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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

Components of the AxiALIF 2 level implant. Indirect distraction at L4-5 is created as a result of a variable thread pitch of the L4-5 component. Manual indirect distraction at L5-S1 is created by rotating the distraction rod and the S1 anchor components.
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Figure 0003: Components of the AxiALIF 2 level implant. Indirect distraction at L4-5 is created as a result of a variable thread pitch of the L4-5 component. Manual indirect distraction at L5-S1 is created by rotating the distraction rod and the S1 anchor components.

Mentions: After discectomy the size of the presacral implant (Trans1, Inc., Wilmington, NC, model AxiaLIF 2L + ) to be inserted was finalized using c arm images and standard templates provided by the manufacturer. Bone graft was not inserted into the disc spaces for the cadaveric procedure. The implant was a 2 piece assembly that consisted of the L4-L5 rod and the sacral anchor lagged together by a distraction rod. The L4-L5 disc space is distracted by the pitch differential between the L4 and L5 components of the L4-L5 rod (Figure 3). The L5-S1 disc space is distracted manually by a screw driver that engages the distraction rod that lags the L4-L5 rod with the S1 anchor (Figure 3). At L4-L5 various levels of pitch differential are available and a pitch differential level of 10-12 was used in this study. This is the maximum pitch differential offered with the implant and meant there were 10 threads per inch in the L5 section and 12 threads per inch in the L4 section of the L4-L5 rod. A fixation rod locked the implant after completion of manual distraction (Figure 3).


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)

Components of the AxiALIF 2 level implant. Indirect distraction at L4-5 is created as a result of a variable thread pitch of the L4-5 component. Manual indirect distraction at L5-S1 is created by rotating the distraction rod and the S1 anchor components.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 0003: Components of the AxiALIF 2 level implant. Indirect distraction at L4-5 is created as a result of a variable thread pitch of the L4-5 component. Manual indirect distraction at L5-S1 is created by rotating the distraction rod and the S1 anchor components.
Mentions: After discectomy the size of the presacral implant (Trans1, Inc., Wilmington, NC, model AxiaLIF 2L + ) to be inserted was finalized using c arm images and standard templates provided by the manufacturer. Bone graft was not inserted into the disc spaces for the cadaveric procedure. The implant was a 2 piece assembly that consisted of the L4-L5 rod and the sacral anchor lagged together by a distraction rod. The L4-L5 disc space is distracted by the pitch differential between the L4 and L5 components of the L4-L5 rod (Figure 3). The L5-S1 disc space is distracted manually by a screw driver that engages the distraction rod that lags the L4-L5 rod with the S1 anchor (Figure 3). At L4-L5 various levels of pitch differential are available and a pitch differential level of 10-12 was used in this study. This is the maximum pitch differential offered with the implant and meant there were 10 threads per inch in the L5 section and 12 threads per inch in the L4 section of the L4-L5 rod. A fixation rod locked the implant after completion of manual distraction (Figure 3).

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