Use of Supplemental Short Pre-Contoured Accessory Rods and Cobalt Chrome Alloy Posterior Rods Reduces Primary Rod Strain and Range of Motion Across the Pedicle Subtraction Osteotomy Level: An In Vitro Biomechanical Study

Dennis Winge Hallager; Poul Martin Gehrchen; Benny Dahl; Jonathan A Harris; Manasa Gudipally; Sean Jenkins; Ai-Min Wu; Brandon S Bucklen

doi:10.1097/BRS.0000000000001282

Use of Supplemental Short Pre-Contoured Accessory Rods and Cobalt Chrome Alloy Posterior Rods Reduces Primary Rod Strain and Range of Motion Across the Pedicle Subtraction Osteotomy Level: An In Vitro Biomechanical Study

Dennis Winge Hallager, Poul Martin Gehrchen, Benny Dahl, Jonathan A Harris, Manasa Gudipally, Sean Jenkins, Ai-Min Wu, Brandon S Bucklen

Department of Clinical Medicine

36 Citations (Scopus)

Abstract

Study Design. In vitro cadaveric biomechanical study. Objective. To assess effects of 4-rod reconstruction, rod material, and anterior column support on motion and surface rod strain in a pedicle subtraction osteotomy model. Summary of Background Data. Pedicle subtraction osteotomy (PSO) can correct significant sagittal deformity of the lumbar spine; however, revision rates are high. To reduce rod strain and the incidence of rod fracture, clinical use of multi-rod construction, cobalt chrome (CoCr) alloy rods, and interbody spacers adjacent to PSO has been proposed. Investigating both motion and rod strain is necessary to determine the biomechanical efficacy of these techniques. Methods. Five specimens (T12-S1) underwent PSO at L3 with pedicle screw stabilization at L1-S1. Pedicle subtraction was adjusted to achieve a final lordosis of 70°. Flexion-extension (FE), lateral bending, and axial rotation were applied. Linear strain gauges measured surface rod strain during FE on primary and accessory rods at PSO level. Testing evaluated (1) accessory rods (4-Rod) added at PSO level versus primary rods (2-Rod); (2) Ti versus CoCr rods; and (3) lateral interbody spacers (S) inserted adjacent to PSO. One-way and three-way analysis of variance was performed (P≤0.05). Results. All constructs significantly reduced FE and lateral bending motion relative to intact (P<0.001). The main effect of accessory rods in reducing FE motion was significant (P=0.021). Accessory and CoCr rods reduced relative surface strain on the primary rod, irrespective of construct (P<0.001). CoCr 4-Rod+S provided the greatest reduction in strain (76% decrease; P=0.003). Conclusion. Accessory and CoCr rods provided greatest reduction in motion and rod strain at PSO level. Interbody devices minimally affected motion-induced strain and might act primarily to maintain disc height. Clinicians must assess whether surface strain and motion reduction minimize the incidence of rod fracture.

Original language	English
Journal	Spine
Volume	41
Issue number	7
Pages (from-to)	E388-E395
ISSN	0362-2436
DOIs	https://doi.org/10.1097/BRS.0000000000001282
Publication status	Published - Apr 2016

Keywords

Biomechanical Phenomena
Chromium Alloys
Humans
Internal Fixators
Lumbar Vertebrae
Models, Biological
Osteotomy
Range of Motion, Articular
Spinal Fusion
Journal Article
Research Support, Non-U.S. Gov't

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Hallager, D. W., Gehrchen, P. M., Dahl, B., Harris, J. A., Gudipally, M., Jenkins, S., Wu, A.-M., & Bucklen, B. S. (2016). Use of Supplemental Short Pre-Contoured Accessory Rods and Cobalt Chrome Alloy Posterior Rods Reduces Primary Rod Strain and Range of Motion Across the Pedicle Subtraction Osteotomy Level: An In Vitro Biomechanical Study. Spine, 41(7), E388-E395. https://doi.org/10.1097/BRS.0000000000001282

Use of Supplemental Short Pre-Contoured Accessory Rods and Cobalt Chrome Alloy Posterior Rods Reduces Primary Rod Strain and Range of Motion Across the Pedicle Subtraction Osteotomy Level: An In Vitro Biomechanical Study. / Hallager, Dennis Winge; Gehrchen, Poul Martin; Dahl, Benny et al.
In: Spine, Vol. 41, No. 7, 04.2016, p. E388-E395.

