Management of Symptomatic Osteoporotic Vertebral Compression

Chapter 220 Management of Symptomatic Osteoporotic Vertebral Compression



Vertebroplasty



Krzysztof Siemionow, Robert F. McLain


Osteoporosis is a bone mineralization disorder characterized by decreased bone density, disruption of trabecular architecture, and increased susceptibility to fractures. There are approximately 700,000 vertebral body compression fractures in the United States each year, resulting in about 70,000 hospitalizations. Osteolytic lesions of the spine also are a growing problem, affecting as many as 70% of patients with metastatic disease or multiple myeloma. Tumor-induced osteolysis may lead to pain, dysfunction, and ultimately vertebral collapse. If left untreated, vertebral body compression fractures can lead to progressive kyphosis, spinal cord compromise, and intractable pain.



Vertebral Augmentation


Kyphoplasty and vertebroplasty currently are used to treat neurologically intact patients suffering from vertebral compression fractures resulting from osteoporosis and certain neoplasms. Percutaneous vertebroplasty (PV) is an imaging-guided procedure that reinforces a compromised vertebra with polymethylmethacrylate (PMMA), alleviating pain and improving the patient’s mobility. Initially described in 1987 as a treatment for painful hemangiomas,1 the procedure now is used most widely to treat fractures and destructive lesions that cause vertebral collapse and pain. The goal of vertebral augmentation procedures is to reduce fracture pain by stabilizing the vertebral fracture, allowing patients to return to their daily living activities and exercise.


The primary indications for PV are persistently painful compression fractures, most commonly related to osteoporosis, that are unresponsive to correct medical treatment, and benign or malignant osteolytic neoplasms (e.g., hemangioma, metastasis, and myeloma). In the setting of osteoporotic fracture, PV is done primarily for pain management and secondarily to prevent further collapse.2 For neoplasm, the indications are somewhat broader, and the procedure may be done for pain management and/or stabilization. PV is not an ablative procedure, but reinforcement may reduce pain while facilitating other therapies such as radiation therapy or surgical resection and fixation and minimizing the risk of further collapse or fracture.


The specific indications for PV are as follows:



• Osteoporotic compression fractures causing pain refractory to nonsurgical therapy and interfering with normal activities of daily living


• Osteonecrosis


• Multiple compression deformities resulting in, or threatening to result in, respiratory or gastrointestinal compromise or loss of balance, increasing fall risk


• Unstable compression fractures showing movement or progressive collapse


• Osteolysis due to malignant or benign neoplasms with fracture or impending risk of fracture


The indications have been expanded to include nonunions of chronic traumatic fractures, which typically show a pseudarthrosis with a fluid-filled cleft or cystic findings on MRI evaluation.


As with any spine operation, precise patient selection is essential to the therapeutic success of PV. Patients with prior unsuccessful spinal surgery generally do not respond as well to PV.


The absolute contraindications to PV for either osteoporotic or neoplastic conditions are as follows:



• Infection (osteomyelitis and discitis)


• Uncorrectable coagulopathy


• Allergy to any component required for the procedure.


Relative contraindications include the following:



• An asymptomatic and stable fracture


• A patient showing symptomatic improvement with time


• Prophylactic vertebral augmentation in the absence of any acute compression fracture


Other, less common, relative contraindications are (1) retropulsion of fracture fragment(s) causing substantial spinal canal compromise (e.g., a burst-type fracture); (2) neoplasm extending into the epidural space with substantial spinal canal compromise; (3) severe vertebral collapse such that it would be technically challenging to place a needle; (4) chronic stable fracture without pain; and (5) treatment of more than three levels at any one time. Acute traumatic fracture of a nonosteoporotic vertebra also is considered a contraindication.



Patient Selection


Preoperative evaluation entails imaging to demonstrate the level of fracture (by plain radiography), to confirm an “active” fracture by MRI (demonstrating bone marrow edema) or nuclear medicine scintigram (“bone scan”), and excluding unsuspected malignancy or degenerative disease (e.g., herniated discs). This usually entails obtaining recent MRI examinations, within 7 to 10 days of consultation.


