Vertebroplasty – Indications, Contraindications, Procedure

Anatomy and Physiology

Bone mineral density tends to decrease with age following peak bone mass, leading to osteoporotic bone. Osteoporotic bone is of normal quality but decreased in quantity. The cancellous bone has decreased trabecular quantity and thin cortical bone, leading to a decreased load to failure capacity and more prone to fracture. Vertebral compression fractures (VCFs) are the result of axial force overcoming bony integrity. VCFs are defined as a loss of about 20% or at least 4 mm of anterior, middle, or posterior vertebral height.[rx] The thoracolumbar spine (T12-L2) is the most frequently affected site (60-75%), followed by the lower lumbar region (L2-L5).[rx]

Compression fractures characteristically involve the anterior column of the spine which is comprised of the anterior two-thirds of the vertebral body, the anterior two-thirds of the intervertebral disc, and the anterior longitudinal ligament. Unlike vertebral burst or Chance fractures, a compression fracture does not compromise the posterior tension band.[rx] The posterior tension band is characterized by muscles, ligaments, processes, and pedicles that maintain spinal stability.[rx] Therefore, compression fractures are deemed stable fractures.

Posterior tension band components include:

• Posterior ligamentous complex: Supraspinous and interspinous ligaments, ligamentum flavum
• Musculature: Longissimus, iliocostalis, spinalis, semispinalis, rotatores, intertransversarii, multifidus
• Bone: Transverse and spinous processes, pedicles, facets

Indications

The standard treatment options for

• Vertebral compression fracture consists of conservative therapies involving analgesics,
• An external orthosis or foreign body entered into vertebrate
• Significant pain has persisted for at least 2 weeks. If the pain does not start to get better within a week or two, surgery to stabilize the compression fracture might bring quicker pain relief than other methods. Vertebroplasty is typically performed 4 to 6 weeks after the fracture has occurred.
• Pain worsens with axial load. If pain increases when weight is placed on the spine from above, such as when getting out of bed or carrying a heavy item, it is more likely that the vertebral compression fracture is actually the pain source and would thus respond favorably to a vertebroplasty procedure.
• No associated neurologic deficits. If any part of the bone is pushing against the spinal cord or a nerve root and causing neurological deficits, such as tingling, numbness, weakness, and/or problems with coordination, vertebroplasty is unlikely to relieve these signs and symptoms.
• No significant kyphosis or another spinal deformity. Vertebroplasty essentially cements the vertebra in its current position, which works fine if the spine is close to its normal shape. However, if one or more vertebral compression fractures have caused the spine to curve too far forward (kyphosis), a different surgery, called kyphoplasty, may be recommended. Kyphoplasty is similar to vertebroplasty, except that it helps restore the damaged vertebrae closer to their normal height, which can correct a kyphosis deformity. With other types of deformity, a different surgery may be needed, such as a fusion.
• The fracture has not already healed. If the compression fracture has already healed, vertebroplasty is unlikely to help reduce pain.

In recently published AAOS (American Academy of Orthopedic Surgeon) guidelines for osteoporotic compression fractures, they recommend strongly against the use of vertebroplasty.[rx] However, kyphoplasty remains a viable option for the treatment of these injuries.

Contraindications

An absolute contraindication to vertebroplasty and kyphoplasty is an asymptomatic compression fracture. Often found incidentally on chest x-rays, healed compression fractures will not benefit from intervention. The procedure should not be performed if there are ongoing local or systemic infectious processes such as osteomyelitis or discitis. Relative contraindications include fracture extension into the posterior vertebral body wall that can risk cement extravasation into the spinal canal, and severe compression fractures/deformity.[rx]

• An osteoporotic vertebral fracture that is completely healed or is clearly responding to conservative management
• Presence of untreated coagulopathy
• Presence of discitis/osteomyelitis or sepsis
• Significant compromise of the spinal canal by retropulsion bone fragment or tumor
• Fracture older than one year
• Greater than 80 to 90 percent collapse of the vertebral body

Equipment

VP/KP is best performed using high-quality fluoroscopy to confirm the needle placement. This is best accomplished with the use of C-arm fluoroscopy. This procedure can be performed with one C-arm transitioning between anteroposterior AP and lateral images, or with two C-arms, one positioned for AP, and the other for lateral images. The two C-arm technique alleviates the need to constantly change the C-arm position. A list of types of equipment is given below[rx]:

• Local anesthetic
• Fluoroscope
• Trochar (large hollow tube)
• For kyphoplasty, a balloon tamp and catheter are needed to inflate the vertebral body
• Peripheral intravenous cannula with intravenous fluids
• The vital sign monitoring device
• Orthopedic bone cement
• Bone cement delivery device
• Spinal needle
• Spinal needle stylets, with diamond-shaped multi-bevel and single-bevel
• Polymethacrylate (PMMA) cement
• +/- Kyphoplasty balloon catheter (See Technique for details)

Personnel

Vertebroplasty and kyphoplasty are performed primarily by

• The physician performing the procedure: often specializes in interventional radiology, interventional pain, or neurosurgery
• Nurse technologist
• The operator of the fluoroscope: X-ray technician or medical assistant
• interventional radiologists,
• interventional pain management physicians, and
• neurosurgical/orthopedic spine specialists.
• Intraoperative personnel may also include a fluoroscopy technician, nurse, and a company representative. If general sedation is implemented, an anesthesiologist is also present.

