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Walking balance and compensatory gait mechanisms in surgically treated patients with adult spinal deformity
Accepted Manuscript Title: Walking balance and compensatory gait mechanisms in surgically treated patients with adult spinal deformity Author: Mitsuru Yagi, Hideaki Ohne, Tsunehiko Konomi, Kanehiro Fujiyoshi, Shinjiro Kaneko, Masakazu Takemitsu, Masafumi Machida, Yoshiyuki Yato, Takashi Asazuma PII: DOI: Reference:
S1529-9430(16)31020-8 http://dx.doi.org/doi: 10.1016/j.spinee.2016.10.014 SPINEE 57185
To appear in:
The Spine Journal
Received date: Revised date: Accepted date:
24-3-2016 29-7-2016 13-10-2016
Please cite this article as: Mitsuru Yagi, Hideaki Ohne, Tsunehiko Konomi, Kanehiro Fujiyoshi, Shinjiro Kaneko, Masakazu Takemitsu, Masafumi Machida, Yoshiyuki Yato, Takashi Asazuma, Walking balance and compensatory gait mechanisms in surgically treated patients with adult spinal deformity, The Spine Journal (2016), http://dx.doi.org/doi: 10.1016/j.spinee.2016.10.014. 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.
Gait ability and pattern in ASD patients
1
Walking balance and compensatory gait mechanisms in surgically treated patients with adult spinal
2
deformity
3
4
Mitsuru Yagi M.D., Ph.D.1,2, Hideaki Ohne M.D.2, Tsunehiko Konomi M.D., Ph.D.1, Kanehiro
5
Fujiyoshi M.D., Ph.D.1, Shinjiro Kaneko M.D.1, Ph.D., Masakazu Takemitsu M.D., Ph.D.1, Masafumi
6
Machida M.D., Ph.D.1,Yoshiyuki Yato M.D., Ph.D.1, Takashi Asazuma M.D., Ph.D.1
7
8
Affiliations
9
1. Department of Orthopedic Surgery, National Hospital Organization Murayama Medical Center
10
2. Department of Orthopedic Surgery, Keio University School of Medicine
11
12
Name and address for correspondence:
13
Mitsuru Yagi, M.D., Ph.D.
14
2-37-1 Musahsimurayama City Gakuen, Tokyo, Japan
1
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Gait ability and pattern in ASD patients
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Tel: +81.42.561.1221; fax: +81.42.564.2210; e-mail: [email protected].
2
This study was approved by the appropriate institutional review board.
3
ABSTRACT
4
Background Context
5
Gait patterns and their relationship to demographic and radiographic data in patients with adult spinal
6
deformity (ASD) have not been fully documented.
7
Purpose
8
To assess gait pattern in patients with ASD and the effect of corrective spinal surgery on gait.
9
Study Design/Setting
10
Prospective case series.
11
Patient Sample
12
The gait patterns of 33 consecutive female with ASD (age 67.1 years; body mass index (BMI)
13
22.5±2.5 kg/m2, Cobb angle 46.8±18.2º, CVA 1.5±3.7 cm, C7SVA 9.1±6.4 cm, PI-LL 38.2±22.1º, and
2
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Gait ability and pattern in ASD patients
1
lean volume of the lower leg, 5.5±0.6 kg) before and after corrective surgery were compared with those
2
of 33 age- and gender-matched healthy volunteers.
3
Outcome Measures
4
SRS22, ODI, and forceplate analysis
5
Methods
6
All subjects underwent gait analysis on a custom-built force plate using optical markers placed on all
7
joints and spinal processes. DXA scores were used to calculate the lean composition of the lower legs.
8
Subjects with ASD were followed for at least 2 years post-op.
9
Results
10
Pre-op mean values showed that ASD patients had a significantly worse gait velocity (54±10 m/min vs.
11
70.7±12.9 m/min, p<.01) and stride (97.8±13.4 cm vs. 115.3±15.1 cm, p<.01), but no difference was
12
observed in the stance-swing ratio. The right and left ground reaction force vectors were also discordant
13
in the ASD group (vertical direction; r=.84 vs. r=.97, p=.01). The hip ROM was also significantly
14
decreased in ASD. Correlation coefficient showed moderate correlations between the preoperative gait
15
velocity and the gravity line, PI, ROM of the lower-extremity joints, and lean volume, and between the
16
stride and the lean volume, GL, and PI−LL. Gait pattern, stride, and velocity all improved significantly 3
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Gait ability and pattern in ASD patients
1
in the ASD patients after surgery, but were still not as good as in healthy volunteers. The SRS22
2
satisfaction domain correlated moderately with postoperative gait velocity (r=.34).
3
Conclusions
4
The ASD patients had an asymmetric gait pattern and impaired gait ability compared to healthy
5
volunteers. Gait ability correlated significantly with the GL, spinopelvic alignment, lower-extremity
6
joint ROM, and lean volume. The surgical correction of spinopelvic alignment and exercises to build
7
muscle strength may improve the gait pattern and ability in patients with ASD.
8
Keywords: adult spinal deformity;
9
gait analysis;
10
sagittal alignment;
11
spinopelvic alignment;
12
4
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INTRODUCTION
2
Although gait disturbance is a characteristic difficulty for patients with adult spinal deformity (ASD),
3
there is little information about the subjective assessment of gait ability in these patients [1-4].
4
Relationships between gait pattern or ability and demographic and radiographic data in patients with
5
ASD are not well documented. A positive sagittal alignment can cause fatigue of the back muscles with
6
subsequent pain and disability [5-11]. Schwab et al. described the essential role of pelvic parameters and
7
spinopelvic alignment in maintaining a standing posture [12]. A positive sagittal malalignment due to
8
pelvic retroversion requires ASD patients to compensate by flexing the hip and knee joints while
9
standing and when the heel first contacts the floor while walking [7,8,13]. Various outcome
10
measurements show a clear gait disability in ASD patients [7,8,13]. Despite these objective outcome
11
measurements, gait ability and pattern are not usually subjectively evaluated in daily practice or in
12
clinical research. Furthermore, the effect of corrective spinal surgery on gait ability or pattern in patients
13
with ASD has not been determined. To our knowledge, only four reports have addressed gait patterns in
14
ASD patients [13-16]. After assessing 12 patients with ASD, Gottipati et al. concluded that a positive
15
sagittal alignment resulted in a crouching posture and gait that were resolved after multi-segment
16
reconstructive spinal surgery [14]. Similarly, Engsberg et al. assessed ASD patients’ gait characteristics
17
before and after reconstructive spinal surgery, and concluded that the surgery resolved difficulties in gait
18
pattern and endurance [15,16]. The present study was conducted to assess gait patterns in ASD and the
19
effect of corrective spinal surgery. 5
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Gait ability and pattern in ASD patients
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MATERIALS AND METHODS
2
Funding
3
No external funding was used for this study. The authors report no conflict of interest.
4
Inclusion criteria
5
This prospective case series included 33 consecutive females who were treated surgically for ASD and
6
33 healthy gender- and age-matched volunteers. The inclusion criteria for ASD were as follows: an age
7
of more than 50 years; a main-curve Cobb angle greater than 20° or a C7 sagittal vertical axis (SVA)
8
greater than 5 cm, and a follow-up period of at least two years. Subjects who could not walk without
9
assistance or had a previous spinal surgery or joint replacement, inappropriate radiography, or a
10
syndromic, neuromuscular, or other pathological condition were excluded.
11
12
Methods
13
We reviewed ASD patients’ charts and radiographs and analyzed their gait before and after surgery;
14
these data were compared with those of 33 gender-, age-, and height- matched healthy volunteers. This
15
study was approved by our institution's review board.
6
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Gait ability and pattern in ASD patients
1
Demographic data included age, gender, and clinical outcomes. Radiographic data included the coronal
2
vertical axis (CVA), trunk shift, Cobb angle, gravity line (GL), C7SVA, C2-C7, T5-T12 (thoracic
3
kyphosis), T10-L2 (thoracolumbar kyphosis), T12-S (lumbar lordosis [LL]), sacral slope (SS), pelvic tilt
4
(PT), and pelvic incidence (PI). We also reviewed the spinopelvic alignment (PI minus LL [PI−LL]),
5
and calculated the lean composition of the lower legs from whole-body dual-X ray absorptiometry
6
(DXA) scores. Radiographs were obtained for all ASD patients prior to and two years after corrective
7
surgery.
8
We assessed relationships among radiographic parameters and walking pattern and ability, and
9
compared the radiographic data, gait patterns, and walking ability between ASD patients (preoperative
10
and postoperative) and healthy volunteers.
11
12
Patient outcomes
13
Patient outcomes were evaluated using the Scoliosis Research Society Patient Questionnaire (SRS22r)
14
and the Oswestry Disability Index (ODI). Completed questionnaires were available for 31 of the 33
15
ASD patients.
16
7
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Gait ability and pattern in ASD patients
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Study population
2
The mean age of the ASD patients was 67.2 years (51–72 years) and of healthy volunteers was
3
72.2 years (63–75 years) (Table 1). There was no difference in age or height between the ASD patients
4
and healthy volunteers. The mean lean volume of the right leg in preoperative ASD patients was
5
5.5±1.1 kg. Among the preoperative ASD patients, 27 of the 33 had a severe PI−LL mismatch (PI−LL >
6
20º), and six patients had a moderate mismatch (PI−LL<20º) (Table 2). All ASD patients were treated
7
by posterior spinal fusion. The mean number of fused vertebrae was 11.2±2.2. The majority of the
8
patients (27/33) had a lower instrumented vertebra (LIV) at the pelvis. The upper instrumented vertebra
9
(UIV) was at the proximal thoracic vertebrae (T2-T5) in 5 patients and at the distal thoracic vertebrae
10
(T9-T11) in 28 patients.
