Session 1: Spine
13. November
09:00 - 10:30
Lokale: Sal B
Chair: Casper Dragsted & Haisheng Li
1. Instrumented fusion in one level spondylolisthesis causes hypolordosis at two-year follow-up - a secondary analysis of a randomized control trial
Andreas Duch Kiilerich Andersem1, Niklas Tøndevold2, Benny Dahl2, Martin Gehrchen2
1. Rygkirurgsik afsnit, Rygcenter Syddanmark, Middelfart sygehus
2. Orthopeadic department U, Copenhagen University hospital, Rigshospitalet
Background: Degenerative spondylolisthesis (DS) is one of
the most commonly treated spinal pathologies. In
recent years there has been an increased focus
on the sagittal balance of the spine; especially in
adult spinal deformity. However, as most
deformities in the elderly are iatrogenic, special
attention should be addressed to first spinal
procedure. While instrumentation creates a
stable fixation, it may also alter the sagittal profile
of the lumbar spine, especially if lordosis is not
addressed and further activation of the
compensatory mechanisms at the fused levels
are compromised.
Aim: Examine the difference in the lordosis at the fused
level regardless of fusion method
Materials and Methods: Patients scheduled for one-level fusion due to
DS were randomized to either instrumented or
un-instrumented in-situ fusion. Patients
underwent 36” lateral X-rays before surgery and
at one- and two-year follow up. Patient reported
outcomes (PROs) were ODI, SF-36, EQ-5D VAS
leg and -back.
Radiological parameters measured were local
lordosis at the spondylolisthesis (LS), Pelvic
Incidence (PI), Pelvic Tilt (PT), Sacral Slope (SS)
Sagittal Vertical Axis (SVA), Global Lordosis
(GL), Segmental Lordosis (SL), lordosis at L4-
S1(L4-S1) and Thoracic Kyphosis (TK).
Results: A total of 98 patients were eligible for inclusion, with
51 in the instrumented group. The mean age at
surgery was 72 years, there we no preoperative
differences in demographics, PROs and radiological
parameters. The instrumented group had longer
duration of surgery (124 vs 87 min; P <0.001) and
increased blood loss (384 mL vs. 238 mL;
P<0.0001). Mean LS was 16.8°, with no difference
between groups (p=0.978). At two-year follow up,
the instrumented group had significantly reduced
lordosis at the fused level (LS) -2.6±4.2° vs.
1.3±5.0°, p=0.004. The difference in lordosis did not
translate into a difference in PROs at two-year
follow up.
Interpretation / Conclusion: We found that one-level instrumented fusion in
degenerative spondylolisthesis resulted in
hypolordosis at the instrumented level compared to
un-instrumented fusion. Long-term studies will show
if this increases the risk of developing ASD.
2. ABM/P-15 versus Allograft in Non-Instrumented Lumbar Fusion - 10 Year Follow Up on a Double Blind Randomized Controlled Trial
Andreas Kiilerich Andresen1,2, Leah Carreon1,2, Mikkel Andersen1,2
1. Center for Spine Surgery and Research, Lillebaelt Hospital, Middelfart, Denmark
2. Institute of Regional Health Research, University of Southern Denmark, Odense C,
Denmark
Background: Lumbar spinal stenosis with degenerative
spondylolisthesis is a common cause of disability
and decreased function in the elderly. In some
patients, fusion in combination with decompression
is preferred to maintain segmental stability at the
decompressed level. Few studies have investigated
the long-term clinical and patient reported outcomes
to guide surgeons and patients in shared decision
making before surgery.
Aim: The purpose of the current study was to long-term
patient reported outcomes (PROs), clinical status
and reoperation rates in patients who underwent
decompression and non-instrumented fusion.
Materials and Methods: Patients with degenerative spondylolisthesis
scheduled for decompression and fusion on one- to
two-levels were enrolled in a Randomized Controlled
Trial and randomized 1:1 to either ABM/P-15 or
allograft bone. Patient reported outcome
measures(PROMs) and reoperation rates were
collected at 1-, 2-, 5- and 10-year follow-up visits.
PROMs included Oswestry Disability Index (ODI),
Visual analogue scale (VAS) for back- and leg pain,
EuroQol-5D(EQ-5D).
