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Optimum pelvic incidence minus lumbar lordosis value after operation for patients with adult degenerative scoliosis
Accepted Manuscript Title: Optimum pelvic incidence minus lumbar lordosis value after operation for patients with adult degenerative scoliosis Author: Xiang-Yao Sun, Xi-Nuo Zhang, Yong Hai PII: DOI: Reference:
S1529-9430(17)30095-5 http://dx.doi.org/doi: 10.1016/j.spinee.2017.03.008 SPINEE 57262
To appear in:
The Spine Journal
Received date: Revised date: Accepted date:
19-11-2016 2-3-2017 15-3-2017
Please cite this article as: Xiang-Yao Sun, Xi-Nuo Zhang, Yong Hai, Optimum pelvic incidence minus lumbar lordosis value after operation for patients with adult degenerative scoliosis, The Spine Journal (2017), http://dx.doi.org/doi: 10.1016/j.spinee.2017.03.008. 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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Optimum pelvic incidence minus lumbar lordosis value after operation for patients with adult
2
degenerative scoliosis
3 4
Xiang-Yao Sun, Xi-Nuo Zhang, Yong Hai
5
Xiang-Yao Sun
6
Department of Orthopedics, Beijing Chaoyang Hospital, Capital Medical University, Beijing,
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100020, China
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E-mail: [email protected]
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Xi-Nuo Zhang
10
Department of Orthopedics, Beijing Chaoyang Hospital, Capital Medical University, Beijing,
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100020, China
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E-mail: [email protected]
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Yong Hai
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Department of Orthopedics, Beijing Chaoyang Hospital, Capital Medical University, Beijing,
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100020, China
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E-mail: [email protected]
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Name of the corresponding author Yong Hai
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E-mail address of the corresponding author [email protected]
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Present Address Department of Orthopedics, Beijing Chaoyang Hospital, No.8 Gong Ren Ti
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Yu Chang Nan Lu Road, Chaoyang District, Beijing 100020, China
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Conflict of interest statement The authors declare that they have no conflict of interest. There is no 1
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funding source. Informed consent was obtained from all individual participants included in the study.
2 3
Ethical Review Committee Statement The study was approved by the institutional review board
4 5
Acknowledgments The authors would like to thank Professor Yong Hai who provided data support
following the declaration of Helsinki principles.
and corrected some mistakes.
6
7
Abstract
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BACKGROUND CONTEXT: Schwab classification for adult degenerative scoliosis (ADS)
9
concluded that health-related quality of life (HRQOL) was closely related to curve type and three
10
sagittal modifiers. It was suggested that pelvic incidence minus lumbar lordosis value (PI-LL) should
11
be corrected within -10°~+10°. However, recent studies also indicated that ideal clinical outcomes
12
could also be achieved in patients without ideal PI-LL mentioned above.
13
PURPOSE: This study evaluated the relation between the clinical outcomes and the pelvic incidence
14
minus lumbar lordosis value (PI-LL) of Chinese patients with ADS who received long posterior
15
internal fixation and fusion.
16
STUDY DESIGN: This was a single-center retrospective comparative study of patients treated by long
17
posterior internal fixation and fusion in the our hospital between 2010 and 2014.
18
PATIENT SAMPLE: Inclusion criteria were age > 45 years at the time of surgery, the Cobb angle of
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lumbar curves ≥ 10°, long posterior internal fixation and fusion ≥ least 3 motion segments, follow-up ≥
20
2 years, complete preoperative and postoperative radiographic data and functional evaluation results.
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Exclusion criteria were history of previous lumbar spine surgery, other kinds of scoliosis, history of
22
severe spinal trauma, spinal tumor, ankylosing spondylitis (AS), spinal tuberculosis. Seventy-four 2
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patients were enrolled in the study.
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OUTCOME MEASURES: Operative parameters included intraoperative blood loss, duration of
3
surgery, length of hospital stay, number of fusion levels and decompression. The radiological
4
measurements included Cobb angle of the curves and PI-LL. Clinical outcomes were evaluated by
5
Japanese Orthopaedic Association (JOA) score, Oswestry disability index (ODI), visual analog scale
6
(VAS) and lumbar stiffness disability index (LSDI). In addition, the complications of surgery were also
7
collected. One-way analysis of variance (ANOVA), Student’s t test, Kruskal-wallis test, Pearson’s
8
chi-square test and curve estimation were calculated for variables.
9
METHODS: All the patients were divided into group 1 (long instrumentation and fusion to L5) and
10
group 2 (long instrumentation and fusion to S1). Operative parameters, radiological measurements,
11
clinical outcomes and complications of surgery were compared between two groups to confirm whether
12
distal fusion level could influence therapeutic effect. Then patients were divided into PI-LL < 10°
13
(group A), 10° ≤ PI-LL ≤ 20° (group B), PI-LL > 20° (group C). Operative parameters, radiological
14
measurements, clinical outcomes and complications of surgery were compared between each two
15
groups. Curve estimation was performed to evaluate the relationship between postoperative PI-LL and
16
clinical outcomes. The researchers declare that they have no conflict of interest. There was no funding
17
source. Informed consent was obtained from all individual participants included in the study.
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RESULTS: No difference was found between group 1 and group 2 in all postoperative parameters (P >
19
0.05). There were significant differences in final ODI (P < 0.001), final LSDI (P < 0.001) among group
20
A, group B and group C. Cubic curve model fitted the relationship between PI-LL and final ODI better
21
than other models (R2 = 0.379, P < 0.001). Cubic curve model fitted the relationship between PI-LL
3
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and final LSDI better than other models (R2 = 0.691, P < 0.001). There was a significant difference in
2
proximal junctional kyphosis (PJK) among groups (P = 0.038). No significant difference was found in
3
other parameters.
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CONCLUSIONS: Optimal PI-LL value may be achieved between 10° and 20° in Chinese patients
5
with ADS after long posterior instrumentation and fusion surgery with excellent clinical outcomes and
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a lower PJK occurrence.
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KEYWORDS: Adult degenerative scoliosis; SRS-Schwab classification; sagittal balance; pelvic
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incidence; lumbar lordosis
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Introduction
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The definition of adult scoliosis (ADS) is spinal deformity with a scoliotic angle of over 10° in patients
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with mature skeleton [1]. The incidence of adult scoliosis ranges from 8.3% to 68% of population [1-3].
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Degenerative scoliosis usually occurs after age fifty, and its incidence and curves would increase with
14
age[4]. This kind of disease represents degenerative changes of the intervertebral disks and facets, then
15
it would lead to deformity in progress [5]. The main symptoms of adult scoliosis are deformity, low
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back pain and radiating to the legs, neurologic deficits, functional limitations or disabilities [6].
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Conservative treatment is always firstly recommended, but the clinical outcomes are commonly
18
unsatisfactory and then surgical treatment would be considered [7]. The aim of surgery is to relieve low
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back pain as well as radiating pain and claudication, and then correct deformity [8].
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Schwab classification [9] categorized the apex of the curve, lumbar lordosis and vertebral body 4
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subluxation based on the relationship between radiological findings and clinical evaluation. It
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concluded that the lower apex of the curve combined with loss of lordosis was associated with poor
3
health-related quality of life (HRQOL). The relationship between spino-pelvic parameters and sagittal
4
balance was considered in SRS-Schwab classification [10]. It concluded that HRQOL was closely
5
related to curve type and three sagittal modifiers. Although Schwab et al. [10, 11] suggested that pelvic
6
incidence minus lumbar lordosis value (PI-LL) should be corrected within -10°~+10°, many studies
7
[12-14] indicated ideal clinical outcomes could also be achieved in patients without ideal PI-LL
8
mentioned above. The purpose of the study was to evaluate the relation between the clinical outcomes
9
and the PI-LL of Chinese ADS patients who received long posterior internal fixation and fusion,
10
according to SRS-Schwab PI-LL sagittal modifier. Whether PI-LL corrected within -10°~+10° was an
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optimistic criterion was also discussed in this study. To our knowledge, this has not been reported.
12
Methods
13
This was a single-center retrospective comparative study of 74 ADS patients treated by long posterior
14
internal fixation and fusion in our hospital between 2010 and 2014. Inclusion criteria were age > 45
15
years at the time of surgery, the Cobb angle of lumbar curves ≥ 10°, long posterior internal fixation and
16
fusion ≥ least 3 motion segments, follow-up ≥ 2 years, complete preoperative and postoperative
17
radiographic data and functional evaluation results. Exclusion criteria were history of previous lumbar
18
spine surgery, other kinds of scoliosis, history of severe spinal trauma, spinal tumor, ankylosing
19
spondylitis (AS), spinal tuberculosis. The study was approved by the institutional review board
20
following the declaration of Helsinki principles. The researchers declared that they have no conflict of
21
interest. There was no funding source. Informed consent was obtained from all individual participants 5
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included in the study.
2
Operative parameters
3
Operative parameters included intraoperative blood loss, duration of surgery, length of hospital stay,
4
number of fusion levels and decompression.
