Introduction
The interspinous spacer procedure provides patients with a minimally invasive solution that is designed to deliver long-term relief from the leg and back pain associated with lumbar spinal stenosis (LSS). The procedure uses a small, titanium alloy spacer that serves as an extension blocker designed to relieve pressure on the affected nerves. This helps minimize the effects of spinal degeneration while fully preserving the patient’s anatomy.
Indications
The interspinous spacer indirect decompression is indicated for treatment of patients with neurogenic claudication from moderate degenerative LSS, in a stable spine, with no greater than grade 1 spondylolisthesis. The ideal candidates are patients who can relieve their symptoms with flexion or sitting. The indications for the interspinous spacer procedure are very specific: mild to moderate central, lateral, and/or foraminal spinal stenosis with neurogenic claudication.
Contraindications
- 1.
Cauda equina syndrome
- 2.
Severe weakness
- 3.
Significant scoliosis
- 4.
Acute fractures of the spinous process or vertebral body
- 5.
Greater than grade 1 spondylolisthesis
- 6.
Prior fusion or decompression at the indicated level
- 7.
Severe osteoporosis (DEXA scan equivalent greater than 2.5 standard deviation)
- 8.
Active local or systemic infection
- 9.
Allergy to titanium
In addition to the contraindications listed here, there are anatomical considerations to be aware of.
“Kissing spine”
Where spinous processes are in very close approximation ( Fig. 5.1 ), or in contact (i.e., “kissing”), this anatomy may result in increased difficulty in placement of the cannula.
Thin, or “gracile” spinous processes
When a spinous process is unusually thin ( Fig. 5.2 ), or measures less than 20 mm in superior-inferior dimension, the likelihood of a postoperative spinous process fracture may be increased.
Perioperative considerations
Patient selection
The ideal candidates for the interspinous spacer procedure are patients who can relieve their symptoms with flexion or sitting. The procedure is appropriate for treating various types of spinal stenosis, including central, lateral, and foraminal (or combinations thereof) with neurogenic claudication.
Preoperative considerations
Table 5.1 describes some important aspects of the procedure setup.
| Anesthesia |
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| Positioning |
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| Antimicrobial actions |
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Procedure
The device is implanted utilizing the tools provided in a sterile tool kit ( Fig. 5.3 ).
- 1.
Patient position should be in the prone position with optimally flexed lumbar spine ( Fig. 5.4 ).
Fig. 5.4
Patient positioning: flexed.
(Courtesy of Boston Scientific Corporation.)
- 2.
Identify level to be treated.
Use dilator assembly, hemostat, spinal needle, or K-wire to confirm midline and axial position ( Fig. 5.5 ). Single or biplane fluoroscopy may be used.
Fig. 5.5
Identify treatment level.
(Courtesy of Boston Scientific Corporation.)
- 3.
Identify the appropriate surgical level and accurate midline position using a spinal needle, dilator assembly, or scalpel with anterioposterior (AP) and lateral fluoroscopy.
After confirmation of the surgical level, create a 12–15 mm midline incision at the operable level with a scalpel ( Fig. 5.6 ). Dissect to the depth of the supraspinous ligament (SSL). Advance the blade with AP and lateral fluoroscopy to produce a longitudinal split of the SSL at midline ( Fig. 5.7 ).
Fig. 5.6
Skin incision.
(Courtesy of Boston Scientific Corporation.)Related posts:
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