Results: Of 101 subjects enrolled, 78 patients were alive at
10-year follow-up and complete follow-up was
available in 57 (73%) patients, 30 in the ABM/P-15
group and 27 in the Allograft. There were no
differences in our primary outcome measure ODI
(22.8±20.7 vs 28.5±23.3, p=0.337) between the
ABM/P-15 group and Allograft at 10 year follow-up
We found significant improvements in PROs in both
groups, which were still significantly improved from
baseline at ten-year follow up. A total of 31
reoperations were performed, 10 in the ABM/P-15-
versus 21 in the Allograft-group (p=0.0495),
interestingly re-operated patients showed similar
improvements at 10-year follow up as non-re-
operated.
Interpretation / Conclusion: Although no difference in PROs between the
AMB/P-15 vs Allograft group at 10-year follow up
were seen, there were significantly more
reoperations in the Allograft- compared to the
AMB/P-15 group, which may be associated with
cost-savings. Our study suggest that patients can
expect long-term relief of pain and improvement of
function regardless of the need for an additional
surgery over a 10-year period.
3. Predicting Two –Year Outcomes of Lumbar Spinal Stenosis Surgery: Utility of the Modic Change Grading Score
Peter Muhareb Udby1, 2, Søren Ohrt-Nissen2, Dino Samartzis3, Leah Carreon 4
1. Spine Unit, Zealand University Hospital
2. Spine Unit, Rigshospitalet
3. Department of Orthopedic Surgery, Rush University, Chicago, USA
4. Middelfart Spine center - part of sygehus Lillebaelt, Denmark
Background: Modic changes (MC) are a common phenotypic
finding on MRI in patients with low back pain (LBP).
In patients with LBP and degenerative spine
conditions undergoing surgery, MC have been
associated with worse patient-reported outcomes
(PROs). A clinically relevant MC grading type have
been suggested by Udby and Modic et al. No
previous studies have evaluated the association
between MC grading and PROs following LSS
surgery.
Aim: To evaluate the utility of the MC grading score in
lumbar spinal stenosis patients
Materials and Methods: Patients from the Danish national spine registry,
DaneSpine, scheduled for LSS surgery were
identified. MC was defined and graded according to
the Udby and Modic et al. classification. In addition,
preoperative and two-year postoperative data were
collected including demographics (age, BMI,
smoking etc.) and PROs consisting of pain scores -
Visual Analogue Scale for back pain (VAS-BP) and
leg pain (VAS-LP); and physical disability score -
Oswestry Disability Index (ODI).
Results: In total, n=208 patients were included, 15% (31 pts)
with MC grade A and 85% (177 pts) with MC grade
=B. There was no significant difference in
preoperative age,BMI or smoking between the two
groups - 68 vs. 67 years (p=0.746); 27 vs. 28 kg/m2
(p=0.370); 19% vs 18% smokers (p=0.546). There
was no significant difference in preoperative pain or
disability scores, VAS-back (VAS-BP) or leg pain
(VAS-LP) and Oswestry Disability Index (ODI),
p>0.1. At two-year follow-up after LSS surgery,
patients with MC grade =B had significantly worse
pain scores, VAS-BP - 32 vs. 44 (p=0.045) and VAS-
LP - 27 vs. 45 (p=0.003). Physical disability was
significantly worse at two-year follow-up in the MC
grade =B group, ODI score - 22 vs. 30 (p=0.036).
Interpretation / Conclusion: This is the first study to evaluate the association
between the MC grading score and PROs in patients
undergoing LSS surgery. MC grade =B was
associated with significantly worse pain scores and
increased disability at two-year follow-up.
We suggest, that future studies include the MC
grading score in order to investigate the possible
impact of MC phenotypes on PROs.
4. Measuring quality of recovery (QoR-15) after degenerative spinal surgery: A prospective observational study
Marianne Lorenzen1,2, Casper Pedersen1,2, Leah Carreon1,2, Jane Clemensen3,4,5,6, Mikkel Andersen1,2
1. Spine Surgery & Research, Spine Center of Southern Denmark, Lillebaelt Hospital,
– University Hospital of Southern Denmark, Middelfart, Denmark
2. Institute of Regional Health Research, University of Southern Denmark, Odense,
Denmark
3 Hans Christian Andersen Children’s Hospital, Odense University Hospital, Odense,
Denmark
4 Center for Innovative Medical Technology, Odense University Hospital, Odense,
Denmark
5 Centre for Compassion in Healthcare, Clinical Institute/Institute for Regional Health
Research, SDU, Denmark
6 Department of Clinical Research, University of Southern Denmark, Odense,
Denmark
Background: The Quality of Recovery (QoR-15) score evaluates
patient’s recovery after surgery and anesthesia.
