CHAPTER 32 Vertebroplasty

SCREENING OF PATIENTS REFERRED FOR VERTEBROPLASTY

Before considering vertebroplasty, one must perform a through history, physical examination, and review appropriate investigations including radiographic analysis. This information should be able to differentiate between the source of pain being vertebral compression fracture or other back problems such as disc herniation, facet arthropathy, or spinal stenosis.¹

History should include the site of pain, cause, inciting event, date of origin, exacerbating factors, alleviating factors, analgesic use, and activities of daily living. The patient should be screened for allergies, medications, medical problems, and conditions which may prevent the patient from lying prone during the procedure. The origin of pain may coincide with minor trauma and is typically exacerbated during activity, movement, or while weight bearing, and is relieved by lying down. Physical examination will reveal a tender site corresponding with the fracture level. If multiple vertebral compression fractures are present, the origin of pain will be elicited by careful clinical examination and analysis of radiographic studies.^1,² Magnetic resonance imaging (MRI) is helpful in patients with multiple fractures and usually reveals edema within the marrow space of the vertebral body that is best visualized on sagittal T2-weighted images. Bone scans can also differentiate the symptomatic level from incidentally discovered fractures.³ Bone scan imaging may be indicated when considering vertebroplasty therapy for patients suffering from multiple vertebral compression fractures of uncertain age or in patients with nonlocalizing pain patterns. We do not, however, routinely perform bone scans.⁴

Blood investigations should include complete blood and platelet counts, measurement of prothrombin time, partial thromboplastin time, International Normalized Ratio, activated clotting time, and complete metabolic panel.^5,⁶

CONSULTATION

Because most vertebral compression fractures occur in the older age group, the initial consultation should include family members involved in the patient’s care.

The time of reporting for the procedure, postprocedure care, and time of discharge from the hospital should be explained. Informed consent must include a through explanation of the procedure, methods, the physician’s prior history of complications, and the expected outcome based on the physician’s own outcome data. The patient should also be informed that the addition of material (barium, tungsten or tantalum) to make the bone cement material opaque technically makes the cement a non-FDA-approved material.^1,⁷

One should carefully temper unrealistic patient expectations. In general, the patient can be told to expect a higher chance of a favorable outcome if his or her fracture is subacute, but a diminished success rate if the fracture is old.

Timing

Early studies performed vertebroplasty only after conventional treatment (medication and rest) had failed.⁸ Later series have advocated treatment as early as weeks or days if the patient requires narcotic medication or admission to hospital secondary to pain. Others have recommended vertebroplasty within 4 months.³ Although late treatment is unlikely to be successful, there are case reports of patients being successfully treated after a few years.⁹

Even though some believe it is a reasonable indication,¹ there are insufficient data to categorically support the treatment of painful tumor infiltration without fracture. In addition, it is unclear whether to treat before or after radiation therapy. Injection of cement into the vertebral body will likely dislodge marrow elements that could potentially be absorbed into the blood stream. This concern for causing metastatic dissemination suggests that vertebroplasty should be performed only after radiation therapy.

Prophylactic vertebroplasty is neither widely accepted nor approved for osteoporotic vertebral compression fractures and no studies have been done to substantiate the utility of this practice.¹

TECHNIQUE

1. Pre-procedure planning. MRI, computed tomography (CT), and X-ray images of the fracture are evaluated in all views specifically looking for the angle of approach to the vertebra through the pedicle. Because normal anatomy (Fig. 32.1) is altered by the fractures, the approach to the body of the vertebra through the pedicle is altered. This altered bone architecture must be carefully analyzed by reviewing all the available radiological films. Specifically, the cortical margins of the bone are reviewed in anteroposterior (AP), lateral, and axial views to preplan the pathway of the trocar to the exact target area within the vertebral body. The angle will be altered based on the characteristics of the fractured vertebra. The vertebra may be approached through one pedicle or both pedicles. If the angle of insertion is achieved in such a way that the tip of the trocar is in the center of the body, then one may use a single-pedicle approach. If the trocar lies on one side of the body of vertebrae, then the other pedicle may be used to approach the other side of the vertebral body.

2. Prior food and medication. For procedure performed in the morning, the patient is informed not to eat or drink after midnight, but is allowed to take medications. When conscious, sedation is used for a procedure to be done later in the day, and the patient should not drink or eat for a minimum of 4 hours beforehand. Diabetics and other chronic medical illness management including the timing of anticoagulants should be coordinated with the primary care physician.

3. Prophylactic antibiotics. Intravenous antibiotics (cefazolin 1 g) are given 30 minutes before the procedure. Ciprofloxacin 500 mg orally twice a day may be given, if the patient is allergic to other medications and should be started 12 hours before the procedure and continued 24 hours after completion of the procedure.⁶

Fig. 32.1 Pedicles. (A) Axial view. (B) Lateral view.

