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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

Posterior view of a rendering of two lumbar vertebrae depicting the neuroforaminal height measurement (black line).
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Figure 0001: Posterior view of a rendering of two lumbar vertebrae depicting the neuroforaminal height measurement (black line).

Mentions: Each specimen was warmed to room temperature before the procedure to avoid effects of temperature on the nitinol components of the instrumentation system. Neuroforaminal height measures were initially collected prior to the procedure. A manual caliper (accuracy of 0.05mm) was used to measure the foraminal height. This technique was adopted because this technique has shown a lower interobserver and intraobserver variability (κ = 0.79 and 0.81, respectively) compared with measurements performed on CT scans or silicon molds of the foramen (κ<0.76 and κ<0.65, respectively).2 All measurements were performed using the same technique. The vertical dimension, or foraminal height, is the shortest distance between the inferior cortex of the upper pedicle and the superior cortex of the lower pedicle. At both L4 and L5 the inferior surface of the pedicle exhibits a concave shape and has an oblique orientation in the coronal plane, the medial border being located cranially with respect to the lateral border, which thus represents the most inferior portion of the pedicle. This inferolateral border, however, is usually located laterally to the top of the pedicle below; therefore, it cannot be used as a bony landmark for the measurement of the foraminal height. So at both L4–L5 and L5–S1 the narrowest vertical diameter through which the nerve root has to pass was measured as a vertical line drawn from the top of the lower pedicle to the inferior border of the upper pedicle (Figure 1). Bilateral neuroforaminal heights at both L5-S1 and L4-L5 were measured preoperatively and recorded as baseline measures.


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)

Posterior view of a rendering of two lumbar vertebrae depicting the neuroforaminal height measurement (black line).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 0001: Posterior view of a rendering of two lumbar vertebrae depicting the neuroforaminal height measurement (black line).
Mentions: Each specimen was warmed to room temperature before the procedure to avoid effects of temperature on the nitinol components of the instrumentation system. Neuroforaminal height measures were initially collected prior to the procedure. A manual caliper (accuracy of 0.05mm) was used to measure the foraminal height. This technique was adopted because this technique has shown a lower interobserver and intraobserver variability (κ = 0.79 and 0.81, respectively) compared with measurements performed on CT scans or silicon molds of the foramen (κ<0.76 and κ<0.65, respectively).2 All measurements were performed using the same technique. The vertical dimension, or foraminal height, is the shortest distance between the inferior cortex of the upper pedicle and the superior cortex of the lower pedicle. At both L4 and L5 the inferior surface of the pedicle exhibits a concave shape and has an oblique orientation in the coronal plane, the medial border being located cranially with respect to the lateral border, which thus represents the most inferior portion of the pedicle. This inferolateral border, however, is usually located laterally to the top of the pedicle below; therefore, it cannot be used as a bony landmark for the measurement of the foraminal height. So at both L4–L5 and L5–S1 the narrowest vertical diameter through which the nerve root has to pass was measured as a vertical line drawn from the top of the lower pedicle to the inferior border of the upper pedicle (Figure 1). Bilateral neuroforaminal heights at both L5-S1 and L4-L5 were measured preoperatively and recorded as baseline measures.

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