Preparation

Vertebroplasty and kyphoplasty are considered a procedure with moderate bleeding risk (Category 2) according to the Society of Interventional Radiology (SIR) Standards of Practice Consensus Guidelines. INR and complete blood count (CBC) should be attained pre-procedure. Recommendations are as follows:

• INR corrected to less than 1.5
• Transfuse for platelets less than 50,000
• ASA: No need to hold
• Clopidogrel: Hold 5 days pre-procedure
• Low molecular weight heparin (LMWH): Hold one dose pre-procedure

Antibiotic prophylaxis is achieved with the administration of 1 gram of intravenous (IV) cefazolin, 1 hour pre-procedure (first-line). Once the patient is intubated, the patient is then placed in the prone position on a well-padded radiolucent table. Proper positioning of the fluoroscopic C-arm is crucial. The affected vertebral level is isolated and proper views are obtained before the start of the procedure and the C-arm position is noted so it can be replicated after surgical preparation. On the (AP) image, you want to view the vertebral body in a direct AP position with the endplates parallel to the X-ray beam, and the spinous process centered between the pedicles.[rx] The pedicles are then marked with a marking pen. The surgical area is prepped and draped in a sterile fashion using the maximum surgical barrier technique. Preprocedural prophylactic antibiotics are given before the start of the procedure.

Technique

VP and kyphoplasty procedure setup and technique are extremely similar, the only difference being that kyphoplasty creates a cavity in the vertebral body by balloon expansion. In the thoracic and lumbar spine, VP is performed using a transpedicular or parapedicular approach.[rx] Using a radiolucent instrument, the incision is marked over the pedicle under fluoroscopic guidance. A small stab incision is made over the entry point, location is confirmed by AP X-ray before an incision is made. The VP hollow needle is then inserted and under AP intermittent fluoroscopic guidance the entry point is confirmed before inserting. The starting point is usually along the superior lateral edge of the pedicle with variable angulation depending on the pedicle level being accessed.[rx] The medial and inferior walls of the pedicle must be clearly visualized in order to decrease injury to nerve roots and the spinal cord.[rx] A mallet can be used to gently tap the device into the starting point, being careful not to cross the medial pedicle wall. If the trajectory is appropriated on the AP view, the C-arm is then transitioned to the lateral view to confirm proper pedicle placement and superior/inferior trajectory in the vertebral body. If the trajectory is appropriate, the C-arm is transitioned back to the AP view, and the VP device further advanced, being careful not to cross the medial pedicle wall. This is continued until the VP device has passed through the pedicle and is in the posterior vertebral body, which is confirmed on the lateral image. Once the posterior vertebral body has been accessed you can now advance the VP device more medial and distal. The tip of the needle should be placed in the anterior to the middle third of the vertebral body as close to the midline as possible.[rx] The final needle position should be confirmed by fluoroscopy before bone cement injection. If performing kyphoplasty, at this point the balloon catheter is then inserted and inflated using visual volume and pressure controls to create a cavity. Inflation is stopped when the pressure above 200-250 psi is obtained when the balloon contacts the cortical surface or expands beyond the border of the vertebral body, or if the height of the vertebrae is restored. The balloon is then deflated and removed. Once the cement is mixed, it is not injected until it reaches the consistency of a paste, this is done in order to prevent leakage in severely osteoporotic bone.[rx] The goal is to deliver the cement at a controlled pace, and evenly in the vertebral body while avoiding extra-vertebral extravasation. Multiple AP and lateral images are utilized to confirm cement injection into the vertebral body and to confirm there is no extra-vertebral extravasation, this will appear as a radiopaque substance that is distinctly differentiated from the surrounding bone. As cement is injected, the needle is slowly pulled back to allow for even distribution throughout the vertebral body. Cement injection is discontinued once it has reached the posterior vertebral body. When removing the needle, in order to avoid a cement tail, a stylet is used to clear the needle of residual cement.

What happens during surgery?

There are five steps to the procedure, which generally takes 1 hour for each vertebra treated.

Step 1: prepare the patient

You will lie on the operative table and be given conscious sedation. Once sedated, you will be positioned on your stomach with your chest and sides supported by pillows. Depending on the section of the spine (cervical, thoracic, or lumbar) where the compressed vertebra is located, your back or neck will be cleansed and prepped.