11
12
Radiographic summary of the patient cohort
13
We found the following mean preoperative values for the ASD patients: Cobb angle 46.8º, CVA
14
1.5±3.7 cm, C7SVA 9.1±6.4 cm, GL 10.1±7.7 cm, thoracic kyphosis 18.2±18.9º, LL −7.4±26.0º, and
15
PI−LL 41.1±25.2º. Most of the parameters were significantly improved 2 years after surgery (Table 2).
16
8
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Gait ability and pattern in ASD patients
1
Gait analysis
2
A custom-built 10.8-meter-long force plate was placed on the floor, and the platform data were
3
processed and displayed on a computer monitor in real time. For the GL position, calibration from data
4
using a dead weight placed at several known locations on the force plate showed that the force plate was
5
accurate to within 1 mm. The GRF location information on the computer monitor was placed within the
6
camera's field of view. Optical markers were attached to the skin over the ear canal, the spinous
7
processes of C7 to S1, the anterior and posterior superior iliac spine (ASIS and PSIS), the great
8
trochanter, the femoral head, the lateral and medial malleolus, the head of the first and fifth metatarsal
9
bones, the acromion, the ulna styloid process, the ulna head, the sternum, and the calcaneus. Marker
10
locations were verified by palpation. While any error in marker placement affects the absolute value of
11
spinal balance, these errors may not have noticeably affected the repeatability, because only relative
12
distance was considered. Patients were instructed to walk naturally on the force plate three times as
13
practice, and then to walk once more for recording and analysis.
14
The concordance of the right and left GRF vectors was estimated from the difference between the GRF
15
vectors of both force plates (patients walked on two force plates, with the right foot on one force plate
16
and the left foot on the other). The center of gravity (COG) was calculated by segmental methods [17].
17
The angles of the pelvis, hip, knee, and ankle were estimated from the positions of the representative
9
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Gait ability and pattern in ASD patients
1
optic markers. Gait analysis was conducted preoperatively and 9–12 months postoperatively for all of
2
the ASD patients.
3
4
Statistical analysis
5
Continuous variables were analyzed by Mann Whitney U test and categorical valuables were analyzed
6
by chi-squared tests. Multiple regression analyses were used for ordinal and nominal data when more
7
than five observations were expected in each category. A p value less than 0.05 with a confidence
8
interval of 95% was considered statistically significant. All analyses used the Statistical Package for the
9
Social Sciences (SPSS version 21.0 IBM Corp., Armonk, NY).
10
11
RESULTS
12
Gait ability and pattern analysis
13
Compared to healthy subjects, the ASD patients had significantly worse preoperative gait velocity
14
(54±10 m/min vs 70.7±12.9 m/min, p<.001) and stride (97.8±13.4 cm vs. 115.3±15.1 cm, p<.001),
15
whereas no difference was observed in stance-swing ratio (stance 63.1±2.9% vs. swing 36.9±2.9% in the
16
preoperative ASD patients). Both velocity and stride improved significantly in the ASD group after 10
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Gait ability and pattern in ASD patients
1
corrective surgery, but were still worse than in healthy subjects. No difference was observed in the
2
preoperative and postoperative cadence in ASD patients. Based on the force-plate GRF data,
3
preoperative Pedotti diagrams in the sagittal plane showed a walking vertical GRF vector distribution
4
with abnormally verticalized vectors at the heel-contact and the toe-off phases (Figure 1).
5
In the coronal plane, differences between the right and left stride were greater in the ASD group than in
6
healthy subjects. Analyses of the preoperative force-plate data for gait motion clearly showed
7
asymmetrical right- and left-side GRF vectors in the ASD group, and correlation coefficient analyses
8
showed discordant right- and left-side GRF vectors in the mediolateral and vertical axes during walking
9
(Tables 3 and 4). Although corrective surgery for ASD significantly improved these parameters, the
10
postoperative difference between the left- and right-side GRF vectors during walking was still larger in
11
ASD patients than in healthy subjects. Postoperatively, Pedotti diagrams in the sagittal plane showed a
12
walking vertical GRF vector distribution with a normal butterfly-wing shape for all of the ASD patients
13
(Figure 2).
14
15
Comparisons of kinematic gait variables
16
The preoperative range of motion (ROM) of the hip joint was significantly less in ASD patients than in
17
healthy subjects during natural walking, whereas no differences in ROM were noted for the lumbar 11
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Gait ability and pattern in ASD patients
1
spine, knees, or ankles. On the other hand, the pelvic ROM was significantly larger in ASD patients than
2
in healthy volunteers. The minimum hip and knee angles during walking were significantly increased
3
and pelvic anteversion was significantly decreased in the ASD patients, indicating that ASD patients
4
flexed the hip and knee in the heel-contact phase to compensate for the loss of pelvic anteversion due to
5
spinopelvic malalignment and the loss of lumbar lordosis. Corrective surgery significantly improved the
6
ROM of all the lower-extremity joints in the ASD group, but the postoperative hip ROM was still worse
7
in ASD patients than in healthy volunteers (Table 5).
8
9
Correlations between gait kinematics and the ROM of the spine and lower-extremity joints
10
Correlation coefficient analyses of gait kinematics and the ROM of the spine and the lower-extremity
11
joints showed a moderate correlation in ASD patients between the preoperative gait velocity and the hip,
12
knee, and ankle ROM, and between the preoperative stride and the hip and ankle ROM (Table 6). No
13
significant correlation was observed between the cadence and the ROM of the spine or lower-extremity
14
joints.
15
Correlations between gait kinematics and demographic and radiographic variables
16
Correlation coefficient analyses of the preoperative values in the ASD group identified significant
17
correlations between the gait velocity and the Cobb angle, GL, SS, PT, PI−LL, and lean volume of the 12
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Gait ability and pattern in ASD patients
1
lower extremity; between stride and the lean volume of the lower extremity and thoracic kyphosis; and
2
between cadence and the GL and SS (Table 7). Age and BMI did not correlate with any gait kinematics
3
in the ASD group. A moderate correlation was observed between the preoperative right and left stride
4
difference and the trunk shift (r=.44). These results indicated that both coronal and sagittal spinal
5
alignment, as well as leg-muscle strength, have a significant effect on gait kinematics.
6
7
Correlations between the preoperative ROM of lower-extremity joints and demographic and
8
radiographic variables
9
Correlation coefficient analyses showed significant correlations between the hip ROM and stride and the
10
lean volume of the lower extremity, the Cobb angle, the trunk shift, and the PI−LL. The lean volume of
11
the lower extremity correlated strongly with the hip ROM. The knee and ankle ROM correlated
12
moderately with the GL and PI−LL (Table 8). Age and BMI did not correlate with the ROM of any
13
lower-extremity joint in the ASD patients These results indicated that both coronal and sagittal spinal
14
alignment and the strength of the leg muscles significantly affect the ROM of the lower-extremity joints.
15
16
Correlation of gait kinetics and clinical outcomes
13
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The preoperative SRS22r scores for the ASD group were as follows: total 3.4±1.0, pain 3.4±0.8,
2
function 2.6±0.8, self-image 3.5±0.5, mental health 3.6±0.4, satisfaction 3.1±0.9; the ODI score was
3
64±13%. All of the outcome scores were improved 2 years after surgery (total 4.1±1.1, pain 4.1±0.6,
4
function 3.9±0.6, self-image 4.2±0.7, mental health 4.1±0.9, satisfaction 4.5±0.8, and ODI 28±10%,
5
p<.05 in the all comparisons).
6
Preoperatively, the SRS22 function domain score correlated weakly with gait velocity in ASD patients
7
(r=.23). Postoperatively, the SRS22 satisfaction domain score correlated moderately with gait velocity
8
after surgery (r=.34); no correlation was found between postoperative gait ability and any other outcome
9
measures.
10
11
DISCUSSION
12
Although the importance of the standing sagittal balance in clinical ASD outcomes is widely recognized,
13
there is little information about how gait ability and patterns in ASD affect clinical outcomes [1-16].
14
Four studies have addressed relationships between spinal alignment and gait pattern in ASD patients.
15
Gottipati et al. concluded that a positive sagittal alignment resulted in a crouching posture and gait that
16
were resolved by multi-segment reconstructive spinal surgery that improved sagittal spinal alignment,
17
and that surgical correction also improved step and stride length [14]. Similarly, Engsberg et al. assessed 14
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Gait ability and pattern in ASD patients
1
the gait ability of 20 primary and revision ASD subjects and concluded that gait patterns and poor
2
endurance were resolved after reconstructive spinal surgery that improved sagittal spinal alignment;
3
however, the ASD postoperative gait velocity was still worse than in healthy volunteers [15,16]. These
4
studies had major limitations in the small sample size, the sample distribution (both primary and revision
5
surgery were included), and the lack of force-plate analysis. Some subjects had fused lumbar vertebrae
6
from a prior spine fusion, which could have significantly affected preoperative gait analysis.
7
The present study compared the preoperative and postoperative gait patterns of ASD patients with those
8
of gender-, age, and height-matched healthy volunteers. We recorded a variety of gait variables,
9
including gait velocity, stride, cadence, spinal alignment, spinopelvic alignment, and GRF, as well as
10
trunk and lower extremity kinematics, to obtain a comprehensive overview of the gait patterns and
11
abilities of ASD patients. To determine these characteristics more precisely, we included only primary
12
ASD patients. We assessed gait patterns and abilities on the force plate, and also evaluated the lean
13
volume of the lower leg. To address the role of gait ability in patient outcomes, we also analyzed
14
correlations between preoperative and postoperative gait abilities and clinical patient outcomes.
15
Gait ability and pattern analysis
16
Our results were consistent with our previous findings. The preoperative gait velocity and stride in ASD
17
patients were significantly worse than in healthy volunteers; both parameters improved after corrective
18
surgery, but were still worse than in healthy subjects. The factors that correlated with gait velocity and 15
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Gait ability and pattern in ASD patients
1
stride were the hip, knee, and ankle ROM, the GL, the spinopelvic alignment, the Cobb angle, the trunk
2
shift, and the lean volume of the lower leg. Postoperatively, radiographic spinal alignment and the ROM
3
of the ankle and knee were improved. On the other hand, hip ROM improved but was still impaired
4
compared to that of healthy volunteers. The limited hip ROM and the low lean volume of the lower leg
5
might affect both gait velocity and stride.
