J Korean Neurosurg Soc.  2014 May;55(5):261-266. 10.3340/jkns.2014.55.5.261.

A Morphometric Study of the Lumbar Interspinous Space in 100 Stanford University Medical Center Patients

• Jang D
• Park S

• KMID: 2018031
• DOI: http://doi.org/10.3340/jkns.2014.55.5.261

Abstract

OBJECTIVE
With the increased use of interspinous spacers in the treatment of lumbar stenosis, knowledge of the geometry of the interspinous space is important. To prevent dislodgment of an interspinous spacer, the accurate depth and width of the interspinous space needs to be established to facilitate the best intraoperative selection of correct spacer size.
METHODS
To determine the depth and width of the interspinous space, two methods are available which utilize plain film and magnetic resonance imaging (MRI). Data analysis of the interspinous depth and width was undertaken in 100 patients.
RESULTS
The standard deviations were variable, since skin thickness (zone 1) was altered by sex and age. The difference in the zone 1 distance between adjacent interspinous processes varied according to gender (p<0.05), but was not influenced by age [p=0.32 by analysis of variance between groups (ANOVA)]. Zone 2, the supraspinous, and zone 3, the interspinous ligament depths, comprise the operative working area during insertion of an interspinous spacer. There were no differences with regard to gender or age (p>0.05). For zones 6 and 7, the interspinous distances at the narrowest and widest points, respectively, were found to decrease with the aging process, but the decrease was not statistically significant. There were no differences with regard to gender (p>0.05).
CONCLUSION
This study provides additional information on the interspinous space. This statistical data are valuable for use in the design of interspinous spacers.

Keyword

Interspinous spacer; Interspinous space; Supraspinous ligament depth; Interspinous ligament depth; Interspinous distance

MeSH Terms

Academic Medical Centers*
Aging
Constriction, Pathologic
Humans
Ligaments
Magnetic Resonance Imaging
Skin
Statistics as Topic

Figure

• 

  Fig. 1 The geometry of the interspinous space is as follows : zone 1 : depth of skin level to spinous process; zone 2 : supraspinous ligament depth; zone 3 : interspinous ligament depth; zone 4 : the distance from the dural sheath to the surface of the ligamentum flavum (transversing the epidural fat+ligamentum flavum); zone 5 : the width of the thecal sac; zone 6 : interspinous distance (at the narrowest point); zone 7 : interspinous distance (at the widest point).

• 

  Fig. 2 The method of measuring zone 1 and zone 2+3 are shown in the above photographs. A : Zone 1, i.e., skin thickness, shown by the horizontal lines at each spinal level, is measured using a midline T2-weighted sagittal MRI image. B : Zone 2+3, the combination of supra- and interspinous ligaments, shown by the various measurements included above, is measured using a midline T2-weighted sagittal MRI image.

• 

  Fig. 3 The method of measuring zones 4 and 5. A : Zone 4, the distance from the dural sheath to the surface of the ligamentum flavum, is measured in this patient at L1-2 using a T2-weighted axial image. B : Zone 5, the anteroposterior width of the dural sac, is measured in an T2-weighted axial image shown here at L1-2.

• 

  Fig. 4 The method of measuring zones 6 and 7. A : Zone 6, the interspinous distance at the narrowest point, is measured on plain X-ray, as shown. B : Zone 7, the interspinous distance at the widest point, is measured on plain X-ray, also shown here.

• 

  Fig. 5 Skin thickness by gender (A) and ages (B).

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  Fig. 6 Interspinous distance : narrowest (zone 6) by gender (A) and ages (B).

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  Fig. 7 Interspinous distance : widest (zone 7) by gender (A) and ages (B).

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