Unipedicular Approach for Percutaneous Vertebroplasty

Published on 10/03/2015 by admin

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Chapter 19 Unipedicular Approach for Percutaneous Vertebroplasty

Kyung-Hoon Kim, MD, PhD, Tae-Kyun Kim, MD, PhD

Unipedicular vertebroplasty is a percutaneous unipedicular approach [1,2] for introducing polymethylmethacrylate (PMMA) cement into the collapsed vertebral body to provide reinforcement that will relieve pain immediately. There are two distinct approaches for percutaneous vertebroplasty (PVP), the transpedicular approach and the extrapedicular approach (Table 19.1). These approaches are further described in Table 19.2 and Figure 19-1.

Table 19.1 Approach Methods for Percutaneous Vertebroplasty

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Table 19.2 Computed Tomography or Magnetic Resonance Imaging Parameters for Needle Placement in Unipedicular Percutaneous Vertebroplasty

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Figure 19–1 Imaginary approaching line for safe unipedicular vertebroplasty. To prevent leakage of the cement into the epidural space, the target point has to be at the anterior ¼ to ⅓ and at the midline of the vertebral body. The skin entry point nearest to the midline will be the extension line from the anterior ¼ through the inner pedicle (red). The farthest skin entry point from the midline is the extension line from the anterior ⅓ through the outer pedicle (blue). In most cases, the skin entry point is between 1.5 and 2.5 times the pedicular distance from the midline in the thoracic or lumbar vertebrae. There are three vertical lines parallel to midline of the body, at 1, 2, and 3 pedicular distances (green).

Most patients (88%) who require vertebroplasty for a collapsed vertebral body also suffer from facet joint pain with radicular pain around the affected vertebrae that is difficult to distinguish from the pain caused by the pathology of the vertebral body. Administration of facet joint or medial branch blocks before PVP will relieve the pain that is caused by the facet joints. These blocks can be given to the patient immediately prior to the PVP procedure, in the same session. The patient can then give crucial information to the operator about the specific pain caused by the collapsed vertebral body. Blocks cannot be performed after PVP because on fluoroscopy, the bone cement makes a shadow around the painful facet joints.

The action mechanisms for pain relief from PVP are as follows:

image Thermal ablation of sinuvertebral and sympathetic nerves from the heat of the PMMA
image Chemical neurolysis from the toxin of the PMMA
image Mechanical stabilization from the volume of PMMA

Preoperative prepations

Preoperative Examination and Medications

Physical examination should reveal the following findings:

image Palpation on the supraspinous region should elicit intractable pain (essential)
image Palpation on the facetal area should elicit radiating pain to the facetal dermatomes (additional)

Imaging diagnosis consists of the following modalities:

image Plain radiographs, thoracic or lumbar series
image Computed tomography or magnetic resonance imaging should show fracture lines or fatty changes on the vertebrae
image Bone scanning should show an active lesion
image Bone mineral density (BMD) testing

Medications for PVP are as follows:

image Major analgesia agents are a weak opioid (codeine) containing nonsteroidal anti-inflammatory drugs and/or acetaminophen.
image Adjuvant analgesia may be achieved with gabapentin for neuropathic pain.
image Prevention and treatment for osteoporosis and metastatic osteolysis consists of 70 mg/week of alendronate.

Indications

The major indication for PVP is intractable pain in weight-bearing postures that lasts more than 4 weeks and is unresponsive to conservative treatment owing to benign osteoporosis or bone tumor and a malignant metastatic lesion.

Contraindications

PVP is contraindicated by the following conditions:

image Metastatic fracture pain in a patient with life expectancy of less than 1 month
image Nonpainful compression fracture

Complications

Possible complications of PVP and their treatment or prevention are as follows:

image Subsequent adjacent fractures in adjacent vertebrae due to lower BMD in the patient with osteoporosis or to active lesions in the patient with malignant metastasis; common medications for osteoporotic and metastatic osteolysis can be prescribed to prevent this occurrence.
image Transient neuropraxia or spinal cord damage due to damage or contusion from vertebral needle passage; anticonvulsant medications can be prescribed for this rare complication.
image Transient hypotension due to sympathetic nerve ablation from polymethylmethacrylate (PMMA) heating and toxin; this complication is rare but preparations should be made for a hypotensive event.
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