6
One possible reason for the limited postoperative ROM of the hip joint is the effect of lumbosacral and
7
pelvic fusion. Preoperative ASD gait analysis showed that the pelvic ROM increased to compensate for
8
a decrease in hip ROM. Most of the ASD patients were treated by lumbosacral fusion to restore
9
spinopelvic alignment [4,18], and lumbosacral fusion reduces the spinal and pelvic ROM to almost zero.
10
The spinal and pelvic ROM in healthy subjects shows the importance of the motion of the lumbar spine
11
and pelvis for a natural gait. Lumbosacral fusion might also affect the hip ROM. We previously reported
12
gait changes after pedicle subtraction osteotomy (PSO) for severe fixed sagittal imbalance, and found
13
that hip ROM was improved but was still limited compared to that in healthy subjects [19]; a similar
14
trend was observed in the current study, even though the study population was different.
15
Another possible reason for the limited hip ROM is weak muscle strength in ASD patients. Elderly ASD
16
patients are often inactive for a lengthy period prior to corrective surgery because of pain and disability,
17
and this inactivity might reduce muscle volume and strength. Although we did not evaluate the
18
lower-leg muscle strength in ASD patients, and did not have these data for the healthy subjects, studies 16
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Gait ability and pattern in ASD patients
1
have shown a moderate correlation between muscle volume and strength in the lower extremity. Our
2
analysis clearly identified a moderate correlation between the lean volume of the lower leg and the gait
3
velocity and stride [20-24]. These findings indicate that preoperative and postoperative exercise can
4
improve the gait in patients who are surgically treated for ASD.
5
Abnormal GRF vectors and gait pattern
6
Force-plate analysis enables us to assess the GRF vectors during gait motion. Our force-plate gait
7
analysis showed that the GRF vector was abnormally vertical at the heel-contact and toe-off phases in
8
ASD patients prior to corrective spinal surgery. The ASD patients compensated for pelvic retroversion
9
by flexing the hip and knee joint when standing and when the heel first contacts the floor while walking
10
[25-31]. The importance of this compensatory mechanism in standing upright or walking long distances
11
is clear from the significant disparity between ASD and healthy subjects in the preoperative minimum
12
hip flexion angle during the heel-contact phase. The GRF vector was verticalized by the increase in the
13
minimum flexion angles of the knee joint during the heel-contact phase and the hip during the toe-off
14
phase, resulting in a decreased stride length.
15
Asymmetric stride and GRF vectors
16
Correlation coefficient analysis of the preoperative ASD stride showed discordant right and left
17
medial/lateral and vertical directions of the GRF vectors, and differences in right and left stride length. 17
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Gait ability and pattern in ASD patients
1
We found that hip ROM correlated with the Cobb angle of the major curve and with trunk shift. The
2
trunk shift and coronal spinal curvature might affect the stability of the contact leg during the swing
3
phase and might reduce the stride of the contralateral side. Jackson et al. reported that coronal spinal
4
malalignment due to fractional lumbosacral curves affects both pain and activity in ASD patients [29].
5
Our findings clearly demonstrate the importance of restoring both coronal balance and sagittal balance
6
when performing corrective spinal surgery.
7
Correlation of gait kinetics and clinical outcomes
8
We also analyzed the impact of gait kinetics on clinical outcomes for ASD, and found a weak
9
correlation between the preoperative SRS22r function score and gait velocity. We found a moderate
10
correlation between the postoperative SRS22r satisfaction domain scores and gait velocity, but no other
11
correlation between postoperative gait and outcome scores. The SRS22r does not directly address gait
12
ability, but questions 5, 9, and 18 are related to it. The ODI questionnaire addresses gait endurance
13
directly in Section 4, and Section 10 asks about daily activity. The preoperative scores for ODI Section 4
14
were widely distributed in the ASD group, from 1 (pain prevents me from walking more than 2
15
kilometers) to 4 (I can only walk with a stick or crutch), and the mean score was 3.4±1.1. Scores after
16
surgery improved to 1.7±0.9, with no patients scoring more than 4. Correlation coefficient analyses
17
showed no correlation between the preoperative or postoperative Section 4 scores and gait
18
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Gait ability and pattern in ASD patients
1
characteristics such as gait velocity, cadence, or stride, indicating that these parameters are not directly
2
correlated with walking endurance.
3
On the other hand, a moderate correlation seen between the postoperative gait velocity and SRS22r
4
satisfaction domain scores indicated that improving gait velocity is important for patient satisfaction.
5
This may be due to the effect of gait velocity on daily activity, since a normal gait velocity is important
6
for walking with family or friends; this idea is supported by the weak correlation seen between the
7
SRS22r function domain score and gait velocity. Our study is the first to demonstrate correlations
8
between gait ability and ASD clinical outcomes, and these correlations will help both surgeons and
9
patients to understand what can be expected from surgical treatment for ASD.
10
The present study has a potential weakness in its relatively small sample size; however, our results
11
clearly documented gait patterns and abilities in ASD patients, including compensatory flexion of the
12
lower-extremity joints and a pelvic posterior shift. Moreover, the present study has the largest sample
13
series to date for gait analysis in ASD. The population of patients with ASD is quite heterogeneous,
14
depending on age and diagnosis, and these differences in patient characteristics must be taken into
15
consideration when treating patients and when analyzing the results of treatment. Further study of the
16
relationships among muscle strength, lumbosacral fusion, and gait ability will improve our
17
understanding of the pathophysiology of ASD.
18 19
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Gait ability and pattern in ASD patients
1
CONCLUSION
2
Patients with ASD have an asymmetric gait pattern and more difficulty walking compared to healthy
3
subjects. We found significant correlations between gait ability and the GL, spinopelvic alignment,
4
ROM in lower-extremity joints, and lower-extremity muscle volume. The surgical correction of
5
spinopelvic alignment and exercises to improve muscle strength may improve the gait pattern and
6
walking ability of patients with ASD. The moderate correlation seen between gait velocity and patient
7
satisfaction indicates the importance of gait analysis when evaluating and treating patients with ASD.
8
20
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1
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Outcomes of Pedicle Subtraction Osteotomy for Fixed Sagittal Imbalance: Does Level of Proximal
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Fusion Affect The Outcome? -Minimum 5years follow-up- Spine Deformity. 2013;1: 123-131.
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9.
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Clin Orthop Relat Res 2001; 384:35-44.
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10.
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junctional kyphosis: surgical outcomes review of adult idiopathic scoliosis. Spine 2011; 36:E60-8.
8
11.
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junctional kyphosis: surgical outcomes review of adult idiopathic scoliosis. Minimum 5 years of
Bridwell KH, Lenke LG, Lewis S. Treatment of spinal stenosis and fixed sagittal imbalance.
Yagi M, Akilah KB, Boachie-Adjei O. Incidence, risk factors and classification of proximal
Yagi M, Akilah KB, Boachie-Adjei O. Incidence, risk factors, and natural course of proximal
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follow-up. Spine 2012; 37:1479-89.
11
12.
12
parameters, and foot position. Spine 2006; 31(25):1-9
13
13.
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with postsurgical sagittal (flatback) deformity: a prospective study of 21 patients. Spine. 2002;
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27(21):2328-37.
Schwab F, Lafage V, Farcy JP, et al. Age-related correlation with spinal parameters, pelvic
Sarwahi V, Boachie-Adjei O, Backus SI, Taira G. Characterization of gait function in patients
22
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14.
Gottipati P, Fatone S, Koski T, Sugrue PA, Ganju A. Crouch gait in persons with positive
2
sagittal spine alignment resolves with surgery. Gait Posture. 2014; 39(1):372-7.
3
15.
4
result of deformity reconstruction surgery in a group of adults with lumbar scoliosis. Spine (Phila Pa
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1976). 2003; 28(16):1836-43; discussion 1844.
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16.
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undergoing long spinal deformity fusion surgery (thoracic to L4, L5, or sacrum) and controls. Spine
8
(Phila Pa 1976). 2001; 26(18):2020-8.
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17.
Engsberg JR, Bridwell KH, Wagner JM, Uhrich ML, Blanke K, Lenke LG. Gait changes as the
Engsberg JR, Bridwell KH, Reitenbach AK, et al. Preoperative gait comparisons between adults
Zatsiorsky V. The Mass and Inertia Characteristics of the Main Segments of the Human Body.
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Biomechanics, vol. V, 1983; 1132–59.
11
18.
12
thoracic and lumbar spines and thoracolumbar junction. Spine. 1989; 14(7):717-21.
13
19.
14
osteotomy in adults with fixed sagittal imbalance. European Spine J. 2016 in press.
Bernhardt M, Bridwell KH. Segmental analysis of the sagittal plane alignment of the normal
Yagi M, Kaneko S, Yato Y, et al. Walking sagittal balance correction by pedicle subtraction
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20.
Hunter SK, Thompson MW, Adams RD. Relationships among age-associated strength changes
2
and physical activity level, limb dominance, and muscle group in women. J Gerontol A Biol Sci Med
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Sci. 2000; 55(6):B264-73.
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21.
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among muscle mass, strength, and the ability to perform physical tasks of daily living in younger and
6
older women. J Gerontol A Biol Sci Med Sci. 2001; 56(10):B443-8.
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22.
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No:41-4.
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23.
Landers KA, Hunter GR, Wetzstein CJ, Bamman MM, Weinsier RL. The interrelationship
Hurley BF. Age, gender, and muscular strength. J Gerontol A Biol Sci Med Sci. 1995; 50 Spec
Suzuki T, Bean JF, Fielding RA. Muscle power of the ankle flexors predicts functional
10
performance in community-dwelling older women. J Am Geriatr Soc. 2001; 49(9):1161-7.
11
24.
12
Williams & Wilkins, 1985 - Health & Fitness – p361-371
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25.
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Patient with Adult Spinal Deformity-Factors Affecting the O-T Discordance- The Spine J. 2015; 15:
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213–221.
