- Email: [email protected]
The comparison of pedicle screw and cortical screw in posterior lumbar interbody fusion: a prospective randomized noninferiority trial
Accepted Manuscript The Comparison of Pedicle Screw and Cortical Screw in Posterior Lumbar Inter-body Fusion: a Prospective Randomized Non-inferiority Trial Gun Woo Lee, MD, Jung-Hwan Son, MD, Myun-Whan Ahn, MD, Ho-Joong Kim, MD, Jin S. Yeom, MD PII:
S1529-9430(15)00204-1
DOI:
10.1016/j.spinee.2015.02.038
Reference:
SPINEE 56221
To appear in:
The Spine Journal
Received Date: 6 June 2014 Revised Date:
15 January 2015
Accepted Date: 18 February 2015
Please cite this article as: Lee GW, Son J-H, Ahn M-W, Kim H-J, Yeom JS, The Comparison of Pedicle Screw and Cortical Screw in Posterior Lumbar Inter-body Fusion: a Prospective Randomized Noninferiority Trial, The Spine Journal (2015), doi: 10.1016/j.spinee.2015.02.038. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
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The Comparison of Pedicle Screw and Cortical Screw in Posterior Lumbar Inter-
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body Fusion: a Prospective Randomized Non-inferiority Trial
Gun Woo Lee, MDa,*, Jung-Hwan Son, MDb, Myun-Whan Ahn, MDc, Ho-Joong Kim,
a
Department of Orthopaedic Surgery, Armed Forces Yangju Hospital, Yangju, 482-863,
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Republic of Korea b
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MDd, Jin S. Yeom, MDd
Department of Orthopaedic Surgery, Kosin University Gospel Hospital, Busan, Republic of Korea
c
Spine Centrer and Department of Orthopaedic Surgery, Yeungnam University Hospital, Daegu, Republic of Korea
Spine Centrer and Department of Orthopaedic Surgery, Seoul National University College
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of Medicine and Seoul National University Bundang Hospital, Sungnam, Korea
* Corresponding author: Gun Woo Lee, MD
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Department of Orthopaedic Surgery, Armed Forces Yangju Hospital, Yongam-ri, 49-1, Eunhyeon-myeon, Yangju-si Gyeonggi-do, 482-863, Republic of Korea Tel: 82-31-863-1319 E-mail address: [email protected]
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Running Head:
Comparison of PS and CS in PLIF
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Acknowledgements: none
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ACCEPTED MANUSCRIPT Comparison of PS and CS in PLIF
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Abstract
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Background Context:
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body fusion (PLIF), but several drawbacks of PS, including the risk of superior facet joint
4
violation and muscle injury, have also pointed out. Recently, cortical screws (CS) were
5
invented, which can be placed without the drawbacks associated with PS. However,
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whether or not CS in PLIF can provide similar or greater clinical and radiological outcomes
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compared to those of PS has not been fully evaluated in clinical research studies.
8
Purpose: To evaluate whether the CS provides similar results to the PS in PLIF, in terms
9
of fusion rate, clinical and surgical outcomes, and complications.
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Pedicle screws (PS) offer great benefits in posterior lumbar inter-
Study Design:
Prospective, randomized, non-inferiority trial
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Patient Sample: Seventy-nine eligible patients were randomly assigned to either group A
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(39 patients), for which PS was utilized, or group B (40 patients), for which CS was
13
utilized.
14
Outcome Measure:
15
dynamic radiographs and CT scans. Secondary endpoints included intensity of lower back
16
pain and pain radiating to the leg using visual analogue scales, and also, functional status
17
using the Oswestry disability index, surgical morbidity, and additional outcomes such as
18
pedicle fracture and mechanical failure.
19
Methods:
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PLIF compared to PS, we compared fusion rates, clinical outcomes, and complications after
21
surgery in both groups.
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any form have been or will be received from a commercial party related directly or
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indirectly to the subject of this manuscript.
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The primary study endpoint was to measure fusion rate using
We compared baseline data in both groups.
To evaluate the efficacy of CS in
No funds were received in support of this work.
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No benefits in
ACCEPTED MANUSCRIPT Comparison of PS and CS in PLIF
Results:
At the six- and twelve-month follow-up points, similar fusion rates were
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observed in both groups (P = 0.81 and 0.61, respectively). According to the clinical
3
outcome, CS provided similar improvements in pain amelioration and functional status
4
compared to PS, with no significant differences.
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less surgical morbidity, including shorter incision length, quicker operative time, and less
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blood loss, compared to PS.
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Conclusion:
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PS in PLIF.
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PS in PLIF.
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Additionally, CS resulted in significantly
CS in PLIF provides similar clinical and radiological outcomes compared to
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Based on the current study, we suggest CS to be a reasonable alternative to
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ACCEPTED MANUSCRIPT Comparison of PS and CS in PLIF
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INTRODUCTION Posterior lumbar inter-body fusion (PLIF) surgery with pedicle screw (PS) has recently been widely used as an effective surgical method for certain lumbar pathologies
4
such as spondylolisthesis [1-5].
5
fusion surgery of the lumbar spine due to its advantages [3,6-11].
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regarding PS include the risk of superior facet joint violation during screw placement or
7
dissection, the skin incision length, and the amount of lateral muscle dissection due to the
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entry point being lateral to the midline, near the lateral wall of facet joint.
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drawbacks, there was little choice for spine surgeons but to utilize PS, resulting from the
PS has been recognized as an irreplaceable instrument in
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However, concerns
In spite of those
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lack of alternatives.
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Recently, cortical screws (CS) using cortical screw trajectories in the lumbar spine were
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introduced for posterior stabilization [12-14].
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demonstrated that CS provide similar strength as compared to PS [12-14].
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al. [12] reported that the bilateral CS-rod fixation technique could provide similar stability
16
in cadaveric experiments compared to PS-rod fixation, regardless of the presence of the
17
inter-body cages.
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favorable passage (through the pedicle supero-laterally from the entry point), CS are
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expected to reduce the rate of facet joint violation, as well as to achieve better clinical and
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surgical outcomes. However, postoperative outcomes when using CS in PLIF have not
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been fully described.
Some experimental studies have Perez-Orribo et
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Because of their favorable entry point (near the pars articularis) and
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To date, the therapeutic efficacy of CS in PLIF has yet to be fully described.
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to the best of our knowledge, outcomes using CS and PS for PLIF have no yet been
3
compared in a prospective randomized study.
4
clinical and radiological outcomes of CS and PS in PLIF, using a prospective, randomized
5
design via a non-inferiority trial.
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efficacy in terms of fusion rate, clinical, and surgical outcomes, in comparison with PS in
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PLIF.
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Therefore, we analyzed and compared the
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We hypothesized that CS would result in comparable
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Furthermore,
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METHODS
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Participants
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This study was approved by the institutional review board.
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follows.
5
with severe foraminal stenosis and isthmic spondylolisthesis, using lumbar spine
6
radiographs, computed tomography (CT) scans, and magnetic resonance images (MRI) that
7
corresponded to clinical manifestations and physical examinations.
8
required to have shown no improvement in clinical symptoms despite several conservative
9
treatments (including medication, physical therapy, and injection treatment) over a period
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Inclusion criteria were as
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First, patients were diagnosed with certain lumbar pathologies, including LSS
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Second, patients were
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of six months or more.
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level using screws (PS or CS) and inter-body polyetheretherketone (PEEK) cages.
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patients were between 40 and 60 years of age.
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study with their written consent.
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longer follow-up period.
Fourth,
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Fifth, patients were volunteers for this
Finally, patients were required to complete a one year or
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Third, patients were required to have undergone PLIF at a single
Exclusion criteria were as follows: fractures, infection or tumors in the lumbar spine;
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osteoporosis diagnosed by a T-score less than -2.5 on dual-energy X-ray absorptiometry
18
(DEXA) bone densitometry measurements, multi-level fusion surgery, hemorrhagic
19
disorders, such as hemophilia and thrombocythemia, patient inability to accurately
20
complete preoperative and postoperative questionnaires, and lack of patient suitability for
21
this study, as judged by the corresponding author.
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were applied in order to avoid confounding effects on outcome variables.
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The inclusion and exclusion criteria
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Sample size estimation
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This study was conducted to determine whether CS are a posterior stabilizer in PLIF
4
surgery compared to PS based on the fusion rate and clinical outcomes. Thus, we used the
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non-inferiority criteria to calculate the appropriate sample size [15].
