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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

An example lateral fluoroscopic view of a lumbar specimen with the implant in place A) prior to manual distraction and B) after manual distraction is complete. Black arrows show the change in displacement of the distraction rod and the white arrows show the resulting change in the neuroforamen.
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Figure 0004: An example lateral fluoroscopic view of a lumbar specimen with the implant in place A) prior to manual distraction and B) after manual distraction is complete. Black arrows show the change in displacement of the distraction rod and the white arrows show the resulting change in the neuroforamen.

Mentions: Following confirmation of acceptable implant placement using fluoroscopy, the neuroforaminal height was measured bilaterally at both L4-L5 and L5-S1. Then graduated distraction at L5-S1 was started. The screwdriver for L5-S1distraction was inserted and rotated until the L4-L5 rod and S1 anchor were engaged by the distracting mechanism. An increase in resistance to the rotation of the screwdriver signaled the beginning of the distraction of the L5-S1 disc space. Distraction was carried out by rotating the screwdriver through 180 degrees (a half a revolution at a time) and then measuring the neuroforaminal heights of L4-5 and L5-S1. This process was continued till the screwdriver lost resistance or the implant was seen backing out at the sacrum. C arm images were taken at regular intervals to monitor the distraction process and to evaluate the implant for loosening. Figure 4 shows C arm images before and after distraction at the L5-S1 disc space in one of the cadavers.


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)

An example lateral fluoroscopic view of a lumbar specimen with the implant in place A) prior to manual distraction and B) after manual distraction is complete. Black arrows show the change in displacement of the distraction rod and the white arrows show the resulting change in the neuroforamen.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 0004: An example lateral fluoroscopic view of a lumbar specimen with the implant in place A) prior to manual distraction and B) after manual distraction is complete. Black arrows show the change in displacement of the distraction rod and the white arrows show the resulting change in the neuroforamen.
Mentions: Following confirmation of acceptable implant placement using fluoroscopy, the neuroforaminal height was measured bilaterally at both L4-L5 and L5-S1. Then graduated distraction at L5-S1 was started. The screwdriver for L5-S1distraction was inserted and rotated until the L4-L5 rod and S1 anchor were engaged by the distracting mechanism. An increase in resistance to the rotation of the screwdriver signaled the beginning of the distraction of the L5-S1 disc space. Distraction was carried out by rotating the screwdriver through 180 degrees (a half a revolution at a time) and then measuring the neuroforaminal heights of L4-5 and L5-S1. This process was continued till the screwdriver lost resistance or the implant was seen backing out at the sacrum. C arm images were taken at regular intervals to monitor the distraction process and to evaluate the implant for loosening. Figure 4 shows C arm images before and after distraction at the L5-S1 disc space in one of the cadavers.

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