Basmajian JV, De Luca CJ. Muscles alive: their functions revealed by electromyography.
Yagi M, Takeda K, Machida M, and Asazuma T. Discordance of Gravity Line and C7PL in
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26.
Le Huec JC, Saddiki R, Franke J, Rigal J, Aunoble S. Equilibrium of the human body and the
2
gravity line: the basics. Eur Spine J. 2011; 5:558-63.
3
27.
4
sagittal sacropelvic morphology and balance in asymptomatic adults. Eur Spine J. 2011; 20 Epub.
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28.
6
parameter for three-dimensional regulation of spinal sagittal curves. Eur Spine J. 1998; 7(2):99-103.
7
29.
8
standing volunteers and patients with low back pain matched for age, sex, and size. A prospective
9
controlled clinical study. Spine. 1994; 19(14):1611-8.
Mac-Thiong JM, Roussouly P, Berthonnaud E, Guigui P. Age- and sex-related variations in
Legaye J, Duval-Beaupère G, Hecquet J, Marty C. Pelvic incidence: a fundamental pelvic
Jackson RP, McManus AC. Radiographic analysis of sagittal plane alignment and balance in
10
30.
Kuntz C 4th, Shaffrey CI, Ondra SL, Durrani AA, Mummaneni PV, Levin LS, Pettigrew DB.
11
Spinal deformity: a new classification derived from neutral upright
12
asymptomatic juvenile, adolescent, adult, and geriatric individuals. Neurosurgery. 2008; 63:25-39.
13
31.
14
alignment from the occiput to the pelvis in asymptomatic adults: a review and resynthesis of the
15
literature. J Neurosurg Spine. 2007; 6:104-12.
spinal alignment measurements in
Kuntz C 4th, Levin LS, Ondra SL, Shaffrey CI, Morgan CJ. Neutral upright sagittal spinal
16 25
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Gait ability and pattern in ASD patients
1
FIGURE LEGENDS
2
Figure 1
3
Case example of gait analysis of ASD patient and healthy volunteer.
4
A; 67 years ASD patient. Pre-operative round reaction vector in vertical direction during natural walking
5
on the force platform. B; 67 years ASD patient. Post-operative round reaction vector in vertical direction
6
during natural walking on the force platform. C; 63 years healthy volunteer. Ground reaction vector in
7
vertical direction during natural walking on the force platform.
8
Figure 2
9
Ground reaction force vector comparisons between ASD and healthy volunteer during walking on the
10
force platform. Gray line indicates the ground reaction vector of the right foot. Black line indicates the
11
ground reaction vector of the left foot
12
Figure 3
13
Pre- and post-operative gait kinematic change in patient with ASD.
14
A; 67 years ASD patient. Pre-operative gait kinematics during natural walking on the force platform. B;
15
67 years ASD patient. Post-operative gait kinematics during natural walking on the force platform. 26
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Gait ability and pattern in ASD patients
1
Table 1. Patient cohort demographics
ASD
HV
P value
No. of patients
33
33
Age (years)
67.2 ± 8.7
72.2 ± 3.8
0.09
Height (cm)
150.9 ± 7.9
148.9 ± 4.7
0.22
Weight (kg)
51.7 ± 5.7
53.3 ± 7.3
0.25
BMI (kg/m2)
22.8 ± 2.5
23.9 ± 2.5
0.46
Lean volume (kg)
5.5 ± 1.1
N/A
2
Means and standard deviations. Patients with adult spinal deformity (ASD) were compared to healthy
3
volunteers (HVs). BMI: body mass index.
4
27
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Gait ability and pattern in ASD patients
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Table 2. Radiographic summary of the ASD patient cohort
Pre-op
Post-op
P value
Cobb angle (deg.)
46.8 ± 18.2
14.4 ± 8.8
.00 *
Trunk shift (cm)
2.4 ± 4.2
1.2 ± 1.2
.19
CVA (C7PL;cm)
1.5 ± 3.7
1.0 ± 3.3
.23
GL (cm)
10.1 ± 7.7
4.1 ± 3.6
.00 *
C7SVA (cm)
9.1 ± 6.4
4.7 ± 4.4
.00 *
C2C7 (deg.)
-15.7 ± 17.9
-17.6 ± 11.2
.08
T5-T12 (deg.)
17.1 ± 15.9
28.5 ± 11.9
.00 *
T10-L2 (deg.)
23.8 ± 17.8
9.7 ± 6.3
.00 *
LL (deg.)
-7.3 ± 21.5
-44.4 ± 11.5
.00 *
SS (deg.)
15.1 ± 12.5
31.1 ± 7.4
.00 *
PI (deg.)
45.5 ± 6.2
45.4 ± 5.3
.91
PT (deg.)
30.5 ± 11.3
13.9 ± 9.2
.00 *
PI-LL (deg.)
38.2 ± 22.0
3.4 ± 4.7
.00 *
Coronal plane
Sagittal plane
2
Means and standard deviations. Pre-op and post-op values were compared in patients with adult spinal
3
deformity (ASD). CVA: coronal vertical axis; GL: gravity line; C7PL: C7 plumb line; LL: lumbar
4
lordosis; SS sacral slope; PI: pelvic incidence; PT: pelvic tilt; PI−LL; PI minus LL. 28
Page 28 of 37
Gait ability and pattern in ASD patients
1
*Statistically significant.
2
29
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Gait ability and pattern in ASD patients
1
Table 3. Comparisons of gait patterns in healthy and ASD subjects
ASD
HV
Pre-op
Post-op
54.0 ± 10.4
59.2 ± 8.9
RT
97.8 ± 13.4
LT
P value
P1
P2
70.7 ± 12.9
.00 *
.05*
107.6 ± 11.1
114.3 ± 15.0
.00 *
.06
96.4 ± 14.8
106.4 ± 12.8
114.5 ± 15.1
.00 *
.09
Cadence (steps/min)
113.1 ± 10.7
110.1 ± 9.9
123.1 ± 8.1
.01 *
.01*
Stance phase (%)
63.1 ± 2.9
63.0 ± 2.7
62.3 ± 1.8
.22
.23
Swing phase (%)
36.9 ± 2.9
36.8 ± 2.7
37.8 ± 1.8
.22
.23
Double stance phase (%)
26.7 ± 4.5
25.9 ± 4.3
24.5 ± 2.6
.08
.14
Stride RT-LT diff. (cm)
3.1 ± 2.5
1.2 ± 1.1
0.9 ± 0.9
.01 *
.78
Velocity (m/min) Stride (cm)
2
Means and standard deviations. Values from healthy volunteers (HVs) were compared with pre-op (P1)
3
and post-op (P2) patients with adult spinal deformity (ASD). *Statistically significant.
4
5
30
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Gait ability and pattern in ASD patients
1
Table 4. Correlation coefficients for GRF vectors in healthy and ASD subjects
ASD
HV
Pre-op
Post-op
Medial/lateral
0.79 ± 0.09
0.88 ± 0.08
Anterior/posterior
0.97 ± 0.06
Vertical
0.82 ± 0.10
P value P1
P2
0.93 ± 0.02
.01*
.02*.
0.97 ± 0.06
0.99 ± 0.02
n.s.
n.s.
0.91 ± 0.11
0.97 ± 0.04
.01*
.01*
2
Means and standard deviations. Values from healthy volunteers (HVs) were compared with
3
pre-op (P1) and post-op (P2) patients with adult spinal deformity (ASD). *Statistically significant;
4
n.s.: not significant.
5
6
31
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Gait ability and pattern in ASD patients
1
Table 5. Comparisons of kinematic gait variables in healthy and ASD subjects
ASD
HV
Pre-op
Post-op
P value
P1
P2
TL
Max
22.2 ± 6.1
11.1 ± 4.8
16.5 ± 6.3
.01*
.14
kyphosis
Min
19.1 ± 7.4
6.3 ± 4.9
13.1 ± 6.9
.02*
.07
(deg.)
range
3.6 ± 1.9
4.8 ± 1.7
3.4 ± 1.7
.44
.11
Pelvis
Max
6.7 ± 9.5
18.4 ± 6.7
13.5 ± 7.3
.02*
.22
(deg.)
Min
0.9 ± 10.2
15.3 ± 7.1
9.4 ± 6.7
.01*
.20
range
5.8 ± 2.9
3.1 ± 2.2
4.0 ± 0.9
.04*
.34
Max
27.9 ± 8.3
27.9 ± 5.8
29.2 ± 7.2
.33
.39
Min
-2.9 ± 11.3
-11.5 ± 8.2
-10.6 ± 8.2
.03*
.19
range
29.1 ± 9.5
35.8 ± 6.1
39.7 ± 5.3
.00*
.00*
Max
65.4 ± 5.2
63.0 ± 8.5
63.6 ± 7.3
.71
.62
Min
9.2 ± 6.4
5.5 ± 3.7
6.7 ± 9.7
.05*
.00*
range
56.2 ± 6.2
55.1 ± 7.2
56.9 ± 5.9
.37
.34
Ankle
Max
5.5 ± 5.2
6.0 ± 3.7
6.4 ± 4.6
.33
.46
(deg.)
Min
-28.1 ± 8.3
-28.2 ± 9.8
-28.0 ± 6.9
.49
.41
range
33.6 ± 5.9
34.2 ± 8.0
34.4 ± 5.6
.37
.40
Hip
(deg.) Knee (deg.)
32
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Gait ability and pattern in ASD patients
1
Means and standard deviations. Values from healthy volunteers (HVs) were compared with pre-op (P1)
2
and post-op (P2) patients with adult spinal deformity (ASD). TL: thoracolumbar. *Statistically
3
significant.
4
33
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Gait ability and pattern in ASD patients
1
2
Table 6. Correlation coefficients for ASD pre-op gait kinematics and spine and leg ROM
Variables
Velocity
Stride
Cadence
Spine ROM
n.s.
n.s.
n.s.
Pelvis ROM
n.s.
n.s.
n.s.