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endpoint was the fusion rate, and the expected fusion rate of the control group using PS
7
(group A) was 93%, which is in agreement with several studies [4-7].
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of CS versus PS in PLIF with a two-sided 5% significance level, a power of 80%, and a
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noninferiority margin of 15%, a sample size of 36 patients for each group was necessary.
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The primary
For noninferiority
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Given an anticipated dropout rate of 10%, a total of 79 patients were required.
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Randomization
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Patients were randomly assigned into group A, for which PS was utilized, or group B, for
14
which CS was utilized.
15
patient, not to the surgeon and other health providers, meaning that this is single-blind
16
study in regards to the patient. Randomization was conducted by a computer-generated
17
allocation program (nQquery Advisor PPS 6.01, Saugus, MA, USA), which assigns
18
numbers in strict chronological sequences and enters regular sequences for each study
19
group.
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smoking status (smoker versus non-smoker), and (3) operation level (L4-5 versus L5-S1).
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Each study participant was allocated a unique randomization number upon screening
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completion.
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The group allocation (PS or CS screw type) was blinded to the
Randomization was stratified via three variables: (1) age (40s versus 50s), (2)
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Surgical procedures and postoperative protocols
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All surgeries were performed by a single orthopedic surgeon who used the same operative
3
technique for each surgery.
4
laminectomy was performed following a posterior midline skin incision. When necessary,
5
a partial or total facetectomy was also performed.
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(CAPSTONE®, Medtronic, Memphis TN, USA) were routinely utilized for inter-body
7
fusion with the auto-graft bone materials that were locally obtained during posterior
8
decompression.
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and demineralized bone matrix (DBM, Korea Bone Bank, Seoul, Korea) were placed and
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In the surgeries, posterior decompression via partial
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In each patient, two PEEK cages
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To improve the fusion rate, mixtures of locally-harvested auto-graft bone
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packed around the cages.
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Legacy system, Medtronic, Memphis TN, USA) were used under fluoroscopic guidance,
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and 6.5 x 45 mm screws were utilized for each patient in group A.
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screw-rod system with CS (MIDLF, Medtronic Sofamor Danek, Memphis TN, USA) was
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used under fluoroscopic guidance (Fig. 1), and 5.5 x 30 mm screws in L4 and L5 and 5.5 x
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35 mm screws in S1 were utilized.
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In group B, a bilateral
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In group A, bilateral screw-rod systems with PS (CD Horizon
Patients in both groups were admitted to the same wards following the operation and were
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then treated with the same postoperative protocols. All patients were permitted to
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ambulate the first day after surgery, and the majority of patients were discharged from the
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hospital on postoperative day fourteen.
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periods of time during the first month following surgery.
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patients were allowed to resume normal activities, including heavy lifting.
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Patients were encouraged to avoid sitting for long
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After three months post-surgery,
ACCEPTED MANUSCRIPT Comparison of PS and CS in PLIF
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Outcome measures
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The primary post-surgery study endpoint was fusion rate.
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six and twelve months after surgery.
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degrees in Cobb angles in lateral radiographs taken in flexion and extension and by the
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presence of a continuous fusion mass either inside or outside the cage as seen on CT
6
imaging.
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degrees, or if the fusion mass on CT scans was discontinuous. An orthopedic spine
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surgeon, who was not involved in patient treatment, performed all dynamic radiography
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and CT measurements.
Fusion status was determined at
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Fusion was defined by the difference less than two
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Non-union was declared if the difference in Cobb angle was greater than two
Dynamic radiograph measurements were carried out using the
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picture archiving and communication system (PACS) program (Infinitt, Bracknell,
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Berkshire, UK). To mitigate measurement error, all dynamic radiograph measurements
12
were performed according to several criteria.
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radiographs were simultaneously viewed on dual monitors. Second, images were viewed
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at 200% magnification.
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detailed evaluation of the bone.
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(Mx8000 IDT; Philips Medical System, Best, Netherlands).
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Third, all radiographs were changed to the bone image setting for All CT scans were taken using 1.0-mm intervals
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First, lateral flexion and extension
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There were several secondary endpoints.
Secondary endpoints included the intensity of
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lower back pain and pain radiating to the lower extremity (each measured separately using
20
a visual analogue scale (VAS)), functional status (using the Oswestry disability index
21
(ODI)), surgical morbidity (based on operating time, incision length, estimated blood loss,
22
and hospital stay), and additional outcomes including infection rate or mechanical failure.
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These data were collected prospectively by the corresponding author, both preoperatively
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and at each regular follow-up visit.
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Statistical analysis
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Independent Student’s t-tests or analysis of variance (ANOVA) tests were used for
6
continuous variables, and the Fisher’s exact test was used for proportional variables.
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SPSS software version 19.0 (SPSS, Chicago, IL, USA) was used for all analyses.
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sided P-values < 0.05 were considered to be statistically significant.
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Two-
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RESULTS
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Patient characteristics
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Seventy-nine eligible patients were randomly assigned to group A (39 patients) and group
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B (40 patients).
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the study, each of whom fully complied with the inclusion criteria (Fig. 2).
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similar between groups with respect to demographic characteristics such as age, gender,
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smoking status, height, weight, BMI, and preoperative lumbar pathology (Table 1).
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Of them, 77 patients (39 in group A and 38 in group B) were qualified for
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Patients were
Primary outcome measure (fusion rate)
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According to the dynamic radiographs, fusion at six months post-surgery was achieved in
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25/39 patients (64.1%) in group A, and in 26/38 patients (68.4%) in group B.
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difference in fusion rate was not significant (P = 0.67).
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fusion was achieved in 34/39 patients (87.2%) in group A and in 34/38 patients (89.5%) in
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group B, which was not a significant difference (P = 0.81) (Table 2).
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At twelve months post-surgery,
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The
On CT scan, fusion at six months post-surgery was achieved in 23/39 patients (59.0%) in
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group A and in 24/38 patients (63.1%) in group B, which was not significantly different
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between groups (P = 0.66). On one year after surgery, 34/39 patients (87.2%) in group A
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and 35/38 patients (92.1%) in group B achieved fusion, with no significant difference
20
between groups (P = 0.61) (Table 2).
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Secondary outcome measures
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ACCEPTED MANUSCRIPT Comparison of PS and CS in PLIF
Mean VAS scores for lower back pain indicated that one-year postoperative pain levels
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were significantly lower than preoperative levels for both groups, with mean scores
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decreasing from 7.6 ± 3.1 preoperatively to 2.0 ± 1.0 at one postoperative year in group A,
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and from 7.7 ± 3.1 to 2.1 ± 1.5 in group B (P = 0.38). These VAS scores were not
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significantly different between the two groups.
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pain at postoperative week one were significantly different between the groups at 4.3 ± 2.1
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for group A and 2.4 ± 1.3 for group B (P = 0.02).
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improved significantly in both groups, with mean scores decreasing from 5.7 ± 1.8
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preoperatively to 1.1 ± 0.4 at one postoperative year in group A, and from 5.9 ± 1.3 to 1.2 ±
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0.6 in group B, but there were no significant differences between the groups (P = 0.67) (Fig.
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3 and Table 3).
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VAS scores for radiating pain also
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In addition, the mean ODI score also improved from 36.5 ± 10.1 preoperatively to 11.0 ±
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2.5 one year after surgery in group A, and from 35.1 ± 9.7 preoperatively to 10.5 ± 2.8 one
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year after surgery in group B.
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the two groups (P = 0.46) (Fig. 4 and Table 3).
These ODI scores were not significantly different between
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Surgical morbidities, including blood loss, operation time, hospital stay, and incision length,
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are described in Table 4.
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compared to group A, in terms of blood loss, operation time, and incision length (P = 0.04,
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0.03, and 0.03, respectively).
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occurred at 7/39 (18%) in group A and 0/38 (0%) in group B, which was significantly
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different between the groups (P < 0.01).
Of which, group B was associated with better outcomes
Facet joint violation as evalutaed on postoperative CT was
Mechanical problems such as bony fracture at 11
ACCEPTED MANUSCRIPT Comparison of PS and CS in PLIF
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the pars or pedicle due to screw placement, screw fracture, screw migration, and cage
2
migration were not present in any patients of either group. On postoperative CT scan,
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malpositioned screws were seen in two in group A patients.