5
Radiological measurement
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The patients were evaluated using standing whole spine X-ray (Philips Digital Diagnost). The plain
7
radiographs included posteroanterior and lateral views. The radiological measurements included Cobb
8
angle of the curves, pelvic incidence minus lumbar lordosis value (PI-LL). LL was defined as Cobb
9
angle from the upper endplate of L1 to the upper endplate of S1. PI was the angle subtended by a
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perpendicular from the upper endplate of S1 and a line connecting the center of the femoral head to the
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center of the upper endplate of S1. Patients were divided into PI-LL < 10° (group A), 10° ≤ PI-LL ≤ 20°
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(group B), PI-LL > 20° (group C) [10].
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Clinical assessment
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Clinical outcomes were evaluated by Japanese Orthopaedic Association (JOA) score, Oswestry
15
disability index (ODI), visual analog scale (VAS) and lumbar stiffness disability index (LSDI). These
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were valid and rigorous functional measures used for assessing spinal disorders. In addition, the
17
complications of surgery were also collected.
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Surgical procedures
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The indication for surgical treatment was claudication or radiating leg pain that was resistant to
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conservative therapy for more than 6 in adult degenerative scoliosis. For a severe lateral subluxation 6
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with large Cobb angle, long fusion including entire curve should be considered. The upper
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instrumented vertebra (UIV) was determined by the surgeon’s judgement based on the curve pattern. In
3
a general way, UIV should not be the apex of the thoracic kyphosis. The upper thoracic (UT) spine was
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selected as UIV for those with thoracic curves. The low thoracic (LT) spine was selected as UIV for
5
those with thoracolumbar curve. When the L5-S1 segment was symptomatic or sufficiently
6
degenerated that it was not desirable to leave it as an unfused segment, or when inclusion was deemed
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necessary to achieve improved coronal and sagittal balance, fusion to the sacrum was performed.
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Considering all these factors, the final fusion level was determined by each surgeon’s preference.
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Surgery was performed under the general anesthesia for all patients. Locally hypertrophic ligamentum
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flavum and upper and inferior zygopophysis with hyperplasia and cohesion were cleaned as much as
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possible during decompression. In some circumstances, a Ponte osteotomy was performed for
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correction. Pedicle screw was placed. In order to reduce scoliosis, rod-rotation maneuver was first tried,
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and compression of the rod was added when more correction was required. The rod was prebent to fit
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the desired lumbar lordosis before inserting rod. In situ bending technique was not usually performed
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to avoid weakening of the rod. The application of bone grating between vertebral plates was
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determined by specific surgical condition and amount of crush bone. Anesthesia wake-up test was
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performed during surgery to confirmed normal function of both lower extremities. Fixation screws
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were tightened one by one. X-ray was performed to confirm restoration condition after surgery.
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Negative pressure drainage was placed before the surgical incision was closed.
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Statistical analysis
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The statistical analysis was performed using the Statistical Package for Social Sciences version 17.0 7
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software (SPSS, Inc., Chicago, IL). Continuous variables were reported as mean ± standard deviations
2
(SD), while noncontiguous data was presented as number or ratio. Normality of the continuous data
3
was tested using the Kolmogorov-Smirnov test. Normally distributed values were analyzed by one-way
4
analysis of variance (ANOVA) or Student’s t test. However, skew distributed values were analyzed by
5
Kruskal-wallis test. However, the statistical significance of noncontiguous data was performed by
6
Pearson’s chi-square test. Curve estimation was performed to evaluate the relative influences of
7
postoperative PI-LL on postoperative radiographic parameters, clinical outcomes and operative
8
parameters. A P value < 0.05 was statistically significant.
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Results
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Demographics
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Of the 74 patients enrolled in the study, 21 were male and 53 were female, with an average age of 63.7
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± 4.6 years. They underwent 7.0 ± 1.8 levels of fusion and 2.2 ± 0.8 levels of decompression. Levels of
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fusion included T9-S1 (1, 1.35%), T10-S1 (11, 14.9%), L2-S1 (18, 24.3%), T10-L5 (36, 48.6%), L2-L5
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(8, 10.8%). The mean follow-up time was 3.2 ± 0.7 years. The mean operative time was 237.8 ± 39.7
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minutes. The intraoperative blood loss was 1017.2 ± 813.3 ml. The length of hospital stay was 14.5 ±
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1.3 days. Cobb angle of curves, PI-LL, ODI, JOA, VAS in the preoperative periods were 20.3 ± 2.8°,
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36.0 ± 4.4°, 63.0 ± 2.8, 5.6 ± 1.2, 6.9 ± 1.3, respectively. Postoperative PI-LL was 16.6 ± 8.7°. Cobb
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angle of curves, ODI, JOA, VAS, LSDI at the time of last follow-up were 4.2 ± 1.8°, 25.6 ± 8.0, 3.1 ±
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1.4, 3.1± 1.0, 1.8 ± 1.4, respectively (Table 1).
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Relationship between distal fusion level and therapeutic effects
8
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All the patients were divided into group 1 (long instrumentation and fusion to L5) and group 2 (long
2
instrumentation and fusion to S1). Comparison of therapeutic effects between the two groups was
3
performed to find whether difference in distal fusion level would influence the results. The results
4
revealed that there was no significant difference in operative time (P = 0.126), intraoperative blood loss
5
(P = 0.962), length of hospital stay (P = 0.379), Cobb angle of the curves at last follow-up time (P =
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0.662), ODI at last follow-up (P = 0.851). JOA at last follow-up time (P = 0.873), final VAS (P =
7
0.254), LSDI at last follow-up (P = 0.176), postoperative incision infection rate (P = 0.461), PJK rate
8
(P = 0.590), loosening of fixation rate (P = 1.000), reoperation rate (P = 0.146) (Table 2). These
9
confirmed that the difference in distal fusion level would not influence the later analysis.
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Relationship between PI-LL and therapeutic effects
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Patients were divided into group A (n = 22), group B (n = 28) and group C (n = 24), as mention above.
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No significant difference was found in operative time (P = 0.078), intraoperative blood loss (P = 0.379),
13
length of hospital stay (P = 0.195), Cobb angle of the curves at last follow-up time (P = 0.260), JOA at
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last follow-up time (P = 0.228), final VAS (P = 0.789) among these groups. There were significant
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differences in final ODI (P < 0.001), final LSDI (P < 0.001) among these groups (Table 2). Final ODI
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was significantly better in B group compared to A group (P < 0.001) and C group (P < 0.001). The final
17
ODI in group A was significantly better than group C (P < 0.001). The LSDI at last follow-up time in
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group B was significantly better than group A (P < 0.001). No significant difference was found
19
between group B and group C (P = 0.116). The LSDI at last follow-up time in group A was
20
significantly better than group C (P < 0.001).
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Curve estimation was performed to evaluate the relationship between postoperative PI-LL and 9
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clinical outcomes. All the curve models in SPSS 17.0 were tested. The results showed that s curve
2
model fitted the relationship between PI-LL and Cobb angle of the curves at last follow-up time better
3
than other models (R2 = 0.506 , P < 0.001). Cubic curve model fitted the relationship between PI-LL
4
and final ODI better than other models (R2 = 0.379, P < 0.001). No model fitted the relationship
5
between PI-LL and final JOA (P > 0.05). There was no model fitting the relationship between PI-LL
6
and final VAS (P > 0.05). Cubic curve model fitted the relationship between PI-LL and final LSDI
7
better than other models (R2 = 0.691, P < 0.001) (Table 4).
8
Relationship between PI-LL and complications
9
Postoperative incision infection occurred in 3 patients in group A (13.6 %), 3 patients in group B
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(10.7 %), 2 patients in group C (9.1 %). No significant difference was found in postoperative incision
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infection rate among groups (P = 0.846). Proximal junctional kyphosis (PJK) occurred in 6 patients in
12
group A (27.3 %), 3 patients in group B (12.0 %), 10 patients in group C (41.7 %). There was a
13
significant difference among groups (P = 0.038). There was no significant difference in PJK occurrence
14
between group A and group B (P = 0.157). No significant difference was found in PJK occurrence
15
between group A and group C (P = 0.306). PJK occurrence in group B was significantly less than group
16
C (P = 0.022). Loosening of fixation occurred in 2 patients in group A (P = 9.1 %), 1 patients in group
17
B (P = 3.6%), 4 patients in group C (P = 16.7%) (Fig. 1). No significant difference was found in
18
loosening of fixation occurrence among groups (P = 0.274). Reoperation occurred in 3 patients in
19
group A (13.6 %), 2 patients in group B (7.1 %), 4 patients in group C (16.7 %). No significant
20
difference was found in reoperation rate among groups (P = 0.560) (Table 3). The reoperation was
21
caused by severe PJK in our study. 10
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Discussion
2
This study investigated the correlation between postoperative PI-LL and clinical outcomes based on
3
SRS-Schwab PI-LL sagittal modifiers in ADS [10]. In the comparison of radiographic parameters,
4
there was no significant difference in Cobb angle of curves in the last follow-up time among the groups,
5
while all the Cobb angles were less than 10°, which indicated the effectivity in coronial realignment.
6
Our results showed that although s curve model fitted the relationship between postoperative PI-LL and
7
final Cobb angle of curves, there was no significant difference among groups. These indicated
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postoperative PI-LL might not significantly influence coronal spinal parameters.
9
The relationship between spino-pelvic parameters and the quality of life remains controversial.
