Biomechanical Effects of a Dynamic Topping off Instrumentation in a Long Rigid Pedicle Screw Construct

Michael Reichl, Rebecca A. Kueny, Reza Danyali, Peter Obid, Hüseyin Übeyli, Klaus Püschel, Michael M. Morlock, Gerd Huber, Thomas Niemeyer, Alexander Richter

Research output: Contribution to journalArticleResearchpeer-review

Abstract

Study Design: Biomechanical ex vivo study. 

Objective: To determine if topping off instrumentation can reduce the hypermobility in the adjacent segments when compared with the classic rigid spinal instrumentation. 

Summary of the Background Data: Long rigid instrumentation might increase the mechanical load in the adjacent segments, the resulting hypermobility, and the risk for adjacent segment disease. Topping off instrumentation intends to reduce the hypermobility at the adjacent level by more evenly distributing segmental motion and, thereby, potentially mitigating adjacent level disease. 

Materials and Methods: Eight human spines (Th12-L5) were divided into 2 groups. In the rigid group, a 3-segment metal rod instrumentation (L2-L5) was performed. The hybrid group included a 2-segment metal rod instrumentation (L3-L5) with a dynamic topping off instrumentation (L2-L3). Each specimen was tested consecutively in 3 different configurations: native (N=8), 2-segment rod instrumentation (L3-L5, N=8), 3-segment instrumentation (rigid: N=4, hybrid: N=4). For each configuration the range of motion (ROM) of the whole spine and each level was measured by a motion capture system during 5 cycles of extension-flexion (angle controlled to ±5 degrees, 0.1 Hz frequency, no preload). 

Results: In comparison with the intact spine, both the rigid 3-segment instrumentation and the hybrid instrumentation significantly reduced the ROM in the instrumented segments (L2-L5) while increasing the movement in the adjacent segment L1-L2 (P=0.002, η 2 =0.82) and in Th12-L1 (P<0.001, η 2 =0.90). There were no ROM differences between the rigid and hybrid instrumentation in all segments. 

Conclusions: Introducing the dynamic topping off did not impart any significant difference in the segmental motion when compared with the rigid instrumentation. Therefore, the current biomechanical study could not show a benefit of using this specific topping off instrumentation to solve the problem of adjacent segment disease.

Original languageEnglish
Pages (from-to)E440-E447
Number of pages8
JournalClinical Spine Surgery
Volume30
Issue number4
DOIs
Publication statusPublished - May 2017
Externally publishedYes

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Articular Range of Motion
Spine
Metals
Pedicle Screws

Cite this

Reichl, Michael ; Kueny, Rebecca A. ; Danyali, Reza ; Obid, Peter ; Übeyli, Hüseyin ; Püschel, Klaus ; Morlock, Michael M. ; Huber, Gerd ; Niemeyer, Thomas ; Richter, Alexander. / Biomechanical Effects of a Dynamic Topping off Instrumentation in a Long Rigid Pedicle Screw Construct. In: Clinical Spine Surgery. 2017 ; Vol. 30, No. 4. pp. E440-E447.
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title = "Biomechanical Effects of a Dynamic Topping off Instrumentation in a Long Rigid Pedicle Screw Construct",
abstract = "Study Design: Biomechanical ex vivo study. Objective: To determine if topping off instrumentation can reduce the hypermobility in the adjacent segments when compared with the classic rigid spinal instrumentation. Summary of the Background Data: Long rigid instrumentation might increase the mechanical load in the adjacent segments, the resulting hypermobility, and the risk for adjacent segment disease. Topping off instrumentation intends to reduce the hypermobility at the adjacent level by more evenly distributing segmental motion and, thereby, potentially mitigating adjacent level disease. Materials and Methods: Eight human spines (Th12-L5) were divided into 2 groups. In the rigid group, a 3-segment metal rod instrumentation (L2-L5) was performed. The hybrid group included a 2-segment metal rod instrumentation (L3-L5) with a dynamic topping off instrumentation (L2-L3). Each specimen was tested consecutively in 3 different configurations: native (N=8), 2-segment rod instrumentation (L3-L5, N=8), 3-segment instrumentation (rigid: N=4, hybrid: N=4). For each configuration the range of motion (ROM) of the whole spine and each level was measured by a motion capture system during 5 cycles of extension-flexion (angle controlled to ±5 degrees, 0.1 Hz frequency, no preload). Results: In comparison with the intact spine, both the rigid 3-segment instrumentation and the hybrid instrumentation significantly reduced the ROM in the instrumented segments (L2-L5) while increasing the movement in the adjacent segment L1-L2 (P=0.002, η 2 =0.82) and in Th12-L1 (P<0.001, η 2 =0.90). There were no ROM differences between the rigid and hybrid instrumentation in all segments. Conclusions: Introducing the dynamic topping off did not impart any significant difference in the segmental motion when compared with the rigid instrumentation. Therefore, the current biomechanical study could not show a benefit of using this specific topping off instrumentation to solve the problem of adjacent segment disease.",
keywords = "adjacent segment degeneration, dynamic stabilization, hybrid construct, lumbar spine",
author = "Michael Reichl and Kueny, {Rebecca A.} and Reza Danyali and Peter Obid and H{\"u}seyin {\"U}beyli and Klaus P{\"u}schel and Morlock, {Michael M.} and Gerd Huber and Thomas Niemeyer and Alexander Richter",
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Reichl, M, Kueny, RA, Danyali, R, Obid, P, Übeyli, H, Püschel, K, Morlock, MM, Huber, G, Niemeyer, T & Richter, A 2017, 'Biomechanical Effects of a Dynamic Topping off Instrumentation in a Long Rigid Pedicle Screw Construct', Clinical Spine Surgery, vol. 30, no. 4, pp. E440-E447. https://doi.org/10.1097/BSD.0000000000000244