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were seen in group B.
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infection for any patient.
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at the surgical site in one of group A patient.
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complication after wound debridement.
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No malpositioned screws
There were no complications such as fever, swelling, or deep
However, there was one instance of a local superficial infection
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The infection was resolved without
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ACCEPTED MANUSCRIPT Comparison of PS and CS in PLIF
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DISCUSSION
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There were several principle findings of the current study.
3
observed in both groups at six- and twelve-month follow-up, with no significant differences
4
between the groups.
5
functional status as compared to PS in PLIF.
6
morbidity measured by blood loss, operation time, and incision length, as compared to PS.
7
Based on the current study, we suggest that using CS in PLIF could provide similar
8
outcomes to PS at the one-year follow-up point, and thus, CS might be a reasonable
9
alternative to PS in PLIF.
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Similar fusion rates were
Clinically, CS provided similar improvements in pain relief and
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In addition, CS resulted in lower surgical
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Some experimental studies have demonstrated the ability of CS to provide sufficient
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strength to endure a similar level of stress compared to PS [12-14].
13
[12] also reported that the bilateral CS-rod fixation technique could provide similar stability
14
in cadaveric experiments compared to PS-rod fixation, regardless of whether an inter-body
15
device is present.
16
fusion rates without complications has not yet been fully evaluated in clinical research
17
studies. Thus, we aimed to evaluate the fusion rate, clinical outcomes, and potential
18
complications of CS in PLIF, and to compare these outcomes to PS in PLIF, using a
19
prospective, randomized, non-inferiority design.
20
not significantly different between the two screw types.
21
the first postoperative year was 87.2% in group A versus 89.5% in group B according to
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dynamic radiographs and 87.2% in group A versus 92.1% in group B according to CT scans
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Perez-Orribo et al.
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However, whether CS could provide sufficient clinical outcomes and
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In the current study, fusion rates were For example, the fusion rate at
ACCEPTED MANUSCRIPT Comparison of PS and CS in PLIF
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(P = 0.81 and 0.61, respectively).
Radiologic complications such as loosened or pulled-
2
out screw were not observed in any patients of both groups.
3
statistically significant difference between the two groups in improvement in pain intensity
4
and ODI scores. However, in the immediate postoperative period, within one week of
5
surgery, CS provided significantly better lower back pain scores compared to PS, which
6
was caused by smaller skin incision and with less muscle dissection of CS, as described the
7
surgical outcomes of the current study.
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Clinically, there was no
PS has been recognized as an irreplaceable instrument in fusion surgery of the lumbar spine
10
due to its advantages, such as its ability to produce sufficient stability to the destabilized
11
lumbar segment and its ease of use and placement in the area [3,5-7,10,16], but some
12
drawbacks to PS have been pointed out.
13
articulating facet violation during screw placement or dissection [7,8,11,17], and another is
14
the need of long skin incision and significant muscle dissection due to the very lateral to
15
midline entry point of PS, at the lateral wall of the pedicle.
16
superior facet joint violations were a common occurrence during PS placement, with an
17
incidence of 4%-24% in open surgery and 11%-100% in percutaneous surgery [8,17].
18
the late 2000s, CS using cortical screw trajectories was invented, such that screws could be
19
placed without those drawbacks of PS [12-14,18].
20
near the pars articularis, which is far from the superior facet joint, the risk of superior facet
21
violation is much lower than in PS.
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violation occurred at 18% in group A and 0% in group B (P < 0.01).
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entry point allows screw placement with a smaller skin incision and with less muscle
Previous studies revealed that
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One concern for PS is the risk of superior
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Due to the entry point of the CS being
The current study also showed that the facet joint
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In addition, the CS
ACCEPTED MANUSCRIPT Comparison of PS and CS in PLIF
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dissection and injury compared to PS, which were also demonstrated by outcomes of the
2
current study.
3
when using CS is less than when using PS because CS placement is made during the
4
visualization of several landmarks.
5
line bisecting the pars interarticular, which is approximately 10 to 15 mm below the
6
superior facet joint capsule.
7
under fluoroscopy.
8
at the pars or pedicle due to CS placement because the angle of screw insertion is too steep
9
and the CS screw length is shorter than PS, but no fracture was observed in the current
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For example, the starting point is at the crosshairs of a
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Also, determination of the CS placement can be easily made
Moreover, there has been concern regarding the risk of bony fracture
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In addition, the risk of cortical bone violation of the pedicle or the pars
study.
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The current study has some limitations.
First, we did not conduct the current study with a
13
sufficient sample size because this study was designed as a non-inferiority trial. There have
14
not been reports of the outcomes of CS in PLIF, so we conducted this study as a
15
preliminary clinical trial.
16
additional comparative study between CS and PS in PLIF with a larger sample size and
17
longer follow-up times.
18
better establish the outcomes of CS in PLIF for LSS patients, further studies should be
19
performed using a larger sample size, an extended follow-up period, and a prospective
20
study design. Third, this study was conducted on patients without osteoporosis, as seen on
21
DEXA scan, who underwent single-level PLIF surgery in the L4-5 or L5-S1 segments.
22
other words, the results of this study cannot be applied to subjects having multilevel fusion
23
surgeries, surgeries on other lumbar segments, or those with osteoporotic bone.
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Since the completion of this study, we have performed an
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Second, this study had a short follow-up period of one year.
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Fourth,
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ACCEPTED MANUSCRIPT Comparison of PS and CS in PLIF
because this study was conducted in limited population, mainly males between the ages of
2
40-60 years, statistical analysis may be complicated due to the inherent non-normal
3
distribution, and our conclusions might not be acceptable for all patient populations. Thus,
4
further studies should be performed with patients of a broader age range and with both
5
sexes.
6
radiologic images, and other health care providers due to the nature of the study type,
7
which might produce the performance bias.
8
has some unique strengths.
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visits for each enrolled patient were possible. Also, this is the first clinical research study
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Finally, this study was not blinded to the surgeons, assessors for evaluating the
Despite these limitations, the current study
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Because our hospital is an armed force hospital, follow-up
with a prospective-randomized design to evaluate CS outcomes in PLIF.
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data in the current study were obtained from a homogenous population with respect to
12
physical activity, since the research was performed at an armed forces hospital.
13
population homogeneity reduces the risk of confounding factors on outcome variables.
14
Due to a paucity of articles regarding the efficacy of CS in PLIF, hopefully this study can
15
serve as a baseline for further research on CS.
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Moreover, the
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CONCLUSION
2
The current study was conducted to evaluate the efficacy of CS compared to PS in PLIF
3
one year after surgery using a prospective, randomized, non-inferiority design.
4
no significant difference in fusion rate between CS and PS, which was the primary endpoint.
5
In addition, there was no statistically significant difference in clinical outcomes, based on
6
pain intensity and ODI status, between CS and PS use. Moreover, CS in PLIF resulted in
7
less facet joint violation and surgical morbidity than PS.
8
suggest that the CS would provide similar outcomes compared to PS in PLIF at one year
9
after surgery, and thus, CS is a reasonable alternative to PS in PLIF.
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There was
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Based on these results, we
Additional studies
should be performed with larger sample sizes, extended follow-up periods, and with
11
prospective-randomized designs to better understand the clinical and radiological outcomes
12
of these two screws.
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Funding
2
No funds were received in support of the present work.
3
been or will be received from a commercial party related directly or indirectly to the subject
4
of this manuscript.
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No benefits in any form have
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References
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[1] Szpalski M, Gunzburg R. Lumbar spinal stenosis in the elderly: an overview. Eur Spine J 2003;12:S170–5.
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[2] Abbas J, Hamoud K, May H, et al. Socioeconomic and Physical Characteristics of
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Individuals With Degenerative Lumbar Spinal Stenosis. Spine 2013;38:E554–61.
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[3] Pannell WC, Savin DD, Scott TP, Wang JC, Daubs MD. Trends in the surgical treatment of lumbar spine disease in the United States. Spine J doi:
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10.1016/j.spinee.2013.10.014. [Epub ahead of print]
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[4]
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Liu X, Wang Y, Qiu G, Weng X, Yu B. A systematic review with meta-analysis of posterior interbody fusion versus posterolateral fusion in lumbar spondylolisthesis.
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Eur Spine J 2013;23:43–56.
