Fig. 6.1 Basic approaches: (a) transpedicular, (b) parapedicular, and (c) extrapedicular. Dashed line indicates the longitudinal axis of the pedicle.
Summary
Percutaneous vertebral augmentation procedures and vertebral body biopsy may be performed using a variety of unilateral or bilateral image guided approaches. The choice of approach will depend on many factors, including fracture level and vertebral morphology, as well as operator experience and preference. Herein, we describe the approaches along with the indications, risks and benefits offered by each. As with any image-guided procedure, preoperative positioning of the patient and the fluoroscope is paramount and a detailed understanding of relevant anatomy is essential.
Keywords: vertebral augmentation, percutaneous, minimally invasive, transpedicular, extrapedicular, parapedicular, anterolateral, transoral, vertebral body biopsy
The first vertebroplasty was performed in 1984 and then introduced in the literature by Galibert et al in 1987.1 Polymethyl methacrylate (PMMA) cement was injected percutaneously via a transoral approach into a C2 vertebra that had been partially disrupted by an aggressive vertebral hemangioma. This injection of cement was effective in decreasing the patient’s pain and discomfort for an extended period of time. In spite of the fact that the first vertebroplasty was accomplished via a transoral approach, this is currently one of the least commonly utilized approaches to the vertebral bodies that exist.
A posterolateral extrapedicular approach was subsequently used in the thoracic spine, but after cement leakage along the track of the needle induced a case of intercostal radiculopathy, the transpedicular needle approach was developed. With the transpedicular approach, the needle passed through the pedicle into the vertebral body and was thought to result in a lower risk of cement discharging posteriorly along the needle track.2
Since the introduction of vertebral augmentation procedures, many approaches have been explored to provide the safest and most effective treatment of pain and deformity resulting from many types of vertebral body compression fractures. In addition to the anterolateral procedure first described, approaches now include transpedicular, extrapedicular, parapedicular (▶Fig. 6.1), and modified extrapedicular and parapedicular approaches. In the cervical spine, the anterolateral approach has been employed (▶Fig. 6.2). The transpedicular approach directs the needle through the longitudinal axis of the pedicle into the vertebral body. The parapedicular path enters the vertebral body at the vertebral body/pedicle junction near the mid to superior point and traverses into the vertebral body without breaching the medial pedicle wall. Finally, the extrapedicular approach enters the vertebral body directly either just lateral to the transverse process at the level of the pedicle progressing horizontally into the vertebral body or accessing the vertebral body just anterior to the pedicle and just above the inferior end plate entering the vertebral body at a 45-degree angle. Both of these extrapedicular approaches are performed without passing through the pedicle. The choice of approach will depend on many factors, including fracture level and vertebral morphology, as well as operator experience and preference.
The most common indication for percutaneous vertebral augmentation is stabilization of a painful osteoporotic vertebral body compression fracture. Other common indications include fracture nonunion, pain from a primary tumor, osteolysis following malignant infiltration of a vertebra, pain from vertebral body involvement of an aggressive hemangioma, and a painful fracture resulting from osteonecrosis.3–9
Each vertebra consists of a body and a vertebral arch with articular, transverse, and spinous processes. The vertebral body consists primarily of cancellous bone and marrow encased by cortical bone at the margins, including the superior and inferior end plates. The vertebral arch consists of right and left pedicles (which connect it to the body) and right and left laminae (▶Fig. 6.3). The transverse processes project laterally at the junction of the pedicles and laminae, and the dorsal or posterior spinous process projects from the midline junction of the laminae. Postganglionic nerve roots exit bilaterally beneath the pedicle via foramina. Thoracic intercostal arteries and four pairs of lumbar arteries are located adjacent to the vertebrae.