10
Postoperative flat-back syndrome was proved to be a factor leading to unsatisfactory clinical outcomes
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after lumbar fusion surgery [15]. Schwab et al. [11] showed that PI-LL was related to LBP and
12
disability in their systematic evaluation method to classify sagittal spinal alignment in the cases of
13
fat-back syndrome. Mac-Thiong et al. [16] demonstrated that sagittal spinal and global balance was
14
strongly associated with the ODI in adults with scoliosis, while coronal spinal and global balance did
15
not influence the ODI in their study. However, Schwab et al. [2] reported there was no significant
16
correlations between adult scoliosis and visual analog scale scores or nutritional status in healthy,
17
elderly volunteers. Previous clinical outcome instruments do not seek information regarding the impact
18
of spinal stiffness on functional ability. Therefore, Hart et al. [17] developed and validated Lumbar
19
Stiffness Disability Index (LSDI) as an outcome instrument to measure the collateral effect of stiffness
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after lumbar fusion on functional ability. Daniels et al. [18] reported that stiffness-related disability
21
correlates with pain and functional related disability measures among patients with spinal deformity. 11
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Our results showed that distal fusion level to S1 or not might not influence postoperative ODI,
2
postoperative VAS, postoperative JOA, LSDI and so on (Table 2). Our study also found the tendency of
3
final ODI was downward from group A to group B and upward from group B to group C. Although the
4
tendency of final LSDI was downward from group A to group C, there was no between-group
5
difference between group B and group C. Considering PI is a constant anatomic parameter, this
6
indicates smaller lumbar lordosis may be associated with less postoperative spinal stiffness. However,
7
results in our study showed that JOA and VAS might not be good outcome instruments to assess
8
therapeutic effects for ADS. These indicated that LSDI and ODI were optimum outcome instruments,
9
and ideal sagittal realignment might be in group B (10° ≤ PI-LL ≤ 20°).
10
Our results showed that there was no significant difference in postoperative incision infection rate
11
among groups. This might be explained by the similarity in fusion and instrumentation into the lumbar,
12
amount of blood transfusions, management of postoperative drainage, past medical histories of patients,
13
the time of surgery as well as the surgical technique among groups [19]. Initial treatment included
14
wound debridement and broad spectrum antibiotics, until culture results showed the final antibiotic
15
regimen [20]. All the patients finally recovered without internal fixation removal. PJK is an important
16
complication in adult deformity surgery. Senteler et al. [21] discovered that patients with higher PI-LL
17
were associated with a higher risk for adjacent segment disease. A higher PI-LL correlates with an
18
increase in shear and compression forces in the L3-L4 and L4-L5 motion segments [21]. Our study
19
demonstrated that PI-LL between 10° and 20° might be an optimal sagittal alignment to reduce PJK
20
occurrence; there was low correlation between PI-LL and loosening of fixation occurrence or
21
reoperation rate; loosening of implant fixation was not serious complications because no related
22
clinical symptoms were induced. 12
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Different from conclusions of previous researches [11, 22], our results showed that patients with
2
postoperative PI-LL in group B (10° ≤ PI-LL ≤ 20°) would have better surgical outcomes. Previous
3
studies[14, 22-24] reported that sagittal spino-pelvic alignment varied with age. Patients in our study
4
was older than the patients in the research of Schwab et al. [22] (67.3 vs. 51.9). Therefore, we
5
speculated that mean age of the patients would be one of the explanations for these results. Inami et al.
6
[13] concluded that an optimum PI-LL is inconsistent, because it depends on the individual PI. Zhu et
7
al. [24] also found obvious variations of spinopelvic parameters between populations with different
8
ethnicity background, which might be another explanation for our results. Banno et al. [25] and Zhu et
9
al. [24] both reported that PI-LL were worse in women and progressed with age. Considering the ratio
10
of female and male was 2.5:1 in our study, gender difference might partly explain our results. Linear
11
regression, logistic regression analysis, Student’s t test, 2 test were widely used in studying PI-LL [12,
12
22-24]. We advise that curve estimation should be discussed in the research to find out which kind of
13
model fit the data better. Considering there is still a lack of large-scaled multicenter studies performed
14
to further confirm the optimal PI-LL for corrective surgery in Chinese patients with ADS, dividing
15
patients into two groups according to PI-LL within -10°~+10° or not may not be appropriate. The
16
difference in the method of analysis would be another cause of the different results in our study
17
compared with previous studies.
18
There are some limitations of this study. Firstly, this is a retrospective study that may cause
19
unavoidable selection bias; secondly, the follow-up time was relatively short, which may influence the
20
evaluation of the possible relationship between radiographic parameters and clinical outcomes; thirdly,
21
sample size is limited in this single-center study. Due to all these limitations, a multicenter, prospective
22
randomized study is required to find out the ideal PI-LL in Chinese patients. 13
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To sum up, we conclude that optimal PI-LL value may be achieved between 10° and 20° in
2
Chinese patients with ADS after long posterior instrumentation and fusion surgery with excellent
3
clinical outcomes and a lower PJK occurrence; smaller lumbar lordosis may be associated with less
4
postoperative spinal stiffness; compared with LSDI and ODI, JOA and VAS may not be ideal outcome
5
instruments to evaluate therapeutic effects for ADS.
6
References
7
[1] Carter OD, Haynes SG. Prevalence rates for scoliosis in US adults: results from the first National
8
Health and Nutrition Examination Survey. Int J Epidemiol. 1987 1987-12-01;16(4):537-44.
9
[2] Schwab F, Dubey A, Gamez L, El FA, Hwang K, Pagala M, et al. Adult scoliosis: prevalence,
10
SF-36, and nutritional parameters in an elderly volunteer population. Spine (Phila Pa 1976). 2005
11
2005-05-01;30(9):1082-5.
12
[3] Hong JY, Suh SW, Modi HN, Hur CY, Song HR, Park JH. The prevalence and radiological
13
findings
14
2010-07-01;92(7):980-3.
15
in
1347
elderly
patients
with
scoliosis.
J
Bone
Joint
Surg
Br.
2010
[4] Pritchett JW, Bortel DT. Degenerative symptomatic lumbar scoliosis. Spine (Phila Pa 1976). 1993
16
1993-05-01;18(6):700-3.
17
[5] Glassman SD, Bridwell K, Dimar JR, Horton W, Berven S, Schwab F. The impact of positive
18
sagittal balance in adult spinal deformity. Spine (Phila Pa 1976). 2005 2005-09-15;30(18):2024-9.
19
[6] Pellise F, Vila-Casademunt A, Ferrer M, Domingo-Sabat M, Bago J, Perez-Grueso FJ, et al.
20
Impact on health related quality of life of adult spinal deformity (ASD) compared with other
21
chronic conditions. Eur Spine J. 2015 2015-01-01;24(1):3-11. 14
Page 14 of 21
1
[7] Cho KJ, Kim YT, Shin SH, Suk SI. Surgical treatment of adult degenerative scoliosis. Asian
2 3
Spine J. 2014 2014-06-01;8(3):371-81. [8] Bradford DS, Tay BK, Hu SS. Adult scoliosis: surgical indications, operative management,
4 5
complications, and outcomes. Spine (Phila Pa 1976). 1999 1999-12-15;24(24):2617-29. [9] Schwab F, Farcy JP, Bridwell K, Berven S, Glassman S, Harrast J, et al. A clinical impact
6
classification of scoliosis in the adult. Spine (Phila Pa 1976). 2006 2006-08-15;31(18):2109-14.
7
[10] Schwab F, Ungar B, Blondel B, Buchowski J, Coe J, Deinlein D, et al. Scoliosis Research
8
Society-Schwab adult spinal deformity classification: a validation study. Spine (Phila Pa 1976).
9
2012 2012-05-20;37(12):1077-82.
10
[11] Schwab F, Patel A, Ungar B, Farcy JP, Lafage V. Adult spinal deformity-postoperative standing
11
imbalance: how much can you tolerate? An overview of key parameters in assessing alignment
12
and planning corrective surgery. Spine (Phila Pa 1976). 2010 2010-12-01;35(25):2224-31.
13
[12] Yamada K, Abe Y, Yanagibashi Y, Hyakumachi T, Satoh S. Mid- and long-term clinical
14
outcomes of corrective fusion surgery which did not achieve sufficient pelvic incidence minus
15
lumbar lordosis value for adult spinal
deformity. Scoliosis. 2015 2015-01-20;10(Suppl 2):S17.
16
[13] Inami S, Moridaira H, Takeuchi D, Shiba Y, Nohara Y, Taneichi H. Optimum pelvic incidence
17
minus lumbar lordosis value can be determined by individual pelvic incidence. Eur Spine J. 2016
18
2016-04-12.
19
[14] Lafage R, Schwab F, Challier V, Henry JK, Gum J, Smith J, et al. Defining Spino-Pelvic
20
Alignment Thresholds: Should Operative Goals in Adult Spinal Deformity Surgery Account for
21
Age? Spine (Phila Pa 1976). 2016 2016-01-01;41(1):62-8.
22
[15] Kostuik JP, Maurais GR, Richardson WJ, Okajima Y. Combined single stage anterior and 15
Page 15 of 21
1
posterior osteotomy for correction of iatrogenic lumbar kyphosis. Spine (Phila Pa 1976). 1988
2
1988-03-01;13(3):257-66.
