Session 6: Spine

Torsdag den 22. oktober
09:00 – 10:30
Lokale: Helsinki/Oslo
Chairmen: Ebbe Stender Hansen / Stig Mindedahl Jespersen

61. Cobb angel measurement without X-ray, a novel method.
Ane Simony, Karen Hoejmark Hansen, Hanne Thomsen, Mikkel Meyer Andersen, Morten Vuust
Sector for Spine Surgery & Research, Middelfart Hospital; Department of radiology, Frederikshavn Sygehus; Department of Mathematics and Statistics., Aalborg University

Background: Cobb angel measurement is the most important tool, to determine curve progression and effect of treatment. The patients are children or adolescent and standard x-rays of the spine expose the breast area, the thyroid, and the gonads, with ionizing radiation. Increased incidence of cancer is observed among patients, treated for adolescent idiopathic scoliosis.
Purpose / Aim of Study: To validate the accuracy of The Manual Method, against convention radiographs.
Materials and Methods: 130 consecutive patients, referred to standing x-ray of the spine, were invited to participate. 78 patients fulfilled the inclusion criteria. Before x-ray, the Spinous processes where manually palpated from T1 to S1, and marked with a pen. The patient was placed for X-ray, and the photo was taken with the patient standing in exactly the same position, as the AP X-ray. Marking and photographs where taken by a Research nurse. X- rays were evaluated by 2 independent doctors, and the photographs were evaluated by the same 2 doctors, 2 weeks later. The measurements where evaluated by an independent statistician.
Findings / Results: For the thoracic curves, the mean difference was 6.9 (p value < 0.0001), such that on average, the angle measured with x-ray was 6.9 degrees larger than that measured with photo. The Pearson correlation between x-ray and photo angle was 0.58 (p value < 0.0001). For the thoracolumbal curves, the mean difference was 5.2 (p value < 0.0001). The Pearson correlation between x-ray and photo angle was 0.66 (p value < 0.0001). In the lumbar group, only 7 patients participated. This is not enough to evaluate the methods feasibility, and these results are not presented.
Conclusions: The method has been proven successful in thoracic and the thoraco- lumbar region. Further examination is needed, to evaluate if this method is useable in the lumbar region.

62. Incidence of cancer and infertility, in patients treated for adolescent idiopathic scoliosis 25 years prior.
Ane Simony, Leah Y Carreon, Karl Erik Jensen, Steen Bach Christensen, Mikkel Ø Andersen
Rygkirurgisk afdeling, Middelfart Sygehus; Neuroradiologisk afdeling, Rigshospitalet

Background: Adolescent females with idiopathic scoliosis are exposed to substantial amounts of radiation during treatment and follow-up for AIS.
Purpose / Aim of Study: The purpose of this study was to determine the amount radiation exposure patients received during treatment for AIS and report the incidence of infertility and cancer in adulthood.
Materials and Methods: 219 consecutive AIS patients treated at Rigshospitalet, Copenhagen between 1983-1990 were invited to participate in a follow-up study. The incidence of cancer was determined through chart review and interviews. In addition, the subjects and age-matched controls were queried regarding infertility, age at first pregnancy and spontaneous abortions. Using X -ray reports that included patient position, mAs and kV used and the number of x-rays taken, a radiation physicist calculated the total radiation dose during treatment and follow-up adjusted for BMI and sex.
Findings / Results: 159 (78 %) patients participated in the follow up study, and medical charts were available in 209 patients. 2 patients had passed away, one due to cardiac arrest and one to breast cancer. 8 patients had emigrated. Radiation information was available in 211 patients. The mean calculated total radiation exposure was 1.58 mSv (0,44- 6,9). 16.3 (range, 8-34) x-rays were taken during treatment. The rate of infertility (10%) and spontaneous abortion (23%) is similar to the normal controls. 9 (4.3%) AIS patients developed cancer, mostly breast (3) and endometrial (4). The incidence of cancer in this cohort is 17 times greater than the incidence of cancer in the Danish agematched population.
Conclusions: The infertility and spontaneous abortion rate was similar between AIS patients and an age matched cohort. The cancer rate in the AIS patients is 17 times higher than expected compared to the age- matched Danish population.