Fig. 6.2 Anteroposterior (a) and lateral (b) fluoroscopic views of the cervical spine shows an 11-gauge needle entering the anterolateral C6 vertebral body from the patient’s right side (black arrows in a and b). Lateral fluoroscopic views of the cervical spine shows the needle in place in the anterior C6 vertebral body with the drill placed through the needle (white arrow in c) to create a channel for the inflatable bone tamp (white arrow in d). Anteroposterior (e) and lateral (f) fluoroscopic views shown after injection of polymethyl methacrylate (PMMA) into the C6 vertebral body shows the radiopaque cement present within the vertebral body (white arrows in e and f). The vertebral augmentation kyphoplasty at C6 was performed due to a painful aggressive hemangioma. (These images are provided courtesy of Dr. Douglas P. Beall.)
The levels most commonly affected by vertebral compression fractures (VCFs) are at the mid-thoracic spine and thoracolumbar junction.10 Bony landmarks are not reliably palpable; therefore, surgical planning and execution is dependent on imaging. Size of the pedicles can be important in determining needle gauge and trajectory. The pedicle angle of entry to the vertebra determines the trajectory. In the thoracic spine, the angles are steeper (more anteroposterior [AP]) than in the lumbar spine; therefore, the extrapedicular, modified extrapedicular, or parapedicular approaches may be indicated. In addition to the normal anatomy, changes caused by the fracture will also dictate the approach. For example, compression of the superior end plate may require a more caudal trajectory, while an inferior end plate deformity may require a more cranial entry point and horizontal direction. In the case of a biconcave fracture, the needle entry and trajectory should be equidistant from both end plates. A vertebra plana leaves little room for passage of a needle into the center of the vertebral body, but there is usually sparing of the more lateral portions of the vertebral body, which can be accessed despite prominent central compression. Breach of the vertebral posterior margin by a fracture risks cement escape into the spinal canal, but previous authors have shown that these fractures can be treated very safely.11
There are substantial data supporting the bilateral approach for optimal outcomes in vertebral augmentation with balloon kyphoplasty; however, the unilateral approach may offer similar outcomes with reduced operative times and radiation exposure.
In a retrospective study of 296 patients with osteoporotic VCFs, Bozkurt et al identified significantly better height restoration following bilateral kyphoplasty compared to unilateral kyphoplasty and vertebroplasty.12 The advantage of height restoration with a bilateral technique is also supported by a meta-analysis of five studies that reported a short-term follow-up.13 Bilateral kyphoplasty had a significantly (p = 0.03) better degree of anterior vertebral height restoration than unilateral kyphoplasty.13
The unilateral approach was first introduced in an effort to overcome the challenge of visualizing superimposed cannulas and the second injection site in the lateral view. Depending on the fracture and vertebral morphology, pedicle size, pedicle angle of entry, bone quality, and experience of the operator, the unilateral approach has been used with equal success and favorable outcomes.
When multiple levels are being treated, they are typically all cannulated before the injection, allowing the bone fill material to be mixed once and injected in short order. If the levels to be treated are contiguous and the distance between levels is relatively small, the side of needle placement can be alternated for multiple unilateral approaches. This can significantly reduce operative time and radiation exposure to the operator as well as to give more working space for the needles than the same procedure with all of the levels done from the same side.
Several large systematic reviews of randomized control trials have examined the differences in height restoration, correction of kyphotic angulation, and patient ratings of pain associated with unilateral and bilateral approaches.