Plain radiography is useful for showing the vertebral level involved and to determine the degree of collapse. With complete or near complete vertebral collapse, PV usually is unlikely to be successful.


A specific protocol is employed with sagittal T1-weighted conventional spin echo (CSE), sagittal T2-weighted fast spin echo (FSE), or turbo spin echo (TSE) with fat saturation and axial T2-weighted FSE through areas of abnormality. If fat suppression is not available for the T2-weighted images, then a short tau inversion recovery (STIR) sequence should be substituted. The fluid-sensitive sequences (T2 with fat suppression or STIR images) are necessary to identify an “active” compression fracture. While the causes of bone marrow edema are legion, in the context of compression fractures and appropriate clinical symptoms, it often indicates a persistent pain generator. The age of the compression fracture is less important than the presence of bone marrow edema on MRI. This becomes relevant for people who have had symptoms for months or years due to unhealed fractures.


Concordant pain evaluation also is a critical aspect for determining whether patients with benign compression fractures will respond to PV. Under fluoroscopy, the back may be percussed and palpated over the spinous processes, marking the areas of tenderness relative to the recognized compression fracture. The patient also may assume any position that triggers the pain while the physician marks the painful site. If the pain corresponds to the fracture level (usually within one level above or below), then the symptoms are likely to be amenable to PV at that vertebral level. If pain is not concordant (for instance, lumbosacral pain associated with a thoracolumbar fracture), PV is much less likely to help.


If the patient is a candidate for PV, a further workup is required. Patients taking warfarin must have it discontinued prior to the procedure and potentially be switched to heparin for the periprocedural period. Patients with a fever, leukocytosis, or an elevated erythrocyte sedimentation rate must wait until the cause is diagnosed and treated (presumably an infection). For patients taking steroids, it is necessary to work closely with the primary care provider to manage the dose during the periprocedural period.


The informed consent process usually is a comprehensive discussion of the risks, benefits, and alternatives to PV. Risks include bleeding, infection, allergic reaction to the PMMA, fracture (pedicle or rib), and PMMA extravasation. Pneumothorax also is a potential risk for thoracic levels. Informed consent should also explain the goal of treatment (e.g., pain management, prevention of further deformity, stabilization for radiation therapy), theoretical background (e.g., stabilization by internal “casting”), technical aspects (e.g., needle procedure versus open surgery), and clinical data regarding PV. This often includes answering questions regarding the nature of osteoporosis and the status of PV as “standard of care” versus an “experimental procedure,” including the off-label use of the cement (PMMA) and the modification of PMMA by additional sterile barium to increase opacification (thus allowing early detection of extravasation). The possible need for emergent spinal decompression should be addressed with the patient.


Anesthesia for PV may be accomplished with neuroleptic anesthesia (i.e., conscious sedation), with the advantage that the patient is able to report any symptoms of a complication immediately, allowing the operator to halt the injection and minimize further injury. It also facilitates PV as a same-day outpatient procedure with a quicker recovery period. For these reasons, intravenous CS (IVCS) is considered the preferred mode of sedation for PV. Intravenous antibiotic coverage is recommended using cefazolin, or vancomycin if the patient has penicillin allergy, as infection prophylaxis.



Technical Performance of Vertebroplasty


The traditional mode for PV has been to perform bilateral injections via a transpedicular or dorsolateral (parapedicular) approach using a two-needle technique (Figs. 220-1 to 220-5). Unipedicular injections also can provide substantial vertebral reinforcement when enough cement is injected to cross the midline of the vertebral body and provide a similar distribution to bipedicular injections.3


image

FIGURE 220-1 Parasagittal approach. Anteroposterior projection fluoroscopic images show the typical position for the parasagittal transpedicular puncture. A, Note that the initial puncture site is with the needle tip located in the superolateral corner of the ring shadow of the pedicle (arrowhead). B, The needle has been advanced to the ventral one third of the vertebral body, and the tip is somewhat centrally located but still ipsilateral. Note the intradiscal cement from injection of the level above (arrow).