Research output: Contribution to journal › Journal article › Research › peer-review

Hallager, DW, Gehrchen, PM, Dahl, B, Harris, JA, Gudipally, M, Jenkins, S, Wu, A-M & Bucklen, BS 2016, 'Use of Supplemental Short Pre-Contoured Accessory Rods and Cobalt Chrome Alloy Posterior Rods Reduces Primary Rod Strain and Range of Motion Across the Pedicle Subtraction Osteotomy Level: An In Vitro Biomechanical Study', Spine, vol. 41, no. 7, pp. E388-E395. https://doi.org/10.1097/BRS.0000000000001282

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title = "Use of Supplemental Short Pre-Contoured Accessory Rods and Cobalt Chrome Alloy Posterior Rods Reduces Primary Rod Strain and Range of Motion Across the Pedicle Subtraction Osteotomy Level: An In Vitro Biomechanical Study",

abstract = "Study Design. In vitro cadaveric biomechanical study. Objective. To assess effects of 4-rod reconstruction, rod material, and anterior column support on motion and surface rod strain in a pedicle subtraction osteotomy model. Summary of Background Data. Pedicle subtraction osteotomy (PSO) can correct significant sagittal deformity of the lumbar spine; however, revision rates are high. To reduce rod strain and the incidence of rod fracture, clinical use of multi-rod construction, cobalt chrome (CoCr) alloy rods, and interbody spacers adjacent to PSO has been proposed. Investigating both motion and rod strain is necessary to determine the biomechanical efficacy of these techniques. Methods. Five specimens (T12-S1) underwent PSO at L3 with pedicle screw stabilization at L1-S1. Pedicle subtraction was adjusted to achieve a final lordosis of 70°. Flexion-extension (FE), lateral bending, and axial rotation were applied. Linear strain gauges measured surface rod strain during FE on primary and accessory rods at PSO level. Testing evaluated (1) accessory rods (4-Rod) added at PSO level versus primary rods (2-Rod); (2) Ti versus CoCr rods; and (3) lateral interbody spacers (S) inserted adjacent to PSO. One-way and three-way analysis of variance was performed (P≤0.05). Results. All constructs significantly reduced FE and lateral bending motion relative to intact (P<0.001). The main effect of accessory rods in reducing FE motion was significant (P=0.021). Accessory and CoCr rods reduced relative surface strain on the primary rod, irrespective of construct (P<0.001). CoCr 4-Rod+S provided the greatest reduction in strain (76% decrease; P=0.003). Conclusion. Accessory and CoCr rods provided greatest reduction in motion and rod strain at PSO level. Interbody devices minimally affected motion-induced strain and might act primarily to maintain disc height. Clinicians must assess whether surface strain and motion reduction minimize the incidence of rod fracture.",

keywords = "Biomechanical Phenomena, Chromium Alloys, Humans, Internal Fixators, Lumbar Vertebrae, Models, Biological, Osteotomy, Range of Motion, Articular, Spinal Fusion, Journal Article, Research Support, Non-U.S. Gov't",

author = "Hallager, {Dennis Winge} and Gehrchen, {Poul Martin} and Benny Dahl and Harris, {Jonathan A} and Manasa Gudipally and Sean Jenkins and Ai-Min Wu and Bucklen, {Brandon S}",

year = "2016",

month = apr,

doi = "10.1097/BRS.0000000000001282",

language = "English",

volume = "41",

pages = "E388--E395",

journal = "Spine",

issn = "0362-2436",

publisher = "Lippincott Williams & Wilkins",

number = "7",

}

TY - JOUR

T1 - Use of Supplemental Short Pre-Contoured Accessory Rods and Cobalt Chrome Alloy Posterior Rods Reduces Primary Rod Strain and Range of Motion Across the Pedicle Subtraction Osteotomy Level