3
[16] Mac-Thiong JM, Transfeldt EE, Mehbod AA, Perra JH, Denis F, Garvey TA, et al. Can c7
4
plumbline and gravity line predict health related quality of life in adult scoliosis? Spine (Phila Pa
5
1976). 2009 2009-07-01;34(15):E519-27.
6
[17] Hart RA, Gundle KR, Pro SL, Marshall LM. Lumbar Stiffness Disability Index: pilot testing of
7
consistency, reliability, and validity. SPINE J. 2013 2013-02-01;13(2):157-61.
8
[18] Daniels AH, Smith JS, Hiratzka J, Ames CP, Bess S, Shaffrey CI, et al. Functional Limitations
9
Due to Lumbar Stiffness in Adults With and Without Spinal Deformity. Spine (Phila Pa 1976).
10 11
2015 2015-10-15;40(20):1599-604. [19] Hsieh MK, Chen LH, Niu CC, Fu TS, Lai PL, Chen WJ. Postoperative anterior spondylodiscitis
12 13
after posterior pedicle screw instrumentation. SPINE J. 2011 2011-01-01;11(1):24-9. [20] Pappou IP, Papadopoulos EC, Sama AA, Girardi FP, Cammisa FP. Postoperative infections in
14
interbody
15
2006-03-01;444:120-8.
fusion
for
degenerative
spinal
disease.
Clin
Orthop
Relat
Res.
2006
16
[21] Senteler M, Weisse B, Snedeker JG, Rothenfluh DA. Pelvic incidence-lumbar lordosis mismatch
17
results in increased segmental joint loads in the unfused and fused lumbar spine. Eur Spine J.
18
2014 2014-07-01;23(7):1384-93.
19
[22] Schwab FJ, Blondel B, Bess S, Hostin R, Shaffrey CI, Smith JS, et al. Radiographical spinopelvic
20
parameters and disability in the setting of adult spinal deformity: a prospective multicenter
21
analysis. Spine (Phila Pa 1976). 2013 2013-06-01;38(13):E803-12.
22
[23] Xu L, Qin X, Zhang W, Qiao J, Liu Z, Zhu Z, et al. Estimation of the Ideal Lumbar Lordosis to 16
Page 16 of 21
1
Be Restored From Spinal Fusion Surgery: A Predictive Formula for Chinese Population. Spine
2
(Phila Pa 1976). 2015 2015-07-01;40(13):1001-5.
3
[24] Zhu Z, Xu L, Zhu F, Jiang L, Wang Z, Liu Z, et al. Sagittal alignment of spine and pelvis in
4
asymptomatic adults: norms in Chinese populations. Spine (Phila Pa 1976). 2014
5
2014-01-01;39(1):E1-6.
6
[25] Banno T, Togawa D, Arima H, Hasegawa T, Yamato Y, Kobayashi S, et al. The cohort study for
7
the determination of reference values for spinopelvic parameters (T1 pelvic angle and global tilt)
8
in elderly volunteers. Eur Spine J. 2016 2016-02-01.
9
10
Fig.1 This 72 year-old woman had degenerative lumbar scoliosis. (A) The preoperative Cobb angle was
11
21.5°. (B) She underwent pedicle screw instrumentation from T9 to S1. The Cobb angle corrected to 3°.
12
PI-LL was 27°. (C) Two years after surgery, the lateral roentgenogram showed loosening of sacral
13
screws. The Cobb angle was 5°.
14
17
Page 17 of 21
1
Table 1 Patient demographics Number of cases
74
Gender (male/female)
21/53
Age at surgery (years old)
63.7 ± 4.6
Levels of fusion (n)
7.0 ± 1.8
Levels of decompression (n)
2.2 ± 0.8
Follow-up time (years)
3.2 ± 0.7
Operative time (minutes)
237.8 ± 39.7
Intraoperative blood loss (ml)
1017.2 ± 813.3
Length of hospital stay (days)
14.5 ± 1.3
Preoperative Cobb angle of curves (°)
20.3 ± 2.8
Preoperative PI-LL (°)
36.0 ± 4.4°
Preoperative ODI
63.0 ± 2.8
Preoperative JOA (LBP)
5.6 ± 1.2
Preoperative VAS (LBP)
6.9 ± 1.3
Postoperative PI-LL (°)
16.6 ± 8.7
Cobb angle of curves at last follow-up (°)
4.2 ± 1.8
ODI at last follow-up
25.6 ± 8.0
JOA at last follow-up (LBP)
3.1 ± 1.4
VAS at last follow-up (LBP)
3.1± 1.0
LSDI at last follow-up
1.8 ± 1.4
2 3
Value is expressed as the mean ± standard deviation or number. PI-LL, pelvic incidence minus lumbar
4 5 6
analog Scale; LBP, low back pain; LSDI, lumbar stiffness disability index. P < 0.05, compared with
lordosis value; JOA, Japanese Orthopaedic Association; ODI, Oswestry disability index; VAS, visual preoperative result.
18
Page 18 of 21
1
Table 2 Comparison of therapeutic effects or complications between groups with long instrumentation
2
and fusion to L5 or S1.
3 4 5 6 7 8
Variables
Group1
Group2
P
Number of cases
44
30
-
Operative time (minutes)
243.5 ± 40.6
229.3 ± 37.4
0.126
Intraoperative blood loss (ml)
1020.9 ± 629.3
1011.7 ± 1038.1
0.962
Length of hospital stay (days)
14.5 ± 1.4
14.2 ± 1.4
0.379
Cobb angle of curves at last follow-up (°)
4.3 ± 1.6
4.1 ± 2.0
0.662
ODI at last follow-up
25.4 ± 7.7
25.8 ± 8.5
0.851
JOA at last follow-up (LBP)
3.1 ± 1.4
3.2 ± 1.4
0.873
VAS at last follow-up (LBP)
3.0 ± 1.0
3.2 ± 0.9
0.254
LSDI at last follow-up
1.6 ± 1.3
2.1 ± 1.5
0.176
Postoperative incision infection
6
2
0.461
PJK
10
9
0.590
Loosening of fixation
4
3
1.000
Reoperation
3
6
0.146
Value is expressed as the mean ± standard deviation or number. PI, pelvic incidence; LL, lumbar lordosis; PI-LL, mismatch between pelvic incidence and lumbar lordosis; JOA, Japanese Orthopaedic Association; ODI, Oswestry disability index; VAS, visual analog Scale; LBP, low back pain; LSDI, lumbar stiffness disability index; PJK, proximal junctional kyphosis. P, comparison between two groups.
19
Page 19 of 21
1
2 3 4 5 6 7
Table 3 Comparison of therapeutic effects or complications among groups. Variables
Group A
Group B
Group C
P
Number of cases
22
28
24
-
Operative time (minutes)
234.5 ± 41.7
245.9 ± 37.1
231.3 ± 40.7
0.078
Intraoperative blood loss (ml)
1344.1 ± 331.8
889.3 ± 331.8
866.7 ± 339.0
0.379
Length of hospital stay (days)
14.9 ± 1.6
14.4 ± 1.0
13.8 ± 1.5
0.195
Cobb angle of curves at last follow-up (°)
4.4 ± 2.7
3.8 ± 1.3
4.5 ± 0.8
ODI at last follow-up
26.6 ± 4.1
18.4 ± 5.8
JOA at last follow-up (LBP)
2.7 ± 1.3
3.2 ± 1.2
VAS at last follow-up (LBP)
3.0 ± 1.2
3.2 ± 0.9
LSDI at last follow-up
3.2 ± 1.0
1.4 ± 1.2
Postoperative incision infection
3
3
$
0.260
33.0 ± 5.0
$&
3.4 ± 1.6
0.228
3.0 ± 0.8 $
1.0 ± 0.9
<0.001 0.789
$
2
<0.001 0.846
&
PJK
6
3
10
0.038
Loosening of fixation
2
1
4
0.274
Reoperation
3
2
4
0.560
Value is expressed as the mean ± standard deviation or number. PI, pelvic incidence; LL, lumbar lordosis; PI-LL, mismatch between pelvic incidence and lumbar lordosis; JOA, Japanese Orthopaedic Association; ODI, Oswestry disability index; VAS, visual analog Scale; LBP, low back pain; LSDI, lumbar stiffness disability index; PJK, proximal junctional kyphosis. P, comparison among three groups. $ P < 0.05, compared with group A; & P < 0.05, compared with group B.
20
Page 20 of 21
1 2
Table 4 Curve estimation evaluating the relationship between postoperative PI-LL and Cobb angle of the curves, ODI or LSDI at last follow-up time. Variables
Cobb angle
ODI
LSDI
Model
Strokes equation
Cubic equation
Cubic equation
0.506
0.379
0.691
P
< 0.001
< 0.001
< 0.001
Constant
1.536
28.871
4.708
b1
-1.495
-0.740
-0.373
b2
-
-0.010
0.017
b3
-
0.002
< 0.001
R
3 4 5
2
2
ODI, Oswestry disability index; LSDI, lumbar stiffness disability index. R , correlation coefficient squared; b1, monomial coefficient of equation; b2, quadratic coefficient of equation; b3, cubic coefficient of equation.