image

FIGURE 220-2 “Scotty dog” approach. Oblique projection fluoroscopic image shows the typical position for transpedicular puncture when using the “Scotty dog” approach. Note that the target is the ring shadow of the pedicle in an approximately 45-degree obliquity (arrowhead points to the pedicle below the punctured level for reference). This trajectory places the needle tip centrally and facilitates filling of both sides from a unilateral injection.


image

FIGURE 220-3 Needle-tip position. Sagittal projection fluoroscopic image shows appropriate needle-tip position within the ventral one quarter to one third of the vertebral body. Note the small amount of cement injected that has begun to fill the fracture line (arrow).


image

FIGURE 220-4 Cement extravasation. Sagittal projection fluoroscopic image shows a small amount of cement that has extravasated ventrally (arrow) outside of the vertebral body into the retroperitoneum. Extravasation in this location usually is not clinically significant.


image

FIGURE 220-5 Cement distribution. The axial CT image shows hyperattenuating cement in the ventral and mid-portions of the vertebral body. Note that the dorsal vertebral margin is concave (arrowhead). This forms the dorsal vertebral line on lateral radiography or fluoroscopy and also is the location where the basivertebral venous plexus perforates the cortex (not shown). Therefore, cement should not be injected in an attempt to fill the entire dorsal aspect of the vertebral body under fluoroscopy.


The modalities used for imaging are either fluoroscopy or CT. PV can be accomplished with either single-plane or biplane fluoroscopy. Biplane fluoroscopy is considered ideal because one can view orthogonal projections without changing tube position, greatly reducing procedure time. CT requires repositioning the gantry between needle manipulations, imaging, and injection, consuming useful injection. CT fluoroscopy allows the user to generate real-time CT sections while performing procedures, but concerns with CT fluoroscopy revolve around the increased radiation dose delivered to personnel and the operator in the room during the procedure. For most purposes, C-arm fluoroscopy provides adequate imaging, is readily available, and is less time-consuming.


The needles used are standard bone marrow biopsy-type needles that have a Luer-lock connection. Either beveled or pointed tips can be used effectively, and which to use is based largely on operator preference and experience. The goal is to fill the focus of the fracture, which typically is ventral and rostral, and to avoid injection into the larger vascular sinusoids of the basivertebral plexus, which could allow extravasation into the epidural space. Initial cortical puncture and purchase should be obtained by hand, and then needle advancement may be by hand or with the assistance of a mallet. For lumbar levels, 10- to 11-gauge needles are used, but for the thoracic levels, some authors advocate using 13- to 14-gauge needles. The needle tips should be advanced to the ventral one fourth to one third of the vertebral body, approaching the midline.


The cement flow must be monitored carefully, and the injection should cease if there is resistance or if cement approaches the dorsal vertebral margin. If any extraosseous cement is identified, the injection should be terminated immediately. Up to three levels can be done in a single operation. The risk of doing more numerous levels simultaneously is the possibility that PMMA could cause fat emboli syndrome and respiratory compromise through marrow displacement.


Postprocedure, the patient remains flat in bed for at least 1 hour, followed by bedrest for an additional 1 to 3 hours with the head of bed elevated less than 45 degrees. If any new, severe pain or new neurologic symptoms develop, a CT scan should be done immediately to evaluate the distribution of cement.



Cement Handling


There are many issues related to the cement used in PV. The bone cement currently used for PV most commonly is PMMA. The U.S. Food and Drug Administration (FDA) treats bone cement as a device, but there currently is no PMMA specifically approved for PV. Considerations for choice of any PV agent include safety, ability to increase vertebral strength and stiffness, visibility under fluoroscopy, ease of delivery, and simplicity of use.