Favoring the unilateral approach, an analysis of 15 randomized controlled trials including 850 patients by Yang et al found no difference in quality of life or complications from surgery.14 Chen et al found that the unilateral approach resulted in a shorter operative time, a smaller amount of cement injected, and a lower risk of cement leakage.6 There was no statistically significant differences in Visual Analog Scale pain scores, height changes, or kyphotic angle changes between the groups.15 Papanastassiou et al found no difference in clinical or radiological outcomes in multiple myeloma patients treated with the unilateral approach.16 In a review of five studies including 253 patients, Huang et al found no clinically important differences but suggested that unilateral kyphoplasty is advantageous due to decreased operative time and cost.17 Similarly, in a systematic review and meta-analysis including 563 patients, Sun et al noted that the unilateral approach led to decreased surgical time, cement consumption, and cement leakage; reduced radiation dose and hospitalization costs; and improved short-term general health.9 In a comparison between unilateral transverse process-pedicle and bilateral puncture techniques in percutaneous kyphoplasty, Yan et al noted that both bilateral and unilateral approaches for kyphoplasty provide effective treatment for patients with painful osteoporotic VCFs.18 However, patients treated with the unilateral procedure received significantly less radiation, had shorter operation time, fewer complications, and significantly less cement leakage. In this study, the unilateral approach offered a higher degree of deformity correction, local sagittal angle, and vertebral body height restoration (anterior and posterior). Although both techniques had the ability to restore vertebral height and to improve alignment, more postoperative height was restored in the unilateral group. This was attributed to the bone cement distribution, which was placed mainly in the anterior and middle vertebral bodies.18
In the bilateral group, 10.5% of patients had obvious pain in the puncture sites at 1 month postoperatively. With local block treatment, the pain disappeared in all patients at the last follow-up.13 These complications were probably related to puncture technique as this issue has not been commonly reported. Compared with the bilateral technique, the puncture point of the unilateral technique was more lateral to the facet joint. Therefore, in the unilateral group, the violation of facet joint was rare and the bone cement was mainly distributed in the anterior and middle of the vertebral body.13 There was no statistically significant difference in pain relief and functional improvement between the two groups during the 12-month follow-up. Similar clinical outcomes were achieved with either treatment procedure.13
In general, based on the above manuscripts and analyses, the unilateral approach provides the advantages of reduced procedure time, costs, radiation exposure, and cement leakage with improved short-term health. Kyphoplasty using a bilateral approach has been shown to provide significantly less vertebral height loss over 2 years than the same procedure performed via a unilateral approach.19 There appears to be no significant difference in pain reduction or quality-of-life improvement when comparing the unilateral versus bilateral approaches.18 Procedural complications, such as cement leakage, show varied results among studies and may be operator dependent and dependent on which imaging modality is used to detect this extravasation as computed tomography (CT) is more sensitive at detecting small amounts of extravasation as compared with plain film radiography or fluoroscopy.
The procedure is guided with single-plane or biplanar fluoroscopy or, in some cases, CT. In our experience, fluoroscopy is sufficient to identify the salient anatomy and affected vertebral bodies. If uncertainty remains about the fracture anatomy and extent of vertebral involvement, CT may be performed. Fracture age and anatomy can be assessed with magnetic resonance (MR) imaging.3,20 Nuclear bone scan imaging may also be helpful in characterizing a fracture, although the anatomic detail is limited and the spatial resolution poor.
As with any image-guided procedure, preoperative positioning of the patient and fluoroscopes is paramount. Either conscious sedation or general anesthesia may be performed, but most patients with VCFs have multiple comorbidities and conscious sedation would be preferred over general anesthesia in this fragile patient population. The patient is positioned prone with shoulder and pelvis/hip bolsters. All pressure points are padded. The lateral image should be a “true lateral” that demonstrates the posterior margin of the vertebral body, spinal canal, and an optimized view of superimposed pedicles. The adjacent vertebrae can be used as guides if there is significant deformity of the fractured body. The AP view should be directed such that the spinous process is midline and both pedicles are visible and similar in size and shape and in the upper half of the incident vertebral body (▶Fig. 6.4). In this way, two-dimensional imaging is used to guide a three-dimensional approach. Although we routinely use this fluoroscopic approach, some may prefer the en face approach, a view straight down the pedicle that demonstrates a circle or oval outline of the edges of the pedicle for guidance (▶Fig. 6.5). This requires a 10- to 30-degree ipsilateral oblique angulation from the true AP. It is important to remember that the lateral imaging is used only for superior and inferior directional adjustments, while the AP image is only to be relied on for guidance with medial and lateral corrections.