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[5]
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Lidar Z, Beaumont A, Lifshutz J, Maiman DJ. Clinical and radiological relationship between posterior lumbar interbody fusion and posterolateral lumbar fusion. Surg
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Neurol 2005;64:303–8.
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[6]
Wang Z, Fu S, Wu ZX, Zhang Y, Lei W. Ti2448 Pedicle Screw System
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Augmentation for Posterior Lumbar Interbody Fusion. Spine 2013;38:2008–15.
[7] Athanasakopoulos M, Mavrogenis AF, Triantafyllopoulos G, Koufos S, Pneumaticos SG. Posterior Spinal Fusion Using Pedicle Screws. Orthopedics 2013;36:e951–7.
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[8] Jones-Quaidoo SM, Djurasovic M, Owens RK, Carreon LY. Superior articulating facet violation: percutaneous versus open techniques: Clinical article. J Neurosurg
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Spine 2013;18:593–7.
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[9] Hu MW, Liu ZL, Zhou Y, et al. Posterior lumbar interbody fusion using spinous process and laminae. J Bone Joint Surg Br 2012;94:373-7.
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[10] Parker SL, Amin AG, Santiago-Dieppa D, et al. Incidence and Clinical Significance
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of Vascular Encroachment Resulting from Free Hand Placement of Pedicle Screws
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in the Thoracic and Lumbar Spine: Analysis of 6,816 Consecutive Screws. Spine
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2014 Jan 29. [Epub ahead of print]
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[11] Oh HS, Kim JS, Lee SH, Liu WC, Hong SW. Comparison between the accuracy of percutaneous and open pedicle screw fixations in lumbosacral fusion. Spine J
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2013;13:1751–7.
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[12] Perez-Orribo L, Kalb S, Reyes PM, Chang SW, Crawford NR. Biomechanics of Lumbar Cortical Screw–Rod Fixation Versus Pedicle Screw–Rod Fixation With and
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Without Interbody Support. Spine 2013;38:635–41.
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[13] Santoni BG, Hynes RA, McGilvray KC, et al. Cortical bone trajectory for lumbar pedicle screws. Spine J 2009;9:366–73.
[14]
Matsukawa K, Yato Y, Kato T, et al. In Vivo Analysis of Insertional Torque During
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Pedicle Screwing Using Cortical Bone Trajectory Technique. Spine 2014;39:E240–
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5.
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[15] Piaggio G, Elbourne DR, Pocock SJ, Evans SJ, Altman DG; CONSORT Group.
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Reporting of noninferiority and equivalence randomized trials: extension of the
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CONSORT 2010 statement. JAMA 2012;308:2594–604.
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[16]
Wu Y, Tang H, Li Z, Zhang Q, Shi Z. Outcome of posterior lumbar interbody fusion versus posterolateral fusion in lumbar degenerative disease. J Clin Neurosci
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2011;18:780–3. [17]
Lau D, Terman SW, Patel R, La Marca F, Park P. Incidence of and risk factors for
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superior facet violation in minimally invasive versus open pedicle screw placement
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during transforaminal lumbar interbody fusion: a comparative analysis: Clinical
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article. J Neurosurg Spine 2013;18:356–61.
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Mobbs RJ. The “medio-lateral-superior trajectory technique”: an alternative cortical trajectory for pedicle fixation. Orthop Surg 2013;5:56-9.
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[18]
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Figure Legends
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Figure 1.
On axial (A, L5; B, S1) and sagittal (C, L5; D, S1)
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CT images, the CS was inserted through the pedicle in a the supero-lateral direction from
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the entry point, which was located near the pars articularis.
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Figure 2.
Flow diagram for enrolled patients.
Figure 3.
Mean VAS for back pain (A), mean VAS for radiating pain to the lower
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Cortical screw trajectory.
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extremity (B), and mean ODI (C) scores by time point. The VAS and ODI were collected
11
at each follow-up time. Error bars represent standard deviations.
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* Statistically significant difference between scores at baseline and at each follow-up time
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(P < 0.05)
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** Statistically significant difference between groups at the follow-up times (P < 0.05)
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ACCEPTED MANUSCRIPT Table 1. Demographic Data Group C
P
39
38
-
51.9 ± 11.7
51.3 ± 12.4
0.71
34 / 5
33 / 5
0.83
Height (cm)
166.8 ± 10.4
164.7 ± 9.4
0.98
Weight (kg)
68.8 ± 13.4
65.3 ± 11.4
0.33
BMI (kg/m2)
24.9 ± 2.9
BMD (T-score)
2.2 ± 0.7
Age (year)
Smoking status smoker (%)
0.40
2.3 ± 0.9
0.52
15 (38.5)
16 (42.1%)
24 (61.5)
22 (57.9%)
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non-smoker (%) Lumbar pathology (%)
24.6 ± 3.4
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Gender (male / female)
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Group B
10 (25.6)
9 (23.7)
Isthmic spondylolisthesis
21 (53.9)
24 (63.2)
8 (20.5)
5 (13.1)
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LSS with foraminal stenosis
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Degenerative spondylolisthesis Fusion level
0.95
0.93
L4-5 (%)
19 (48.7)
18 (47.4)
L5-S1 (%)
20 (51.3)
20 (52.6)
Values in data cells represent mean ± SD (standard deviation). BMI, body mass index; BMD, bone mineral density; LSS, lumbar spinal stenosis
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Group C (n = 38)
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Using dynamic radiographs at postoperative one year 34
34
Nonunion
5
4
87.2
89.5
Union rate (%)
34
35
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Fusion Nonunion
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3
87.2
92.1
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Union rate (%)
0.81
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Using CT scans at postoperative one year
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Fusion
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0.61
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Group C (n = 38)
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Pre-operative
7.6 ± 3.1
7.7 ± 3.1
0.63
1 week postoperative
4.3 ± 2.1
2 weeks postoperative
2.1 ± 1.0
3 weeks postoperative
2.0 ± 0.9
1 month postoperative
1.7 ± 0.6
Clinical Parameters
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VAS for lower back pain
0.02*
2.0 ± 0.8
0.71
1.8 ± 1.1
0.52
1.5 ± 0.9
0.45
1.6 ± 0.5
1.5 ± 1.0
0.51
2.0 ± 1.2
1.8 ± 0.9
0.57
2.0 ± 1.0
2.1 ± 1.5
0.38
5.7 ± 1.8
5.9 ± 1.3
0.35
1.2 ± 0.3
1.0 ± 0.5
0.55
3 months postoperative
1.0 ± 0.2
0.8 ± 0.5
0.43
6 months postoperative
1.2 ± 0.6
1.1 ± 0.7
0.51
1 year postoperative
1.1 ± 0.4
1.2 ± 0.6
0.67
Pre-operative
36.5 ± 10.1
35.1 ± 9.7
0.51
3 months postoperative
17.3 ± 5.9
17.5 ± 4.8
0.60
6 months postoperative
10.7 ± 1.4
8.5 ± 0.6
0.53
6 months postoperative
VAS for radiating pain Pre-operative
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1 year postoperative
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3 months postoperative
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1 month postoperative
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2.9 ± 1.3
ODI score
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11.0 ± 2.5
10.5 ± 2.8
0.46
Values in data cells represent mean ± SD (standard deviation). VAS, visual analogue scale; ODI, oswestry disability index
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*, meaning significant difference between groups (P < 0.05)
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P
Blood loss (mL)
450 ± 25
360 ± 30
0.04*
Operation time (hours)
2.6 ± 0.2
2.1 ± 0.3
0.03*
Hospital stay (day)
13.8 ± 1.7
13.7 ± 2.2
0.47
107.2 ± 15.4
73.1 ± 9.3
0.03*
Incision length (mm)
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Values in data cells represent mean ± SD (standard deviation).