T2 - An In Vitro Biomechanical Study

AU - Hallager, Dennis Winge

AU - Gehrchen, Poul Martin

AU - Dahl, Benny

AU - Harris, Jonathan A

AU - Gudipally, Manasa

AU - Jenkins, Sean

AU - Wu, Ai-Min

AU - Bucklen, Brandon S

PY - 2016/4

Y1 - 2016/4

N2 - Study Design. In vitro cadaveric biomechanical study. Objective. To assess effects of 4-rod reconstruction, rod material, and anterior column support on motion and surface rod strain in a pedicle subtraction osteotomy model. Summary of Background Data. Pedicle subtraction osteotomy (PSO) can correct significant sagittal deformity of the lumbar spine; however, revision rates are high. To reduce rod strain and the incidence of rod fracture, clinical use of multi-rod construction, cobalt chrome (CoCr) alloy rods, and interbody spacers adjacent to PSO has been proposed. Investigating both motion and rod strain is necessary to determine the biomechanical efficacy of these techniques. Methods. Five specimens (T12-S1) underwent PSO at L3 with pedicle screw stabilization at L1-S1. Pedicle subtraction was adjusted to achieve a final lordosis of 70°. Flexion-extension (FE), lateral bending, and axial rotation were applied. Linear strain gauges measured surface rod strain during FE on primary and accessory rods at PSO level. Testing evaluated (1) accessory rods (4-Rod) added at PSO level versus primary rods (2-Rod); (2) Ti versus CoCr rods; and (3) lateral interbody spacers (S) inserted adjacent to PSO. One-way and three-way analysis of variance was performed (P≤0.05). Results. All constructs significantly reduced FE and lateral bending motion relative to intact (P<0.001). The main effect of accessory rods in reducing FE motion was significant (P=0.021). Accessory and CoCr rods reduced relative surface strain on the primary rod, irrespective of construct (P<0.001). CoCr 4-Rod+S provided the greatest reduction in strain (76% decrease; P=0.003). Conclusion. Accessory and CoCr rods provided greatest reduction in motion and rod strain at PSO level. Interbody devices minimally affected motion-induced strain and might act primarily to maintain disc height. Clinicians must assess whether surface strain and motion reduction minimize the incidence of rod fracture.

AB - Study Design. In vitro cadaveric biomechanical study. Objective. To assess effects of 4-rod reconstruction, rod material, and anterior column support on motion and surface rod strain in a pedicle subtraction osteotomy model. Summary of Background Data. Pedicle subtraction osteotomy (PSO) can correct significant sagittal deformity of the lumbar spine; however, revision rates are high. To reduce rod strain and the incidence of rod fracture, clinical use of multi-rod construction, cobalt chrome (CoCr) alloy rods, and interbody spacers adjacent to PSO has been proposed. Investigating both motion and rod strain is necessary to determine the biomechanical efficacy of these techniques. Methods. Five specimens (T12-S1) underwent PSO at L3 with pedicle screw stabilization at L1-S1. Pedicle subtraction was adjusted to achieve a final lordosis of 70°. Flexion-extension (FE), lateral bending, and axial rotation were applied. Linear strain gauges measured surface rod strain during FE on primary and accessory rods at PSO level. Testing evaluated (1) accessory rods (4-Rod) added at PSO level versus primary rods (2-Rod); (2) Ti versus CoCr rods; and (3) lateral interbody spacers (S) inserted adjacent to PSO. One-way and three-way analysis of variance was performed (P≤0.05). Results. All constructs significantly reduced FE and lateral bending motion relative to intact (P<0.001). The main effect of accessory rods in reducing FE motion was significant (P=0.021). Accessory and CoCr rods reduced relative surface strain on the primary rod, irrespective of construct (P<0.001). CoCr 4-Rod+S provided the greatest reduction in strain (76% decrease; P=0.003). Conclusion. Accessory and CoCr rods provided greatest reduction in motion and rod strain at PSO level. Interbody devices minimally affected motion-induced strain and might act primarily to maintain disc height. Clinicians must assess whether surface strain and motion reduction minimize the incidence of rod fracture.

KW - Biomechanical Phenomena

KW - Chromium Alloys

KW - Humans

KW - Internal Fixators

KW - Lumbar Vertebrae

KW - Models, Biological

KW - Osteotomy

KW - Range of Motion, Articular

KW - Spinal Fusion

KW - Journal Article

KW - Research Support, Non-U.S. Gov't

U2 - 10.1097/BRS.0000000000001282

DO - 10.1097/BRS.0000000000001282

M3 - Journal article

C2 - 27018904

SN - 0362-2436

VL - 41

SP - E388-E395

JO - Spine

JF - Spine

IS - 7

ER -