There is a lack of studies focusing on the patients’
quality of recovery in the early post-discharge phase
after elective lumbar spine surgery.
Aim: We aimed to identify the QoR-15 score in patients
who underwent surgery for degenerative low back
conditions. Furthermore, we aimed to identify the
individual items of the QoR-15 that are crucial for
the patients’ quality of recovery.
Materials and Methods: The study was conducted at a spine center in
Denmark from December 2021 to September 2022.
Data were collected, using a mobile health
application, preoperatively and at 3 time points after
hospital discharge. Descriptive analysis followed by
within-subjects longitudinal repeated measures was
conducted. The individual items of the QoR-15
score were explored using a heatmap.
Results: Data from 46 patients were analyzed. The mean
QoR-15 sum score at baseline was 105.4 ± 18.3.
The mean QoR-15 sum scores were 108.1 ± 19.2
on post-discharge day 1, 118.5 ± 17.4 on day 7, and
120.7 ± 20.9 on day 14. The mean QoR-15 score
from day 1 to day 7 improved significantly. Eight of
the 15 items influenced the overall QoR-15 score.
Interpretation / Conclusion: This study applied the QoR-15 score in lumbar
spine surgery patients. We identified specific items
from the QoR-15 scale that are crucial to improving
patients’ recovery after hospital discharge. Further
research is needed to identify specific needs in the
post-discharge period in this group of patients.
5. Effect of early surgical intervention in traumatic spine fractures: A Retrospective Study
Charlotte Mosbak Festersen1, Josefine Lysen1, Peter Muhareb Udby1, Søren Ohrt-Nissen 1, Line Parst Sørensen1, Martin Heegaard1, Martin Gehrchen1, Benny Dahl1
1. Spine Unit, Department of Orthopedic Surgery, Rigshospitalet, Copenhagen, Denmark
Background: Surgical management of spinal fractures is
considered if stability, alignment and/or neurological
function is compromised. Preoperatively, patients
are often immobilized, while full mobilization is
permitted after surgical stabilization. In other types
of skeletal trauma there is a strong association
between surgical delay and postoperative
complications, but whether this association exists for
spinal trauma is unknown.
Aim: The purpose of this study was to determine if the
prognosis and mortality after spinal fractures were
related to the timing of surgery, and to investigate
factors associated with hospital readmission.
Materials and Methods: This was a single-center retrospective cohort study
on patients with traumatic spine fractures
undergoing surgical stabilization from October 2016
to April 2022. Patients were identified from the
hospital's database. Individual clinical information
was collected from journal records including age,
gender, time of radiographic diagnosis, time of
primary spine surgery, 30-day hospital readmission
and two-year survival status.
Results: We included 565 patients (69% males). In the
cervical region there was 22% (n=126) of the
fractures, 41% (n=231) in the thoracic region,
33% (n=185) in the lumbar region and 4% (n=23)
in multiple regions. Of the traumas, 62% (n=352)
were low-energy and 38% (n=213) high-energy.
Within 30 days, 15% (n=82) of the patients were
readmitted. Mean time from trauma to surgery
was 9.1 days vs. 13.8 days in the non-
readmission and readmission groups,
respectively (p=0.117). In the non-readmission
group, 19% underwent surgery within 48 hours
compared to 17% in the readmission group
(p=0.704). In the non-readmission group, two-
year mortality was 9% vs. 28% in the
readmission group (p<0,001). Mean age was
55.8y vs. 63.1y (p=0.002). There was no
significant difference in the distribution of low- vs.
high-energy trauma or fracture levels between
groups.
Interpretation / Conclusion: This study suggests that late surgery (>48h) in
patients with traumatic spine injury is not associated
with a significantly higher risk of hospital
readmission, however increased age is. The two-
year mortality was significantly higher in patients
who were readmitted compared to those who were
not.
6. Does patients with multiple myeloma and vertebral compression fracture have slower recovery of pain than patients with osteoporosis and vertebral compression fracture?
