31: Interspinous Process Motion-Sparing Implant

Published on 04/05/2015 by admin

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Last modified 04/05/2015

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Procedure 31 Interspinous Process Motion-Sparing Implant

Christopher F. Wolf, Mark M. Mikhael, Arya Nick Shamie

Indications

image Lumbar stenosis at one or two levels

• Central stenosis
• Lateral recess stenosis
• Foraminal stenosis
• Facet hypertrophy and cyst formation

image Patient must report a resolution of symptoms when seated or flexed forward (i.e., “shopping cart” sign) when upright.

Indications Pitfalls

• Symptoms unresolved with lumbar flexion

• Axial back pain as the main complaint (versus buttock and/or leg pain)

• Osteoporosis with recent history of fragility fracture (severe osteoporosis)

• Spondylolisthesis greater than 25% on static or dynamic radiographs

• Significant scoliosis (greater than 25 degrees at the level of stenosis)

• Ankylosis of the involved segment

Indications Controversies

• “Mild to moderate” stenosis indication for ISP implantation refers to patients’ symptoms (able to walk at least 50 feet), not the MRI findings.

• Although studies show that claudication in patients with severe stenosis (on magnetic resonance imaging [MRI]) can be helped with ISP implants, some surgeons reserve this device for mild to moderate stenosis (on MRI) patients only.

• Three-level implantation of the device is not currently approved. Some surgeons have had success with treatment of three-level stenosis with ISP implantation.

Figures 31-3, 31-5, 31-6, and 31-8 © 2011 Medtronic Spine, LLC. Used with permission.

Examination/Imaging

image Standing anteroposterior (AP), lateral (neutral, extension [left] and flexion [right]) views (Figure 31-1)

• If patient has grade 2 spondylolisthesis on static or dynamic films, that condition is considered a contraindication to the interspinous process (ISP) procedure.

image MRI with axial, sagittal, and coronal imaging to assess disk herniation, canal stenosis, and Modic changes (Figure 31-2)

image

FIGURE 31-1

image

FIGURE 31-2

Treatment Options

• Nonsurgical management, that is, physical therapy, epidural steroid injections, and so forth

• Laminectomy without fusion or with fusion in setting of spondylolisthesis

• Anterior versus lateral interbody fusion alone with indirect decompression

• Disk arthroplasty

Surgical Anatomy

image Midline skin incision with bilateral fascial incision exposing the inferior and superior aspects of the spinous processes at the selected interspinous segment (Figure 31-3)

image Careful preservation of the supraspinous ligament

image Avoiding disruption of the facet joint anatomy

image

FIGURE 31-3

Positioning

image Lateral positioning on radiolucent table (Figure 31-4)

image Prone positioning on a Jackson table with a Wilson frame for maximal flexion at the index level

image

FIGURE 31-4

Positioning Pearls

• Radiolucent table

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