The two most popular preparations used for PV are Cranioplastic Type I Slow Set (Codman, Johnson & Johnson) and Simplex P (Stryker-Howmedica-Osteonics). Simplex P is approved by the FDA as a structural device for use in pathologic fractures in bones throughout the body, but the approval does not specify PV per se. Simplex P was the original PMMA used for the first PV by Deramond in 1984 and has remained popular for this application in Europe and the United States. In a comparison of three types of PMMA in cadavers (Cranioplastic, Osteobond, and Simplex P), vertebrae were significantly stronger after cement injection, regardless of cement type. However, Simplex P restored stiffness to initial values, whereas vertebrae injected with Cranioplastic were significantly less stiff than in their initial state.4


These preparations (mixed according to the package insert) produce cement that is difficult to inject and poorly visualized by fluoroscopy (although quite suitable for radiography). Thus the addition of an opaque agent (sterile barium, tantalum, or tungsten) is required. Sterile barium preparations are available from Parallax (Mountain View, CA) or Bryan Corporation (Woburn, MA). It has been determined that PMMA mixtures containing approximately 25% to 30% by weight of barium sulfate will provide opacification sufficient for the performance of fluoroscopically guided PV.4,5


Another challenge has been to obtain suitable working times for injection. This goal is accomplished by prolonging the polymerization phase. Some operators add the liquid monomer to a modified powder (PMMA with barium) until it reaches a certain consistency. However, alterations in the monomer-to-polymer ratio change setting time and leave the biomechanical properties uncertain. Another method of altering the polymerization time is to manipulate the temperature of the materials or room, to control the work time of the cement. Refrigerating all the cement components (monomer, polymer, and barium) prior to use can greatly extend the working window. In addition, the reservoir holding the PMMA mixture may be chilled with a sterile saline pack or sterile cold-water bath. Cement should be mixed only after all needle placements have been completed.


Despite the desire to maximize the working time for the injection, however, cement should not be injected in a completely liquid state (prior to beginning polymerization), because this increases the risk of leak into communicating vascular elements.


Options for actual cement delivery have been to use multiple high-pressure, small-volume (1–3 mL) syringes, or to utilize a reservoir-type injector that is connected via a Luer-lock mechanism to the delivery needle. If a reservoir system is used, cement is loaded into the delivery system only after all needles have been placed, and keeping the cement that is not being injected chilled prolongs its useful work time.


Injection is done into one needle at a time. Suitable filling from the first needle may obviate the need to inject through the second needle.


With respect to how much cement mixture to inject, an in vitro study demonstrated that initial vertebral body strength is restored with as little as 2 mL of cement, but significantly greater stiffness requires 4 to 8 mL, depending on vertebral level and type of cement.6 These data provide guidance on the cement volumes needed to restore biomechanical integrity and parallel the clinical experience that many patients do well without having the cement fill an entire vertebral body. Hence, the trend has been to use less cement, minimizing the risk of complications from extravasation.


New biomaterials such as nanoparticles and Orthocomp (a glass-ceramic-reinforced BisGMA/BisEMA/TEGDMA matrix composite) are being actively pursued, and it is likely that specific formulations will be available for PV in the near future.7



Treating Tumors


Vertebroplasty may play an important role in palliation for the patient with vertebral metastases and in improving independence and function during more definitive systemic therapy. Tumors that are particularly radiosensitive are most appropriate to PV, because local control can be obtained as easily after stabilization as before. Tumors that require resection with a surgical margin, such as primary malignancies or locally aggressive benign tumors, are not appropriate for PV. Although there is some theoretical margin of tumor-kill associated with the thermal effect of the PMMA mass,8 the application of PV in the setting of neoplasm is not intended as an ablative procedure, and the goal is to provide structural support primarily, with the secondary goal of pain relief. The amount of PMMA used may be greater in an osteolytic spinal lesion than in a compression fracture, because the trend to minimize injectant volume in osteoporosis (i.e., filling the fracture line) does not apply in an erosive or destructive lesion.


Metastases are the lesions most commonly treated by PV, but large, symptomatic hemangiomas also may require ablation and stabilization with PMMA injection. Hemangiomas have a benign histology, but may grow aggressively and cause pain through either tissue distortion or pathologic fracture. PV stabilizes the vertebral body and obliterates the vascular sinusoids that make up the mass of the hemangioma. Subsequent surgery may then be focused on decompression, if needed.9 In this fashion, PV is another adjuvant treatment akin to intralesional sclerosis or embolotherapy preoperatively. PV also is effective in treating vertebral metastases that result in pain or instability, providing immediate and long-term pain relief.10 MRI is crucial for preoperative planning to evaluate the soft tissue extent of the tumor (e.g., spinal canal involvement, neuroforaminal encroachment, and status of the posterior longitudinal ligament).