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Group B (n = 39)
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*, meaning significant difference between groups (P < 0.05)
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S1529-9430(15)00204-1
DOI:
10.1016/j.spinee.2015.02.038
Reference:
SPINEE 56221
To appear in:
The Spine Journal
Received Date: 6 June 2014 Revised Date:
15 January 2015
Accepted Date: 18 February 2015
Please cite this article as: Lee GW, Son J-H, Ahn M-W, Kim H-J, Yeom JS, The Comparison of Pedicle Screw and Cortical Screw in Posterior Lumbar Inter-body Fusion: a Prospective Randomized Noninferiority Trial, The Spine Journal (2015), doi: 10.1016/j.spinee.2015.02.038. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
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The Comparison of Pedicle Screw and Cortical Screw in Posterior Lumbar Inter-
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body Fusion: a Prospective Randomized Non-inferiority Trial
Gun Woo Lee, MDa,*, Jung-Hwan Son, MDb, Myun-Whan Ahn, MDc, Ho-Joong Kim,
a
Department of Orthopaedic Surgery, Armed Forces Yangju Hospital, Yangju, 482-863,
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Republic of Korea b
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MDd, Jin S. Yeom, MDd
Department of Orthopaedic Surgery, Kosin University Gospel Hospital, Busan, Republic of Korea
c
Spine Centrer and Department of Orthopaedic Surgery, Yeungnam University Hospital, Daegu, Republic of Korea
Spine Centrer and Department of Orthopaedic Surgery, Seoul National University College
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of Medicine and Seoul National University Bundang Hospital, Sungnam, Korea
* Corresponding author: Gun Woo Lee, MD
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Department of Orthopaedic Surgery, Armed Forces Yangju Hospital, Yongam-ri, 49-1, Eunhyeon-myeon, Yangju-si Gyeonggi-do, 482-863, Republic of Korea Tel: 82-31-863-1319 E-mail address: [email protected]
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Running Head:
Comparison of PS and CS in PLIF
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Acknowledgements: none
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ACCEPTED MANUSCRIPT Comparison of PS and CS in PLIF
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Abstract
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Background Context:
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body fusion (PLIF), but several drawbacks of PS, including the risk of superior facet joint
4
violation and muscle injury, have also pointed out. Recently, cortical screws (CS) were
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invented, which can be placed without the drawbacks associated with PS. However,
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whether or not CS in PLIF can provide similar or greater clinical and radiological outcomes
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compared to those of PS has not been fully evaluated in clinical research studies.
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Purpose: To evaluate whether the CS provides similar results to the PS in PLIF, in terms
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of fusion rate, clinical and surgical outcomes, and complications.
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Pedicle screws (PS) offer great benefits in posterior lumbar inter-
Study Design:
Prospective, randomized, non-inferiority trial
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Patient Sample: Seventy-nine eligible patients were randomly assigned to either group A
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(39 patients), for which PS was utilized, or group B (40 patients), for which CS was
13
utilized.
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Outcome Measure:
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dynamic radiographs and CT scans. Secondary endpoints included intensity of lower back
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pain and pain radiating to the leg using visual analogue scales, and also, functional status
17
using the Oswestry disability index, surgical morbidity, and additional outcomes such as
18
pedicle fracture and mechanical failure.
19
Methods:
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PLIF compared to PS, we compared fusion rates, clinical outcomes, and complications after
21
surgery in both groups.
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any form have been or will be received from a commercial party related directly or
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indirectly to the subject of this manuscript.
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The primary study endpoint was to measure fusion rate using
We compared baseline data in both groups.
To evaluate the efficacy of CS in
No funds were received in support of this work.
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No benefits in
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Results:
At the six- and twelve-month follow-up points, similar fusion rates were
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observed in both groups (P = 0.81 and 0.61, respectively). According to the clinical
3
outcome, CS provided similar improvements in pain amelioration and functional status
4
compared to PS, with no significant differences.
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less surgical morbidity, including shorter incision length, quicker operative time, and less
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blood loss, compared to PS.
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Conclusion:
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PS in PLIF.
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PS in PLIF.
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Additionally, CS resulted in significantly
CS in PLIF provides similar clinical and radiological outcomes compared to
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Based on the current study, we suggest CS to be a reasonable alternative to
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1 2
INTRODUCTION Posterior lumbar inter-body fusion (PLIF) surgery with pedicle screw (PS) has recently been widely used as an effective surgical method for certain lumbar pathologies
4
such as spondylolisthesis [1-5].
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fusion surgery of the lumbar spine due to its advantages [3,6-11].
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regarding PS include the risk of superior facet joint violation during screw placement or
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dissection, the skin incision length, and the amount of lateral muscle dissection due to the
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entry point being lateral to the midline, near the lateral wall of facet joint.
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drawbacks, there was little choice for spine surgeons but to utilize PS, resulting from the
PS has been recognized as an irreplaceable instrument in
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However, concerns
In spite of those
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lack of alternatives.
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Recently, cortical screws (CS) using cortical screw trajectories in the lumbar spine were
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introduced for posterior stabilization [12-14].
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demonstrated that CS provide similar strength as compared to PS [12-14].
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al. [12] reported that the bilateral CS-rod fixation technique could provide similar stability
16
in cadaveric experiments compared to PS-rod fixation, regardless of the presence of the
17
inter-body cages.
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favorable passage (through the pedicle supero-laterally from the entry point), CS are
19
expected to reduce the rate of facet joint violation, as well as to achieve better clinical and
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surgical outcomes. However, postoperative outcomes when using CS in PLIF have not
21
been fully described.
Some experimental studies have Perez-Orribo et
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Because of their favorable entry point (near the pars articularis) and
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To date, the therapeutic efficacy of CS in PLIF has yet to be fully described.
2
to the best of our knowledge, outcomes using CS and PS for PLIF have no yet been
3
compared in a prospective randomized study.
4
clinical and radiological outcomes of CS and PS in PLIF, using a prospective, randomized
5
design via a non-inferiority trial.
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efficacy in terms of fusion rate, clinical, and surgical outcomes, in comparison with PS in
7
PLIF.
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Therefore, we analyzed and compared the
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We hypothesized that CS would result in comparable
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Furthermore,
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METHODS
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Participants
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This study was approved by the institutional review board.
4
follows.
5
with severe foraminal stenosis and isthmic spondylolisthesis, using lumbar spine
6
radiographs, computed tomography (CT) scans, and magnetic resonance images (MRI) that
7
corresponded to clinical manifestations and physical examinations.
8
required to have shown no improvement in clinical symptoms despite several conservative
9
treatments (including medication, physical therapy, and injection treatment) over a period
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Inclusion criteria were as
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First, patients were diagnosed with certain lumbar pathologies, including LSS
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Second, patients were
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of six months or more.
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level using screws (PS or CS) and inter-body polyetheretherketone (PEEK) cages.
12
patients were between 40 and 60 years of age.
13
study with their written consent.
14
longer follow-up period.
Fourth,
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Fifth, patients were volunteers for this
Finally, patients were required to complete a one year or
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Third, patients were required to have undergone PLIF at a single
Exclusion criteria were as follows: fractures, infection or tumors in the lumbar spine;
17
osteoporosis diagnosed by a T-score less than -2.5 on dual-energy X-ray absorptiometry
18
(DEXA) bone densitometry measurements, multi-level fusion surgery, hemorrhagic
19
disorders, such as hemophilia and thrombocythemia, patient inability to accurately
20
complete preoperative and postoperative questionnaires, and lack of patient suitability for
21
this study, as judged by the corresponding author.
22
were applied in order to avoid confounding effects on outcome variables.
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The inclusion and exclusion criteria
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Sample size estimation
3
This study was conducted to determine whether CS are a posterior stabilizer in PLIF
4
surgery compared to PS based on the fusion rate and clinical outcomes. Thus, we used the
5
non-inferiority criteria to calculate the appropriate sample size [15].
6
endpoint was the fusion rate, and the expected fusion rate of the control group using PS
7
(group A) was 93%, which is in agreement with several studies [4-7].
8
of CS versus PS in PLIF with a two-sided 5% significance level, a power of 80%, and a
9
noninferiority margin of 15%, a sample size of 36 patients for each group was necessary.
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The primary
For noninferiority
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Given an anticipated dropout rate of 10%, a total of 79 patients were required.
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Randomization
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Patients were randomly assigned into group A, for which PS was utilized, or group B, for
14
which CS was utilized.
15
patient, not to the surgeon and other health providers, meaning that this is single-blind
16
study in regards to the patient. Randomization was conducted by a computer-generated
17
allocation program (nQquery Advisor PPS 6.01, Saugus, MA, USA), which assigns
18
numbers in strict chronological sequences and enters regular sequences for each study
19
group.
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smoking status (smoker versus non-smoker), and (3) operation level (L4-5 versus L5-S1).
21
Each study participant was allocated a unique randomization number upon screening
22
completion.