Line Adsbøll Wickstrøm1,2, Mikkel Østerheden Andersen1,2, Leah Carreon1,2
1. Centre for Spine Surgery and Research, Region of Southern Denmark, Østre
Hougvej 55, DK-5500, Middelfart, Denmark
2. Department of Clinical Research and Institute of Regional Health Research,
University of Southern Denmark, Winsløwparken 19, 3, DK-5000, Odense C,
Denmark
Background: Multiple myeloma (MM) is a plasma cell
cancer and is associated with osteoclastic
bone degradation and inhibited osteoblast
function, causing increased bone breakdown
and inhibited regeneration of new bone. This
leads to a high risk of vertebral compression
fracture (VCF).
Patients with osteoporosis are also in risk of
having VCF. However, as bone regeneration
is not affected in osteoporotic patients, one
might hypothesize that patients with MM
experience protracted healing due to
inhibition of new bone formation.
Aim: Our objective is to compare pain scores from
baseline to week 1 to 4 for MM patients and
osteoporosis patients with VCF.
Materials and Methods: The patients consisted of two groups
followed in an ongoing and an earlier
randomized controlled trial, investigating the
effect of vertebral augmentation in patients
with MM and patients with osteoporosis,
respectively. All patients in the current study
had non-surgical treatment, and Visual
Analogue Score (VAS) back pain were
measured at inclusion and in week 1-4 after
inclusion. The data was analyzed in
STATA/BE 17.0, using a two-sided t-test for
differences between baseline and follow-up
within each patient group. It was also used to
test for difference in difference between the
groups at each subsequent time point.
Results: 22 patients were available for analysis in the
MM group and 24 in the osteoporosis group.
In the MM group, we saw no statistical
significant improvement in VAS back pain
from inclusion to week 1 (p = 0.11), but a
significant improvement was observed in
week 2, 3 and 4 (p = 0,04, p 0 0,04, p =
0,03). In the osteoporosis group there was a
significant improvement in VAS back pain
from inclusion to all 4 time points (p <
0.0001).
When comparing the MM and osteoporosis
group we see no difference between the
groups at baseline (p = 0,30). The decrease
in VAS back pain relative to baseline was
significantly higher in the osteoporosis group
than in the MM group in week 1-4 (p =
0,0035, p = 0,0017, p < 0,0001, p < 0,0001).
Interpretation / Conclusion: Patients with MM and osteoporosis and VCF
experience pain relief in a period of 4 weeks.
However, patients with MM improve to a lower
extend within the period compared with patients
with osteoporosis.
7. Can Coronal Deformity Angular Ratio Predict Progression in Adolescent Idiopathic Scoliosis?
Lærke Ragborg1,2, David Thornberg2, Megan Johnson2, Amy McIntosh2, Daniel Sucato2, Martin Gehrchen1, Benny Dahl1, Søren Ohrt-Nissen1
1 Spine Unit, Department of Orthopedic Surgery, Rigshospitalet, Denmark
2 Texas Scottish Rite for Children, Dallas, Texas
Background: A limited number of studies have examined the
relationship between C-DAR and curve progression.
C-DAR is calculated
as the Cobb angle magnitude divided by the number
of vertebrae in the curve, yielding a larger value in
short curves.
Prior studies have shown curves involving fewer
vertebras tend to be less flexible,
Aim: The purpose of this study was to assess
whether C-DAR is a useful predictor for progression
to surgical magnitude in AIS patients treated with
TLSO.
Materials and Methods: Patients diagnosed with AIS, prescribed a full-time
TLSO, major curve Cobb between 20-40°, Risser 0-
2, who wore the
brace =12.9 hours and reached skeletal
maturity/surgery were included. The main outcome
of this study was to examine
the association between C-DAR and the risk of
progression to surgical magnitude (>45°). Logistic
regression models
included sex, curve location, BMI, in-brace
correction (IBC) and Risser.
Results: A total of 165 patients with a mean Cobb angle of
30±6° were included. Of these, 46/165 (28%)
progressed =6° and
26/165 (16%) had reached surgical magnitude at
the end of treatment. At baseline, the groups
differed significantly on CDAR, pre-treatment
Cobb angle magnitude and IBC, but not on
remaining variables (Table 1).
Multiple logistic regression found that C-DAR was a
significant predictor for risk of progression to
surgical magnitude
with an OR of 1.9 (CI 1.2-2.9) per unit increase in C-
DAR. A threshold value of 5.15 was established. C-
DAR exceeding
5.15 yielded an OR of 5.9 (CI 2.1-17.9).