The goal in PMMA application during tumor treatment is to obtain craniocaudal filling (attempting to get superior-to-inferior end-plate filling) that crosses the midline transversely, providing a vertical strut. The cement may fill part of the tumor, but this is not the goal. Metastatic lesions and plasma cell tumors are not cystic structures—any space filled with cement likely represents tumor tissue that has been displaced somewhere. There is a small risk that the neoplastic tissue may be displaced into the canal or neural foramen, causing root or cord compression. Adjuvant therapy (surgery, chemotherapy, or radiation therapy) will be required to control the tumor locally. For cases involving malignant neoplasm, there often is concern regarding vascular seeding of the displaced tumor as the PMMA infiltrates the tumor bed, displacing tumor into the vascular system. Although there is no literature to support or refute this concern, it is believed to be a nontrivial risk.



Complications


Fortunately, major complications are uncommon. The most common complication is radicular pain caused by migration of cement into the epidural venous plexus. In most patients, intradiscal and paravertebral leaks of cement have no clinical importance.11 However, there have been case reports of severe neurologic complications, underscoring the need for appropriate safeguards as outlined previously.12 Permanent paralysis has been reported, but is exceptionally uncommon if the procedure is performed in a controlled, image-guided fashion (by using a biplane real-time fluoroscopy suite). Rib, pedicle, or transverse process fractures also have been noted. One case has been reported of a pulmonary embolism caused by acrylic cement. This rare complication was believed to have occurred because perivertebral venous migration was not recognized.13 The anticipated complication rate is higher when treating neoplasms (10%) than for osteoporotic compression fractures (1% to 3%).



Outcomes


Taylor et al. performed a systematic review and meta-regression to compare the efficacy and safety of balloon kyphoplasty and vertebroplasty for the treatment of vertebral compression fractures, and to examine the prognostic factors that predict outcome. They found level III evidence to support balloon kyphoplasty and vertebroplasty as effective therapies in the management of patients with symptomatic osteoporotic vertebral compression fractures refractory to conventional medical therapy. Although there was a good ratio of benefit to harm for both procedures, balloon kyphoplasty appeared to offer the better adverse event profile.14


In a follow-up study, the same authors concluded that in direct comparison to conventional medical management, patients undergoing kyphoplasty experienced superior improvements in pain, functionality, vertebral height, and kyphotic angle, at least up to 3 years postprocedure. Reductions in pain with kyphoplasty appeared to be greatest in patients with newer fractures. The authors concluded that there are prospective studies of low bias, with follow-up of 12 months or more, that demonstrate balloon kyphoplasty to be more effective than medical management of osteoporotic vertebral compression fractures and at least as effective as vertebroplasty.15


Kallmes et al. randomly assigned 131 patients who had one to three painful osteoporotic vertebral compression fractures to undergo either vertebroplasty or a simulated procedure without cement injection (served as control group).16 The primary outcomes were scores on the modified Roland-Morris Disability Questionnaire (RDQ) and patients’ ratings of average pain intensity during the preceding 24 hours at 1 month. Patients were allowed to cross over to the other study group after 1 month. Interestingly, both groups had immediate improvement in disability and pain scores after the intervention. At 1 month, there was no significant difference between the vertebroplasty group and the control group in either the RDQ score or the pain rating. The authors found a trend toward a higher rate of clinically meaningful improvement in pain (a 30% decrease from baseline) in the vertebroplasty group at 1 month. At 3 months, there was a higher crossover rate in the control group than in the vertebroplasty group. There was one serious adverse event in each group. The authors concluded that improvements in pain and pain-related disability associated with osteoporotic compression fractures in patients treated with vertebroplasty were similar to the improvements in a control group.


