Jernal of Spinou

ISSN: 2165-7939

Li et al., J Spine 2019, S8
DOI: 10.4172/2165-7939.S8-001

Journal of Spine

Research Article

Open Access

Laterally Placed Expandable Interbody Spacers with Adjustable Lordosis
Improve Radiographic and Clinical Outcomes
Yan Michael Li1* , Zheng Huang2, James Towner1, Yan Icy Li1, Jessica R. Riggleman3 and Charles G. Ledonio3
Department of Neurosurgery and Oncology, Medical Center School of Medicine and Dentistry, University of Rochester, New York, USA
Department of Orthopaedics, Guanghua Hospital, P.R. China
3
Musculoskeletal Education and Research Center, A Division of Globus Medical Inc., Audubon, Pennsylvania, USA
1
2

Abstract
Introduction: Minimally invasive lateral lumbar interbody fusion (MIS LLIF) has been shown to minimize soft tissue
dissection and blood loss in comparison to open posterior lumbar interbody fusion. This study describes the clinical andradiographic outcomes of patients treated with expandable interbody spacers with adjustable lordosis for MIS LLIF.
Methods: This is a single surgeon retrospective Institutional Review Board-exempt chart review on 57 consecutive
patients who underwent MIS LLIF at 1–2 contiguous level(s) using expandable spacers with adjustable lordosis, whichallow for expansion in height and lordosis. Radiographic and clinical functional outcomes were collected and compared at
preoperative and postoperative time points up to 12 months. Statistical results were significant if P<0.05.
Results: Fifty-seven consecutive patients were evaluated with an average age of 58 ± 12.3 years, and 49.1% werefemale. Visual Analog Scale (VAS) for back pain and Oswestry Disability Index (ODI) scores decreased significantly
at 12 months (P<0.001). Lumbar lordosis improved by a mean of 5.1° at 12 months (P<0.001). Anterior, middle, andposterior disc height significantly increased at 12 months by means of 5.2 mm, 4.6 mm, and 2.6 mm respectively (P<0.001).
Neuroforaminal height increased by a mean of 3.7 mm (P<0.001) while segmental lordosis improved by 3.7° at 12 months.
Discussion and Conclusion: This study showed significant positive clinical and radiographic outcomes for patients
who underwent MIS LLIF using expandable interbody spacers with adjustable lordosis based on decreased VAS back pain
and ODI scores at 1-year follow-up. The use of expandable spacers with adjustable lordosis was shown to be safe andeffective for the cohort studied.

Keywords: Expandable; Fusion; LLIF; Minimally invasive; Lateral
lumbar interbody fusion
Introduction
First described by Ozgur and co-authors in 2006, lateral lumbarinterbody fusion (LLIF) is a popular retroperitoneal transpsoas
approach to access the disk space for lumbar spine interbody fusion[1]. The potential advantages of this approach include minimizing therisk of complications associated with either the anterior approach or theposterior approaches [2,3].
A critical component to the success of the lateral procedure is
the interbody spacer, which can help to achieve sagittal correction.
Since preservation or restoration of sagittal alignment is a significant
predictor in determining patient outcomes, maximizing disc height,
segmental lordosis, and achieving adequate indirect decompression
is of the utmost importance [4-6]. Fusing the lumbar spine in ahypolordotic alignment predisposes the patient to development ofadjacent segment disease (ASD) [7,8]. Consequently, postoperative
sagittal plane abnormalities are correlated with ASD development [9].
There are many interbody spacer designs, some with builtin lordosis. The effects of increasing anterior lordosis without
proportionally increasing disc height may have conflicting results.
There are conflicting results in the literature on the effects of interbody
spacer design with or without built-in lordosis on segmental lordosis[10]. Other interbody spacer designs that are highly lordotic could
possibly present a challenge to insert in disc spaces that are collapsed.
One of the advantages of an expandable spacer is that the spacer isdelivered in a collapsed state and expanded in-situ. Developments in
expandable technology now allow for cages to increase in both height
and lordosis in a controlled expansion. Clinical outcome studies areneeded to generate evidence of effectiveness and safety. The objective
J Spineof this study is to determine the clinical and radiographic outcomesof patients who underwent MIS LLIF using an expandable interbody
spacer with an adjustable lordosis (RISE-AL® Globus Medical Inc.
Audubon, PA) (Figures 1 and 2).