Interpretation / Conclusion: C-DAR is an independent predictor for progression
to a surgical magnitude in a compliant population
even when
adjusting for in-brace correction. Patients with a
higher C-DAR should be counseled to help set
realistic expectations in
regard to likelihood of curve progression despite
compliance with brace wear.
8. Perioperative opioid consumption in patients who undergo surgery due to spine related pain. -A Danish nationwide cohort study.
Andreas Kiilerich Andresen1,2, Leah Y. Carreon1,2, Carsten Bjarkam3, Rune Bech4, Simon Skov5, Louise Møller Jørgensen6, Rikke Rousing7, Michael Nielsen8, Mikkel Andersen1,2
1. Center for Spine Surgery and Research, Lillebaelt Hospital, Middelfart, Denmark
2. Institute of Regional Health Research, University of Southern Denmark, Odense C,
Denmark.
3. Neurokirurgisk afdeling Aalborg Universitetshospital. 9000 Aalborg
4. Rygklinikken Sjællands Universitetshospital, Køge
5. Ortopædkirurgisk Rygklinik i Silkeborg, 8600 Silkeborg
6. Copenhagen Spine Research Unit at Copenhagen University Hospital – Rigshospitalet,
2600 Glostrup
7. Rygsektionen OUH Odense Universitetshospital, 5000 Odense
8. aCure Privathospital, 2800 Kgs. Lyngby
Background: During the last decade, the use of opioids in
management of non-malignant pain has been a topic
of interest to surgeons and politicians worldwide with
reference to the “opioid epidemic” in the United
States. Recent guidelines recommend limiting or
avoiding preoperative opioid use, but high
preoperative usage prevalence challenges
implementation.
Aim: The purpose of the current study is to describe long-
term opioid use following lumbar surgery to treat
degenerative spine disease, and to characterize the
risk factors associated with prolonged opioid use.
Materials and Methods: This is an observational study using the national
Danish spine registry (DaneSpine) from 2016-2022,
where all data is collected prospectively. Patients
who underwent primary lumbar surgery to treat
spinal stenosis, spondylolisthesis and disc herniation
were included. We included patients from nine public
and seven private spine facilities. Statistical analysis
included descriptive statistics and Relative Risk
analysis for factors associated with one-year
postoperative opioid use.
Results: Data on pre- and postoperative use of pain
medicine and opioids were available on 14.082
patients who underwent spine surgery due to
spinal stenosis (n=7.932), disc herniation
(n=4.573) and spondylolisthesis (n=1.577). 36%
of patients were on prescription opioids before
surgery, at one-year follow up 17.0% of patients
were persistent users. (p<0.001).
Overall, patients with preoperative opioid use
had an increased relative risk (RR) of 4.58
(p<0.001) of being prolonged opioid users in all
patient groups combined, this correlation was
strongest for patients with spinal stenosis
(RR=5.33, p<0.001). Modifiable risk factors for
prolonged postoperative opioid use included pain
duration, body mass index, smoking and
comorbidities.
Interpretation / Conclusion: While opioid use is down overall during the seven-
year study period, we found that preoperative opioid
use, duration of pain, smoking and high BMI were all
predictors for prolonged opioid use. Especially in
patients who underwent surgery due to spinal
stenosis, who were on opioids before surgery. This
questions the current guidelines of prolonged
conservative treatment and the prescription of
opioids.
9. The effect of night-time versus full-time bracing on the sagittal profile in adolescent idiopathic scoliosis: a propensity score-matched study
Martin Heegaard1, Lærke Ragborg1,2, Amy L. Mcintosh2, Megan E. Johnson2, Martin Gehrchen1, Daniel Sucato2, Benny Dahl1, Søren Ohrt-Nissen1
1. Spine Unit, Rigshospitalet, Copenhagen University Hospital, Denmark
2. Texas Scottish Rite Hospital For Children, Texas, USA
Background: Recent research indicates that brace treatment in
adolescent idiopathic scoliosis (AIS) may induce
hypokyphosis or even flat back deformity. Whether
this effect differs between night-time bracing (NTB)
and full-time bracing (FTB) is unknown.
Aim: The current study aims to investigate the impact of
NTB and FTB on the sagittal profile in AIS patients.