We do not give any prophylactic antibiotics and prescribe antibiotics postoperatively for a week.

4. Position of patient. The patient is placed in a prone position for surgery in the thoracic and lumbar region and supine for cervical region.³ It is critical to confirm the level of pain and fracture under fluoroscopy before beginning vertebroplasty.¹ Applying pressure with the thumb or palm of the hand over each spinous process or side-to-side movement of the spinous process will often elicit tenderness. As the patient is awake during the procedure and placed in a prone position, the patient should be made comfortable with padding and arm supports.

5. Anesthesia. Percutaneous vertebroplasty is performed using local anesthesia typically combined with neuroleptanalgesia ^2,^3,^5,^10,¹¹ or general anesthesia.^10,^11,¹² The authors use a combination of intravenous midazolam (Versed; Roche, Manate, Puerto Rico) and fentanyl (Sublimaze; Abbott Laboratories, North Chicago, IL).^13,¹⁴ Dosages are based on patient size and condition and can be titrated during the procedure based on the patient’s response. General anesthesia is rarely used for this procedure. Two to 3 ml of 1% solution of lidocaine injected into the marrow through the needle will relieve pain, which some patient may experience when cement is injected into the bone.^6,¹⁵

6. Prepping and draping. The skin is prepared with iodine and then draped. As the position is checked many times in AP and lateral views, the field of procedure should be well protected with sufficient drapes.

7. CT scan versus C-arm fluoroscopy. Vertebroplasty is performed using biplanar fluoroscopy,^3,¹¹ C-arm fluoroscopy, and dual-guidance CT.^3,¹⁶ CT is only used for extremely difficult cases, such as tumor destruction of the posterior vertebral wall⁶ or vertebra plana.¹⁷ When using a single-plane C-arm fluoroscopy all the movements during the procedures should be confirmed in two planes, AP and lateral.

8. Approach to the vertebral body. Cervical vertebroplasty has been done with transoral approach,^18,¹⁹ lateral, and anterolateral approach.²⁰ The authors do, however, have concerns about the transoral approach. This technique necessitates traversing the oropharynx which is riddled with bacteria ready to flourish in the vertebral body. Consequently, we prefer the anterolateral approach used by Deramond in the first described vertebroplasty procedure.²¹ As osteoporotic fractures are rare in the cervical area, vertebroplasty is rarely done in the cervical region except for conditions such as tumors. During the needle placement one must be careful to avoid the carotid artery and internal jugular vein.⁶ Both structures are displaced laterally and the esophagus and trachea medially to reach the body of cervical vertebrae (Fig. 32.2).

Fig. 32.2 Cervical body, anterior.

The thoracic and lumbar vertebral bodies are usually approached through one or, most commonly, both pedicles.^2,^8,²¹^–²⁷ Various approaches are used including a costovertebral,⁵ paravertebral, posterolateral, or anterolateral (cervical) approach. The parapedicular or transcostovertebral²⁸ approach is used when a transpedicular approach cannot be used because of small pedicles, a fractured pedicle, or tumor invading the pedicle. Like most physicians, the authors prefer the transpedicular approach instead of the parapedicular approach, which may increase the chance of both a pneumothorax and that a paraspinous hematoma may not be controlled with application local pressure.⁶ The posterolateral approach increased the risk of injuring the exiting nerve root and segmental artery,⁶ and has largely been abandoned although some authors recommend it for lumbar vertebrae.^20,^23,²⁸

There are many companies which supply cement and delivery equipment: Parallax Medical Inc./Arthrocare Corporation; Cook Group Inc.; Interpore Cross International Inc.; Interpore Cross International Inc./American OsteoMedix Corp.; Medtronic Inc./Medtronic Sofamor Danek; Orthofix International NV/Orthofix Inc.; Stryker Corp.; Tecres SPA.²⁹ These sets contain stylets, needles, tubing, injectors, and injector barrels, but the end result is the same. The equipment allows one to inject cement into the anterior part of the vertebral body. Some authors have, however, modified the equipment and technique,³⁰^–³³ and before these sets were available, operators recommended using 1 mL syringes for injection of cement.^7,^11,^17,²⁴

9. Needle insertion. Mark a point on the skin after viewing the fractured vertebra in the anteroposterior and lateral views. This is the planned insertion site of the cannula. The initiation site should correspond with superolateral aspect of the pedicle. It should not be near the inferior or medial margins of the pedicle. Local anesthetic is infiltrated into the skin, subcutaneous tissue, and up to the periosteum of the pedicle. We inject 2–3 mL of lidocaine 1% with 25-gauge 1.5 inch needle for local anesthesia (Fig. 32.3).

Fig. 32.3 Injecting local anesthetic.

