Abstract
Background Context
There have been conflicting results on the surgical outcome of lumbar fusion surgery
using two different techniques: robot-assisted pedicle screw fixation and conventional
freehand technique. In addition, there have been no studies about the biomechanical
issues between both techniques.
Purpose
This study aimed to investigate the biomechanical properties in terms of stress at
adjacent segments using robot-assisted pedicle screw insertion technique (robot-assisted,
minimally invasive posterior lumbar interbody fusion, Rom-PLIF) and freehand technique
(conventional, freehand, open approach, posterior lumbar interbody fusion, Cop-PLIF)
for instrumented lumbar fusion surgery.
Study Design
This is an additional post-hoc analysis for patient-specific finite element (FE) model.
Patient Sample
The sample is composed of patients with degenerative lumbar disease.
Outcome Measures
Intradiscal pressure and facet contact force are the outcome measures.
Methods
Patients were randomly assigned to undergo an instrumented PLIF procedure using a
Rom-PLIF (37 patients) or a Cop-PLIF (41), respectively. Five patients in each group
were selected using a simple random sampling method after operation, and 10 preoperative
and postoperative lumbar spines were modeled from preoperative high-resolution computed
tomography of 10 patients using the same method for a validated lumbar spine model.
Under four pure moments of 7.5 Nm, the changes in intradiscal pressure and facet joint
contact force at the proximal adjacent segment following fusion surgery were analyzed
and compared with preoperative states.
Results
The representativeness of random samples was verified. Both groups showed significant
increases in postoperative intradiscal pressure at the proximal adjacent segment under
four moments, compared with the preoperative state. The Cop-PLIF models demonstrated
significantly higher percent increments of intradiscal pressure at proximal adjacent
segments under extension, lateral bending, and torsion moments than the Rom-PLIF models
(p=.032, p=.008, and p=.016, respectively). Furthermore, the percent increment of
facet contact force was significantly higher in the Cop-PLIF models under extension
and torsion moments than in the Rom-PLIF models (p=.016 under both extension and torsion
moments).
Conclusions
The present study showed the clinical application of subject-specific FE analysis
in the spine. Even though there was biomechanical superiority of the robot-assisted
insertions in terms of alleviation of stress increments at adjacent segments after
fusion, cautious interpretation is needed because of the small sample size.
Keywords
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Article info
Publication history
Published online: November 17, 2016
Accepted:
November 14,
2016
Received in revised form:
October 19,
2016
Received:
March 22,
2016
Footnotes
FDA device/drug status: Approved (Renaissance).
Author disclosures: H-JK: Grant: Mazor Robotics (In kind, Paid to the institution), Medtronic (C, Paid to the institution), pertaining to submitted manuscript. K-TK: Grant: Mazor Robotics (In kind, Paid to the institution), Medtronic (C, Paid to the institution), pertaining to submitted manuscript. S-CP: Grant: Mazor Robotics (In kind, Paid to the institution), Medtronic (C, Paid to the institution), pertaining to submitted manuscript. O-HK: Nothing to disclose. JS: Nothing to disclose. B-SC: Nothing to disclose. C-KL: Nothing to disclose. JSY: Grant: Mazor Robotics (In kind, Paid to the institution), Medtronic (C, Paid to the institution), pertaining to submitted manuscript. LGL: Nothing to disclose.
The disclosure key can be found on the Table of Contents and at www.TheSpineJournalOnline.com.
Ho-Joong Kim and Kyoung-Tak Kang equally contributed to this work.
This study was partially supported in kind by Mazor Robotics and Medtronic Inc, which provided the robot system.
Identification
Copyright
© 2016 Elsevier Inc. All rights reserved.