Hip ROM
0.22
0.44
n.s.
Knee ROM
0.44
n.s.
n.s.
Ankle ROM
0.44
0.53
n.s.
ROM: range of motion; n.s.: not significant.
3
4
34
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Gait ability and pattern in ASD patients
1
Table 7. Correlation coefficients for ASD pre-op gait kinematics and demographic and radiographic
2
variables
Variables
Velocity
Stride
Cadence
Age
n.s.
n.s.
n.s.
BMI
n.s.
n.s.
n.s.
Lean volume/BW
0.34.
0.31
n.s.
Cobb angle
0.46
n.s.
n.s.
Trunk shift
n.s.
n.s.
n.s.
CVA
n.s.
n.s.
n.s.
GL
-0.72
-0.61
-0.50
T5-T12
n.s.
n.s.
n.s.
T10-L2
n.s.
0.46
n.s.
SS
0.61
n.s.
0.59
PT
-0.53
n.s.
n.s.
PI−LL
-0.46
n.s.
n.s.
3
BMI: body mass index; BW: body weight; CVA: coronal vertical axis; GL: gravity line; SS sacral slope;
4
PT: pelvic tilt; PI−LL: pelvic incidence (PI) minus lumbar lordosis (LL); n.s.: not significant.
5 35
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Gait ability and pattern in ASD patients
1
Table 8. Correlation coefficients for the ROMs of the lower extremity joints and demographic and
2
radiographic valuables in pre-op ASD patients
Variables
Hip ROM
Knee ROM
Ankle ROM
Age
n.s.
n.s.
n.s.
BMI
n.s.
n.s.
n.s.
Lean volume/BW
0.78
n.s.
n.s.
Cobb angle
0.33
n.s.
n.s.
Trunk shift
0.46
n.s.
n.s.
CVA
n.s.
n.s.
n.s.
GL
n.s.
0.36
0.35
T5T12
n.s.
n.s.
n.s.
T10L2
n.s.
n.s.
n.s.
SS
n.s.
n.s.
n.s.
PT
n.s.
n.s.
n.s.
PI−LL
0.39
0.36
0.31
3
BMI: body mass index; BW: body weight; CVA: coronal vertical axis; GL: gravity line; SS sacral slope;
4
PT: pelvic tilt; PI−LL: pelvic incidence (PI) minus lumbar lordosis (LL); n.s.: not significant.
5
36
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Gait ability and pattern in ASD patients
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2
37
Page 37 of 37
S1529-9430(16)31020-8 http://dx.doi.org/doi: 10.1016/j.spinee.2016.10.014 SPINEE 57185
To appear in:
The Spine Journal
Received date: Revised date: Accepted date:
24-3-2016 29-7-2016 13-10-2016
Please cite this article as: Mitsuru Yagi, Hideaki Ohne, Tsunehiko Konomi, Kanehiro Fujiyoshi, Shinjiro Kaneko, Masakazu Takemitsu, Masafumi Machida, Yoshiyuki Yato, Takashi Asazuma, Walking balance and compensatory gait mechanisms in surgically treated patients with adult spinal deformity, The Spine Journal (2016), http://dx.doi.org/doi: 10.1016/j.spinee.2016.10.014. 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.
Gait ability and pattern in ASD patients
1
Walking balance and compensatory gait mechanisms in surgically treated patients with adult spinal
2
deformity
3
4
Mitsuru Yagi M.D., Ph.D.1,2, Hideaki Ohne M.D.2, Tsunehiko Konomi M.D., Ph.D.1, Kanehiro
5
Fujiyoshi M.D., Ph.D.1, Shinjiro Kaneko M.D.1, Ph.D., Masakazu Takemitsu M.D., Ph.D.1, Masafumi
6
Machida M.D., Ph.D.1,Yoshiyuki Yato M.D., Ph.D.1, Takashi Asazuma M.D., Ph.D.1
7
8
Affiliations
9
1. Department of Orthopedic Surgery, National Hospital Organization Murayama Medical Center
10
2. Department of Orthopedic Surgery, Keio University School of Medicine
11
12
Name and address for correspondence:
13
Mitsuru Yagi, M.D., Ph.D.
14
2-37-1 Musahsimurayama City Gakuen, Tokyo, Japan
1
Page 1 of 37
Gait ability and pattern in ASD patients
1
Tel: +81.42.561.1221; fax: +81.42.564.2210; e-mail: [email protected].
2
This study was approved by the appropriate institutional review board.
3
ABSTRACT
4
Background Context
5
Gait patterns and their relationship to demographic and radiographic data in patients with adult spinal
6
deformity (ASD) have not been fully documented.
7
Purpose
8
To assess gait pattern in patients with ASD and the effect of corrective spinal surgery on gait.
9
Study Design/Setting
10
Prospective case series.
11
Patient Sample
12
The gait patterns of 33 consecutive female with ASD (age 67.1 years; body mass index (BMI)
13
22.5±2.5 kg/m2, Cobb angle 46.8±18.2º, CVA 1.5±3.7 cm, C7SVA 9.1±6.4 cm, PI-LL 38.2±22.1º, and
2
Page 2 of 37
Gait ability and pattern in ASD patients
1
lean volume of the lower leg, 5.5±0.6 kg) before and after corrective surgery were compared with those
2
of 33 age- and gender-matched healthy volunteers.
3
Outcome Measures
4
SRS22, ODI, and forceplate analysis
5
Methods
6
All subjects underwent gait analysis on a custom-built force plate using optical markers placed on all
7
joints and spinal processes. DXA scores were used to calculate the lean composition of the lower legs.
8
Subjects with ASD were followed for at least 2 years post-op.
9
Results
10
Pre-op mean values showed that ASD patients had a significantly worse gait velocity (54±10 m/min vs.
11
70.7±12.9 m/min, p<.01) and stride (97.8±13.4 cm vs. 115.3±15.1 cm, p<.01), but no difference was
12
observed in the stance-swing ratio. The right and left ground reaction force vectors were also discordant
13
in the ASD group (vertical direction; r=.84 vs. r=.97, p=.01). The hip ROM was also significantly
14
decreased in ASD. Correlation coefficient showed moderate correlations between the preoperative gait
15
velocity and the gravity line, PI, ROM of the lower-extremity joints, and lean volume, and between the
16
stride and the lean volume, GL, and PI−LL. Gait pattern, stride, and velocity all improved significantly 3
Page 3 of 37
Gait ability and pattern in ASD patients
1
in the ASD patients after surgery, but were still not as good as in healthy volunteers. The SRS22
2
satisfaction domain correlated moderately with postoperative gait velocity (r=.34).
3
Conclusions
4
The ASD patients had an asymmetric gait pattern and impaired gait ability compared to healthy
5
volunteers. Gait ability correlated significantly with the GL, spinopelvic alignment, lower-extremity
6
joint ROM, and lean volume. The surgical correction of spinopelvic alignment and exercises to build
7
muscle strength may improve the gait pattern and ability in patients with ASD.
8
Keywords: adult spinal deformity;
9
gait analysis;
10
sagittal alignment;
11
spinopelvic alignment;
12
4
Page 4 of 37
Gait ability and pattern in ASD patients
1
INTRODUCTION
2
Although gait disturbance is a characteristic difficulty for patients with adult spinal deformity (ASD),
3
there is little information about the subjective assessment of gait ability in these patients [1-4].
4
Relationships between gait pattern or ability and demographic and radiographic data in patients with
5
ASD are not well documented. A positive sagittal alignment can cause fatigue of the back muscles with
6
subsequent pain and disability [5-11]. Schwab et al. described the essential role of pelvic parameters and
7
spinopelvic alignment in maintaining a standing posture [12]. A positive sagittal malalignment due to
8
pelvic retroversion requires ASD patients to compensate by flexing the hip and knee joints while
9
standing and when the heel first contacts the floor while walking [7,8,13]. Various outcome
10
measurements show a clear gait disability in ASD patients [7,8,13]. Despite these objective outcome
11
measurements, gait ability and pattern are not usually subjectively evaluated in daily practice or in
12
clinical research. Furthermore, the effect of corrective spinal surgery on gait ability or pattern in patients
13
with ASD has not been determined. To our knowledge, only four reports have addressed gait patterns in
14
ASD patients [13-16]. After assessing 12 patients with ASD, Gottipati et al. concluded that a positive
15
sagittal alignment resulted in a crouching posture and gait that were resolved after multi-segment
16
reconstructive spinal surgery [14]. Similarly, Engsberg et al. assessed ASD patients’ gait characteristics
17
before and after reconstructive spinal surgery, and concluded that the surgery resolved difficulties in gait
18
pattern and endurance [15,16]. The present study was conducted to assess gait patterns in ASD and the
19
effect of corrective spinal surgery. 5
Page 5 of 37
Gait ability and pattern in ASD patients
1
MATERIALS AND METHODS
2
Funding
3
No external funding was used for this study. The authors report no conflict of interest.
4
Inclusion criteria
5
This prospective case series included 33 consecutive females who were treated surgically for ASD and
6
33 healthy gender- and age-matched volunteers. The inclusion criteria for ASD were as follows: an age
7
of more than 50 years; a main-curve Cobb angle greater than 20° or a C7 sagittal vertical axis (SVA)
8
greater than 5 cm, and a follow-up period of at least two years. Subjects who could not walk without
9
assistance or had a previous spinal surgery or joint replacement, inappropriate radiography, or a
10
syndromic, neuromuscular, or other pathological condition were excluded.
11
12
Methods
13
We reviewed ASD patients’ charts and radiographs and analyzed their gait before and after surgery;
14
these data were compared with those of 33 gender-, age-, and height- matched healthy volunteers. This
15
study was approved by our institution's review board.