All vertebral augmentation procedures require the establishment of a working channel for delivery of cement or an implant. Each of the following approaches begins with a small (~5 mm) skin incision and the introduction of a Jamshidi-style needle to establish the working channel extending into the vertebral body. An 11-gauge Jamshidi needle is generally used in the lumbar and lower thoracic spine. Smaller needles may be used in upper thoracic spine and as needed at other levels. Larger needles may be used in the lumbar spine or during the insertion of vertebral body implants. Needles are available in 10- to 15-mm lengths.
Fig. 6.5 Ipsilateral fluoroscopic view with a 25-degree ipsilateral angulation of the image intensifier shows the en face view of the pedicle with the target located in the upper outer portion of the pedicle (white circle).
Each approach is associated with a unique set of indications and risks as described. Common to many of the approaches are the risks of rib or transverse process fractures, infection, hematoma, pulmonary embolism, injury to surrounding organs, direct neural injury, and cement leakage with subsequent neural compression requiring immediate access to personnel and facilities for surgical decompression.
The basic bilateral transpedicular approach is considered standard for percutaneous access to the lumbar and lower thoracic vertebrae (▶Fig. 6.6). The transpedicular needle path offers protection for the surrounding tissues, including the postganglionic nerve roots, but is most likely to require bilateral needle insertion to accomplish proper balloon placement and adequate cement fill. In the upper thoracic spine, the transpedicular approach will not allow proper medial placement of the instruments and balloons placed too laterally will not achieve proper fracture reduction and may result in violation of the lateral cortex before fracture reduction is achieved.
Following sterile preparation and confirmation of appropriate imaging, the incision site just superior and lateral (1–2 cm) to the target pedicle is determined (▶Fig. 6.6). The surgeon must visualize the passage of a working channel from that site through the length of the pedicle and two-thirds of the vertebral body, ending at or near the midline. The imagined course must not enter or traverse the spinal canal. Corresponding lateral and AP landmarks along the course (▶Fig. 6.6) will ensure that instruments do not stray from the planned trajectory, risking injury.
Landmarks that must be identified include the pedicles, the spinous process, and the end plates (▶Fig. 6.6). In a true AP view, the spinous process will be midline and the pedicles will be seen as symmetric ovals equidistance from the process and superimposed over the upper half of the vertebral body. End plates will be parallel (allowing for defects of the fracture). It is very important to locate these landmarks on true AP and lateral images before beginning (▶Fig. 6.6). After injecting local anesthetic, a small approximately 5-mm stab incision is made (▶Fig. 6.6). The Jamshidi needle is introduced and “docked” at the superolateral border of each pedicle (“10 and 2 o’clock positions”’; ▶Fig. 6.6). Just as the AP imaging demonstrates this starting point (▶Fig. 6.6), lateral imaging should confirm that the needle tip is at the posterior margin of the pedicle (▶Fig. 6.6). As the needle is advanced, it should reach mid-pedicle on both AP (▶Fig. 6.6) and lateral imaging. As the needle reaches the medial aspect of the pedicle as seen on AP imaging (▶Fig. 6.6), it should be seen in or near the posterior portion of the vertebral body on lateral imaging (▶Fig. 6.6). The needle must not violate the medial pedicle wall, thereby entering the spinal canal and risking serious injury. After the Jamshidi needle is advanced via the pedicle into the vertebral body, a contralateral needle is placed if necessary. When performing a vertebroplasty, the needle(s) is/are advanced into the anterior one-third of the vertebral body and cement is then injected (▶Fig. 6.7). During a balloon kyphoplasty procedure, the needles are place approximately 0.5 to 1.0 cm into the posterior portion of the vertebral body and then either a bone biopsy needle (if a biopsy is desired) or a drill is passed into the anterior portion of the vertebral body up to within 0.3 to 0.5 cm of the anterior vertebral body wall cortex (▶Fig. 6.8).