A small incision is made using a No. 11 knife blade and the introducer needle from the set is inserted (Fig. 32.4). A 15-gauge needle is used for cervical vertebrae and 10-gauge for thoracic and lumbar vertebrae.³ Currently, even thinner needles (13-gauge) are being used.⁶ The needle entry site is localized in the AP view. The authors use a diamond-tipped needle to start the entry.

Fig. 32.4 Needle is inserted and viewed on the monitor with the clamp holding the needle.

During the procedure, one must confirm all the movements and steps in both the AP and lateral fluorosopic views.

The needle is held with forceps to minimize radiation exposure to the operator.⁶ After confirming the position, the vertebroplasty needle is advanced through the superior-lateral cortex of the pedicle (Fig. 32.5). The vertical and horizontal diameter of the pedicle increases from upper thoracic to lower lumbar vertebrae (Table. 32.1). Proximally, in the sagittal plane, the direction of the pedicle is more oblique. (Fig. 32.6)

Fig. 32.5 Initial tap into the pedicle.

Table 32.1 Vertical and horizontal pedicle diameter

Pedicles	T3	L4
Vertical diameter	0.7 cm	1.5 cm
Horizontal diameter	0.7 cm	1.6 cm

Fig. 32.6 (A) Direction of insertion of the trocar and cannular (axial view). (B) Approach to vertebra on lateral view.

The authors start with a diamond-tipped needle and then change it to beveled needle to make directional adjustments.⁷ The bevel of the needle is directed so that the tip is pointed laterally to avoid the spinal canal.

The needle is directed anteriorly, medially, and inferiorly through the pedicle to reach the anterior third of the vertebral body in the midline in the sagittal plane.

Incremental changes in position of the needle are observed in the AP and lateral views to ensure that the proper pathway is being pursued.

In osteoporotic bones it may be easy to advance the needle by hand, but in cases where the bone is dense, as in pathologic fractures, a mallet is necessary to advance the needle.⁶ While advancing the needle by hand the direction of needle may change, and using the mallet may keep the needle advancing in the direction wanted. We invariably use a mallet to advance the needle as this provides much greater control of the needle direction. As the needle is slowly advanced through the pedicle, we are hypervigilant about the location of the needle tip and the orientation of the needle. At no point do we want to breach the medial wall and subject the patient to the risk of cement extravasation into the spinal canal. When we reach the anterior part of the pedicle on lateral view, the trocar should be just lateral to the medial border of the pedicle on anteroposterior view. This ensures we are not going to break the medial wall of the pedicle. In addition, we do not want to fracture the roof or the base of the pedicle and inadvertently pierce an exiting nerve root. Advancing the needle through the lateral border of the pedicle will deposit cement intramuscularly. We have experienced this latter scenario on a few occasions and it is not associated with any adverse effects. Theoretically, it is conceivable that the needle could be placed too close to the aorta if the needle breaks through the lateral margin of the left pedicle, but this is a highly unlikely event. It is also important to be sure that the angle of inclination will allow the needle to ultimately rest in the anterior one-third of the vertebral body. To obtain ideal terminal position, it is critical that one repeatedly re-checks the cephalocaudal tilt while traversing through the pedicle. It is very difficult to re-orient the angle of inclination once the needle has passed through the pedicle and enters the vertebral body. If the angle of inclination is too steep then gentle downward pressure on the hub will minimize this angle, especially if the needle is still within the pedicle. We emphasize the term ‘gentle’ since osteoporotic bone can easily fracture if aggressive motions are used. If such gentle pressure does not achieve the intended result, a beveled needle can be substituted for the diamond-tipped needle. The bevel can be rotated so that the needle courses in the direction of choice. After the needle is observed to enter the vertebral body using a lateral view, the AP perspective does not need to be checked until the cement is injected. An AP view is needed at three points during the procedure: when planning where to insert he needle, checking the progress of the needle as it courses through the pedicle, and then later when cement is injected. Once the needle is in the vertebral body it should be rotated so that the tip is opening medially.

10. Biopsy. If a biopsy is required, it is done by introducing the needle coaxially ³⁴ or thorough the needle. The biopsy is done before the cement is injected.¹ The authors introduce a thinner biopsy cannula through cannula already through the pedicle. Biopsy kits are commercially available and the biopsy needle size is compatible with the vertebroplasty cannula. After the trocar and cannula have been placed in the vertebral body through the pedicle, the trocar is removed. The biopsy needle is inserted through the vertebroplasty cannula. The biopsy needle is longer than the vertebroplasty cannula and precaution should be taken not to pierce the anterior cortex. The authors initially stop the vertebroplasty cannula in the posterior third of the vertebral body. The biopsy needle is then inserted and advanced through the vertebroplasty cannula in a rotating motion and then pulled out. After the biopsy is obtained, the trocar is reinserted into vertebroplasty cannula and it is advanced anteriorly to the target area.

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