6
Page 6 of 37
Gait ability and pattern in ASD patients
1
Demographic data included age, gender, and clinical outcomes. Radiographic data included the coronal
2
vertical axis (CVA), trunk shift, Cobb angle, gravity line (GL), C7SVA, C2-C7, T5-T12 (thoracic
3
kyphosis), T10-L2 (thoracolumbar kyphosis), T12-S (lumbar lordosis [LL]), sacral slope (SS), pelvic tilt
4
(PT), and pelvic incidence (PI). We also reviewed the spinopelvic alignment (PI minus LL [PI−LL]),
5
and calculated the lean composition of the lower legs from whole-body dual-X ray absorptiometry
6
(DXA) scores. Radiographs were obtained for all ASD patients prior to and two years after corrective
7
surgery.
8
We assessed relationships among radiographic parameters and walking pattern and ability, and
9
compared the radiographic data, gait patterns, and walking ability between ASD patients (preoperative
10
and postoperative) and healthy volunteers.
11
12
Patient outcomes
13
Patient outcomes were evaluated using the Scoliosis Research Society Patient Questionnaire (SRS22r)
14
and the Oswestry Disability Index (ODI). Completed questionnaires were available for 31 of the 33
15
ASD patients.
16
7
Page 7 of 37
Gait ability and pattern in ASD patients
1
Study population
2
The mean age of the ASD patients was 67.2 years (51–72 years) and of healthy volunteers was
3
72.2 years (63–75 years) (Table 1). There was no difference in age or height between the ASD patients
4
and healthy volunteers. The mean lean volume of the right leg in preoperative ASD patients was
5
5.5±1.1 kg. Among the preoperative ASD patients, 27 of the 33 had a severe PI−LL mismatch (PI−LL >
6
20º), and six patients had a moderate mismatch (PI−LL<20º) (Table 2). All ASD patients were treated
7
by posterior spinal fusion. The mean number of fused vertebrae was 11.2±2.2. The majority of the
8
patients (27/33) had a lower instrumented vertebra (LIV) at the pelvis. The upper instrumented vertebra
9
(UIV) was at the proximal thoracic vertebrae (T2-T5) in 5 patients and at the distal thoracic vertebrae
10
(T9-T11) in 28 patients.
11
12
Radiographic summary of the patient cohort
13
We found the following mean preoperative values for the ASD patients: Cobb angle 46.8º, CVA
14
1.5±3.7 cm, C7SVA 9.1±6.4 cm, GL 10.1±7.7 cm, thoracic kyphosis 18.2±18.9º, LL −7.4±26.0º, and
15
PI−LL 41.1±25.2º. Most of the parameters were significantly improved 2 years after surgery (Table 2).
16
8
Page 8 of 37
Gait ability and pattern in ASD patients
1
Gait analysis
2
A custom-built 10.8-meter-long force plate was placed on the floor, and the platform data were
3
processed and displayed on a computer monitor in real time. For the GL position, calibration from data
4
using a dead weight placed at several known locations on the force plate showed that the force plate was
5
accurate to within 1 mm. The GRF location information on the computer monitor was placed within the
6
camera's field of view. Optical markers were attached to the skin over the ear canal, the spinous
7
processes of C7 to S1, the anterior and posterior superior iliac spine (ASIS and PSIS), the great
8
trochanter, the femoral head, the lateral and medial malleolus, the head of the first and fifth metatarsal
9
bones, the acromion, the ulna styloid process, the ulna head, the sternum, and the calcaneus. Marker
10
locations were verified by palpation. While any error in marker placement affects the absolute value of
11
spinal balance, these errors may not have noticeably affected the repeatability, because only relative
12
distance was considered. Patients were instructed to walk naturally on the force plate three times as
13
practice, and then to walk once more for recording and analysis.
14
The concordance of the right and left GRF vectors was estimated from the difference between the GRF
15
vectors of both force plates (patients walked on two force plates, with the right foot on one force plate
16
and the left foot on the other). The center of gravity (COG) was calculated by segmental methods [17].
17
The angles of the pelvis, hip, knee, and ankle were estimated from the positions of the representative
9
Page 9 of 37
Gait ability and pattern in ASD patients
1
optic markers. Gait analysis was conducted preoperatively and 9–12 months postoperatively for all of
2
the ASD patients.
3
4
Statistical analysis
5
Continuous variables were analyzed by Mann Whitney U test and categorical valuables were analyzed
6
by chi-squared tests. Multiple regression analyses were used for ordinal and nominal data when more
7
than five observations were expected in each category. A p value less than 0.05 with a confidence
8
interval of 95% was considered statistically significant. All analyses used the Statistical Package for the
9
Social Sciences (SPSS version 21.0 IBM Corp., Armonk, NY).
10
11
RESULTS
12
Gait ability and pattern analysis
13
Compared to healthy subjects, the ASD patients had significantly worse preoperative gait velocity
14
(54±10 m/min vs 70.7±12.9 m/min, p<.001) and stride (97.8±13.4 cm vs. 115.3±15.1 cm, p<.001),
15
whereas no difference was observed in stance-swing ratio (stance 63.1±2.9% vs. swing 36.9±2.9% in the
16
preoperative ASD patients). Both velocity and stride improved significantly in the ASD group after 10
Page 10 of 37
Gait ability and pattern in ASD patients
1
corrective surgery, but were still worse than in healthy subjects. No difference was observed in the
2
preoperative and postoperative cadence in ASD patients. Based on the force-plate GRF data,
3
preoperative Pedotti diagrams in the sagittal plane showed a walking vertical GRF vector distribution
4
with abnormally verticalized vectors at the heel-contact and the toe-off phases (Figure 1).
5
In the coronal plane, differences between the right and left stride were greater in the ASD group than in
6
healthy subjects. Analyses of the preoperative force-plate data for gait motion clearly showed
7
asymmetrical right- and left-side GRF vectors in the ASD group, and correlation coefficient analyses
8
showed discordant right- and left-side GRF vectors in the mediolateral and vertical axes during walking
9
(Tables 3 and 4). Although corrective surgery for ASD significantly improved these parameters, the
10
postoperative difference between the left- and right-side GRF vectors during walking was still larger in
11
ASD patients than in healthy subjects. Postoperatively, Pedotti diagrams in the sagittal plane showed a
12
walking vertical GRF vector distribution with a normal butterfly-wing shape for all of the ASD patients
13
(Figure 2).
14
15
Comparisons of kinematic gait variables
16
The preoperative range of motion (ROM) of the hip joint was significantly less in ASD patients than in
17
healthy subjects during natural walking, whereas no differences in ROM were noted for the lumbar 11
Page 11 of 37
Gait ability and pattern in ASD patients
1
spine, knees, or ankles. On the other hand, the pelvic ROM was significantly larger in ASD patients than
2
in healthy volunteers. The minimum hip and knee angles during walking were significantly increased
3
and pelvic anteversion was significantly decreased in the ASD patients, indicating that ASD patients
4
flexed the hip and knee in the heel-contact phase to compensate for the loss of pelvic anteversion due to
5
spinopelvic malalignment and the loss of lumbar lordosis. Corrective surgery significantly improved the
6
ROM of all the lower-extremity joints in the ASD group, but the postoperative hip ROM was still worse
7
in ASD patients than in healthy volunteers (Table 5).
8
9
Correlations between gait kinematics and the ROM of the spine and lower-extremity joints
10
Correlation coefficient analyses of gait kinematics and the ROM of the spine and the lower-extremity
11
joints showed a moderate correlation in ASD patients between the preoperative gait velocity and the hip,
12
knee, and ankle ROM, and between the preoperative stride and the hip and ankle ROM (Table 6). No
13
significant correlation was observed between the cadence and the ROM of the spine or lower-extremity
14
joints.
15
Correlations between gait kinematics and demographic and radiographic variables
16
Correlation coefficient analyses of the preoperative values in the ASD group identified significant
17
correlations between the gait velocity and the Cobb angle, GL, SS, PT, PI−LL, and lean volume of the 12
Page 12 of 37
Gait ability and pattern in ASD patients
1
lower extremity; between stride and the lean volume of the lower extremity and thoracic kyphosis; and
2
between cadence and the GL and SS (Table 7). Age and BMI did not correlate with any gait kinematics
3
in the ASD group. A moderate correlation was observed between the preoperative right and left stride
4
difference and the trunk shift (r=.44). These results indicated that both coronal and sagittal spinal
5
alignment, as well as leg-muscle strength, have a significant effect on gait kinematics.
6
7
Correlations between the preoperative ROM of lower-extremity joints and demographic and
8
radiographic variables
9
Correlation coefficient analyses showed significant correlations between the hip ROM and stride and the
10
lean volume of the lower extremity, the Cobb angle, the trunk shift, and the PI−LL. The lean volume of
11
the lower extremity correlated strongly with the hip ROM. The knee and ankle ROM correlated
12
moderately with the GL and PI−LL (Table 8). Age and BMI did not correlate with the ROM of any
13
lower-extremity joint in the ASD patients These results indicated that both coronal and sagittal spinal
14
alignment and the strength of the leg muscles significantly affect the ROM of the lower-extremity joints.
15
16
Correlation of gait kinetics and clinical outcomes
13
Page 13 of 37
Gait ability and pattern in ASD patients
1
The preoperative SRS22r scores for the ASD group were as follows: total 3.4±1.0, pain 3.4±0.8,
2
function 2.6±0.8, self-image 3.5±0.5, mental health 3.6±0.4, satisfaction 3.1±0.9; the ODI score was
3
64±13%. All of the outcome scores were improved 2 years after surgery (total 4.1±1.1, pain 4.1±0.6,
4
function 3.9±0.6, self-image 4.2±0.7, mental health 4.1±0.9, satisfaction 4.5±0.8, and ODI 28±10%,
5
p<.05 in the all comparisons).
6
Preoperatively, the SRS22 function domain score correlated weakly with gait velocity in ASD patients
7
(r=.23). Postoperatively, the SRS22 satisfaction domain score correlated moderately with gait velocity
8
after surgery (r=.34); no correlation was found between postoperative gait ability and any other outcome
9
measures.
10
11
DISCUSSION
12
Although the importance of the standing sagittal balance in clinical ASD outcomes is widely recognized,
13
there is little information about how gait ability and patterns in ASD affect clinical outcomes [1-16].
