Session 1: Spine

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.

Andreas Kiilerich Andresen^1,2, Leah Carreon^1,2, Mikkel Andersen^1,2
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.

Peter Muhareb Udby^{1, 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.

Marianne Lorenzen^1,2, Casper Pedersen^1,2, Leah Carreon^1,2, Jane Clemensen^3,4,5,6, Mikkel Andersen^1,2
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.

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.

Line Adsbøll Wickstrøm^1,2, Mikkel Østerheden Andersen^1,2, Leah Carreon^1,2
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.

Lærke Ragborg^1,2, 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.

Andreas Kiilerich Andresen^1,2, Leah Y. Carreon^1,2, Carsten Bjarkam³, Rune Bech⁴, Simon Skov⁵, Louise Møller Jørgensen⁶, Rikke Rousing⁷, Michael Nielsen⁸, Mikkel Andersen^1,2
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.

Martin Heegaard¹, Lærke Ragborg^1,2, 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.

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.