Step 2: insert the needle

A local anesthetic is injected in the area where a small, half-inch skin incision will be made over the fractured bone. With the aid of a fluoroscope (a special X-ray), two large diameter needles are inserted into the vertebral body through the pedicles (Fig 2). The fluoroscopy monitor allows the surgeon to see exactly where the needles are positioned and how far they are inserted. The needles are advanced through the bone using either a twisting motion or a tapping mallet. The needles are angled to avoid the spinal cord. Depending on the vertebral level, a single needle may be used.

Figure 2. Using fluoroscopy, the hollow needle (trocar) is inserted through the skin to a point behind the pedicle. The needle is tapped through the pedicle into the collapsed vertebral body (viewed from above).

Step 3: restore vertebra height (kyphoplasty only)

If the vertebra is significantly wedge-shaped, the surgeon will insert inflatable balloons through the needles into the vertebra. To insert the balloon tamps, the surgeon first uses a drill to create a working channel. The surgeon carefully inflates the balloons, raising the vertebra back to its normal height (Fig. 3). The amount of height restored depends on the age of the fracture. The balloons are deflated and withdrawn, leaving a space in the middle of the vertebra. This procedure is called kyphoplasty because it reduces unwanted kyphosis, or forward curvature, before the bone is stabilized.

Figure 3. The balloon is inserted into the working channel inside the vertebra, then inflated to raise the vertebra to the appropriate height.

Step 4: inject bone cement

Bone cement is slowly injected under pressure, filling the deepest area first, then withdrawing the needle slightly to fill top areas (Fig 4). The pressure and amount of cement injected are closely monitored to avoid leakage into unwanted areas. While complete filling of the vertebral body is ideal, it is not always possible or necessary for pain relief.

Figure 4. The balloon is removed and bone cement is injected into the cavity. Fluoroscopic x-ray shows cement in the upper vertebra (red arrow) and the needle inserted in the lower vertebra.

Step 5: closure

The needles are withdrawn promptly before the cement hardens. The small skin incision is closed with skin glue or steri-strips. You will not be moved from the operating table until the remaining cement in the mixing bowl hardens.

What happens after surgery?

You will return to the recovery area. Your blood pressure, heart rate, and respiration will be monitored, and your pain will be addressed. You’ll remain lying down for the first hour after the procedure. After 1 hour you may sit up. After 2 hours you may get up and walk. Most patients stay in the hospital overnight for observation and are released the next morning. Some patients can be released home the same day.

Discharge instructions

Discomfort

• Take pain medication as directed by your surgeon. Narcotics can be addictive and are used for a limited period of time.
• Narcotics can also cause constipation. Drink lots of water and eat high-fiber foods. Laxatives and stool softeners such as Dulcolax, Senokot, Colace, and Milk of Magnesia are available without a prescription.
• Ice your incision 3-4 times a day for 15-20 minutes to reduce pain and swelling.

Restrictions

• Avoid bending, lifting or twisting your back for the next 2 weeks.
• Do not lift anything heavier than 5 pounds for 2 weeks after surgery.
• No strenuous activity for the next 2 weeks including yard work, housework and sex.
• Do not drive for 2-3 days. Once the haziness from anesthesia wears off you can resume driving.
• Do not drink alcohol for 2 weeks after surgery or while you are taking narcotic medication.

Activity

• Get up and walk 5-10 minutes every 3-4 hours. Gradually increase your walking time, as you are able.
• Learn the proper way to stand, sit, sleep, and lift.

Bathing/Incision Care

• Wash your hands thoroughly before and after cleaning your incision to prevent infection.
• You may shower the day after surgery.
• If you have a Band-aid over the incision, remove it one day after surgery.
• Gently wash the incision covered in Dermabond (skin glue) with soap and water. Pat dry. Inspect and wash the incision daily.
• Do not submerge or soak the incision in water (bath, pool or tub).
• Do not apply any lotions or ointments over the incision.

When to Call Your Doctor

• If your temperature exceeds 101.5 °F or if the incision begins to separate or show signs of infection, such as redness, swelling, pain, or drainage.
• If you experience difficulty walking or bowel or bladder problems.

Complications

Complications occur in about 50% of the patients who undergo vertebroplasty, but about 95% of them are clinically asymptomatic.[rx] A list of common complications is listed below.

• Infection and bleeding: Universally recognized risks of any interventional procedure.
• Radiculopathy or neurological deficit: If the spinal needle violates the inferior or medial wall of the pedicle during entry, there is a significant risk of damage to a nerve root or the spinal cord.
• The most common complication associated with vertebroplasty is PMMA leakage into the surrounding tissue, intradiscal, and spinal canal. This is more common for VP because no cavity is created as in kyphoplasty and increased pressure is needed to inject the PMMA.[rx]
• Spinal stenosis: Cement leakage into the epidural space can essentially cause iatrogenic spinal stenosis, however, this is a rare complication.
• Pulmonary embolization: Cement particles introduced into a vein have the potential to embolize to the lungs, however, this is a rare complication