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The group allocation (PS or CS screw type) was blinded to the
Randomization was stratified via three variables: (1) age (40s versus 50s), (2)
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Surgical procedures and postoperative protocols
2
All surgeries were performed by a single orthopedic surgeon who used the same operative
3
technique for each surgery.
4
laminectomy was performed following a posterior midline skin incision. When necessary,
5
a partial or total facetectomy was also performed.
6
(CAPSTONE®, Medtronic, Memphis TN, USA) were routinely utilized for inter-body
7
fusion with the auto-graft bone materials that were locally obtained during posterior
8
decompression.
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and demineralized bone matrix (DBM, Korea Bone Bank, Seoul, Korea) were placed and
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In the surgeries, posterior decompression via partial
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In each patient, two PEEK cages
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To improve the fusion rate, mixtures of locally-harvested auto-graft bone
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packed around the cages.
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Legacy system, Medtronic, Memphis TN, USA) were used under fluoroscopic guidance,
12
and 6.5 x 45 mm screws were utilized for each patient in group A.
13
screw-rod system with CS (MIDLF, Medtronic Sofamor Danek, Memphis TN, USA) was
14
used under fluoroscopic guidance (Fig. 1), and 5.5 x 30 mm screws in L4 and L5 and 5.5 x
15
35 mm screws in S1 were utilized.
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In group B, a bilateral
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In group A, bilateral screw-rod systems with PS (CD Horizon
Patients in both groups were admitted to the same wards following the operation and were
18
then treated with the same postoperative protocols. All patients were permitted to
19
ambulate the first day after surgery, and the majority of patients were discharged from the
20
hospital on postoperative day fourteen.
21
periods of time during the first month following surgery.
22
patients were allowed to resume normal activities, including heavy lifting.
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Patients were encouraged to avoid sitting for long
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After three months post-surgery,
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Outcome measures
2
The primary post-surgery study endpoint was fusion rate.
3
six and twelve months after surgery.
4
degrees in Cobb angles in lateral radiographs taken in flexion and extension and by the
5
presence of a continuous fusion mass either inside or outside the cage as seen on CT
6
imaging.
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degrees, or if the fusion mass on CT scans was discontinuous. An orthopedic spine
8
surgeon, who was not involved in patient treatment, performed all dynamic radiography
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and CT measurements.
Fusion status was determined at
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Fusion was defined by the difference less than two
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Non-union was declared if the difference in Cobb angle was greater than two
Dynamic radiograph measurements were carried out using the
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picture archiving and communication system (PACS) program (Infinitt, Bracknell,
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Berkshire, UK). To mitigate measurement error, all dynamic radiograph measurements
12
were performed according to several criteria.
13
radiographs were simultaneously viewed on dual monitors. Second, images were viewed
14
at 200% magnification.
15
detailed evaluation of the bone.
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(Mx8000 IDT; Philips Medical System, Best, Netherlands).
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Third, all radiographs were changed to the bone image setting for All CT scans were taken using 1.0-mm intervals
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First, lateral flexion and extension
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There were several secondary endpoints.
Secondary endpoints included the intensity of
19
lower back pain and pain radiating to the lower extremity (each measured separately using
20
a visual analogue scale (VAS)), functional status (using the Oswestry disability index
21
(ODI)), surgical morbidity (based on operating time, incision length, estimated blood loss,
22
and hospital stay), and additional outcomes including infection rate or mechanical failure.
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These data were collected prospectively by the corresponding author, both preoperatively
2
and at each regular follow-up visit.
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Statistical analysis
5
Independent Student’s t-tests or analysis of variance (ANOVA) tests were used for
6
continuous variables, and the Fisher’s exact test was used for proportional variables.
7
SPSS software version 19.0 (SPSS, Chicago, IL, USA) was used for all analyses.
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sided P-values < 0.05 were considered to be statistically significant.
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RESULTS
2
Patient characteristics
3
Seventy-nine eligible patients were randomly assigned to group A (39 patients) and group
4
B (40 patients).
5
the study, each of whom fully complied with the inclusion criteria (Fig. 2).
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similar between groups with respect to demographic characteristics such as age, gender,
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smoking status, height, weight, BMI, and preoperative lumbar pathology (Table 1).
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Of them, 77 patients (39 in group A and 38 in group B) were qualified for
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Patients were
Primary outcome measure (fusion rate)
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According to the dynamic radiographs, fusion at six months post-surgery was achieved in
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25/39 patients (64.1%) in group A, and in 26/38 patients (68.4%) in group B.
12
difference in fusion rate was not significant (P = 0.67).
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fusion was achieved in 34/39 patients (87.2%) in group A and in 34/38 patients (89.5%) in
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group B, which was not a significant difference (P = 0.81) (Table 2).
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At twelve months post-surgery,
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The
On CT scan, fusion at six months post-surgery was achieved in 23/39 patients (59.0%) in
17
group A and in 24/38 patients (63.1%) in group B, which was not significantly different
18
between groups (P = 0.66). On one year after surgery, 34/39 patients (87.2%) in group A
19
and 35/38 patients (92.1%) in group B achieved fusion, with no significant difference
20
between groups (P = 0.61) (Table 2).
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Secondary outcome measures
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Mean VAS scores for lower back pain indicated that one-year postoperative pain levels
2
were significantly lower than preoperative levels for both groups, with mean scores
3
decreasing from 7.6 ± 3.1 preoperatively to 2.0 ± 1.0 at one postoperative year in group A,
4
and from 7.7 ± 3.1 to 2.1 ± 1.5 in group B (P = 0.38). These VAS scores were not
5
significantly different between the two groups.
6
pain at postoperative week one were significantly different between the groups at 4.3 ± 2.1
7
for group A and 2.4 ± 1.3 for group B (P = 0.02).
8
improved significantly in both groups, with mean scores decreasing from 5.7 ± 1.8
9
preoperatively to 1.1 ± 0.4 at one postoperative year in group A, and from 5.9 ± 1.3 to 1.2 ±
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0.6 in group B, but there were no significant differences between the groups (P = 0.67) (Fig.
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3 and Table 3).
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1
SC
However, the VAS scores for lower back
M AN U
VAS scores for radiating pain also
12
In addition, the mean ODI score also improved from 36.5 ± 10.1 preoperatively to 11.0 ±
14
2.5 one year after surgery in group A, and from 35.1 ± 9.7 preoperatively to 10.5 ± 2.8 one
15
year after surgery in group B.
16
the two groups (P = 0.46) (Fig. 4 and Table 3).
These ODI scores were not significantly different between
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17
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13
18
Surgical morbidities, including blood loss, operation time, hospital stay, and incision length,
19
are described in Table 4.
20
compared to group A, in terms of blood loss, operation time, and incision length (P = 0.04,
21
0.03, and 0.03, respectively).
22
occurred at 7/39 (18%) in group A and 0/38 (0%) in group B, which was significantly
23
different between the groups (P < 0.01).
Of which, group B was associated with better outcomes
Facet joint violation as evalutaed on postoperative CT was
Mechanical problems such as bony fracture at 11
ACCEPTED MANUSCRIPT Comparison of PS and CS in PLIF
1
the pars or pedicle due to screw placement, screw fracture, screw migration, and cage
2
migration were not present in any patients of either group. On postoperative CT scan,
3
malpositioned screws were seen in two in group A patients.
4
were seen in group B.
5
infection for any patient.
6
at the surgical site in one of group A patient.
7
complication after wound debridement.
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No malpositioned screws
There were no complications such as fever, swelling, or deep
However, there was one instance of a local superficial infection
AC C
EP
TE D
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SC
The infection was resolved without
12
ACCEPTED MANUSCRIPT Comparison of PS and CS in PLIF
1
DISCUSSION
2
There were several principle findings of the current study.
3
observed in both groups at six- and twelve-month follow-up, with no significant differences
4
between the groups.
5
functional status as compared to PS in PLIF.
6
morbidity measured by blood loss, operation time, and incision length, as compared to PS.
7
Based on the current study, we suggest that using CS in PLIF could provide similar
8
outcomes to PS at the one-year follow-up point, and thus, CS might be a reasonable
9
alternative to PS in PLIF.
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Similar fusion rates were
Clinically, CS provided similar improvements in pain relief and
10
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SC
In addition, CS resulted in lower surgical
11
Some experimental studies have demonstrated the ability of CS to provide sufficient
12
strength to endure a similar level of stress compared to PS [12-14].