Biomechanical Effects of a Dynamic Topping off Instrumentation in a Long Rigid Pedicle Screw Construct. / Reichl, Michael; Kueny, Rebecca A.; Danyali, Reza; Obid, Peter; Übeyli, Hüseyin; Püschel, Klaus; Morlock, Michael M.; Huber, Gerd; Niemeyer, Thomas; Richter, Alexander.

In: Clinical Spine Surgery, Vol. 30, No. 4, 05.2017, p. E440-E447.

Research output: Contribution to journalArticleResearchpeer-review

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T1 - Biomechanical Effects of a Dynamic Topping off Instrumentation in a Long Rigid Pedicle Screw Construct

AU - Reichl, Michael

AU - Kueny, Rebecca A.

AU - Danyali, Reza

AU - Obid, Peter

AU - Übeyli, Hüseyin

AU - Püschel, Klaus

AU - Morlock, Michael M.

AU - Huber, Gerd

AU - Niemeyer, Thomas

AU - Richter, Alexander

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N2 - Study Design: Biomechanical ex vivo study. Objective: To determine if topping off instrumentation can reduce the hypermobility in the adjacent segments when compared with the classic rigid spinal instrumentation. Summary of the Background Data: Long rigid instrumentation might increase the mechanical load in the adjacent segments, the resulting hypermobility, and the risk for adjacent segment disease. Topping off instrumentation intends to reduce the hypermobility at the adjacent level by more evenly distributing segmental motion and, thereby, potentially mitigating adjacent level disease. Materials and Methods: Eight human spines (Th12-L5) were divided into 2 groups. In the rigid group, a 3-segment metal rod instrumentation (L2-L5) was performed. The hybrid group included a 2-segment metal rod instrumentation (L3-L5) with a dynamic topping off instrumentation (L2-L3). Each specimen was tested consecutively in 3 different configurations: native (N=8), 2-segment rod instrumentation (L3-L5, N=8), 3-segment instrumentation (rigid: N=4, hybrid: N=4). For each configuration the range of motion (ROM) of the whole spine and each level was measured by a motion capture system during 5 cycles of extension-flexion (angle controlled to ±5 degrees, 0.1 Hz frequency, no preload). Results: In comparison with the intact spine, both the rigid 3-segment instrumentation and the hybrid instrumentation significantly reduced the ROM in the instrumented segments (L2-L5) while increasing the movement in the adjacent segment L1-L2 (P=0.002, η 2 =0.82) and in Th12-L1 (P<0.001, η 2 =0.90). There were no ROM differences between the rigid and hybrid instrumentation in all segments. Conclusions: Introducing the dynamic topping off did not impart any significant difference in the segmental motion when compared with the rigid instrumentation. Therefore, the current biomechanical study could not show a benefit of using this specific topping off instrumentation to solve the problem of adjacent segment disease.

AB - Study Design: Biomechanical ex vivo study. Objective: To determine if topping off instrumentation can reduce the hypermobility in the adjacent segments when compared with the classic rigid spinal instrumentation. Summary of the Background Data: Long rigid instrumentation might increase the mechanical load in the adjacent segments, the resulting hypermobility, and the risk for adjacent segment disease. Topping off instrumentation intends to reduce the hypermobility at the adjacent level by more evenly distributing segmental motion and, thereby, potentially mitigating adjacent level disease. Materials and Methods: Eight human spines (Th12-L5) were divided into 2 groups. In the rigid group, a 3-segment metal rod instrumentation (L2-L5) was performed. The hybrid group included a 2-segment metal rod instrumentation (L3-L5) with a dynamic topping off instrumentation (L2-L3). Each specimen was tested consecutively in 3 different configurations: native (N=8), 2-segment rod instrumentation (L3-L5, N=8), 3-segment instrumentation (rigid: N=4, hybrid: N=4). For each configuration the range of motion (ROM) of the whole spine and each level was measured by a motion capture system during 5 cycles of extension-flexion (angle controlled to ±5 degrees, 0.1 Hz frequency, no preload). Results: In comparison with the intact spine, both the rigid 3-segment instrumentation and the hybrid instrumentation significantly reduced the ROM in the instrumented segments (L2-L5) while increasing the movement in the adjacent segment L1-L2 (P=0.002, η 2 =0.82) and in Th12-L1 (P<0.001, η 2 =0.90). There were no ROM differences between the rigid and hybrid instrumentation in all segments. Conclusions: Introducing the dynamic topping off did not impart any significant difference in the segmental motion when compared with the rigid instrumentation. Therefore, the current biomechanical study could not show a benefit of using this specific topping off instrumentation to solve the problem of adjacent segment disease.

KW - adjacent segment degeneration

KW - dynamic stabilization

KW - hybrid construct

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