8.3.1 Procedure Materials

Many forms of vertebroplasty needles are commercially available. Typically, needles are hollow, straight, and range from 10 to 15 gauge in caliber. Smaller systems may be necessary in small pedicles or in the upper thoracic or cervical spine. Needle tips are available in diamond-shaped, single-beveled, or multibeveled designs. The diamond-tip needle configuration provides optimal ease of needle penetration into cortical bone. Beveled needles have superior control and maneuverability, and are useful for changing the needle direction according to which direction the bevel is oriented. Curved needle systems have been recently developed that possess the ability to arc up to 90 degrees, allowing access to sites that are difficult to reach with straight needles. Polymethyl methacrylate (PMMA) remains the most common bone cement utilized. ⁵ The majority of vertebroplasty procedures are performed using fluoroscopic guidance. The procedure room should include equipment for patient monitoring, including electrocardiography, blood pressure and pulse oximetry, and cardiopulmonary resuscitation equipment. Patients commonly receive local anesthesia and moderate conscious sedation, as well as prophylactic antibiotics prior to the procedure. Preprocedural imaging should be available to ensure treatment of the correct vertebral levels. In the rare event of symptomatic complications during the procedure, it is important to have rapid availability of CT and magnetic resonance imaging (MRI) facilities. Modern fluoroscopic units may also have on-table cone beam CT functionality that can be useful in large or obese patients where fluoroscopic landmarks may be difficult to identify or where intraprocedural complications are suspected.

8.3.2 Sedation and Anesthetic Preparation

Analgesia is necessary for all vertebroplasty procedures. For the majority of patients, this is achieved by using a combination of local anesthetics (e.g., lidocaine and bupivacaine) and moderate conscious sedation (e.g., intravenous fentanyl and midazolam). The skin, subcutaneous tissues, and periosteum along the needle tract and at the bone entry point should be thoroughly infiltrated with local anesthetic to minimize pain. Some mild discomfort may be expected as the needle traverses periosteum during the initial cortical penetration. Additional discomfort may occur when the PMMA is injected; in these cases, additional intravenous analgesics may be required. The advantage of conscious sedation is it allows feedback from the patient, such as worsening pain or neurologic dysfunction, which may alert the operator to potential complications. However, general anesthesia may be required in some cases, such as in those with severe pain, high doses of opioid analgesia, or those at risk of cardiopulmonary complications from prone positioning. All cases require continuous monitoring of blood pressure, heart rate, and oxygen saturations. Patient monitoring and sedation are performed by the proceduralists, anesthesiologists, anesthetic nurses, or other certified nursing personnel. For patients with significant preprocedure cardiac or respiratory disease, evaluation by an anesthesiologist may be required to determine the requirements for additional monitored anesthesia care. In all patients, fasting from food and drink is required for at least 4 to 6 hours prior to the procedure.

8.3.3 Positioning

Thoracic and lumbar vertebroplasty is typically performed with the patient in the prone position. However, it is acceptable to allow the patient freedom to place themself in a prone oblique position to improve their comfort during the procedure. This may introduce approximately 10 to 15 degrees of obliquity. Cushion support should be applied under the upper chest and pelvis (▶Fig. 8.2). This promotes patient comfort, allows clear access to the spine, reduces kyphosis, and maximizes extension of the fractured vertebral segments, which may widen and allow cement penetration. ⁶ The patient’s arms should be placed toward the head to keep them out of the path of the fluoroscope beam. Analgesia should be considered prior to positioning the patient, as transfer from the bed to operating table may be painful. Particular care should be taken when positioning those who are elderly or have advanced osteoporosis or myelomatous infiltration, as transfer may result in new vertebral or rib fractures.

8.3.4 Antibiotic Prophylaxis and Skin Preparation

While no clear data currently support or opposes prevertebroplasty administration of antibiotics in nonimmunocompromized patients, ⁷ there are reports of postprocedure spinal infections that are rendered difficult to treat due to the use of PMMA cement. ^{8 , 9} Prophylactic antibiotics are thus commonly used. Typical regimens include intravenous doses of cefazolin (1–2 g), or clindamycin (600 mg) in patients with penicillin allergy and gentamycin (80–160 mg). Infection risk is further minimized by following standard operating room guidelines for sterile skin preparation, draping, and operator scrubbing.

8.3.5 Needle Placement

The vertebroplasty needle is advanced via a small incision, through the skin and subcutaneous tissues and into the target vertebra. It is critical to maintain a needle trajectory that is lateral to the medial cortex and superior to the inferior cortex of the pedicle prior to entry of the needle into the posterior portion of the vertebral body. This prevents passage of the needle into the spinal canal or neural foramen, lowering the risk of spinal cord, cauda equina, or nerve root injury. Ideally, the final needle position should be at the midline of the vertebral body or tumoral target.

In thoracic and lumbar vertebroplasty, the needle may be placed via a transpedicular or parapedicular approach (▶Fig. 8.3). A transpedicular approach involves advancing the needle from the posterior surface of the pedicle, through the entire length of the pedicle, and into the vertebral body. This long intraosseous pathway protects the postganglionic nerve roots and surrounding soft tissues. This approach also provides a clear anatomic landmark for the operator that allows access from the skin into the vertebral body. However, the pedicle configuration can limit the ability to achieve an optimal final needle tip position. The parapedicular approach may permit a more medial placement of the needle tip, and is particularly useful when treating anatomically smaller pedicles, such as in the thoracic spine. The needle is directed along the lateral surface of the pedicle, penetrating the vertebral body at its junction with the pedicle.

Vertebroplasty can be performed with placement of bilateral needles or a single unilateral needle. ¹⁰ The aim in either approach is the midline spread of cement across the vertebral body from the superior to the inferior end plate. A single needle is often sufficient to achieve this. If the midline position is difficult to achieve due to anatomic constraints, a second needle may be placed on the contralateral side. When performing vertebroplasty, there is little difference in the clinical outcomes achieved with unipedicular versus bipedicular approaches and there are advantages to each approach. ¹¹ The primary benefits of a unipedicular approach include reduced procedure time, elimination of the risks associated with placement of a second needle, and lower rates of cement leakage. ¹² The main advantage of a bipedicular approach is the capacity to inject a greater cement volume. ^{13 , 14}