13
[12] also reported that the bilateral CS-rod fixation technique could provide similar stability
14
in cadaveric experiments compared to PS-rod fixation, regardless of whether an inter-body
15
device is present.
16
fusion rates without complications has not yet been fully evaluated in clinical research
17
studies. Thus, we aimed to evaluate the fusion rate, clinical outcomes, and potential
18
complications of CS in PLIF, and to compare these outcomes to PS in PLIF, using a
19
prospective, randomized, non-inferiority design.
20
not significantly different between the two screw types.
21
the first postoperative year was 87.2% in group A versus 89.5% in group B according to
22
dynamic radiographs and 87.2% in group A versus 92.1% in group B according to CT scans
TE D
Perez-Orribo et al.
AC C
EP
However, whether CS could provide sufficient clinical outcomes and
13
In the current study, fusion rates were For example, the fusion rate at
ACCEPTED MANUSCRIPT Comparison of PS and CS in PLIF
1
(P = 0.81 and 0.61, respectively).
Radiologic complications such as loosened or pulled-
2
out screw were not observed in any patients of both groups.
3
statistically significant difference between the two groups in improvement in pain intensity
4
and ODI scores. However, in the immediate postoperative period, within one week of
5
surgery, CS provided significantly better lower back pain scores compared to PS, which
6
was caused by smaller skin incision and with less muscle dissection of CS, as described the
7
surgical outcomes of the current study.
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SC M AN U
8 9
Clinically, there was no
PS has been recognized as an irreplaceable instrument in fusion surgery of the lumbar spine
10
due to its advantages, such as its ability to produce sufficient stability to the destabilized
11
lumbar segment and its ease of use and placement in the area [3,5-7,10,16], but some
12
drawbacks to PS have been pointed out.
13
articulating facet violation during screw placement or dissection [7,8,11,17], and another is
14
the need of long skin incision and significant muscle dissection due to the very lateral to
15
midline entry point of PS, at the lateral wall of the pedicle.
16
superior facet joint violations were a common occurrence during PS placement, with an
17
incidence of 4%-24% in open surgery and 11%-100% in percutaneous surgery [8,17].
18
the late 2000s, CS using cortical screw trajectories was invented, such that screws could be
19
placed without those drawbacks of PS [12-14,18].
20
near the pars articularis, which is far from the superior facet joint, the risk of superior facet
21
violation is much lower than in PS.
22
violation occurred at 18% in group A and 0% in group B (P < 0.01).
23
entry point allows screw placement with a smaller skin incision and with less muscle
Previous studies revealed that
AC C
EP
TE D
One concern for PS is the risk of superior
In
Due to the entry point of the CS being
The current study also showed that the facet joint
14
In addition, the CS
ACCEPTED MANUSCRIPT Comparison of PS and CS in PLIF
1
dissection and injury compared to PS, which were also demonstrated by outcomes of the
2
current study.
3
when using CS is less than when using PS because CS placement is made during the
4
visualization of several landmarks.
5
line bisecting the pars interarticular, which is approximately 10 to 15 mm below the
6
superior facet joint capsule.
7
under fluoroscopy.
8
at the pars or pedicle due to CS placement because the angle of screw insertion is too steep
9
and the CS screw length is shorter than PS, but no fracture was observed in the current
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For example, the starting point is at the crosshairs of a
SC
Also, determination of the CS placement can be easily made
Moreover, there has been concern regarding the risk of bony fracture
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10
In addition, the risk of cortical bone violation of the pedicle or the pars
study.
11
The current study has some limitations.
First, we did not conduct the current study with a
13
sufficient sample size because this study was designed as a non-inferiority trial. There have
14
not been reports of the outcomes of CS in PLIF, so we conducted this study as a
15
preliminary clinical trial.
16
additional comparative study between CS and PS in PLIF with a larger sample size and
17
longer follow-up times.
18
better establish the outcomes of CS in PLIF for LSS patients, further studies should be
19
performed using a larger sample size, an extended follow-up period, and a prospective
20
study design. Third, this study was conducted on patients without osteoporosis, as seen on
21
DEXA scan, who underwent single-level PLIF surgery in the L4-5 or L5-S1 segments.
22
other words, the results of this study cannot be applied to subjects having multilevel fusion
23
surgeries, surgeries on other lumbar segments, or those with osteoporotic bone.
TE D
12
EP
Since the completion of this study, we have performed an
To
AC C
Second, this study had a short follow-up period of one year.
15
Fourth,
In
ACCEPTED MANUSCRIPT Comparison of PS and CS in PLIF
because this study was conducted in limited population, mainly males between the ages of
2
40-60 years, statistical analysis may be complicated due to the inherent non-normal
3
distribution, and our conclusions might not be acceptable for all patient populations. Thus,
4
further studies should be performed with patients of a broader age range and with both
5
sexes.
6
radiologic images, and other health care providers due to the nature of the study type,
7
which might produce the performance bias.
8
has some unique strengths.
9
visits for each enrolled patient were possible. Also, this is the first clinical research study
RI PT
1
SC
Finally, this study was not blinded to the surgeons, assessors for evaluating the
Despite these limitations, the current study
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Because our hospital is an armed force hospital, follow-up
with a prospective-randomized design to evaluate CS outcomes in PLIF.
11
data in the current study were obtained from a homogenous population with respect to
12
physical activity, since the research was performed at an armed forces hospital.
13
population homogeneity reduces the risk of confounding factors on outcome variables.
14
Due to a paucity of articles regarding the efficacy of CS in PLIF, hopefully this study can
15
serve as a baseline for further research on CS.
EP AC C
16
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10
16
Moreover, the
Such
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1
CONCLUSION
2
The current study was conducted to evaluate the efficacy of CS compared to PS in PLIF
3
one year after surgery using a prospective, randomized, non-inferiority design.
4
no significant difference in fusion rate between CS and PS, which was the primary endpoint.
5
In addition, there was no statistically significant difference in clinical outcomes, based on
6
pain intensity and ODI status, between CS and PS use. Moreover, CS in PLIF resulted in
7
less facet joint violation and surgical morbidity than PS.
8
suggest that the CS would provide similar outcomes compared to PS in PLIF at one year
9
after surgery, and thus, CS is a reasonable alternative to PS in PLIF.
SC
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There was
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Based on these results, we
Additional studies
should be performed with larger sample sizes, extended follow-up periods, and with
11
prospective-randomized designs to better understand the clinical and radiological outcomes
12
of these two screws.
EP AC C
13
TE D
10
17
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Funding
2
No funds were received in support of the present work.
3
been or will be received from a commercial party related directly or indirectly to the subject
4
of this manuscript.
RI PT
No benefits in any form have
5
AC C
EP
TE D
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SC
6
18
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1
References
2
[1] Szpalski M, Gunzburg R. Lumbar spinal stenosis in the elderly: an overview. Eur Spine J 2003;12:S170–5.
RI PT
3
[2] Abbas J, Hamoud K, May H, et al. Socioeconomic and Physical Characteristics of
5
Individuals With Degenerative Lumbar Spinal Stenosis. Spine 2013;38:E554–61.
6
SC
4
[3] Pannell WC, Savin DD, Scott TP, Wang JC, Daubs MD. Trends in the surgical treatment of lumbar spine disease in the United States. Spine J doi:
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10.1016/j.spinee.2013.10.014. [Epub ahead of print]
9
[4]
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7
Liu X, Wang Y, Qiu G, Weng X, Yu B. A systematic review with meta-analysis of posterior interbody fusion versus posterolateral fusion in lumbar spondylolisthesis.
11
Eur Spine J 2013;23:43–56.
12
[5]
TE D
10
Lidar Z, Beaumont A, Lifshutz J, Maiman DJ. Clinical and radiological relationship between posterior lumbar interbody fusion and posterolateral lumbar fusion. Surg
14
Neurol 2005;64:303–8.
16
17 18
[6]
Wang Z, Fu S, Wu ZX, Zhang Y, Lei W. Ti2448 Pedicle Screw System
AC C
15
EP
13
Augmentation for Posterior Lumbar Interbody Fusion. Spine 2013;38:2008–15.