6
21
Page 21 of 21
S1529-9430(17)30095-5 http://dx.doi.org/doi: 10.1016/j.spinee.2017.03.008 SPINEE 57262
To appear in:
The Spine Journal
Received date: Revised date: Accepted date:
19-11-2016 2-3-2017 15-3-2017
Please cite this article as: Xiang-Yao Sun, Xi-Nuo Zhang, Yong Hai, Optimum pelvic incidence minus lumbar lordosis value after operation for patients with adult degenerative scoliosis, The Spine Journal (2017), http://dx.doi.org/doi: 10.1016/j.spinee.2017.03.008. 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.
1
Optimum pelvic incidence minus lumbar lordosis value after operation for patients with adult
2
degenerative scoliosis
3 4
Xiang-Yao Sun, Xi-Nuo Zhang, Yong Hai
5
Xiang-Yao Sun
6
Department of Orthopedics, Beijing Chaoyang Hospital, Capital Medical University, Beijing,
7
100020, China
8
E-mail: [email protected]
9
Xi-Nuo Zhang
10
Department of Orthopedics, Beijing Chaoyang Hospital, Capital Medical University, Beijing,
11
100020, China
12
E-mail: [email protected]
13
Yong Hai
14
Department of Orthopedics, Beijing Chaoyang Hospital, Capital Medical University, Beijing,
15
100020, China
16
E-mail: [email protected]
17
Name of the corresponding author Yong Hai
18
E-mail address of the corresponding author [email protected]
19
Present Address Department of Orthopedics, Beijing Chaoyang Hospital, No.8 Gong Ren Ti
20
Yu Chang Nan Lu Road, Chaoyang District, Beijing 100020, China
21
Conflict of interest statement The authors declare that they have no conflict of interest. There is no 1
Page 1 of 21
1
funding source. Informed consent was obtained from all individual participants included in the study.
2 3
Ethical Review Committee Statement The study was approved by the institutional review board
4 5
Acknowledgments The authors would like to thank Professor Yong Hai who provided data support
following the declaration of Helsinki principles.
and corrected some mistakes.
6
7
Abstract
8
BACKGROUND CONTEXT: Schwab classification for adult degenerative scoliosis (ADS)
9
concluded that health-related quality of life (HRQOL) was closely related to curve type and three
10
sagittal modifiers. It was suggested that pelvic incidence minus lumbar lordosis value (PI-LL) should
11
be corrected within -10°~+10°. However, recent studies also indicated that ideal clinical outcomes
12
could also be achieved in patients without ideal PI-LL mentioned above.
13
PURPOSE: This study evaluated the relation between the clinical outcomes and the pelvic incidence
14
minus lumbar lordosis value (PI-LL) of Chinese patients with ADS who received long posterior
15
internal fixation and fusion.
16
STUDY DESIGN: This was a single-center retrospective comparative study of patients treated by long
17
posterior internal fixation and fusion in the our hospital between 2010 and 2014.
18
PATIENT SAMPLE: Inclusion criteria were age > 45 years at the time of surgery, the Cobb angle of
19
lumbar curves ≥ 10°, long posterior internal fixation and fusion ≥ least 3 motion segments, follow-up ≥
20
2 years, complete preoperative and postoperative radiographic data and functional evaluation results.
21
Exclusion criteria were history of previous lumbar spine surgery, other kinds of scoliosis, history of
22
severe spinal trauma, spinal tumor, ankylosing spondylitis (AS), spinal tuberculosis. Seventy-four 2
Page 2 of 21
1
patients were enrolled in the study.
2
OUTCOME MEASURES: Operative parameters included intraoperative blood loss, duration of
3
surgery, length of hospital stay, number of fusion levels and decompression. The radiological
4
measurements included Cobb angle of the curves and PI-LL. Clinical outcomes were evaluated by
5
Japanese Orthopaedic Association (JOA) score, Oswestry disability index (ODI), visual analog scale
6
(VAS) and lumbar stiffness disability index (LSDI). In addition, the complications of surgery were also
7
collected. One-way analysis of variance (ANOVA), Student’s t test, Kruskal-wallis test, Pearson’s
8
chi-square test and curve estimation were calculated for variables.
9
METHODS: All the patients were divided into group 1 (long instrumentation and fusion to L5) and
10
group 2 (long instrumentation and fusion to S1). Operative parameters, radiological measurements,
11
clinical outcomes and complications of surgery were compared between two groups to confirm whether
12
distal fusion level could influence therapeutic effect. Then patients were divided into PI-LL < 10°
13
(group A), 10° ≤ PI-LL ≤ 20° (group B), PI-LL > 20° (group C). Operative parameters, radiological
14
measurements, clinical outcomes and complications of surgery were compared between each two
15
groups. Curve estimation was performed to evaluate the relationship between postoperative PI-LL and
16
clinical outcomes. The researchers declare that they have no conflict of interest. There was no funding
17
source. Informed consent was obtained from all individual participants included in the study.
18
RESULTS: No difference was found between group 1 and group 2 in all postoperative parameters (P >
19
0.05). There were significant differences in final ODI (P < 0.001), final LSDI (P < 0.001) among group
20
A, group B and group C. Cubic curve model fitted the relationship between PI-LL and final ODI better
21
than other models (R2 = 0.379, P < 0.001). Cubic curve model fitted the relationship between PI-LL
3
Page 3 of 21
1
and final LSDI better than other models (R2 = 0.691, P < 0.001). There was a significant difference in
2
proximal junctional kyphosis (PJK) among groups (P = 0.038). No significant difference was found in
3
other parameters.
4
CONCLUSIONS: Optimal PI-LL value may be achieved between 10° and 20° in Chinese patients
5
with ADS after long posterior instrumentation and fusion surgery with excellent clinical outcomes and
6
a lower PJK occurrence.
7
KEYWORDS: Adult degenerative scoliosis; SRS-Schwab classification; sagittal balance; pelvic
8
incidence; lumbar lordosis
9
10
Introduction
11
The definition of adult scoliosis (ADS) is spinal deformity with a scoliotic angle of over 10° in patients
12
with mature skeleton [1]. The incidence of adult scoliosis ranges from 8.3% to 68% of population [1-3].
13
Degenerative scoliosis usually occurs after age fifty, and its incidence and curves would increase with
14
age[4]. This kind of disease represents degenerative changes of the intervertebral disks and facets, then
15
it would lead to deformity in progress [5]. The main symptoms of adult scoliosis are deformity, low
16
back pain and radiating to the legs, neurologic deficits, functional limitations or disabilities [6].
17
Conservative treatment is always firstly recommended, but the clinical outcomes are commonly
18
unsatisfactory and then surgical treatment would be considered [7]. The aim of surgery is to relieve low
19
back pain as well as radiating pain and claudication, and then correct deformity [8].
20
Schwab classification [9] categorized the apex of the curve, lumbar lordosis and vertebral body 4
Page 4 of 21
1
subluxation based on the relationship between radiological findings and clinical evaluation. It
2
concluded that the lower apex of the curve combined with loss of lordosis was associated with poor
3
health-related quality of life (HRQOL). The relationship between spino-pelvic parameters and sagittal
4
balance was considered in SRS-Schwab classification [10]. It concluded that HRQOL was closely
5
related to curve type and three sagittal modifiers. Although Schwab et al. [10, 11] suggested that pelvic
6
incidence minus lumbar lordosis value (PI-LL) should be corrected within -10°~+10°, many studies
7
[12-14] indicated ideal clinical outcomes could also be achieved in patients without ideal PI-LL
8
mentioned above. The purpose of the study was to evaluate the relation between the clinical outcomes
9
and the PI-LL of Chinese ADS patients who received long posterior internal fixation and fusion,
10
according to SRS-Schwab PI-LL sagittal modifier. Whether PI-LL corrected within -10°~+10° was an
11
optimistic criterion was also discussed in this study. To our knowledge, this has not been reported.
12
Methods
13
This was a single-center retrospective comparative study of 74 ADS patients treated by long posterior
14
internal fixation and fusion in our hospital between 2010 and 2014. Inclusion criteria were age > 45
15
years at the time of surgery, the Cobb angle of lumbar curves ≥ 10°, long posterior internal fixation and
16
fusion ≥ least 3 motion segments, follow-up ≥ 2 years, complete preoperative and postoperative
17
radiographic data and functional evaluation results. Exclusion criteria were history of previous lumbar
18
spine surgery, other kinds of scoliosis, history of severe spinal trauma, spinal tumor, ankylosing
19
spondylitis (AS), spinal tuberculosis. The study was approved by the institutional review board
20
following the declaration of Helsinki principles. The researchers declared that they have no conflict of
21
interest. There was no funding source. Informed consent was obtained from all individual participants 5
Page 5 of 21
1
included in the study.
2
Operative parameters
3
Operative parameters included intraoperative blood loss, duration of surgery, length of hospital stay,
4
number of fusion levels and decompression.
5
Radiological measurement
6
The patients were evaluated using standing whole spine X-ray (Philips Digital Diagnost). The plain
7
radiographs included posteroanterior and lateral views. The radiological measurements included Cobb
8
angle of the curves, pelvic incidence minus lumbar lordosis value (PI-LL). LL was defined as Cobb
9
angle from the upper endplate of L1 to the upper endplate of S1. PI was the angle subtended by a
10
perpendicular from the upper endplate of S1 and a line connecting the center of the femoral head to the
11
center of the upper endplate of S1. Patients were divided into PI-LL < 10° (group A), 10° ≤ PI-LL ≤ 20°
12
(group B), PI-LL > 20° (group C) [10].