Research Methodology
This is a retrospective study from a prospectively collectedconsecutive cohort of patients who were diagnosed with symptomaticdegenerative disc disease with or without grade 1 spondylolisthesis
in one or two contiguous levels and underwent MIS LLIF using anovel expandable interbody spacer with adjustable lordosis with
supplemental fixation. Patient demographics, VAS back pain, ODI
scores and radiographic parameters were collected at 6 weeks, 3, 6 and12 months postoperatively.

Surgical technique
After induction of general anesthesia, patients were placed in thelateral decubitus position and secured to the operating table withadhesive medical tape. Under fluoroscopic guidance, an oblique*Corresponding author: Dr. Yan Michael Li, Neurosurgery and Oncology
University of Rochester Medical Center School of Medicine and Dentistry Rochester
NY, USA, Tel: +5856781198; E-mail: Dr.yanli@gmail.com
Received May 01, 2019; Accepted May 15, 2019; Published May 22, 2019
Citation: Li YM, Huang Z, Towner J, Li YI, Riggleman JR, et al. (2019) Laterally
Placed Expandable Interbody Spacers with Adjustable Lordosis Improve Radiographic
and Clinical Outcomes. J Spine S8: 001. doi:10.4172/2165-7939.S8-001
Copyright: © 2019 Li YM, et al. This is an open-access article distributed under
the terms of the Creative Commons Attribution License, which permits unrestricted
use, distribution, and reproduction in any medium, provided the original author andsource are credited.

Minimally Invasive Spine Surgery -III

ISSN: 2165-7939, an open access journalCitation: Li YM, Huang Z, Towner J, Li YI, Riggleman JR, et al. (2019) Laterally Placed Expandable Interbody Spacers with Adjustable Lordosis
Improve Radiographic and Clinical Outcomes. J Spine S8: 001.
Page 2 of 5

fluoroscopy images were taken to verify the screw and rod position.
Surgical incisions were cleaned and closed in the standard fashion.

Quantitative measurements

Figure 1: Oblique view of the titanium expandable interbody spacer withadjustable lordosis.

Radiographic lumbosacral parameters were measured on uprightlateral radiographs using imaging software (Intellispace PACS 4.4©;
Koninklijke Philips N.V, Amsterdam, Netherlands) (Figure 4).
Measurements included disc heights, neuroforaminal height, segmental
lordosis, and lumbar lordosis. Disc height was defined as the distance
between the inferior and superior endplates at the anterior, middle, andposterior portions of the vertebral body. Neuroforaminal height refers
to the interpedicular height, or the rostral and caudal boundaries ofthe foramen. Segmental lordosis was measured as the Cobb angle ofthe inferior endplate of the level below the TLIF and the superior
endplate of the level above the TLIF. Lumbar lordosis was measured
as the angle between the superior endplate of L1 and the superior
endplate of S1.

Statistical analysis
The statistical analysis was performed using IBM® SPSS® Version
25 (IBM® Corp.; Armonk, NY, USA). Descriptive statistics arepresented as frequencies and percentages. Clinical and radiographic
measurements are presented as means and standard deviations.
Statistical significance was shown at P<0.05.

Results
Patient demographics
A total of 57 consecutive patients underwent MIS LLIF
from August 2016 to November 2017, and were implanted with atitanium expandable interbody spacer with adjustable lordosis.
The patients were 49.1% (28/57) female and 50.9% (29/57) male withan average age of 58 ± 12.3 years (range: 21-79 years). The averagepatients Charlson comorbidity index (CCI) score was 2.6 ± 1.9 (range:0-8) (Table 1).

