). Three patients were able to discontinue all opioids. Three patients reduced total daily opioid usage. Only one patient required higher doses of opioids (from 1,856 mg to 2,160 mg) because of progression of her underlying metastatic disease. Hence, 63.6% required opioids preoperatively and 36.3% required opioids postoperatively. The average opioid consumption in morphine equivalents was 268.82 mg (SD5566.8) pre-op and 202.27 mg (SD5649.55) at last follow-up. If we exclude this one patient with severe progression of underlying metastatic disease, average opioid consumption (morphine equivalent) among the remaining 10 was 110.1 mg (SD5221.5) pre-op and 6.5 mg (SD518.86) at last follow-up. There was no significant difference in opioid consumption between pre-op and last
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follow-up, p5.0625. If we exclude the one patient consuming very large doses of opioids, the sample size is too small, and significance could not be reached. From a descriptive standpoint, mean opioid consumption doses among patients drop from pre-op to last follow-up. One caveat is that morphine equivalency calculators (Global Rph Calculator) [27] may not be accurate. However, use of the same calculator for each patient at specified time periods allows one to follow a change in opioid equivalency consumption [27]. Postoperative period Six patients were discharged home. Three patients were transferred to a skilled nursing facility. Two patients were transferred to an inpatient rehabilitation facility. The functional status after the procedure, on discharge from the hospital, was improved in most patients: bedbound (zero patients), wheelchair bound (three patients), ambulatory with rolling walker (four patients), and ambulatory (four patients). Two of the patients remained wheelchair bound because of frailty (metastatic cancer) and Parkinson disease. Immediate postoperative complications, as discussed above, occurred in one patient: S1 radiculitis. Five patients developed medical issues, unrelated to the kyphoplasty, during their extended follow-up: death because of metastatic carcinoma; femoral fracture; progressive dementia, aspiration pneumonia, and associated sepsis; severe pain because of metastatic carcinoma; and Parkinson disease. There were no surgical sites, deep tissues, or bone infections. Two patients required SI joint injections within 4 months of the procedure; the SI joint pain in these patients was distinct from the SIF pain; the SI joint pain was less severe and caused no functional impairment, as compared with SIF pain. This improvement in function parallels improvement in pain and reduction in opioid consumption.
Discussion Technique review Sacroplasty is performed with different imaging methods (fluoroscopy [11,12]; CT [28]; CT-fluoroscopy [29]), and approaches (short axis, modified (angular) short axis, or long axis [11,12,24,26,28,30]). Proponents of CT guidance raise concerns about adequately visualizing foramina in an osteoporotic sacrum, breaching the anterior cortex, and monitoring cement leakage [28,31,32]. Cement leakage, however, can even occur with CT guidance [24,32,33]. A modified (angular) short-axis approach [11,12] has been safely used for the largest sacroplasty series. I used the long axis for two patients and then switched to the modified short axis. I found the long axis to be cumbersome, whereas the modified short axis was simpler to adopt. The modified short axis allows greater directional control and targeted cement placement.
Fluoroscopy alone may be safely used for sacroplasty based on cadaveric dissection, fluoroscopic landmarks, and clinical outcome studies [11,12,34,35]. Technical vigilance, image quality, multiplanar views, and cannula placement in Denis Zone 1 are emphasized [11,12,24,26,36]. Denis Zone 3 lesions have been rarely accessed: hemangioma [22], tumor [6], and fracture [37]. Fluoroscopy has several additional advantages over CT guidance: reduced cost, reduced radiation exposure, real-time imaging, and accessibility in the hospital/clinic. Balloon kyphoplasty creates a cavitary void in trabecular bone. Cavity creation, along with use of landmarks, may help avoid an anterior cortical breach and facilitate cement containment [35,37]. The feasibility and safety, of sacral kyphoplasty, have been demonstrated in cadavers and in case reports: SIFs, hemangioma, pelvic fracture [22,23,25,35,37,38]. This author noted several advantages with kyphoplasty, despite cost and additional fluoroscopy time. The balloon is a three-dimensional, radiopaque, and roughly spherical structure with a measurable volume and diameter. This helps gauge depth, width, and volume under fluoroscopy. The outer boundaries of the inflated balloon delimit the size of the bone void. This is necessary to predict cement spread and volume. With slow insufflation, one can visualize the balloon perimeter expanding toward the cortex. This may help predict and prevent a Denis Zone 2 [36], anterior cortex, or SI joint breach. Attention to several factors will help enhance safety, with fluoroscopically guided sacral kyphoplasty: preprocedural CT or MRI; instrument trajectory planning with PACS software tools; modified (angular) short-axis technique; cannula placement lateral to the bone bridges (fused articular pillars); cannula placement in Zone 1, with a sufficiently steep angle to avoid the foramina and anterior cortex; real-time fluoroscopic monitoring of cement delivery, in multiple planes; adequate cement viscosity; use of low cement volumes; early recognition of cement extravasation; postoperative CT scanning in the event of extravasation; and practitioner experience. Data review Recent articles indicate that patients with chronic vertebral compression fractures or acute metastases may have similar levels of pain; both groups, however, may benefit from vertebral augmentation [39–42]. Sacral kyphoplasty addresses a similar need. My sacral kyphoplasty outcomes are comparable to the sacroplasty results presented in two multicenter prospective trials [11,12]. My patients demonstrated early and rapid pain reduction. The pain relief was sustained for almost 1 year (mean5302 days, range: 79–669 days). Patients demonstrated functional improvement. Most patients advanced to an ambulatory status with or without a walking aid (rolling walker).