14
Four studies have addressed relationships between spinal alignment and gait pattern in ASD patients.
15
Gottipati et al. concluded that a positive sagittal alignment resulted in a crouching posture and gait that
16
were resolved by multi-segment reconstructive spinal surgery that improved sagittal spinal alignment,
17
and that surgical correction also improved step and stride length [14]. Similarly, Engsberg et al. assessed 14
Page 14 of 37
Gait ability and pattern in ASD patients
1
the gait ability of 20 primary and revision ASD subjects and concluded that gait patterns and poor
2
endurance were resolved after reconstructive spinal surgery that improved sagittal spinal alignment;
3
however, the ASD postoperative gait velocity was still worse than in healthy volunteers [15,16]. These
4
studies had major limitations in the small sample size, the sample distribution (both primary and revision
5
surgery were included), and the lack of force-plate analysis. Some subjects had fused lumbar vertebrae
6
from a prior spine fusion, which could have significantly affected preoperative gait analysis.
7
The present study compared the preoperative and postoperative gait patterns of ASD patients with those
8
of gender-, age, and height-matched healthy volunteers. We recorded a variety of gait variables,
9
including gait velocity, stride, cadence, spinal alignment, spinopelvic alignment, and GRF, as well as
10
trunk and lower extremity kinematics, to obtain a comprehensive overview of the gait patterns and
11
abilities of ASD patients. To determine these characteristics more precisely, we included only primary
12
ASD patients. We assessed gait patterns and abilities on the force plate, and also evaluated the lean
13
volume of the lower leg. To address the role of gait ability in patient outcomes, we also analyzed
14
correlations between preoperative and postoperative gait abilities and clinical patient outcomes.
15
Gait ability and pattern analysis
16
Our results were consistent with our previous findings. The preoperative gait velocity and stride in ASD
17
patients were significantly worse than in healthy volunteers; both parameters improved after corrective
18
surgery, but were still worse than in healthy subjects. The factors that correlated with gait velocity and 15
Page 15 of 37
Gait ability and pattern in ASD patients
1
stride were the hip, knee, and ankle ROM, the GL, the spinopelvic alignment, the Cobb angle, the trunk
2
shift, and the lean volume of the lower leg. Postoperatively, radiographic spinal alignment and the ROM
3
of the ankle and knee were improved. On the other hand, hip ROM improved but was still impaired
4
compared to that of healthy volunteers. The limited hip ROM and the low lean volume of the lower leg
5
might affect both gait velocity and stride.
6
One possible reason for the limited postoperative ROM of the hip joint is the effect of lumbosacral and
7
pelvic fusion. Preoperative ASD gait analysis showed that the pelvic ROM increased to compensate for
8
a decrease in hip ROM. Most of the ASD patients were treated by lumbosacral fusion to restore
9
spinopelvic alignment [4,18], and lumbosacral fusion reduces the spinal and pelvic ROM to almost zero.
10
The spinal and pelvic ROM in healthy subjects shows the importance of the motion of the lumbar spine
11
and pelvis for a natural gait. Lumbosacral fusion might also affect the hip ROM. We previously reported
12
gait changes after pedicle subtraction osteotomy (PSO) for severe fixed sagittal imbalance, and found
13
that hip ROM was improved but was still limited compared to that in healthy subjects [19]; a similar
14
trend was observed in the current study, even though the study population was different.
15
Another possible reason for the limited hip ROM is weak muscle strength in ASD patients. Elderly ASD
16
patients are often inactive for a lengthy period prior to corrective surgery because of pain and disability,
17
and this inactivity might reduce muscle volume and strength. Although we did not evaluate the
18
lower-leg muscle strength in ASD patients, and did not have these data for the healthy subjects, studies 16
Page 16 of 37
Gait ability and pattern in ASD patients
1
have shown a moderate correlation between muscle volume and strength in the lower extremity. Our
2
analysis clearly identified a moderate correlation between the lean volume of the lower leg and the gait
3
velocity and stride [20-24]. These findings indicate that preoperative and postoperative exercise can
4
improve the gait in patients who are surgically treated for ASD.
5
Abnormal GRF vectors and gait pattern
6
Force-plate analysis enables us to assess the GRF vectors during gait motion. Our force-plate gait
7
analysis showed that the GRF vector was abnormally vertical at the heel-contact and toe-off phases in
8
ASD patients prior to corrective spinal surgery. The ASD patients compensated for pelvic retroversion
9
by flexing the hip and knee joint when standing and when the heel first contacts the floor while walking
10
[25-31]. The importance of this compensatory mechanism in standing upright or walking long distances
11
is clear from the significant disparity between ASD and healthy subjects in the preoperative minimum
12
hip flexion angle during the heel-contact phase. The GRF vector was verticalized by the increase in the
13
minimum flexion angles of the knee joint during the heel-contact phase and the hip during the toe-off
14
phase, resulting in a decreased stride length.
15
Asymmetric stride and GRF vectors
16
Correlation coefficient analysis of the preoperative ASD stride showed discordant right and left
17
medial/lateral and vertical directions of the GRF vectors, and differences in right and left stride length. 17
Page 17 of 37
Gait ability and pattern in ASD patients
1
We found that hip ROM correlated with the Cobb angle of the major curve and with trunk shift. The
2
trunk shift and coronal spinal curvature might affect the stability of the contact leg during the swing
3
phase and might reduce the stride of the contralateral side. Jackson et al. reported that coronal spinal
4
malalignment due to fractional lumbosacral curves affects both pain and activity in ASD patients [29].
5
Our findings clearly demonstrate the importance of restoring both coronal balance and sagittal balance
6
when performing corrective spinal surgery.
7
Correlation of gait kinetics and clinical outcomes
8
We also analyzed the impact of gait kinetics on clinical outcomes for ASD, and found a weak
9
correlation between the preoperative SRS22r function score and gait velocity. We found a moderate
10
correlation between the postoperative SRS22r satisfaction domain scores and gait velocity, but no other
11
correlation between postoperative gait and outcome scores. The SRS22r does not directly address gait
12
ability, but questions 5, 9, and 18 are related to it. The ODI questionnaire addresses gait endurance
13
directly in Section 4, and Section 10 asks about daily activity. The preoperative scores for ODI Section 4
14
were widely distributed in the ASD group, from 1 (pain prevents me from walking more than 2
15
kilometers) to 4 (I can only walk with a stick or crutch), and the mean score was 3.4±1.1. Scores after
16
surgery improved to 1.7±0.9, with no patients scoring more than 4. Correlation coefficient analyses
17
showed no correlation between the preoperative or postoperative Section 4 scores and gait
18
Page 18 of 37
Gait ability and pattern in ASD patients
1
characteristics such as gait velocity, cadence, or stride, indicating that these parameters are not directly
2
correlated with walking endurance.
3
On the other hand, a moderate correlation seen between the postoperative gait velocity and SRS22r
4
satisfaction domain scores indicated that improving gait velocity is important for patient satisfaction.
5
This may be due to the effect of gait velocity on daily activity, since a normal gait velocity is important
6
for walking with family or friends; this idea is supported by the weak correlation seen between the
7
SRS22r function domain score and gait velocity. Our study is the first to demonstrate correlations
8
between gait ability and ASD clinical outcomes, and these correlations will help both surgeons and
9
patients to understand what can be expected from surgical treatment for ASD.
10
The present study has a potential weakness in its relatively small sample size; however, our results
11
clearly documented gait patterns and abilities in ASD patients, including compensatory flexion of the
12
lower-extremity joints and a pelvic posterior shift. Moreover, the present study has the largest sample
13
series to date for gait analysis in ASD. The population of patients with ASD is quite heterogeneous,
14
depending on age and diagnosis, and these differences in patient characteristics must be taken into
15
consideration when treating patients and when analyzing the results of treatment. Further study of the
16
relationships among muscle strength, lumbosacral fusion, and gait ability will improve our
17
understanding of the pathophysiology of ASD.
18 19
Page 19 of 37
Gait ability and pattern in ASD patients
1
CONCLUSION
2
Patients with ASD have an asymmetric gait pattern and more difficulty walking compared to healthy
3
subjects. We found significant correlations between gait ability and the GL, spinopelvic alignment,
4
ROM in lower-extremity joints, and lower-extremity muscle volume. The surgical correction of
5
spinopelvic alignment and exercises to improve muscle strength may improve the gait pattern and
6
walking ability of patients with ASD. The moderate correlation seen between gait velocity and patient
7
satisfaction indicates the importance of gait analysis when evaluating and treating patients with ASD.
8
20
Page 20 of 37
Gait ability and pattern in ASD patients
1
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gravity line: the basics. Eur Spine J. 2011; 5:558-63.
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parameter for three-dimensional regulation of spinal sagittal curves. Eur Spine J. 1998; 7(2):99-103.
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standing volunteers and patients with low back pain matched for age, sex, and size. A prospective
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Mac-Thiong JM, Roussouly P, Berthonnaud E, Guigui P. Age- and sex-related variations in
Legaye J, Duval-Beaupère G, Hecquet J, Marty C. Pelvic incidence: a fundamental pelvic
Jackson RP, McManus AC. Radiographic analysis of sagittal plane alignment and balance in
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Kuntz C 4th, Shaffrey CI, Ondra SL, Durrani AA, Mummaneni PV, Levin LS, Pettigrew DB.
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Spinal deformity: a new classification derived from neutral upright
12
asymptomatic juvenile, adolescent, adult, and geriatric individuals. Neurosurgery. 2008; 63:25-39.
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alignment from the occiput to the pelvis in asymptomatic adults: a review and resynthesis of the
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spinal alignment measurements in
Kuntz C 4th, Levin LS, Ondra SL, Shaffrey CI, Morgan CJ. Neutral upright sagittal spinal
16 25
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Gait ability and pattern in ASD patients
1
FIGURE LEGENDS
2
Figure 1
3
Case example of gait analysis of ASD patient and healthy volunteer.