63. Health-related Quality-of-life in Adolescent idiopathic scoliosis patients 25 years after treatment
Ane Simony, Leah Y Carreon, Steen Bach Christensen, Mikkel Ø Andersen
Rygkirurgisk afdeling, Middelfart Sygehus

Background: Very few longterm studíes exists, focusing on the health realted outcomes after scoliosis treatment.
Purpose / Aim of Study: The purpose of this study was to evaluate the long term clinical outcomes using validated measures of health- related quality-of-life (HRQOL), 25 years after termination of treatment for adolescent idiopathic scoliosis.
Materials and Methods: 219 consecutive patients treated with Boston brace or posterior spinal fusion (PSF) using Harrington- DDT instrumentation between 1983 and 1990 at Rigshospitalet Copenhagen, were invited to participate in a long-term evaluation study. A validated Danish version of the Scoliosis Research Society 22R (SRS22R) and Short Form- 36 (SF36v1) were administrated to the patients two weeks before the clinical and radiological examination.
Findings / Results: 159 (72,6 %) patients participated in the clinical follow up and questionnaires, 11 patients participated only in the questionnaires, 8 emigrated, 4 were excluded due to progressive neurological disease and 2 were deceased. The total follow up was 170 patients (83%), and the average follow up was 24.5 years (range, 22-30 years). SRS22R domain scores were within the range described as normal for the general population with no statistical difference between the groups except in the Satisfaction domain, where the PSF group had better scores than the braced group.The SF36 PCS and MCS scores in both AIS cohorts were similar to the scores for the general population.
Conclusions: HRQOLs, as measured by the SRS22R and SF-36, of adult AIS patients treated with Boston brace or PSF during adolescence were similar to the general population. No clinical progression of the deformity has been detected during the 25-year follow up period. The PSF group had a small but statistically significant higher score in the Satisfaction domain compared to the braced group.

64. The association between severity of scoliosis and lung clearance index (LCI) in patients with adolescent idiopathic scoliosis (AIS)
Anne Katrine Blyme, Birgitte Hanel, Martin Gehrchen, Benny Dahl
Spine Unit, Department of Orthopaedic Surgery, Rigshospitalet and University of Copenhagen; Danish Pediatric Pulmonary Service, Rigshospitalet and University of Copenhagen

Background: AIS causes thoracic distortion but the effect on ventilation inhomogeneity is scarcely reported. The lung clearance index (LCI) is an advanced pulmonary function test reflecting ventilation inhomogeneity of the lungs.
Purpose / Aim of Study: To assess the correlation between LCI and Cobb angle in AIS-patients.
Materials and Methods: A consecutive series of patients with AIS was included. Pulmonary function testing using spirometry, wholebody-plethysmography and N2 MBW was performed obtaining: forced expiratory volume in 1 s (FEV1) and capacity (FVC), total lung capacity (TLC), and LCI. An independent observer registered largest Cobb angle and apical vertebrae. Correlation analysis using Spearman´s correlation test was applied due to the index nature of the LCI. Comparison of LCI-values with reference values was done using unpaired t-test. A p-value < 0.05 was considered significant.
Findings / Results: The study population consisted of 41 patients with an average age of 14.7 (10-18) years. The average Cobb angle was 49 (11-99) degrees and 88% of the curves were thoracic. LCI was significantly increased in AIS-patients compared to the age matched reference population; 7.35 vs. 6.54 (p = 0.001). There was a significant correlation between Cobb angle and LCI (r = 0.477, p = 0.002), whereas the correlation between TLC and largest Cobb angle was small and not statistical significant (r = 0.273, p = 0.084). No significant correlation was found between Cobb angles and spirometric values.
Conclusions: Increased LCI indicates increased pulmonary ventilation inhomogeneity in AIS, reflecting a more complex affection of lung function than previously reported. Future studies will reveal if surgical treatment improves LCI or can be used as an additional variable in the assessment of curve progression.

