Abstract
Background: Although the rib cage provides substantial stability to the thoracic spine, few biomechanical studies have incorporated it into their testing model, and no studies have determined the influence of the rib cage on adjacent segment motion of long fusion constructs. The present biomechanical study aimed to determine the mechanical contribution of the intact rib cage during the testing of instrumented specimens. Methods: A cyclic loading (CL) protocol with instrumentation (T4–L2 pedicle screw-rod fixation) was conducted on five thoracic spines (C7–L2) with intact rib cages. Range of motion (±5 Nm pure moment) in flexion-extension, lateral bending, and axial rotation was captured for intact ribs, partial ribs, and no ribs conditions. Comparisons at the supra-adjacent (T2–T3), adjacent (T3–T4), first instrumented (T4–T5), and second instrumented (T5–T6) levels were made between conditions (P ≤ 0.05). Findings: A trend of increased motion at the adjacent level was seen for partial ribs and no ribs in all 3 bending modes. This trend was also observed at the supra-adjacent level for both conditions. No significant changes in motion compared to the intact ribs condition were seen at the first and second instrumented levels (P > 0.05). Interpretation: The segment adjacent to long fusion constructs, which may appear more grossly unstable when tested in the disarticulated spine, is reinforced by the rib cage. In order to avoid overestimating adjacent level motion, when testing the effectiveness of surgical techniques of the thoracic spine, inclusion of the rib cage may be warranted to better reflect clinical circumstances.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 217-222 |
| Number of pages | 6 |
| Journal | Clinical Biomechanics |
| Volume | 70 |
| DOIs | |
| State | Published - Dec 2019 |
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Keywords
- Adjacent segment motion
- Biomechanics
- Posterior instrumentation
- Rib cage
- Thoracic spine
ASJC Scopus subject areas
- Biophysics
- Orthopedics and Sports Medicine
Cite this
Stabilizing effect of the rib cage on adjacent segment motion following thoracolumbar posterior fixation of the human thoracic cadaveric spine : A biomechanical study. / Rahm, Mark D.; Brooks, Daina M.; Harris, Jonathan A.; Hart, Robert A.; Hughes, Jessica L.; Ferrick, Bryan J.; Bucklen, Brandon S.
In: Clinical Biomechanics, Vol. 70, 12.2019, p. 217-222.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Stabilizing effect of the rib cage on adjacent segment motion following thoracolumbar posterior fixation of the human thoracic cadaveric spine
T2 - A biomechanical study
AU - Rahm, Mark D.
AU - Brooks, Daina M.
AU - Harris, Jonathan A.
AU - Hart, Robert A.
AU - Hughes, Jessica L.
AU - Ferrick, Bryan J.
AU - Bucklen, Brandon S.
PY - 2019/12
Y1 - 2019/12
N2 - Background: Although the rib cage provides substantial stability to the thoracic spine, few biomechanical studies have incorporated it into their testing model, and no studies have determined the influence of the rib cage on adjacent segment motion of long fusion constructs. The present biomechanical study aimed to determine the mechanical contribution of the intact rib cage during the testing of instrumented specimens. Methods: A cyclic loading (CL) protocol with instrumentation (T4–L2 pedicle screw-rod fixation) was conducted on five thoracic spines (C7–L2) with intact rib cages. Range of motion (±5 Nm pure moment) in flexion-extension, lateral bending, and axial rotation was captured for intact ribs, partial ribs, and no ribs conditions. Comparisons at the supra-adjacent (T2–T3), adjacent (T3–T4), first instrumented (T4–T5), and second instrumented (T5–T6) levels were made between conditions (P ≤ 0.05). Findings: A trend of increased motion at the adjacent level was seen for partial ribs and no ribs in all 3 bending modes. This trend was also observed at the supra-adjacent level for both conditions. No significant changes in motion compared to the intact ribs condition were seen at the first and second instrumented levels (P > 0.05). Interpretation: The segment adjacent to long fusion constructs, which may appear more grossly unstable when tested in the disarticulated spine, is reinforced by the rib cage. In order to avoid overestimating adjacent level motion, when testing the effectiveness of surgical techniques of the thoracic spine, inclusion of the rib cage may be warranted to better reflect clinical circumstances.
AB - Background: Although the rib cage provides substantial stability to the thoracic spine, few biomechanical studies have incorporated it into their testing model, and no studies have determined the influence of the rib cage on adjacent segment motion of long fusion constructs. The present biomechanical study aimed to determine the mechanical contribution of the intact rib cage during the testing of instrumented specimens. Methods: A cyclic loading (CL) protocol with instrumentation (T4–L2 pedicle screw-rod fixation) was conducted on five thoracic spines (C7–L2) with intact rib cages. Range of motion (±5 Nm pure moment) in flexion-extension, lateral bending, and axial rotation was captured for intact ribs, partial ribs, and no ribs conditions. Comparisons at the supra-adjacent (T2–T3), adjacent (T3–T4), first instrumented (T4–T5), and second instrumented (T5–T6) levels were made between conditions (P ≤ 0.05). Findings: A trend of increased motion at the adjacent level was seen for partial ribs and no ribs in all 3 bending modes. This trend was also observed at the supra-adjacent level for both conditions. No significant changes in motion compared to the intact ribs condition were seen at the first and second instrumented levels (P > 0.05). Interpretation: The segment adjacent to long fusion constructs, which may appear more grossly unstable when tested in the disarticulated spine, is reinforced by the rib cage. In order to avoid overestimating adjacent level motion, when testing the effectiveness of surgical techniques of the thoracic spine, inclusion of the rib cage may be warranted to better reflect clinical circumstances.
KW - Adjacent segment motion
KW - Biomechanics
KW - Posterior instrumentation
KW - Rib cage
KW - Thoracic spine
UR - http://www.scopus.com/inward/record.url?scp=85073994891&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85073994891&partnerID=8YFLogxK
U2 - 10.1016/j.clinbiomech.2019.10.008
DO - 10.1016/j.clinbiomech.2019.10.008
M3 - Article
C2 - 31669919
AN - SCOPUS:85073994891
VL - 70
SP - 217
EP - 222
JO - Clinical Biomechanics
JF - Clinical Biomechanics
SN - 0268-0033
ER -