In the case of balloon kyphoplasty, the bone tamp (balloon) is inserted through the working channel and guided into the tract created by the drill (▶Fig. 6.8). The radiopaque markers on the tamp are visualized distal to the cannula sheath on at least the lateral view (▶Fig. 6.8) but preferably both the AP and lateral fluoroscopic images. This procedure is repeated on the contralateral side and each bone tamp is inflated (▶Fig. 6.8) while being monitored with AP and lateral imaging. In the case of kyphoplasty, manometric controls are used to monitor the pressure of the balloons as they are inflated in small increments to the intended pressure. The inflation is done according to a combination of pressure, fracture characteristics, and balloon shape. The endpoint of balloon inflation is achieved when any of the following occurrences are seen: fracture reduction achieved, maximum inflation volume reached, maximum sustained balloon pressure achieved, cortical wall contact, or adequate cavity creation performed. The maximum balloon volume and balloon pressure will vary according to the balloon type and manufacturer.
After a void is created and height restoration is achieved as safely permitted, the bone tamps are removed and internal fixation is achieved through a low-pressure injection of bone void filler (▶Fig. 6.8). After the cavity is filled and there is adequate interdigitation of cement into the interstices of the surrounding cancellous bone, the cannulas are removed.
The transpedicular approach is effective in most cases, but it is difficult to achieve percutaneous access in certain situations. Reduced pedicle width and AP pedicular angle of the mid and upper thoracic vertebral pedicles compared to lumbar vertebrae often precludes a transpedicular approach in this area. Extrapedicular or parapedicular approaches are more appropriate for levels above T9. These approaches also accommodate placement of instruments too large for the transpedicular approach and can allow access to the vertebral body in a patient with existing hardware such as pedicle screws.21 The extrapedicular approach is also more appropriate for a fracture that results in depression of the superior end plate to a location below the point of pedicle entry.22
Fig. 6.8 Lateral fluoroscopic views showing the vertebral drill (black arrow in a) placed to within 0.5 cm of the anterior vertebral cortex (black line in a). Lateral fluoroscopic view showing the balloon being inserted with the anterior and posterior radiopaque marker bands completely through the needle and into the vertebral body (black arrows in b). The marker bands show the proximal and distal boundaries of the noninflated balloons. The balloon is then inflated with contrast (black arrow in c) with subsequent reduction of the vertebral body. After the balloons are deflated and removed, bone fillers are used to inject bone cement into the vertebral body (white arrows in d).
Downward-angled ribs sometimes limit extrapedicular access in the thoracic spine and the entry point may require the needle to pass under the rib, immediately adjacent to the intercostal neurovascular bundle. Further, wide pedicles at the L5 level as well as the obstructing presence of iliac crests make the extrapedicular approach particularly difficult at this level. However, the favorable needle trajectory allowed by the extrapedicular approach allows for a consistent and predictable approach to the vertebral body.