Materials and Methods: We retrospectively included skeletally immature AIS
patients with main curves ranging from 25-45°
treated with either NTB or FTB. The two cohorts
were propensity-score matched on Risser stage,
age, major curve size, and global kyphosis at brace
initiation. Coronal and sagittal radiographic
parameters were gathered at the initiation and
completion of brace treatment.
Results: Two-hundred seventy patients were eligible for
inclusion. The matched cohorts included 73
patients in each group. The groups were well-
matched although, in the NTB group, 85% were
females compared with 69% in the FTB group
(p=0.019). In the coronal plane, curve
progression >5° was seen in 63% in the NTB
group and 43% in FTB (p=0.012). Progression to
>50° was seen in 45% vs. 29% (p=0.040),
respectively. The global kyphosis increased
during bracing from 33±12° to 37±13° in the NTB
group compared to a decrease from 32±12° to
30±12° in the FTB group (p=0.001). Ten percent
(n=7) were hypokyphotic (global kyphosis <20°)
post bracing in the NTB group compared with
25% (n=18) in the FTB group (p=0.016). Pelvic
incidence (PI) and sacral slope (SS) were similar
post bracing between the two groups, with pelvic
tilt (PT) being slightly different (PI: NTB 46° ±10,
FTB 44° ±9, p=0.270; SS: NTB 39° ±8, FTB 40°
±9, p=0.530; PT: NTB 7° ±7, FTB 4° ±7,
p=0.022).
Interpretation / Conclusion: Patients treated with a NTB were statistically more
likely to experience frontal plane curve progression
>5° (63%) and progression to a surgical magnitude
(45%) when compared to FTB patients. Despite the
frontal plane curve progression, the NTB group had
more normal sagittal alignment, with fewer patients
exhibiting global hypokyphosis (<20°) than the FTB
at the completion of bracing.
10. Inter- and intrarater agreement using the AO spine-DGOU Osteoporotic Fracture (OF) Classification system
Shakib Ba-Ali, Rune D. Bech, Dennis W. Hallager
Rygsektionen & Center for Evidensbaseret Ortopædkirurgi
Ortopædkirurgisk Afdeling
Sjællands Universitetshospital, Køge
&
Institut for Klinisk Medicin
Københavns Universitet
Background: The increasing incidence of osteoporotic
vertebral fractures requires a reliable
classification system as an integral part of
therapeutic decision-making. The AO spine-
DGOU Osteoporotic Fracture (OF) Classification
system offers a structured approach, yet its
reproducibility using different imaging modalities
has not previously been investigated.
Aim: The purpose of this study was to assess the
inter- and intra-rater reliability of the AO spine-
DGOU osteoporotic Fracture Classification
system among spine surgeons using
radiography and computed tomography (CT).
Materials and Methods: Radiography and CT scans were retrieved from
64 consecutive patients diagnosed with an
osteoporotic vertebral fracture having the two
imaging modalities performed on the same date.
Four spine surgeons used 10 cases for training
and then independently classified the 64
fractures twice in a blinded manner.
Classifications were made on radiography and
CTs separately. After at least one week, the
classifications were repeated. Crude agreement
(%) and Fleiss’ Kappa (k) were calculated for
radiography and CT separately and for intra-
rater agreement between radiography and CT.
The difference in Interrater agreement between
radiography and CT was compared by testing
the difference in proportion of cases where all
raters agreed (concordant cases) using
McNamar’s test for paired categorical
observations.
Results: Inter-rater agreements were 56% with k 0.49
(95% CI: 0.41-0.57) using radiography
assessment, and 50% with k 0.51 (95%CI: 0.44-
0.57) using CT scans. Intra-rater agreement
ranged 75-81% with k 0.49-0.64 for the two
radiography assessments across the four raters,
and 64-77% with k 0.42-0.63 for CT scans.
Intra-rater agreements between radiography
and CT were 50-73% with k 0.2 to 0.53. The
proportions of concordant inter-rater
observations were not significantly different
between radiography (56%) and CT
assessments (50%), p=0.37.
Interpretation / Conclusion: Conclusions:
The study indicates moderate reliability of the
AO Spine-DGOU Classification system across
radiographs and CT, which corresponds to
previous study findings. Using CT scans does
not seem to increase reproducibility of the
classification.