Surgical data

Figure 2: Preoperative lateral (A) and anteroposterior (B) radiographs andpostoperative lateral (C) and anteroposterior (D) radiographs of a one-level MIS
LLIF using an adjustable lordotic expandable interbody spacer at L4-L5.

incision was made at the operative disc segment. Blunt dissection was
performed under direct visualization through the retroperitoneal space.
Retroperitoneal fat was mobilized anteriorly, exposing the underlying
psoas muscle. The psoas muscle was palpated, and blunt dissection
was performed down to the operative intervertebral disc level. Afterconfirmation of the appropriate level via fluoroscopy, a minimallyinvasive retractor was docked, dilated at the segment, and secured to thetable-mounted arm. An annulotomy was then performed, followed by adiscectomy. Under fluoroscopic imaging, the endplates were prepared.
An expandable trial was used to allow for gradual distraction of
the disc space. An expandable interbody spacer manufactured fromtitanium alloy was selected, packed with autogenous bone graft, andimplanted laterally across the disc space at a contracted height. The
spacer was then expanded to the desired height in situ under fluoroscopic
guidance and backfilled with autogenous bone graft (Figure 3). Pedicle
screws and rods were used for supplemental fixation. Locking caps
were set once the rods were in their proper position. Intraoperative
J SpineOf the 57 patients, 77.2% (44/57) underwent one-level and
22.8% (13/57) underwent two-level MIS LLIF, for a total of 70
spinal levels treated. Of the 70 levels, 45.7% (32/70) were
instrumented at L4-L5 and 32.9% (23/70) at L3-L4. The average
estimated blood loss was less than 50cc for one and two-level fusions
with no blood transfusions. For one-level fusions, the mean operative
time was 53.5 ± 11.0 min and 77.8 ± 21.5 min for two-level fusions.
Mean fluoroscopic time was 27.1 ± 12.0 sec for one-level fusions and29.8 ± 13.2 sec for two-level fusions. Mean length of hospital stay

Figure 3: Additional bone graft may be packed into the graft chamber of theimplant after expansion.

Minimally Invasive Spine Surgery -III

ISSN: 2165-7939, an open access journalCitation: Li YM, Huang Z, Towner J, Li YI, Riggleman JR, et al. (2019) Laterally Placed Expandable Interbody Spacers with Adjustable Lordosis
Improve Radiographic and Clinical Outcomes. J Spine S8: 001.
Page 3 of 5

To the best of the authors’ knowledge, this is the first study todescribe the clinical and radiographic outcomes of the use of an
expandable interbody spacer with an adjustable lordosis in MIS LLIF;
therefore comparison to the literature is challenging. Sembrano andco-authors reported on the radiographic outcomes of patients who
underwent LLIF comparing the use of non-lordotic versus lordotic
interbody spacers [16]. Disc height and segmental lordosis weresignificantly increased by 74.2% and 22.4%, respectively. Lumbar
lordosis decreased by 0.4%, but the change was not significant. No
functional clinical outcomes were reported.

was 3.3 ± 2.0 days for one-level fusions and 4.4 ± 2.7 days for two-level
fusions (Table 2).

Patient Reported Outcomes (VAS and ODI)
Mean VAS back pain scores significantly improved by 51.9% (4.2
± 1.0), 60.5% (4.9 ± 1.2), 72.8% (5.8 ± 1.2), and 80.2% (6.5 ± 1.2) at 6
weeks, 3, 6, and 12 months, respectively (P<0.001) (Figure 5). Mean
ODI scores significantly improved by 38.6% (29.9 ± 13.1 points), 55.1%(42.6 ± 12.2 points), 67.7% (52.4 ± 13.5 points), and 78.9% (61.1 ± 11.9
points) at 6 weeks, 3, 6, and 12 months, respectively (P<0.001) (Figure
6 and Table 3).