65. The Effect of Lumbar Disc Degeneration and Low Back Pain on the Lumbar Lordosis in Supine and Standing: A Cross-Sectional MRI Study
Bjarke Brandt Hansen, Tom Bendix, Jacob Grindsted, Robert GC Riis, Philip Hansen, Mikael Boesen
The Parker Institute, Department of Rheumatology, Copenhagen University Hospital, Bispebjerg and Frederiksberg, Denmark.; Spine Center Copenhagen, Copenhagen University Hospital, Glostrup, Denmark.; Department of Radiology, Copenhagen University Hospital, Bispebjerg and Frederiksberg, Denmark.; Department of Radiology., Copenhagen University Hospital, Bispebjerg and Frederiksberg, Denmark.

Background: The lumbar lordosis increases with a change of position from supine to standing and is known as an essential contributor to positional morphological changes. It is unclear how the lordosis is affected by disc degeneration and low back pain (LBP) in standing positional magnetic resonance imaging (pMRI).
Purpose / Aim of Study: To examine the influence of LBP and lumbar disc degeneration (LDD) on the lumbar lordosis.
Materials and Methods: Patients with LBP above 40 on a 0-100 mm visual analogue scale (VAS) both during activity and rest; and a sex and age-decade matching control group without LBP were scanned in the supine and standing position in a 0.25 T open MRI unit (G-Scan). All images were evaluated and LDD was graded using Pfirrmann’s classification. Subsequently, the L2-S1 lumbar lordosis angle was measured.
Findings / Results: Thirty-eight patients with an average VAS of 58 (±13.8) during rest and 75 (±5.0) during activities and 38 healthy controls were included. MRI changes were common in both groups, whereas, the summation of the lumbar Pfirrmann’s grades (LDD score) was significantly higher in the patients (MD:1.44 , CI:0.80 to 2.10; P <0.001). The patients’ lumbar lordosis angle was lower than that of the controls for both the supine (MD:-6.4, CI:-11.4 to -1.3; P=0.014) and standing position (MD-5.6, CI -10.7 to -0.7; P=0.027). No difference was found for supine-to- standing lordosis changes (MD:0.8, CI: -1.8 to 3.3; P=0.57) between groups. The LDD score was not correlated with the standing or supine lumbar lordosis, but with the supine-to-standing lordosis change in the controls (Pearson: r = -0.54, P< 0.001).
Conclusions: Patients with LBP have a tendency to reduce the lumbar lordosis, presumably to reduce pain. In individuals without LBP age related disc degeneration seems to lead to increased lordotic stiffness.

66. Return to work after lumbar disc surgery is related to the duration of symptoms.
Carsten Ernst, Mikkel Andersen, Jesper Rasmussen, Søren Dahl
Sector for Spine Surgery and Research, Lillebaelt Hospital, Middelfart, Denmark; Department of Occupational Medicine, Hospital of South West Jutland, Esbjerg

Background: Lumbar disc herniation (LDH) is associated with great morbidity and significant socio- economic impact as the majority of the patients are in the working age.
Purpose / Aim of Study: The purpose of this study is to investigate if the return to work rate after lumbar disc herniation surgery are affected by the duration of symptoms and length of sick leave.
Materials and Methods: The present study was conducted as a single center study. All LDH patients who underwent surgery at Lillebaelt Hospital from June 1, 2009 through to December 31 were included. Data were prospectively collected in the database DaneSpine. Questions in DaneSpine include preoperative duration of leg pain, duration of preoperative sick leave and working status one year post operatively.
Findings / Results: Totally, 1329 patients were operated. Overall 62 % of the patients were back to work one year post-operatively. The rate of patients returning to work decreases significantly with the duration of leg pain. Among the patients on sick leave prior to the surgery 80 % returned to work if surgically treated within 3 months whereas 46 % returned to work with sick leave extending 3 months.
Conclusions: The present analysis suggests that the return to work rate after lumbar disc herniation surgery are affected by the duration of symptoms and length of sick leave. Detailed analysis with proper adjustment for confounding factors and a more accurate detection of disease duration after surgery is necessary in order to provide a more reliable assessment of the preoperative disease durations impact on return to work rate.