In the parapedicular approach, the entry site allows establishment of a working channel that effectively traverses the anterior portion of the pedicle at the pedicle–vertebral body junction rather than traveling within the pedicle throughout its course. The size of the cannula is therefore not limited by the diameter of the pedicle and the entry point anterior to the pedicle means there is decreased risk of pedicle fracture. Although this approach offers protection from medial canal breach at the pedicle–vertebral body junction, care must still be taken to avoid neural injury or injury to the pleura in the thoracic region given its more lateral entry point.23
In 2016, Beall et al described a relatively avascular and aneural portion of the inferior vertebral body just anterior to the pedicle. They then treated a total of 96 thoracic and lumbar vertebral fractures using this extrapedicular modified inferior end plate access without any recognized clinical complications from the needle access or the instrumentation. This is an ideal approach when the vertebral body is very compressed superiorly or when a device larger than the size of the pedicle is to be inserted. The technique allows access around existing hardware and the authors noted that it could accommodate the placement of large instruments.21
For this approach, the AP fluoroscope is angled 45 degrees off midline for procedures involving the lumbar spine or 30 degrees off midline for procedures involving the thoracic spine for an oblique view (▶Fig. 6.9). The incision is made at a point just anterior to the pedicle, slightly above the inferior end plate (▶Fig. 6.9). The needle is advanced to the bone and subsequently just into the vertebral body. At this point, the AP view should be checked to confirm medial and lateral position (▶Fig. 6.9). The lateral view will confirm the needle tip to be in the middle to anterior third of the vertebral body. The needle should never go posterior to the pedicle on the oblique view, to avoid damage to the descending ventral ramus, and should never go into the paraspinal soft tissue adjacent to the thoracic spine without having the needle at a shallow angle to avoid damage to the pleura or entrance into the lung. An entry pint too far superior risks injury to the vertebral segmental artery. The operator should always line up the vertebral body in direct AP view (▶Fig. 6.6a) before arcing 45 degrees off midline in the lumbar spine and 30 degrees in the thoracic spine to ensure the angle of entry is appropriate.21
The parapedicular approach is also known as the transcostovertebral approach due to its course along the rib margin in the thoracic spine.24 The needle passes lateral to the pedicle rather than through it and angles more toward the center of the vertebral body than with the transpedicular approach. The costotransverse and costovertebral junctions in the upper thoracic spine typically direct the trajectory of the needle more ipsilateral, thereby making the access to the center of the vertebral body with a unilateral approach more difficult. It is a useful approach if the pedicle is very thin, difficult to see, or affected by tumor. The size of the needle is not limited by the diameter of the pedicle and the risk of pedicle fracture is decreased. There is an increased risk of paraspinal hematoma and a decreased ability to control postprocedural bleeding by local tamponade. In a retrospective evaluation, Chiras and Deramond25 and Chiras et al26 reported parapedicular approach complication rates of 1% in patients with osteoporotic vertebral fracture and between 2.5 and 10% in patients with benign and malignant spinal tumors, respectively. Despite this relatively high complication rate reported in the 1990s, more recent data were reported in 2007 with 102 VCFs treated via a parapedicular access in patients between the ages of 17 and 96 with no nerve root injuries, hematomas, injury to spinal canal contents, or any other complications.22 To avoid needle injury, the surgeon must be aware of nearby intercostal arteries in the thoracic spine and four pairs of lumbar arteries. In the thoracic region, there is also risk of injury to the pleura and a subsequent pneumothorax. As with the extrapedicular approach, wide pedicles of L5 level and occasionally the iliac crests make the parapedicular approach difficult at this level.22
In 2007, to investigate and illustrate a variation on the traditional percutaneous access to the vertebral body via a parapedicular approach, Beall et al identified an effective parapedicular access technique that could safely and reliably guide the needle tip into the center of the vertebral body.22 Developed from cadaver dissection observations for the purpose of clinical use, a total of 102 VCFs from T4 to L5 were treated via this parapedicular access between July 2005 and March 2006. There were 72 patients between the ages of 17 and 96 years (mean age: 68.2 years) who underwent treatment. The cadaver dissection revealed a relatively avascular and aneural portion of the vertebral body along the superior margin of the vertebral body–pedicle junction. A total 102 vertebral fractures were treated using this parapedicular access technique without any recognized clinical complications from the needle access or the instrumentation. This study showed that the thoracic and lumbar vertebral bodies may be safely, reliably, and reproducibly accessed using a percutaneous parapedicular access technique.22
Using a line extending from the contralateral inferior corner of the VB through the ipsilateral superior corner, a point along this line that is approximately one vertebral body width beyond the lateral aspect of the VB is identified (▶Fig. 6.10).22 An incision is made at this point and the needle is the advanced inferiorly toward the vertebral body at a 45-degree angle (▶Fig. 6.10). If the approach is used for a thoracic vertebral body, the needle should be aligned with the medial rib insertion, as this allows passage adjacent to the costotransverse–costovertebral junction, which is the path of least resistance to the center of the vertebral body. The operator should then look enface to ensure both proper needle trajectory and parapedicular location of the needle (▶Fig. 6.10). The operator can then return to the AP view and advance the needle along the selected trajectory. The needle tip should never cross the medial wall of the pedicle in this view prior to penetration of the posterior cortical wall of the vertebral body (▶Fig. 6.10). An AP view should be obtained to verify needle trajectory and position and ensure the medial aspect of the pedicle has not been violated. After confirming the needle tip is positioned within the posterior portion of the vertebral body, the needle can then be further advanced to the desired location within the vertebral body. The proper location is verified when the needle tip is halfway across the vertebral body in both the AP and lateral views (▶Fig. 6.10).22
Of note, more on the approaches to the cervical spine can be seen in Chapter 10 (Cervical and Posterior Arch Augmentation).
