Abstract
Purpose: To discuss whether the standard test method for preclinical evaluation of posterior spine stabilization devices with an anterior support correctly describes the effect of two short-segment posterior stabilization techniques frequently used in clinical practice for the treatment of traumatic, degenerative and iatrogenic instabilities. Methods: A finite element study compared a validated instrumented L2–L4 segment undergoing standing, upper body flexion and extension to ISO 12189 standards model under a compressive load. A bridge instrumentation, with screws only at cranial and caudal levels, and a full stabilization, using screws at every level, are considered for both conditions. The internal loads on the spinal rod and the stress values on the implant are analysed in detail. Results: Using ISO model and a bridge stabilization construct allow to overstress the pedicle screw more than a full stabilization with respect to the corresponding L2–L4 segment undergoing upper body flexion, while the stress on the spinal rod is comparable. Choosing softer/stiffer springs would involve higher/lower loads on every component. Conclusions: ISO model predicts the effects of using both a full and a bridge posterior instrumentation. The study justifies the use of both conditions during in vitro reliability tests to achieve meaningful results easy to compare to clinically relevant loading modes and known in vivo failure modes.
| Original language | English |
|---|---|
| Pages (from-to) | 200-209 |
| Number of pages | 10 |
| Journal | European Spine Journal |
| Volume | 26 |
| Issue number | 1 |
| DOIs | |
| Publication status | Published - 2017 |
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Keywords
- Anterior support
- ASTM F1717
- Bridge instrumentation
- Finite element
- ISO 12189
- Preclinical evaluation
- Spine stabilization
- Standard
ASJC Scopus subject areas
- Surgery
- Orthopedics and Sports Medicine
Cite this
Preclinical evaluation of posterior spine stabilization devices : can we compare in vitro and in vivo loads on the instrumentation? / la Barbera, Luigi; Galbusera, Fabio; Wilke, Hans Joachim; Villa, Tomaso.
In: European Spine Journal, Vol. 26, No. 1, 2017, p. 200-209.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Preclinical evaluation of posterior spine stabilization devices
T2 - can we compare in vitro and in vivo loads on the instrumentation?
AU - la Barbera, Luigi
AU - Galbusera, Fabio
AU - Wilke, Hans Joachim
AU - Villa, Tomaso
PY - 2017
Y1 - 2017
N2 - Purpose: To discuss whether the standard test method for preclinical evaluation of posterior spine stabilization devices with an anterior support correctly describes the effect of two short-segment posterior stabilization techniques frequently used in clinical practice for the treatment of traumatic, degenerative and iatrogenic instabilities. Methods: A finite element study compared a validated instrumented L2–L4 segment undergoing standing, upper body flexion and extension to ISO 12189 standards model under a compressive load. A bridge instrumentation, with screws only at cranial and caudal levels, and a full stabilization, using screws at every level, are considered for both conditions. The internal loads on the spinal rod and the stress values on the implant are analysed in detail. Results: Using ISO model and a bridge stabilization construct allow to overstress the pedicle screw more than a full stabilization with respect to the corresponding L2–L4 segment undergoing upper body flexion, while the stress on the spinal rod is comparable. Choosing softer/stiffer springs would involve higher/lower loads on every component. Conclusions: ISO model predicts the effects of using both a full and a bridge posterior instrumentation. The study justifies the use of both conditions during in vitro reliability tests to achieve meaningful results easy to compare to clinically relevant loading modes and known in vivo failure modes.
AB - Purpose: To discuss whether the standard test method for preclinical evaluation of posterior spine stabilization devices with an anterior support correctly describes the effect of two short-segment posterior stabilization techniques frequently used in clinical practice for the treatment of traumatic, degenerative and iatrogenic instabilities. Methods: A finite element study compared a validated instrumented L2–L4 segment undergoing standing, upper body flexion and extension to ISO 12189 standards model under a compressive load. A bridge instrumentation, with screws only at cranial and caudal levels, and a full stabilization, using screws at every level, are considered for both conditions. The internal loads on the spinal rod and the stress values on the implant are analysed in detail. Results: Using ISO model and a bridge stabilization construct allow to overstress the pedicle screw more than a full stabilization with respect to the corresponding L2–L4 segment undergoing upper body flexion, while the stress on the spinal rod is comparable. Choosing softer/stiffer springs would involve higher/lower loads on every component. Conclusions: ISO model predicts the effects of using both a full and a bridge posterior instrumentation. The study justifies the use of both conditions during in vitro reliability tests to achieve meaningful results easy to compare to clinically relevant loading modes and known in vivo failure modes.
KW - Anterior support
KW - ASTM F1717
KW - Bridge instrumentation
KW - Finite element
KW - ISO 12189
KW - Preclinical evaluation
KW - Spine stabilization
KW - Standard
UR - http://www.scopus.com/inward/record.url?scp=84988353964&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84988353964&partnerID=8YFLogxK
U2 - 10.1007/s00586-016-4766-z
DO - 10.1007/s00586-016-4766-z
M3 - Article
AN - SCOPUS:84988353964
VL - 26
SP - 200
EP - 209
JO - European Spine Journal
JF - European Spine Journal
SN - 0940-6719
IS - 1
ER -