In a prospective study of 30 consecutive patients, Muijs et al. analyzed clinical and radiologic outcome 36 months after percutaneous vertebroplasty for osteoporotic vertebral compression fractures unresponsive to conservative treatment for at least 8 weeks. The authors also examined the quality of life (QOL). The authors reported good pain relief and significant increase in QOL scores, despite finding asymptomatic leakage of cement in 47 of 58 (81%) of treated vertebrae. The authors concluded that percutaneous vertebroplasty in the treatment of chronic vertebral compression fractures results in an immediate, significant, and lasting reduction in back pain, as well as overall improvement in physical and mental health.17


A meta-analysis to study the amount of pain reduction using the visual analog scale (VAS) with kyphoplasty and vertebroplasty in the treatment of osteoporotic vertebral compression fractures revealed that both procedures reduce pain in symptomatic osteoporotic vertebral compression fractures that have failed conservative treatment.18


Pain relief and risk of complications associated with vertebroplasty versus kyphoplasty were evaluated by Eck et al.19 The authors identified a total of 1036 abstracts for potential inclusion. Of these, 168 studies met the inclusion criteria. Mean preoperative and postoperative VAS scores for vertebroplasty were 8.36 and 2.68, respectively, with a mean change of 5.68 (P < .001). The mean preoperative and postoperative VAS scores for kyphoplasty were 8.06 and 3.46, respectively, with a mean change of 4.60 (P < .001). Statistically greater improvement was found with vertebroplasty versus kyphoplasty (P < .001). The risk of new fracture was 17.9% with vertebroplasty versus 14.1% with kyphoplasty (P < .01). The risk of cement leak was 19.7% with vertebroplasty versus 7.0% with kyphoplasty (P < .001). The authors concluded that vertebroplasty had a significantly greater improvement in pain scores but also had statistically greater risk of cement leakage and new fracture.



Outcomes in Patients with Vertebral Compression Fractures


Buchbinder et al. performed a multicenter, randomized, double-blind, placebo-controlled trial. Participants had one or two painful osteoporotic vertebral fractures that were of less than 12 months’ duration and unhealed. Participants were randomly assigned to undergo either vertebroplasty or a sham procedure.20 The primary outcome was overall pain at 3 months. These authors found no beneficial effect of vertebroplasty as compared with a sham procedure in patients with painful osteoporotic vertebral fractures, at 1 week or at 1, 3, or 6 months after treatment.


Masala et al. reviewed 624 patients with 1253 compression fractures that were treated by percutaneous vertebroplasty and found a statistically significant improvement in the patients’ quality of life by 12 months.21 In a separate retrospective study, Masala et al. evaluated the effectiveness, costs, and cost-effectiveness of percutaneous vertebroplasty.22 After 2 weeks of analgesic therapy, 153 patients presented with refractory pain and were offered treatment by percutaneous vertebroplasty. A total of 58 patients accepted and underwent percutaneous vertebroplasty, while 95 refused and underwent conservative medical therapy. Significant reduction in VAS and improvement in ambulation and activities of daily living were observed in both groups at 1 week, 3 months, and 12 months. These results were significantly superior in the percutaneous vertebroplasty group at 1 week and 3 months. Percutaneous vertebroplasty was significantly more cost-effective than medical therapy with regard to VAS and activities of daily living at 1 week. By 3 months, percutaneous vertebroplasty was more cost-effective than medical therapy with regard to ambulation. No significant difference in cost-effectiveness was found between the two groups at 12 months. The authors concluded that percutaneous vertebroplasty should be considered the treatment of first choice in symptomatic acute osteoporotic vertebral fractures with refractory pain after a short period of analgesic therapy.

Only gold members can continue reading. Log In or Register to continue

Related posts:

Fundamentals of Spine Surgery Default ThumbnailCervical Spondylosis with Minimal Myelopathy: To Decompress or Not to Decompress An Approach for Treatment of Complex Adult Spinal Deformity Anesthesia Dorsal Dynamic Spine Stabilization Vertebroplasty and Kyphoplasty

Stay updated, free articles. Join our Telegram channel
Tags:
Aug 31, 2016 | Posted by in NEUROLOGY | Comments Off on Management of Symptomatic Osteoporotic Vertebral Compression

Full access? Get Clinical Tree
Get Clinical Tree app for offline access