Vertebroplasty has been shown to be beneficial for pain control and stabilization of multiple conditions affecting the cervical spine, including osteoporotic fracture, metastasis, aggressive hemangioma, and multiple myeloma.27–30 In the upper cervical spine, the cervical pedicles are small and the vertebral arteries are near, so transpedicular access is difficult. Several variations of approach to the cervical spine have been described since the procedure was introduced by Galibert et al. These include the anterolateral, transoral, posteroanterior, posterolateral, and anterior retropharyngeal approaches.
The anterolateral approach (▶Fig. 6.2), unlike the transoral approach, can be performed without general anesthesia or endotracheal intubation, and the risk of infection is also lower with the anterolateral approach. With manual retraction of the carotid artery and jugular vein laterally, the needle may be safely placed medial to the vessels.
The percutaneous inferior anterolateral approach involves placing a needle under the mandible (Chapter 10, ▶Fig. 10.2). The needle is then directed cephalad and anteromedially into the vertebral body with manual traction of the adjacent vascular and nervous structures. This approach is technically challenging and risks injury to the vagal, spinal accessory, lingual, hypoglossal, marginal mandibular, and laryngeal nerves. The internal jugular vein and the vertebral and carotid arteries are also at risk.27,31–33
Lykomitros et al described the minimally invasive open approach whereby a small incision is made along the medial border of the sternocleidomastoid muscle. The platysma muscle is divided and the carotid sheath and sternocleidomastoid muscle retracted laterally. With fluoroscopic guidance and palpation of the airway, a guide pin is passed medial to the common carotid artery and advanced through the longus colli muscle and into the vertebral body. Positioning is guided by and confirmed with AP and lateral fluoroscopic imaging.34
In 2017, Bao et al retrospectively analyzed data from nine patients treated with percutaneous vertebroplasty via the anterolateral approach to treat late-stage metastatic cancer to 22 cervical vertebrae (mean Tokuhashi score: 6.89 ± 2.14).35 In each case, a small incision was made before a wire was passed medial to the sternocleidomastoid and carotid sheath and lateral to the esophagus and trachea. A working channel was established using the Seldinger technique. The mean volume of cement injected was 1.32 ± 0.49 mL). The cement leakage rate was 63.6% (14 of 22 vertebrae treated). No serious complications were observed, while significant pain relief was noted. VAS decreased from 8.11 ± 1.45 preoperatively to 2.22 ± 0.67) at 3 days after the procedure (p < 0.001).