13
Clinical assessment
14
Clinical outcomes were evaluated by Japanese Orthopaedic Association (JOA) score, Oswestry
15
disability index (ODI), visual analog scale (VAS) and lumbar stiffness disability index (LSDI). These
16
were valid and rigorous functional measures used for assessing spinal disorders. In addition, the
17
complications of surgery were also collected.
18
Surgical procedures
19
The indication for surgical treatment was claudication or radiating leg pain that was resistant to
20
conservative therapy for more than 6 in adult degenerative scoliosis. For a severe lateral subluxation 6
Page 6 of 21
1
with large Cobb angle, long fusion including entire curve should be considered. The upper
2
instrumented vertebra (UIV) was determined by the surgeon’s judgement based on the curve pattern. In
3
a general way, UIV should not be the apex of the thoracic kyphosis. The upper thoracic (UT) spine was
4
selected as UIV for those with thoracic curves. The low thoracic (LT) spine was selected as UIV for
5
those with thoracolumbar curve. When the L5-S1 segment was symptomatic or sufficiently
6
degenerated that it was not desirable to leave it as an unfused segment, or when inclusion was deemed
7
necessary to achieve improved coronal and sagittal balance, fusion to the sacrum was performed.
8
Considering all these factors, the final fusion level was determined by each surgeon’s preference.
9
Surgery was performed under the general anesthesia for all patients. Locally hypertrophic ligamentum
10
flavum and upper and inferior zygopophysis with hyperplasia and cohesion were cleaned as much as
11
possible during decompression. In some circumstances, a Ponte osteotomy was performed for
12
correction. Pedicle screw was placed. In order to reduce scoliosis, rod-rotation maneuver was first tried,
13
and compression of the rod was added when more correction was required. The rod was prebent to fit
14
the desired lumbar lordosis before inserting rod. In situ bending technique was not usually performed
15
to avoid weakening of the rod. The application of bone grating between vertebral plates was
16
determined by specific surgical condition and amount of crush bone. Anesthesia wake-up test was
17
performed during surgery to confirmed normal function of both lower extremities. Fixation screws
18
were tightened one by one. X-ray was performed to confirm restoration condition after surgery.
19
Negative pressure drainage was placed before the surgical incision was closed.
20
Statistical analysis
21
The statistical analysis was performed using the Statistical Package for Social Sciences version 17.0 7
Page 7 of 21
1
software (SPSS, Inc., Chicago, IL). Continuous variables were reported as mean ± standard deviations
2
(SD), while noncontiguous data was presented as number or ratio. Normality of the continuous data
3
was tested using the Kolmogorov-Smirnov test. Normally distributed values were analyzed by one-way
4
analysis of variance (ANOVA) or Student’s t test. However, skew distributed values were analyzed by
5
Kruskal-wallis test. However, the statistical significance of noncontiguous data was performed by
6
Pearson’s chi-square test. Curve estimation was performed to evaluate the relative influences of
7
postoperative PI-LL on postoperative radiographic parameters, clinical outcomes and operative
8
parameters. A P value < 0.05 was statistically significant.
9
Results
10
Demographics
11
Of the 74 patients enrolled in the study, 21 were male and 53 were female, with an average age of 63.7
12
± 4.6 years. They underwent 7.0 ± 1.8 levels of fusion and 2.2 ± 0.8 levels of decompression. Levels of
13
fusion included T9-S1 (1, 1.35%), T10-S1 (11, 14.9%), L2-S1 (18, 24.3%), T10-L5 (36, 48.6%), L2-L5
14
(8, 10.8%). The mean follow-up time was 3.2 ± 0.7 years. The mean operative time was 237.8 ± 39.7
15
minutes. The intraoperative blood loss was 1017.2 ± 813.3 ml. The length of hospital stay was 14.5 ±
16
1.3 days. Cobb angle of curves, PI-LL, ODI, JOA, VAS in the preoperative periods were 20.3 ± 2.8°,
17
36.0 ± 4.4°, 63.0 ± 2.8, 5.6 ± 1.2, 6.9 ± 1.3, respectively. Postoperative PI-LL was 16.6 ± 8.7°. Cobb
18
angle of curves, ODI, JOA, VAS, LSDI at the time of last follow-up were 4.2 ± 1.8°, 25.6 ± 8.0, 3.1 ±
19
1.4, 3.1± 1.0, 1.8 ± 1.4, respectively (Table 1).
20
Relationship between distal fusion level and therapeutic effects
8
Page 8 of 21
1
All the patients were divided into group 1 (long instrumentation and fusion to L5) and group 2 (long
2
instrumentation and fusion to S1). Comparison of therapeutic effects between the two groups was
3
performed to find whether difference in distal fusion level would influence the results. The results
4
revealed that there was no significant difference in operative time (P = 0.126), intraoperative blood loss
5
(P = 0.962), length of hospital stay (P = 0.379), Cobb angle of the curves at last follow-up time (P =
6
0.662), ODI at last follow-up (P = 0.851). JOA at last follow-up time (P = 0.873), final VAS (P =
7
0.254), LSDI at last follow-up (P = 0.176), postoperative incision infection rate (P = 0.461), PJK rate
8
(P = 0.590), loosening of fixation rate (P = 1.000), reoperation rate (P = 0.146) (Table 2). These
9
confirmed that the difference in distal fusion level would not influence the later analysis.
10
Relationship between PI-LL and therapeutic effects
11
Patients were divided into group A (n = 22), group B (n = 28) and group C (n = 24), as mention above.
12
No significant difference was found in operative time (P = 0.078), intraoperative blood loss (P = 0.379),
13
length of hospital stay (P = 0.195), Cobb angle of the curves at last follow-up time (P = 0.260), JOA at
14
last follow-up time (P = 0.228), final VAS (P = 0.789) among these groups. There were significant
15
differences in final ODI (P < 0.001), final LSDI (P < 0.001) among these groups (Table 2). Final ODI
16
was significantly better in B group compared to A group (P < 0.001) and C group (P < 0.001). The final
17
ODI in group A was significantly better than group C (P < 0.001). The LSDI at last follow-up time in
18
group B was significantly better than group A (P < 0.001). No significant difference was found
19
between group B and group C (P = 0.116). The LSDI at last follow-up time in group A was
20
significantly better than group C (P < 0.001).
21
Curve estimation was performed to evaluate the relationship between postoperative PI-LL and 9
Page 9 of 21
1
clinical outcomes. All the curve models in SPSS 17.0 were tested. The results showed that s curve
2
model fitted the relationship between PI-LL and Cobb angle of the curves at last follow-up time better
3
than other models (R2 = 0.506 , P < 0.001). Cubic curve model fitted the relationship between PI-LL
4
and final ODI better than other models (R2 = 0.379, P < 0.001). No model fitted the relationship
5
between PI-LL and final JOA (P > 0.05). There was no model fitting the relationship between PI-LL
6
and final VAS (P > 0.05). Cubic curve model fitted the relationship between PI-LL and final LSDI
7
better than other models (R2 = 0.691, P < 0.001) (Table 4).
8
Relationship between PI-LL and complications
9
Postoperative incision infection occurred in 3 patients in group A (13.6 %), 3 patients in group B
10
(10.7 %), 2 patients in group C (9.1 %). No significant difference was found in postoperative incision
11
infection rate among groups (P = 0.846). Proximal junctional kyphosis (PJK) occurred in 6 patients in
12
group A (27.3 %), 3 patients in group B (12.0 %), 10 patients in group C (41.7 %). There was a
13
significant difference among groups (P = 0.038). There was no significant difference in PJK occurrence
14
between group A and group B (P = 0.157). No significant difference was found in PJK occurrence
15
between group A and group C (P = 0.306). PJK occurrence in group B was significantly less than group
16
C (P = 0.022). Loosening of fixation occurred in 2 patients in group A (P = 9.1 %), 1 patients in group
17
B (P = 3.6%), 4 patients in group C (P = 16.7%) (Fig. 1). No significant difference was found in
18
loosening of fixation occurrence among groups (P = 0.274). Reoperation occurred in 3 patients in
19
group A (13.6 %), 2 patients in group B (7.1 %), 4 patients in group C (16.7 %). No significant
20
difference was found in reoperation rate among groups (P = 0.560) (Table 3). The reoperation was
21
caused by severe PJK in our study. 10
Page 10 of 21
1
Discussion
2
This study investigated the correlation between postoperative PI-LL and clinical outcomes based on
3
SRS-Schwab PI-LL sagittal modifiers in ADS [10]. In the comparison of radiographic parameters,
4
there was no significant difference in Cobb angle of curves in the last follow-up time among the groups,
5
while all the Cobb angles were less than 10°, which indicated the effectivity in coronial realignment.
6
Our results showed that although s curve model fitted the relationship between postoperative PI-LL and
7
final Cobb angle of curves, there was no significant difference among groups. These indicated
8
postoperative PI-LL might not significantly influence coronal spinal parameters.
9
The relationship between spino-pelvic parameters and the quality of life remains controversial.