4
A; 67 years ASD patient. Pre-operative round reaction vector in vertical direction during natural walking
5
on the force platform. B; 67 years ASD patient. Post-operative round reaction vector in vertical direction
6
during natural walking on the force platform. C; 63 years healthy volunteer. Ground reaction vector in
7
vertical direction during natural walking on the force platform.
8
Figure 2
9
Ground reaction force vector comparisons between ASD and healthy volunteer during walking on the
10
force platform. Gray line indicates the ground reaction vector of the right foot. Black line indicates the
11
ground reaction vector of the left foot
12
Figure 3
13
Pre- and post-operative gait kinematic change in patient with ASD.
14
A; 67 years ASD patient. Pre-operative gait kinematics during natural walking on the force platform. B;
15
67 years ASD patient. Post-operative gait kinematics during natural walking on the force platform. 26
Page 26 of 37
Gait ability and pattern in ASD patients
1
Table 1. Patient cohort demographics
ASD
HV
P value
No. of patients
33
33
Age (years)
67.2 ± 8.7
72.2 ± 3.8
0.09
Height (cm)
150.9 ± 7.9
148.9 ± 4.7
0.22
Weight (kg)
51.7 ± 5.7
53.3 ± 7.3
0.25
BMI (kg/m2)
22.8 ± 2.5
23.9 ± 2.5
0.46
Lean volume (kg)
5.5 ± 1.1
N/A
2
Means and standard deviations. Patients with adult spinal deformity (ASD) were compared to healthy
3
volunteers (HVs). BMI: body mass index.
4
27
Page 27 of 37
Gait ability and pattern in ASD patients
1
Table 2. Radiographic summary of the ASD patient cohort
Pre-op
Post-op
P value
Cobb angle (deg.)
46.8 ± 18.2
14.4 ± 8.8
.00 *
Trunk shift (cm)
2.4 ± 4.2
1.2 ± 1.2
.19
CVA (C7PL;cm)
1.5 ± 3.7
1.0 ± 3.3
.23
GL (cm)
10.1 ± 7.7
4.1 ± 3.6
.00 *
C7SVA (cm)
9.1 ± 6.4
4.7 ± 4.4
.00 *
C2C7 (deg.)
-15.7 ± 17.9
-17.6 ± 11.2
.08
T5-T12 (deg.)
17.1 ± 15.9
28.5 ± 11.9
.00 *
T10-L2 (deg.)
23.8 ± 17.8
9.7 ± 6.3
.00 *
LL (deg.)
-7.3 ± 21.5
-44.4 ± 11.5
.00 *
SS (deg.)
15.1 ± 12.5
31.1 ± 7.4
.00 *
PI (deg.)
45.5 ± 6.2
45.4 ± 5.3
.91
PT (deg.)
30.5 ± 11.3
13.9 ± 9.2
.00 *
PI-LL (deg.)
38.2 ± 22.0
3.4 ± 4.7
.00 *
Coronal plane
Sagittal plane
2
Means and standard deviations. Pre-op and post-op values were compared in patients with adult spinal
3
deformity (ASD). CVA: coronal vertical axis; GL: gravity line; C7PL: C7 plumb line; LL: lumbar
4
lordosis; SS sacral slope; PI: pelvic incidence; PT: pelvic tilt; PI−LL; PI minus LL. 28
Page 28 of 37
Gait ability and pattern in ASD patients
1
*Statistically significant.
2
29
Page 29 of 37
Gait ability and pattern in ASD patients
1
Table 3. Comparisons of gait patterns in healthy and ASD subjects
ASD
HV
Pre-op
Post-op
54.0 ± 10.4
59.2 ± 8.9
RT
97.8 ± 13.4
LT
P value
P1
P2
70.7 ± 12.9
.00 *
.05*
107.6 ± 11.1
114.3 ± 15.0
.00 *
.06
96.4 ± 14.8
106.4 ± 12.8
114.5 ± 15.1
.00 *
.09
Cadence (steps/min)
113.1 ± 10.7
110.1 ± 9.9
123.1 ± 8.1
.01 *
.01*
Stance phase (%)
63.1 ± 2.9
63.0 ± 2.7
62.3 ± 1.8
.22
.23
Swing phase (%)
36.9 ± 2.9
36.8 ± 2.7
37.8 ± 1.8
.22
.23
Double stance phase (%)
26.7 ± 4.5
25.9 ± 4.3
24.5 ± 2.6
.08
.14
Stride RT-LT diff. (cm)
3.1 ± 2.5
1.2 ± 1.1
0.9 ± 0.9
.01 *
.78
Velocity (m/min) Stride (cm)
2
Means and standard deviations. Values from healthy volunteers (HVs) were compared with pre-op (P1)
3
and post-op (P2) patients with adult spinal deformity (ASD). *Statistically significant.
4
5
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Table 4. Correlation coefficients for GRF vectors in healthy and ASD subjects
ASD
HV
Pre-op
Post-op
Medial/lateral
0.79 ± 0.09
0.88 ± 0.08
Anterior/posterior
0.97 ± 0.06
Vertical
0.82 ± 0.10
P value P1
P2
0.93 ± 0.02
.01*
.02*.
0.97 ± 0.06
0.99 ± 0.02
n.s.
n.s.
0.91 ± 0.11
0.97 ± 0.04
.01*
.01*
2
Means and standard deviations. Values from healthy volunteers (HVs) were compared with
3
pre-op (P1) and post-op (P2) patients with adult spinal deformity (ASD). *Statistically significant;
4
n.s.: not significant.
5
6
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Table 5. Comparisons of kinematic gait variables in healthy and ASD subjects
ASD
HV
Pre-op
Post-op
P value
P1
P2
TL
Max
22.2 ± 6.1
11.1 ± 4.8
16.5 ± 6.3
.01*
.14
kyphosis
Min
19.1 ± 7.4
6.3 ± 4.9
13.1 ± 6.9
.02*
.07
(deg.)
range
3.6 ± 1.9
4.8 ± 1.7
3.4 ± 1.7
.44
.11
Pelvis
Max
6.7 ± 9.5
18.4 ± 6.7
13.5 ± 7.3
.02*
.22
(deg.)
Min
0.9 ± 10.2
15.3 ± 7.1
9.4 ± 6.7
.01*
.20
range
5.8 ± 2.9
3.1 ± 2.2
4.0 ± 0.9
.04*
.34
Max
27.9 ± 8.3
27.9 ± 5.8
29.2 ± 7.2
.33
.39
Min
-2.9 ± 11.3
-11.5 ± 8.2
-10.6 ± 8.2
.03*
.19
range
29.1 ± 9.5
35.8 ± 6.1
39.7 ± 5.3
.00*
.00*
Max
65.4 ± 5.2
63.0 ± 8.5
63.6 ± 7.3
.71
.62
Min
9.2 ± 6.4
5.5 ± 3.7
6.7 ± 9.7
.05*
.00*
range
56.2 ± 6.2
55.1 ± 7.2
56.9 ± 5.9
.37
.34
Ankle
Max
5.5 ± 5.2
6.0 ± 3.7
6.4 ± 4.6
.33
.46
(deg.)
Min
-28.1 ± 8.3
-28.2 ± 9.8
-28.0 ± 6.9
.49
.41
range
33.6 ± 5.9
34.2 ± 8.0
34.4 ± 5.6
.37
.40
Hip
(deg.) Knee (deg.)
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Means and standard deviations. Values from healthy volunteers (HVs) were compared with pre-op (P1)
2
and post-op (P2) patients with adult spinal deformity (ASD). TL: thoracolumbar. *Statistically
3
significant.
4
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2
Table 6. Correlation coefficients for ASD pre-op gait kinematics and spine and leg ROM
Variables
Velocity
Stride
Cadence
Spine ROM
n.s.
n.s.
n.s.
Pelvis ROM
n.s.
n.s.
n.s.
Hip ROM
0.22
0.44
n.s.
Knee ROM
0.44
n.s.
n.s.
Ankle ROM
0.44
0.53
n.s.
ROM: range of motion; n.s.: not significant.
3
4
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Table 7. Correlation coefficients for ASD pre-op gait kinematics and demographic and radiographic
2
variables
Variables
Velocity
Stride
Cadence
Age
n.s.
n.s.
n.s.
BMI
n.s.
n.s.
n.s.
Lean volume/BW
0.34.
0.31
n.s.
Cobb angle
0.46
n.s.
n.s.
Trunk shift
n.s.
n.s.
n.s.
CVA
n.s.
n.s.
n.s.
GL
-0.72
-0.61
-0.50
T5-T12
n.s.
n.s.
n.s.
T10-L2
n.s.
0.46
n.s.
SS
0.61
n.s.
0.59
PT
-0.53
n.s.
n.s.
PI−LL
-0.46
n.s.
n.s.
3
BMI: body mass index; BW: body weight; CVA: coronal vertical axis; GL: gravity line; SS sacral slope;
4
PT: pelvic tilt; PI−LL: pelvic incidence (PI) minus lumbar lordosis (LL); n.s.: not significant.
5 35
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Table 8. Correlation coefficients for the ROMs of the lower extremity joints and demographic and
2
radiographic valuables in pre-op ASD patients
Variables
Hip ROM
Knee ROM
Ankle ROM
Age
n.s.
n.s.
n.s.
BMI
n.s.
n.s.
n.s.
Lean volume/BW
0.78
n.s.
n.s.
Cobb angle
0.33
n.s.
n.s.
Trunk shift
0.46
n.s.
n.s.
CVA
n.s.
n.s.
n.s.
GL
n.s.
0.36
0.35
T5T12
n.s.
n.s.
n.s.
T10L2
n.s.
n.s.
n.s.
SS
n.s.
n.s.
n.s.
PT
n.s.
n.s.
n.s.
PI−LL
0.39
0.36
0.31
3
BMI: body mass index; BW: body weight; CVA: coronal vertical axis; GL: gravity line; SS sacral slope;
4
PT: pelvic tilt; PI−LL: pelvic incidence (PI) minus lumbar lordosis (LL); n.s.: not significant.
5
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2
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