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Changes in neuroforaminal height with 2 level axial presacral lumbar interbody fusion at L4-S1.

Marawar S, Ordway N, Jung J, Sun M - Int J Spine Surg (2014)

Bottom Line: When the neuroforaminal height was plotted against amount of rotation of the screw driver it was found that the neuroforaminal height at L5-S1 increased by 1mm on average for every complete revolution of the screw driver.At least 2 full rotations of the screw driver were achieved in all cadavers.The transsacral screw construct distracted the disc space and neuroforaminal height in a cadaveric spine model without soft tissue envelope.

View Article: PubMed Central - PubMed

Affiliation: Orthopedic Surgery, SUNY Upstate Medical University.

ABSTRACT

Background: The objective was to examine the changes in neuroforaminal height at L4-L5 and L5-S1 after insertion and graduated foraminal distraction using the 2 level transsacral implant in a cadaveric model.

Methods: Discectomy and transsacral instrumentation was performed in six fresh human cadavers at L4-S1. The neuroforaminal height was measured at L4-L5 and L5-S1 before and after insertion of the implant and then at each stage of manual distraction.

Results: Mean L4-5 neuroforaminal height increased from 18.2 ± 3.1mm to 20.3± 2.9mm (11%) on the left and from 18.8±2.8mm to 20.6± 2.3mm (12%) on the right (P<0.05). Mean L5-S1 neuroforaminal height increased from 15.7±3.0mm to 18.4 ±2.8mm (17%) on the left and from 15.6 ±2.1mm to 18.3 ±1.8mm (17%) on the right (P<0.05). When the neuroforaminal height was plotted against amount of rotation of the screw driver it was found that the neuroforaminal height at L5-S1 increased by 1mm on average for every complete revolution of the screw driver. At least 2 full rotations of the screw driver were achieved in all cadavers.

Conclusions: The transsacral screw construct distracted the disc space and neuroforaminal height in a cadaveric spine model without soft tissue envelope. During the initial process, manual control of disc space distraction predictably correlated with the increase in the neuroforaminal height to a maximum. However, further research is needed to look at variables affecting disc space pliability, implant subsidence, in vivo application, and clinical benefit of this procedure.

No MeSH data available.


Related in: MedlinePlus

The change in mean neuroforaminal height at L5-S1 based on the number of revolutions (turns) of the distraction rod. Changes in neuroforaminal height are similar between the left and right side and are approximately 1mm/revolution.
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Figure 0005: The change in mean neuroforaminal height at L5-S1 based on the number of revolutions (turns) of the distraction rod. Changes in neuroforaminal height are similar between the left and right side and are approximately 1mm/revolution.

Mentions: Mean L4-5 neuroforaminal height increased from 18.2 ± 3.1mm to 20.3 ± 2.9mm on the left and from 18.8 ± 2.8mm to 20.6 ± 2.3mm on the right. This represented a statistically significant increase of 11% on the left and and 12% on the right (P<0.05). Mean L5-S1 neuroforaminal height increased from 15.7 ± 3.0mm to 18.4 ± 2.8mm on the left and from 15.6 ± 2.1mm to 18.3 ± 1.8mm on the right. This represented a statistically significant increase of 17% on both sides at L5-S1 (P<0.05). Figure 5 shows the increase in neuroforaminal height at L5-S1 as the disc space is distracted. The slope was significantly greater than zero with approximately 1mm gain in neuroforaminal height per revolution of the driver. Technically it meant the neuroforamen distracted by 1mm on average for every complete revolution of the screw driver. Maximum distraction occurred between 2-3.5 revolutions of the driver. On continued attempts at distraction the screw started backing out at the sacral end. In each cadaver at least 2 full revolutions of screwdriver were allowed before the screw started backing out. Two out of the 5 cadavers allowed 3 turns, while one cadaver allowed 3.5 turns of distraction. As the disc space reached the point of maximum distraction the resistance to further distraction was found to increase exponentially. On continued attempts at distraction a clear give way was felt as screw started backing out at the sacral end. In the youngest lumbar specimen (which was 28 years of age), it was impossible to rotate the screw any further beyond maximum distraction. In addition, the screw did not back out on attempts at further distraction. There were no significant differences between the left and right neuroforaminal height measurements.