High cervical vertebrae may be reached by using the anterolateral approach, but it is relatively difficult at the C2 level. Tong et al described the transoral approach to C2 in a patient with multiple myeloma resulting in complete pain relief and stabilization of the involved vertebra. According to the authors, the benefits of transoral vertebroplasty include precise needle placement and decreased risk to adjacent neurovascular structures.33 Clarençon et al have also reported their early experience with the transoral approach, used to access C1.36
Although the transoral approach reduces the risk of neurovascular complications with a more direct route through the posterior oropharyngeal wall under fluoroscopic guidance into the VB of C2 (▶Fig. 6.11), the route carries an increased risk of infection and should not be used in patients receiving or expected to receive radiation therapy that might interfere with wound healing. It requires general anesthesia and may require manual cervical stabilization and/or fiberoptic intubation.31,33,37–39 Both anterolateral and transoral approaches have been successfully used in the upper cervical spine and while effective, both have potentially life-threatening complications.32,40–43
Wetzel et al described a technique for posteroanterior access to the lateral portion of C1 to treat osteolytic metastatic disease with precautions to protect the vertebrobasilar arterial supply.44 Cianfoni et al have described a posterolateral approach to C1, also sparing the vertebral artery (VA), suggesting that it may be a therapeutic option in selected patients to avoid occipitocervical fusion but requiring good understanding of the anatomy and rigorous technique to avoid potential complications.45
In 2015, a novel anterior retropharyngeal approach was described by Yang et al as an effective alternative when the transoral approach is unsuitable or contraindicated. The approach involved passing the needle through the vertebral body of C2 into the C1 lateral mass to treat metastatic osteolytic vertebral lesions at each level.46
A percutaneous approach with intraoperative imaging is an excellent minimally invasive method of vertebral body biopsy, offering high accuracy and low complication rates for both thoracic and lumbar vertebral body lesions.47,48 In our practice, we routinely collect biopsies during vertebral augmentation, believing that it is in the best interest of each patient to identify any cause of pathologic fractures for timely and appropriate subsequent treatment. The majority of fractures are attributed to osteoporosis, but other etiologies include multiple myeloma, primary and metastatic disease, and osteomyelitis.49 If infection is a concern, specimen should be submitted for culture and sensitivity.
With the transpedicular approach, an 11-gauge vertebral biopsy introducer needle is advanced and inserted into the posterior portion of the pedicle. It is important to appreciate the feel of the bone as bone affected by neoplasm, infection, or even osteoporosis may be softened, preventing reliable purchase and resistance. The introducer needle is carefully advanced through the pedicle by small, controlled, repetitive impacts with a mallet. The needle is advanced to the proximal edge of the lesion. The inner cannula is removed and biopsy needle advanced into the lesion. With gentle continuous aspiration from a 10- to 20-mL syringe, the biopsy needle is removed. If more tissue is required, the inner cannula is replaced and the introducer needle may be moved to a new location for repeat biopsy. If adequate specimen is obtained, the inner cannula is replaced and the introducer needle is removed under fluoroscopic guidance.
Different needle combinations may be used if it is difficult to obtain tissue. A soft-tissue core biopsy needle may be used through the outer bone needle. Some more resilient tissues may require the use of a high-speed drill. Coaxial technique will facilitate the use of different needles with different characteristics through the outer bone needle in whatever combination that is necessary to obtain an adequate biopsy specimen.
Any of the approaches described in this chapter may be used to access the vertebra of interest and obtain tissue for biopsy.
Percutaneous access to the vertebral body may be used for vertebral augmentation procedures to safely and effectively treat traumatic, neoplastic, or osteoporotic fractures. This minimally invasive access also allows vertebral body biopsy when infection or tumor is suspected. The approach employed will be specific to the patient and determined by many factors including fracture level, vertebral morphology, bone quality, and operator experience and preference. Each approach has specific indications and contraindications.
Planning and preparation are essential. Transpedicular approach is standard and straightforward. Both extrapedicular and parapedicular approaches are easily planned using landmarks that are fluoroscopically identifiable and a trajectory that places the entry point through relatively avascular and aneural tissues. Cervical anterolateral and transoral approaches have inherent risk of injury and, as with all approaches, require good understanding of the anatomy and rigorous technique. These approaches—in the hands of knowledgeable and skilled operators—are invaluable for safe and effective minimally invasive access to vertebrae for augmentation and diagnostic procedures.
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