[7] Athanasakopoulos M, Mavrogenis AF, Triantafyllopoulos G, Koufos S, Pneumaticos SG. Posterior Spinal Fusion Using Pedicle Screws. Orthopedics 2013;36:e951–7.
19
ACCEPTED MANUSCRIPT Comparison of PS and CS in PLIF
1
[8] Jones-Quaidoo SM, Djurasovic M, Owens RK, Carreon LY. Superior articulating facet violation: percutaneous versus open techniques: Clinical article. J Neurosurg
3
Spine 2013;18:593–7.
4
RI PT
2
[9] Hu MW, Liu ZL, Zhou Y, et al. Posterior lumbar interbody fusion using spinous process and laminae. J Bone Joint Surg Br 2012;94:373-7.
5
[10] Parker SL, Amin AG, Santiago-Dieppa D, et al. Incidence and Clinical Significance
7
of Vascular Encroachment Resulting from Free Hand Placement of Pedicle Screws
8
in the Thoracic and Lumbar Spine: Analysis of 6,816 Consecutive Screws. Spine
9
2014 Jan 29. [Epub ahead of print]
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SC
6
[11] Oh HS, Kim JS, Lee SH, Liu WC, Hong SW. Comparison between the accuracy of percutaneous and open pedicle screw fixations in lumbosacral fusion. Spine J
12
2013;13:1751–7.
13
TE D
11
[12] Perez-Orribo L, Kalb S, Reyes PM, Chang SW, Crawford NR. Biomechanics of Lumbar Cortical Screw–Rod Fixation Versus Pedicle Screw–Rod Fixation With and
15
Without Interbody Support. Spine 2013;38:635–41.
17
18
AC C
16
EP
14
[13] Santoni BG, Hynes RA, McGilvray KC, et al. Cortical bone trajectory for lumbar pedicle screws. Spine J 2009;9:366–73.
[14]
Matsukawa K, Yato Y, Kato T, et al. In Vivo Analysis of Insertional Torque During
19
Pedicle Screwing Using Cortical Bone Trajectory Technique. Spine 2014;39:E240–
20
5.
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[15] Piaggio G, Elbourne DR, Pocock SJ, Evans SJ, Altman DG; CONSORT Group.
2
Reporting of noninferiority and equivalence randomized trials: extension of the
3
CONSORT 2010 statement. JAMA 2012;308:2594–604.
RI PT
1
4 5
[16]
Wu Y, Tang H, Li Z, Zhang Q, Shi Z. Outcome of posterior lumbar interbody fusion versus posterolateral fusion in lumbar degenerative disease. J Clin Neurosci
7
2011;18:780–3. [17]
Lau D, Terman SW, Patel R, La Marca F, Park P. Incidence of and risk factors for
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8
SC
6
superior facet violation in minimally invasive versus open pedicle screw placement
9 10
during transforaminal lumbar interbody fusion: a comparative analysis: Clinical
11
article. J Neurosurg Spine 2013;18:356–61.
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14
Mobbs RJ. The “medio-lateral-superior trajectory technique”: an alternative cortical trajectory for pedicle fixation. Orthop Surg 2013;5:56-9.
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[18]
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Figure Legends
2
Figure 1.
On axial (A, L5; B, S1) and sagittal (C, L5; D, S1)
4
CT images, the CS was inserted through the pedicle in a the supero-lateral direction from
5
the entry point, which was located near the pars articularis.
6 7
Figure 2.
Flow diagram for enrolled patients.
Figure 3.
Mean VAS for back pain (A), mean VAS for radiating pain to the lower
M AN U
8 9
SC
Cortical screw trajectory.
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3
extremity (B), and mean ODI (C) scores by time point. The VAS and ODI were collected
11
at each follow-up time. Error bars represent standard deviations.
12
* Statistically significant difference between scores at baseline and at each follow-up time
13
(P < 0.05)
14
** Statistically significant difference between groups at the follow-up times (P < 0.05)
EP
16
AC C
15
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10
22
ACCEPTED MANUSCRIPT Table 1. Demographic Data Group C
P
39
38
-
51.9 ± 11.7
51.3 ± 12.4
0.71
34 / 5
33 / 5
0.83
Height (cm)
166.8 ± 10.4
164.7 ± 9.4
0.98
Weight (kg)
68.8 ± 13.4
65.3 ± 11.4
0.33
BMI (kg/m2)
24.9 ± 2.9
BMD (T-score)
2.2 ± 0.7
Age (year)
Smoking status smoker (%)
0.40
2.3 ± 0.9
0.52
15 (38.5)
16 (42.1%)
24 (61.5)
22 (57.9%)
TE D
non-smoker (%) Lumbar pathology (%)
24.6 ± 3.4
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Gender (male / female)
SC
Case
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Group B
10 (25.6)
9 (23.7)
Isthmic spondylolisthesis
21 (53.9)
24 (63.2)
8 (20.5)
5 (13.1)
EP
LSS with foraminal stenosis
AC C
Degenerative spondylolisthesis Fusion level
0.95
0.93
L4-5 (%)
19 (48.7)
18 (47.4)
L5-S1 (%)
20 (51.3)
20 (52.6)
Values in data cells represent mean ± SD (standard deviation). BMI, body mass index; BMD, bone mineral density; LSS, lumbar spinal stenosis
ACCEPTED MANUSCRIPT Table 2. Fusion rate at one year post-surgery Group B (n = 39)
Group C (n = 38)
P
Using dynamic radiographs at postoperative one year 34
34
Nonunion
5
4
87.2
89.5
Union rate (%)
34
35
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Fusion Nonunion
4
3
87.2
92.1
AC C
EP
TE D
Union rate (%)
0.81
SC
Using CT scans at postoperative one year
RI PT
Fusion
1
0.61
ACCEPTED MANUSCRIPT Table 3. Clinical outcomes Group B (n = 39)
Group C (n = 38)
P
Pre-operative
7.6 ± 3.1
7.7 ± 3.1
0.63
1 week postoperative
4.3 ± 2.1
2 weeks postoperative
2.1 ± 1.0
3 weeks postoperative
2.0 ± 0.9
1 month postoperative
1.7 ± 0.6
Clinical Parameters
RI PT
VAS for lower back pain
0.02*
2.0 ± 0.8
0.71
1.8 ± 1.1
0.52
1.5 ± 0.9
0.45
1.6 ± 0.5
1.5 ± 1.0
0.51
2.0 ± 1.2
1.8 ± 0.9
0.57
2.0 ± 1.0
2.1 ± 1.5
0.38
5.7 ± 1.8
5.9 ± 1.3
0.35
1.2 ± 0.3
1.0 ± 0.5
0.55
3 months postoperative
1.0 ± 0.2
0.8 ± 0.5
0.43
6 months postoperative
1.2 ± 0.6
1.1 ± 0.7
0.51
1 year postoperative
1.1 ± 0.4
1.2 ± 0.6
0.67
Pre-operative
36.5 ± 10.1
35.1 ± 9.7
0.51
3 months postoperative
17.3 ± 5.9
17.5 ± 4.8
0.60
6 months postoperative
10.7 ± 1.4
8.5 ± 0.6
0.53
6 months postoperative
VAS for radiating pain Pre-operative
TE D
1 year postoperative
M AN U
3 months postoperative
AC C
EP
1 month postoperative
SC
2.9 ± 1.3
ODI score
2
ACCEPTED MANUSCRIPT 1 year postoperative
11.0 ± 2.5
10.5 ± 2.8
0.46
Values in data cells represent mean ± SD (standard deviation). VAS, visual analogue scale; ODI, oswestry disability index
AC C
EP
TE D
M AN U
SC
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*, meaning significant difference between groups (P < 0.05)
3
ACCEPTED MANUSCRIPT Table 4. Surgical outcomes Group C (n = 38)
P
Blood loss (mL)
450 ± 25
360 ± 30
0.04*
Operation time (hours)
2.6 ± 0.2
2.1 ± 0.3
0.03*
Hospital stay (day)
13.8 ± 1.7
13.7 ± 2.2
0.47
107.2 ± 15.4
73.1 ± 9.3
0.03*
Incision length (mm)
SC
Values in data cells represent mean ± SD (standard deviation).
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Group B (n = 39)
AC C
EP
TE D
M AN U
*, meaning significant difference between groups (P < 0.05)
4
AC C
EP
TE D
M AN U
SC
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TE D
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SC
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EP
TE D
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SC
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EP
TE D
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