Radiographic parameters
Mean anterior disc height significantly improved by 92.2% (6.7 ±3.0 mm), 82.8% (6.1 ± 3.0 mm), 78.1% (5.5 ± 3.0 mm), and 71.9% (4.5 ±2.9 mm) at 6 weeks, 3, 6, and 12 months, respectively (P<0.001). Mean
middle disc height significantly improved by 86.8% (5.9 ± 2.4 mm),
81.6% (5.3 ± 2.3 mm), 73.7% (5.0 ± 2.3 mm), and 68.4% (4.7 ± 2.4 mm)
at 6 weeks, 3, 6, and 12 months, respectively (P<0.001). Mean posterior
disc height significantly improved by 88.9% (4.0 ± 1.8 mm), 75.6% (3.4
± 1.8 mm), 66.7% (3.0 ± 1.8 mm), and 57.8% (2.6 ± 1.9 mm) at 6 weeks,
3, 6, and 12 months, respectively (P<0.001). Mean neuroforaminal
height significantly improved by 41.8% (5.9 ± 3.9 mm), 38.3% (5.4 ±4.0 mm), 31.2% (4.4 ± 4.0 mm), and 26.2% (3.7 ± 3.9 mm) at 6 weeks,
3, 6, and 12 months, respectively (P<0.001). Mean segmental lordosis
significantly improved by 102.1% (4.8 ± 3.3°), 93.6% (4.4 ± 3.1°), 87.2%(4.1 ± 3.1°), and 78.7% (3.8 ± 2.9°) at 6 weeks, 3, 6, and 12 months,
respectively (P<0.001). Mean lumbar lordosis significantly improved by
18.3% (7.3 ± 8.8°), 15.5% (6.2 ± 8.4°), 14.3% (5.7 ± 8.7°), and 12.8% (5.1
± 8.8°) at 6 weeks, 3, 6, and 12 months, respectively (P<0.001) (Table 4).

Complications
There were no reported implant-related complications, radiolucency,
or subsidence. There was a 0% pseudoarthrosis rate by 12 month follow-up.

Discussion
Radiographic and clinical outcomes are essential to provide
evidence on the use of expandable interbody spacers with adjustable
lordosis for MIS LLIF. At 12-month follow-up, radiographic outcomesof this study showed that MIS LLIF using expandable interbody spacers
with adjustable lordosis significantly corrected middle disc height andsegmental lordosis by 68.4% and 78.7%, respectively. At 12-monthfollow-up, VAS back pain and ODI scores improved by three times theminimally clinical important difference (MCID) [11-15].
J Spine

The use of an adjustable lordotic expandable interbody spacer
illustrates the potential for significant segmental correction within thesagittal plane, with a significant mean improvement of 3.7° of lordosis
shown in this study at 12-month follow-up. Other studies on MIS TLIF
have demonstrated 2-3° of segmental correction in the sagittal plane[17-19]. Additionally, the increase in segmental lordotic restoration in
the current study compares favorably to a weighted average increase of
3.9° published in a review by Uribe and co-authors [20].
In the current study, the mean ODI was 47.5 ± 14.4, 34.7 ± 12.3,
25.0 ± 13.0, and 16.3 ± 11.7 at 6 weeks, 3, 6, and 12 months, respectively.
Significant clinical benefit was achieved, with a mean ODI improvementof at least 20 points at each time interval: mean improvement of 29.8, 42.6,
52.3, and 61.0 points at 6 weeks, 3, 6, and 12 months, respectively [11-15].
Subsidence rates with the use of static interbody spacers have beenreported to be relatively high. In a systematic review by Macki et al.,the pooled subsidence rate with LLIF was 10.3% with a range of 0%
to as high as 30% (n=141/1362 patients in 14 published articles) andreoperation rate for subsidence of 2.7% (n=41/1470 patients in 16
VAS Back Pain
VAS Back Pain, mean

Figure 4: Standing lateral lumbar spine radiograph with superimposed lines
displaying the measurements evaluated in this study. Measurements include
disc heights, neuroforaminal height, segmental lordosis, and lumbar lordosis.

In other studies with expandable interbody spacers, the findings onradiographic and clinical outcomes were similarly improved. In 2016,
Kim and co-authors reported on 50 patients using MIS expandable
interbody spacers using a TLIF approach [17]. The study demonstrated
maintenance of disc height in 1 and 2-level lumbar interbody fusions
with no complications and no subsidence by 12 and 24-monthfollow-up. The findings underline the probable benefits of the use of
expandable interbody spacers with regards to reduced subsidence rates,
which is consistent with the current study. In a similar study, 54 patients
underwent MIS and open lumbar fusion using the TLIF approach with
24-month follow-up [18]. The results indicate a low complication rateand short hospital stay while restoring and maintaining disc height,
neuroforaminal height, and segmental lordosis.

10
9
8
7
6
5
4
3
2
1
0

*

0

1.5

*

3
Postoperative Months

*

6

*
12

Figure 5: Mean VAS back pain is shown. The results show a significant
decrease in VAS back pain scores from baseline and sustained at 1.5, 3, 6 and12 months. *P<0.001 compared to baseline.