Changes in neuroforaminal height with 2 level axial presacral lumbar interbody fusion at L4-S1.

Marawar S, Ordway N, Jung J, Sun M - Int J Spine Surg (2014)

The change in mean neuroforaminal height at L5-S1 based on the number of revolutions (turns) of the distraction rod. Changes in neuroforaminal height are similar between the left and right side and are approximately 1mm/revolution.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4325505&req=5

Figure 0005: The change in mean neuroforaminal height at L5-S1 based on the number of revolutions (turns) of the distraction rod. Changes in neuroforaminal height are similar between the left and right side and are approximately 1mm/revolution.
Mentions: Mean L4-5 neuroforaminal height increased from 18.2 ± 3.1mm to 20.3 ± 2.9mm on the left and from 18.8 ± 2.8mm to 20.6 ± 2.3mm on the right. This represented a statistically significant increase of 11% on the left and and 12% on the right (P<0.05). Mean L5-S1 neuroforaminal height increased from 15.7 ± 3.0mm to 18.4 ± 2.8mm on the left and from 15.6 ± 2.1mm to 18.3 ± 1.8mm on the right. This represented a statistically significant increase of 17% on both sides at L5-S1 (P<0.05). Figure 5 shows the increase in neuroforaminal height at L5-S1 as the disc space is distracted. The slope was significantly greater than zero with approximately 1mm gain in neuroforaminal height per revolution of the driver. Technically it meant the neuroforamen distracted by 1mm on average for every complete revolution of the screw driver. Maximum distraction occurred between 2-3.5 revolutions of the driver. On continued attempts at distraction the screw started backing out at the sacral end. In each cadaver at least 2 full revolutions of screwdriver were allowed before the screw started backing out. Two out of the 5 cadavers allowed 3 turns, while one cadaver allowed 3.5 turns of distraction. As the disc space reached the point of maximum distraction the resistance to further distraction was found to increase exponentially. On continued attempts at distraction a clear give way was felt as screw started backing out at the sacral end. In the youngest lumbar specimen (which was 28 years of age), it was impossible to rotate the screw any further beyond maximum distraction. In addition, the screw did not back out on attempts at further distraction. There were no significant differences between the left and right neuroforaminal height measurements.

Bottom Line: When the neuroforaminal height was plotted against amount of rotation of the screw driver it was found that the neuroforaminal height at L5-S1 increased by 1mm on average for every complete revolution of the screw driver.At least 2 full rotations of the screw driver were achieved in all cadavers.The transsacral screw construct distracted the disc space and neuroforaminal height in a cadaveric spine model without soft tissue envelope.

View Article: PubMed Central - PubMed

Affiliation: Orthopedic Surgery, SUNY Upstate Medical University.

ABSTRACT

Background: The objective was to examine the changes in neuroforaminal height at L4-L5 and L5-S1 after insertion and graduated foraminal distraction using the 2 level transsacral implant in a cadaveric model.

Methods: Discectomy and transsacral instrumentation was performed in six fresh human cadavers at L4-S1. The neuroforaminal height was measured at L4-L5 and L5-S1 before and after insertion of the implant and then at each stage of manual distraction.

Results: Mean L4-5 neuroforaminal height increased from 18.2 ± 3.1mm to 20.3± 2.9mm (11%) on the left and from 18.8±2.8mm to 20.6± 2.3mm (12%) on the right (P<0.05). Mean L5-S1 neuroforaminal height increased from 15.7±3.0mm to 18.4 ±2.8mm (17%) on the left and from 15.6 ±2.1mm to 18.3 ±1.8mm (17%) on the right (P<0.05). When the neuroforaminal height was plotted against amount of rotation of the screw driver it was found that the neuroforaminal height at L5-S1 increased by 1mm on average for every complete revolution of the screw driver. At least 2 full rotations of the screw driver were achieved in all cadavers.

Conclusions: The transsacral screw construct distracted the disc space and neuroforaminal height in a cadaveric spine model without soft tissue envelope. During the initial process, manual control of disc space distraction predictably correlated with the increase in the neuroforaminal height to a maximum. However, further research is needed to look at variables affecting disc space pliability, implant subsidence, in vivo application, and clinical benefit of this procedure.

No MeSH data available.


Related in: MedlinePlus