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Opioid consumption was reduced in almost all patients. One exception was a patient with progressive metastatic carcinoma; this patient skewed the opioid consumption results for the entire series. Frey et al. demonstrated drop in opioid utilization from 71.2% to 21.2%, at 52 weeks [11]. My series demonstrates a similar reduction in opioid consumption from 63.6% of patients to 36.3% of patients. Four patients continued to use opioids: two had metastatic carcinoma; one suffered a femoral fracture; and one had a prior history of chronic low back pain treated with opioids. This patient’s opioid consumption was reduced but not eliminated. Persistency of low back and pelvic pain after vertebroplasty exists. Georgy [43] noted a 23.6% rate of persistent residual pain in patients undergoing vertebral or sacral augmentation. Sacral kyphoplasty may have to be complemented with ongoing multimodal spinal pain care and analgesic usage in some patients [44]. A recent literature review, assessing 108 patients from 15 studies, demonstrated a significant VAS reduction from 8.9 to 2.6 [30]. My series results are comparable to those in this pooled data set and multicenter prospective trials [11,12,21].
Caveats Irrespective of the robust improvements in pain in this series, there are several caveats that readers must acknowledge. Publication in a peer-reviewed journal has the potential to rapidly influence physician, patient, and commercial enterprise behavior, irrespective of the quality of evidence. Retrospective studies are arguably easier to conduct than randomized controlled trials. A retrospective study with positive results can influence practitioner judgment. There may be a time gap between the publication of positive results in a retrospective study and the publication of a confirmatory or refutatory randomized controlled trial. This time gap can be exploited, and interventional procedures can be carried out on numerous patients, before a randomized clinical trial demonstrates lack of effect [45,46]. Dr Eugene Carragee [47] raised concerns about this with respect to vertebroplasty: What seems most impressive in this whole affair has been the relentless shrinking of the apparent vertebroplasty effect size and duration. With each increase in the quality of evidence, the apparent quantity of effect has diminished and diminished until we are searching for any traces of it at all. Like King Lear’s retinue dwindling with each successive scene, we have to wonder, ‘‘now comes it truly as scant a size as this?’’ We have gone from 1998, when 90% of a large cohort had immediate and complete relief of symptoms, perhaps lasting a year or longer—completely attributed to the procedure—to arguing whether even the modest improvement now reported is a totally nonspecific effect, at even 6 weeks after
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treatment. From our editorial prospective, we worry about the decade or so lost, without systematically evaluating this intervention. If there is that subset of patients, miserable with persistent fracture pain, who will have great relief from vertebroplasty, we have not begun to identify them. Just as troubling, there are clearly some patients for whom the procedure is nearly all risk and no benefit—and who are they? So, what is the answer to the mysterious case of the disappearing effect size?’’ At a minimum, I hope practitioners understand that SIFs and metastases are very debilitating pathological syndromes in an often-neglected patient population. Sacral insufficiency fractures and metastases, if left alone, will most likely reach specified end points within a 3- to 6-month period: pain relief and death, respectively. The question is whether sacral kyphoplasty will improve pain relief and function, within this period of time. I have provided a detailed description of this technique. If a physician considers using this technique on their patients, outcome data should be systematically collected and quality assurance should be monitored. Another factor worthy of consideration is to perform this procedure after review by an institutional review board or credentialing committee to monitor the efficacy and safety of this procedure.
Conclusion Sacral kyphoplasty appears to be a safe, useful, and efficacious procedure. Consideration should be given to several technical factors (use of PACS software for targeting, trocar placement between the foramina-bone bridge, radiopaque balloon to create and delimit shape of void) to optimize procedural safety.
Acknowledgment The author thanks Robert Bienkowski, PhD, Erik Dickson, RT, and Mary Hatch, NP.
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