Minimally Invasive Spine Surgery -III

ISSN: 2165-7939, an open access journalCitation: Li YM, Huang Z, Towner J, Li YI, Riggleman JR, et al. (2019) Laterally Placed Expandable Interbody Spacers with Adjustable Lordosis
Improve Radiographic and Clinical Outcomes. J Spine S8: 001.
Page 4 of 5

Oswestry Disability Index
100

ODI, mean

80

*

*

20
0

1.5

3
6
Postoperative Months

Parameters

Overall

Number of Patients

57

6 Months

12 Months

3.2 (1.0)*

2.2 (1.1)*

1.6 (1.2)*

ODI

77.3 (6.9)

47.5 (14.4)*

34.7 (12.3)*

25.0 (13.0)*

16.3(11.7)*

Female, n (%)

28 (49.1%)

Male, n (%)

29 (50.9%)

Age, mean (SD, range)

58 (12.3) (21-79)

CCI, mean (SD, range)

2.6 (1.9) (0-8)

Parameters

Parameters

Baseline

Anterior Disc
Height7.6 (3.1)

Middle Disc
Height6.4 (2.5)

Posterior Disc
Height4.5 (1.8)

Neuroforaminal
14.1 (4.1)
HeightTable 1: Baseline characteristics.

12
Months

6 Weeks

3 Months

6 Months

14.4 (2.2)*

13.8 (2.2)*

13.2 (2.0)* 12.8 (1.9)*

12.3 (2.2)*

11.7 (2.4)*

11.4 (2.3)* 11.0 (2.2)*

8.5 (1.8)*

7.9 (1.6)*

7.5 (1.5)*

20.0 (3.8)*

19.5 (3.6)*

18.5 (3.4)* 17.8 (3.0)*

Segmental
Lordosis

4.7 (2.9)9.5 (3.4)*

9.1 (3.1)*

8.8 (3.0)*

Lumbar
Lordosis39.9 (9.3)

47.2 (7.5)*

46.1 (6.5)*

45.6 (7.0)* 45.0 (7.0)*

7.1 (1.6)*

8.4 (2.6)**P<0.001 compared to baseline. Mean (SD).
Table 4: Radiographic parameters.

Overall percentage

Type of Surgery, n (%)
One-level

44 (77.2%)

Two-level

13 (22.8%)

Levels Treated, n (%)
L1-L2

4 (5.7%)L2-L3

11 (15.7%)

L3-L4

23 (32.9%)

L4-L5

32 (45.7%)

Mean Estimated Blood Loss
One-level<50cc

Two-level<50cc

Mean Operative Time, n (SD)One-level

53.5 (11.0)

Two-level

77.8 (21.5)

Mean Fluoroscopic Time, n (SD)Study Limitations
Although this is a single-surgeon single-site retrospective study
with a small patient population, the results are consistent with findings
from the literature. While this study only demonstrates 12-monthfollow-up, a long-term follow-up study is forthcoming.

Conclusion
This study provides clinical evidence that MIS LLIF using an expandable
interbody spacer with adjustable lordosis is safe and effective at improving
radiographic and clinical outcomes in the studied population. Disc height
and lordosis were significantly restored, correcting sagittal alignment withno cases of subsidence up to 12-month follow-up. All clinical outcomes
were significantly improved from preoperative values.
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One-level

27.1 (12.0)

Two-level

29.8 (13.2)

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Minimally Invasive Spine Surgery -III

ISSN: 2165-7939, an open access journalCitation: Li YM, Huang Z, Towner J, Li YI, Riggleman JR, et al. (2019) Laterally Placed Expandable Interbody Spacers with Adjustable Lordosis
Improve Radiographic and Clinical Outcomes. J Spine S8: 001.
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This article was originally published in a special issue, Minimally Invasive
Spine Surgery -III handled by Editor(s). Anthony T. Yeung, M.D. Clinical professor, University of New Mexico School of Medicine Associate Desert Institute for Spine Care, Phoenix, Arizona Executive director International Intradiscal therapy Society Phoenix, Arizona

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ISSN: 2165-7939, an open access journal