10
Postoperative flat-back syndrome was proved to be a factor leading to unsatisfactory clinical outcomes
11
after lumbar fusion surgery [15]. Schwab et al. [11] showed that PI-LL was related to LBP and
12
disability in their systematic evaluation method to classify sagittal spinal alignment in the cases of
13
fat-back syndrome. Mac-Thiong et al. [16] demonstrated that sagittal spinal and global balance was
14
strongly associated with the ODI in adults with scoliosis, while coronal spinal and global balance did
15
not influence the ODI in their study. However, Schwab et al. [2] reported there was no significant
16
correlations between adult scoliosis and visual analog scale scores or nutritional status in healthy,
17
elderly volunteers. Previous clinical outcome instruments do not seek information regarding the impact
18
of spinal stiffness on functional ability. Therefore, Hart et al. [17] developed and validated Lumbar
19
Stiffness Disability Index (LSDI) as an outcome instrument to measure the collateral effect of stiffness
20
after lumbar fusion on functional ability. Daniels et al. [18] reported that stiffness-related disability
21
correlates with pain and functional related disability measures among patients with spinal deformity. 11
Page 11 of 21
1
Our results showed that distal fusion level to S1 or not might not influence postoperative ODI,
2
postoperative VAS, postoperative JOA, LSDI and so on (Table 2). Our study also found the tendency of
3
final ODI was downward from group A to group B and upward from group B to group C. Although the
4
tendency of final LSDI was downward from group A to group C, there was no between-group
5
difference between group B and group C. Considering PI is a constant anatomic parameter, this
6
indicates smaller lumbar lordosis may be associated with less postoperative spinal stiffness. However,
7
results in our study showed that JOA and VAS might not be good outcome instruments to assess
8
therapeutic effects for ADS. These indicated that LSDI and ODI were optimum outcome instruments,
9
and ideal sagittal realignment might be in group B (10° ≤ PI-LL ≤ 20°).
10
Our results showed that there was no significant difference in postoperative incision infection rate
11
among groups. This might be explained by the similarity in fusion and instrumentation into the lumbar,
12
amount of blood transfusions, management of postoperative drainage, past medical histories of patients,
13
the time of surgery as well as the surgical technique among groups [19]. Initial treatment included
14
wound debridement and broad spectrum antibiotics, until culture results showed the final antibiotic
15
regimen [20]. All the patients finally recovered without internal fixation removal. PJK is an important
16
complication in adult deformity surgery. Senteler et al. [21] discovered that patients with higher PI-LL
17
were associated with a higher risk for adjacent segment disease. A higher PI-LL correlates with an
18
increase in shear and compression forces in the L3-L4 and L4-L5 motion segments [21]. Our study
19
demonstrated that PI-LL between 10° and 20° might be an optimal sagittal alignment to reduce PJK
20
occurrence; there was low correlation between PI-LL and loosening of fixation occurrence or
21
reoperation rate; loosening of implant fixation was not serious complications because no related
22
clinical symptoms were induced. 12
Page 12 of 21
1
Different from conclusions of previous researches [11, 22], our results showed that patients with
2
postoperative PI-LL in group B (10° ≤ PI-LL ≤ 20°) would have better surgical outcomes. Previous
3
studies[14, 22-24] reported that sagittal spino-pelvic alignment varied with age. Patients in our study
4
was older than the patients in the research of Schwab et al. [22] (67.3 vs. 51.9). Therefore, we
5
speculated that mean age of the patients would be one of the explanations for these results. Inami et al.
6
[13] concluded that an optimum PI-LL is inconsistent, because it depends on the individual PI. Zhu et
7
al. [24] also found obvious variations of spinopelvic parameters between populations with different
8
ethnicity background, which might be another explanation for our results. Banno et al. [25] and Zhu et
9
al. [24] both reported that PI-LL were worse in women and progressed with age. Considering the ratio
10
of female and male was 2.5:1 in our study, gender difference might partly explain our results. Linear
11
regression, logistic regression analysis, Student’s t test, 2 test were widely used in studying PI-LL [12,
12
22-24]. We advise that curve estimation should be discussed in the research to find out which kind of
13
model fit the data better. Considering there is still a lack of large-scaled multicenter studies performed
14
to further confirm the optimal PI-LL for corrective surgery in Chinese patients with ADS, dividing
15
patients into two groups according to PI-LL within -10°~+10° or not may not be appropriate. The
16
difference in the method of analysis would be another cause of the different results in our study
17
compared with previous studies.
18
There are some limitations of this study. Firstly, this is a retrospective study that may cause
19
unavoidable selection bias; secondly, the follow-up time was relatively short, which may influence the
20
evaluation of the possible relationship between radiographic parameters and clinical outcomes; thirdly,
21
sample size is limited in this single-center study. Due to all these limitations, a multicenter, prospective
22
randomized study is required to find out the ideal PI-LL in Chinese patients. 13
Page 13 of 21
1
To sum up, we conclude that optimal PI-LL value may be achieved between 10° and 20° in
2
Chinese patients with ADS after long posterior instrumentation and fusion surgery with excellent
3
clinical outcomes and a lower PJK occurrence; smaller lumbar lordosis may be associated with less
4
postoperative spinal stiffness; compared with LSDI and ODI, JOA and VAS may not be ideal outcome
5
instruments to evaluate therapeutic effects for ADS.
6
References
7
[1] Carter OD, Haynes SG. Prevalence rates for scoliosis in US adults: results from the first National
8
Health and Nutrition Examination Survey. Int J Epidemiol. 1987 1987-12-01;16(4):537-44.
9
[2] Schwab F, Dubey A, Gamez L, El FA, Hwang K, Pagala M, et al. Adult scoliosis: prevalence,
10
SF-36, and nutritional parameters in an elderly volunteer population. Spine (Phila Pa 1976). 2005
11
2005-05-01;30(9):1082-5.
12
[3] Hong JY, Suh SW, Modi HN, Hur CY, Song HR, Park JH. The prevalence and radiological
13
findings
14
2010-07-01;92(7):980-3.
15
in
1347
elderly
patients
with
scoliosis.
J
Bone
Joint
Surg
Br.
2010
[4] Pritchett JW, Bortel DT. Degenerative symptomatic lumbar scoliosis. Spine (Phila Pa 1976). 1993
16
1993-05-01;18(6):700-3.
17
[5] Glassman SD, Bridwell K, Dimar JR, Horton W, Berven S, Schwab F. The impact of positive
18
sagittal balance in adult spinal deformity. Spine (Phila Pa 1976). 2005 2005-09-15;30(18):2024-9.
19
[6] Pellise F, Vila-Casademunt A, Ferrer M, Domingo-Sabat M, Bago J, Perez-Grueso FJ, et al.
20
Impact on health related quality of life of adult spinal deformity (ASD) compared with other
21
chronic conditions. Eur Spine J. 2015 2015-01-01;24(1):3-11. 14
Page 14 of 21
1
[7] Cho KJ, Kim YT, Shin SH, Suk SI. Surgical treatment of adult degenerative scoliosis. Asian
2 3
Spine J. 2014 2014-06-01;8(3):371-81. [8] Bradford DS, Tay BK, Hu SS. Adult scoliosis: surgical indications, operative management,
4 5
complications, and outcomes. Spine (Phila Pa 1976). 1999 1999-12-15;24(24):2617-29. [9] Schwab F, Farcy JP, Bridwell K, Berven S, Glassman S, Harrast J, et al. A clinical impact
6
classification of scoliosis in the adult. Spine (Phila Pa 1976). 2006 2006-08-15;31(18):2109-14.
7
[10] Schwab F, Ungar B, Blondel B, Buchowski J, Coe J, Deinlein D, et al. Scoliosis Research
8
Society-Schwab adult spinal deformity classification: a validation study. Spine (Phila Pa 1976).
9
2012 2012-05-20;37(12):1077-82.
10
[11] Schwab F, Patel A, Ungar B, Farcy JP, Lafage V. Adult spinal deformity-postoperative standing
11
imbalance: how much can you tolerate? An overview of key parameters in assessing alignment
12
and planning corrective surgery. Spine (Phila Pa 1976). 2010 2010-12-01;35(25):2224-31.
13
[12] Yamada K, Abe Y, Yanagibashi Y, Hyakumachi T, Satoh S. Mid- and long-term clinical
14
outcomes of corrective fusion surgery which did not achieve sufficient pelvic incidence minus
15
lumbar lordosis value for adult spinal
deformity. Scoliosis. 2015 2015-01-20;10(Suppl 2):S17.
16
[13] Inami S, Moridaira H, Takeuchi D, Shiba Y, Nohara Y, Taneichi H. Optimum pelvic incidence
17
minus lumbar lordosis value can be determined by individual pelvic incidence. Eur Spine J. 2016
18
2016-04-12.
19
[14] Lafage R, Schwab F, Challier V, Henry JK, Gum J, Smith J, et al. Defining Spino-Pelvic
20
Alignment Thresholds: Should Operative Goals in Adult Spinal Deformity Surgery Account for
21
Age? Spine (Phila Pa 1976). 2016 2016-01-01;41(1):62-8.
22
[15] Kostuik JP, Maurais GR, Richardson WJ, Okajima Y. Combined single stage anterior and 15
Page 15 of 21
1
posterior osteotomy for correction of iatrogenic lumbar kyphosis. Spine (Phila Pa 1976). 1988
2
1988-03-01;13(3):257-66.
3
[16] Mac-Thiong JM, Transfeldt EE, Mehbod AA, Perra JH, Denis F, Garvey TA, et al. Can c7
4
plumbline and gravity line predict health related quality of life in adult scoliosis? Spine (Phila Pa
5
1976). 2009 2009-07-01;34(15):E519-27.
6
[17] Hart RA, Gundle KR, Pro SL, Marshall LM. Lumbar Stiffness Disability Index: pilot testing of
7
consistency, reliability, and validity. SPINE J. 2013 2013-02-01;13(2):157-61.
8
[18] Daniels AH, Smith JS, Hiratzka J, Ames CP, Bess S, Shaffrey CI, et al. Functional Limitations
9
Due to Lumbar Stiffness in Adults With and Without Spinal Deformity. Spine (Phila Pa 1976).
10 11
2015 2015-10-15;40(20):1599-604. [19] Hsieh MK, Chen LH, Niu CC, Fu TS, Lai PL, Chen WJ. Postoperative anterior spondylodiscitis
12 13
after posterior pedicle screw instrumentation. SPINE J. 2011 2011-01-01;11(1):24-9. [20] Pappou IP, Papadopoulos EC, Sama AA, Girardi FP, Cammisa FP. Postoperative infections in
14
interbody
15
2006-03-01;444:120-8.
fusion
for
degenerative
spinal
disease.
Clin
Orthop
Relat
Res.
2006
16
[21] Senteler M, Weisse B, Snedeker JG, Rothenfluh DA. Pelvic incidence-lumbar lordosis mismatch
17
results in increased segmental joint loads in the unfused and fused lumbar spine. Eur Spine J.
18
2014 2014-07-01;23(7):1384-93.
19
[22] Schwab FJ, Blondel B, Bess S, Hostin R, Shaffrey CI, Smith JS, et al. Radiographical spinopelvic
20
parameters and disability in the setting of adult spinal deformity: a prospective multicenter
21
analysis. Spine (Phila Pa 1976). 2013 2013-06-01;38(13):E803-12.
22
[23] Xu L, Qin X, Zhang W, Qiao J, Liu Z, Zhu Z, et al. Estimation of the Ideal Lumbar Lordosis to 16
Page 16 of 21
1
Be Restored From Spinal Fusion Surgery: A Predictive Formula for Chinese Population. Spine
2
(Phila Pa 1976). 2015 2015-07-01;40(13):1001-5.
3
[24] Zhu Z, Xu L, Zhu F, Jiang L, Wang Z, Liu Z, et al. Sagittal alignment of spine and pelvis in
4
asymptomatic adults: norms in Chinese populations. Spine (Phila Pa 1976). 2014
5
2014-01-01;39(1):E1-6.
6
[25] Banno T, Togawa D, Arima H, Hasegawa T, Yamato Y, Kobayashi S, et al. The cohort study for
7
the determination of reference values for spinopelvic parameters (T1 pelvic angle and global tilt)
8
in elderly volunteers. Eur Spine J. 2016 2016-02-01.
9
10
Fig.1 This 72 year-old woman had degenerative lumbar scoliosis. (A) The preoperative Cobb angle was
11
21.5°. (B) She underwent pedicle screw instrumentation from T9 to S1. The Cobb angle corrected to 3°.
12
PI-LL was 27°. (C) Two years after surgery, the lateral roentgenogram showed loosening of sacral
13
screws. The Cobb angle was 5°.
14
17
Page 17 of 21
1
Table 1 Patient demographics Number of cases
74
Gender (male/female)
21/53
Age at surgery (years old)
63.7 ± 4.6
Levels of fusion (n)
7.0 ± 1.8
Levels of decompression (n)
2.2 ± 0.8
Follow-up time (years)
3.2 ± 0.7
Operative time (minutes)
237.8 ± 39.7
Intraoperative blood loss (ml)
1017.2 ± 813.3
Length of hospital stay (days)
14.5 ± 1.3
Preoperative Cobb angle of curves (°)
20.3 ± 2.8
Preoperative PI-LL (°)
36.0 ± 4.4°
Preoperative ODI
63.0 ± 2.8
Preoperative JOA (LBP)
5.6 ± 1.2
Preoperative VAS (LBP)
6.9 ± 1.3
Postoperative PI-LL (°)
16.6 ± 8.7
Cobb angle of curves at last follow-up (°)
4.2 ± 1.8
ODI at last follow-up
25.6 ± 8.0
JOA at last follow-up (LBP)
3.1 ± 1.4
VAS at last follow-up (LBP)
3.1± 1.0
LSDI at last follow-up
1.8 ± 1.4
2 3
Value is expressed as the mean ± standard deviation or number. PI-LL, pelvic incidence minus lumbar
4 5 6
analog Scale; LBP, low back pain; LSDI, lumbar stiffness disability index. P < 0.05, compared with
lordosis value; JOA, Japanese Orthopaedic Association; ODI, Oswestry disability index; VAS, visual preoperative result.
18
Page 18 of 21
1
Table 2 Comparison of therapeutic effects or complications between groups with long instrumentation
2
and fusion to L5 or S1.
3 4 5 6 7 8
Variables
Group1
Group2
P
Number of cases
44
30
-
Operative time (minutes)
243.5 ± 40.6
229.3 ± 37.4
0.126
Intraoperative blood loss (ml)
1020.9 ± 629.3
1011.7 ± 1038.1
0.962
Length of hospital stay (days)
14.5 ± 1.4
14.2 ± 1.4
0.379
Cobb angle of curves at last follow-up (°)
4.3 ± 1.6
4.1 ± 2.0
0.662
ODI at last follow-up
25.4 ± 7.7
25.8 ± 8.5
0.851
JOA at last follow-up (LBP)
3.1 ± 1.4
3.2 ± 1.4
0.873
VAS at last follow-up (LBP)
3.0 ± 1.0
3.2 ± 0.9
0.254
LSDI at last follow-up
1.6 ± 1.3
2.1 ± 1.5
0.176
Postoperative incision infection
6
2
0.461
PJK
10
9
0.590
Loosening of fixation
4
3
1.000
Reoperation
3
6
0.146
Value is expressed as the mean ± standard deviation or number. PI, pelvic incidence; LL, lumbar lordosis; PI-LL, mismatch between pelvic incidence and lumbar lordosis; JOA, Japanese Orthopaedic Association; ODI, Oswestry disability index; VAS, visual analog Scale; LBP, low back pain; LSDI, lumbar stiffness disability index; PJK, proximal junctional kyphosis. P, comparison between two groups.
19
Page 19 of 21
1
2 3 4 5 6 7
Table 3 Comparison of therapeutic effects or complications among groups. Variables
Group A
Group B
Group C
P
Number of cases
22
28
24
-
Operative time (minutes)
234.5 ± 41.7
245.9 ± 37.1
231.3 ± 40.7
0.078
Intraoperative blood loss (ml)
1344.1 ± 331.8
889.3 ± 331.8
866.7 ± 339.0
0.379
Length of hospital stay (days)
14.9 ± 1.6
14.4 ± 1.0
13.8 ± 1.5
0.195
Cobb angle of curves at last follow-up (°)
4.4 ± 2.7
3.8 ± 1.3
4.5 ± 0.8
ODI at last follow-up
26.6 ± 4.1
18.4 ± 5.8
JOA at last follow-up (LBP)
2.7 ± 1.3
3.2 ± 1.2
VAS at last follow-up (LBP)
3.0 ± 1.2
3.2 ± 0.9
LSDI at last follow-up
3.2 ± 1.0
1.4 ± 1.2
Postoperative incision infection
3
3
$
0.260
33.0 ± 5.0
$&
3.4 ± 1.6
0.228
3.0 ± 0.8 $
1.0 ± 0.9
<0.001 0.789
$
2
<0.001 0.846
&
PJK
6
3
10
0.038
Loosening of fixation
2
1
4
0.274
Reoperation
3
2
4
0.560
Value is expressed as the mean ± standard deviation or number. PI, pelvic incidence; LL, lumbar lordosis; PI-LL, mismatch between pelvic incidence and lumbar lordosis; JOA, Japanese Orthopaedic Association; ODI, Oswestry disability index; VAS, visual analog Scale; LBP, low back pain; LSDI, lumbar stiffness disability index; PJK, proximal junctional kyphosis. P, comparison among three groups. $ P < 0.05, compared with group A; & P < 0.05, compared with group B.
20
Page 20 of 21
1 2
Table 4 Curve estimation evaluating the relationship between postoperative PI-LL and Cobb angle of the curves, ODI or LSDI at last follow-up time. Variables
Cobb angle
ODI
LSDI
Model
Strokes equation
Cubic equation
Cubic equation
0.506
0.379
0.691
P
< 0.001
< 0.001
< 0.001
Constant
1.536
28.871
4.708
b1
-1.495
-0.740
-0.373
b2
-
-0.010
0.017
b3
-
0.002
< 0.001
R
3 4 5
2
2
ODI, Oswestry disability index; LSDI, lumbar stiffness disability index. R , correlation coefficient squared; b1, monomial coefficient of equation; b2, quadratic coefficient of equation; b3, cubic coefficient of equation.
6
21
Page 21 of 21