67. A Novel Cobalt Chromium Four-Rod Surgical Technique Reduces Motion and Rod Strain Compared to Standard Constructs Following Spinal Deformity Correction: an in vitro Biomechanical Study
Dennis Hallager Nielsen, Martin Gehrchen, Benny Dahl, Jonathan Harris, Manasa Gudipally, Brandon Bucklen
Spine Unit, Dept. of Orthopaedic Surgery, Rigshospitalet, University of Copenhagen; , Globus Medical, Inc., 2560 General Armistead Ave, Audubon, PA 19403, United States of America

Background: Surgical treatment of adult spinal deformity is associated with a 20-30% revision rate; often caused by rod breakage at the level of the lumbar pedicle subtraction osteotomy (PSO). Only a few small clinical studies with ambiguous results have been reported regarding strategies to reduce revision rate.
Purpose / Aim of Study: To assess the biomechanical effects of cobalt chromium (CoCr) vs. Titanium (Ti), the addition of two short pre-contoured rods across the PSO (4- Rod) to the standard construct (2-Rod), and supplemental interbody spacers (S) adjacent to the PSO-level, on rod strain in a biomechanical model.
Materials and Methods: Five human specimens (T12-S1) underwent PSO at L3 with posterior pedicle screw stabilization from L1- S1. The final lordosis of all specimens was 70º. Specimens were subjected to 10 Nm in flexion- extension (FE), lateral bending (LB) and axial rotation (AR) on a custom motion simulator. Linear strain gauges measured surface rod strain during FE motion at the PSO site. Lateral interbody spacers were inserted at L2-L3 and L3-L4 following initial testing of the primary rods. Repeated measures ANOVAs assessed differences between constructs in range of motion (ROM) and strain; three-way repeated measures ANOVAs assessed effects of construct factors.
Findings / Results: CoCr 4-Rod+S constructs provided the most strain reduction compared to standard Ti 2-Rod (76%, p=0.003). Additional rods significantly reduced FE ROM (0.8%, p=0.021) and strain on the primary rods, irrespective of construct (49%, p<0.001). CoCr rods reduced strain (28%, p<0.001), but did not affect ROM in any direction (all p>0.145). Interbody spacers did not significantly reduce strain (6%, p=0.318) or ROM in any direction (all p>0.091).
Conclusions: Additional short rods and the use of CoCr rods significantly reduce primary rod strain across the PSO site.

68. No effect of TLIF over standard posterior instrumented fusion.Results from a RCT 5-10 years follow up.
Kristian Høy, Kamilla Truong , Thomas Andersen, Cody Bünger
Ortopedic Department E, Spine Section, Aarhus University Hospital

Background: Inter-body fusion as a ALIF procedure has earlier been in favour to a standard procedure in long-term follow up..
Purpose / Aim of Study: In order to show a similar trend we made a 5-10 year follow up of your randomized trail, between TLIF and Instrumented Posterolateral fusion. (PLF)
Materials and Methods: During 01.11.2003-.01.11.2008 100 pat`s were prospectively randomized to TLIF or PLF. TLIF´s was operated using TSRH (Medtronic) and Implex (Zimmer), allograft. PLF`s using TSRH, allograft. Inclusions: segmental instability, disc degeneration, former disc herniation, spondylolisthesis < 2. Functional-outcome was registered, prospectively, at 5-10 years, Dallas Pain questionnaire (DPQ), SF-36, Low Back pain questionnaire (LBRS), ODI. At follow up a new MRI and X-ray was done.
Findings / Results: Overall follow up was 93% of available, 94%, (44) in the PLF´s and 92 %, (44) in the TLIF´s no difference. Mean follow up was 8.6 years (5-10 years). Mean age at follow up was 59 years (34-76 years). Reoperation rate in a long-term perspective was 14 % in the TLIF´s and 14 % in the PLF´s. According to LBPRS: Back was pain was 3.8 (Mean), TLIF (3.65) PLF (3.97), Leg pain 2.68 (Mean) 2.90 (TLIF) and 2.48 (PLF) no difference. At follow up, no difference in functional outcome DPQ, ODI, SF-36. When asked after 8.6 years, if they would go through the operation, with now a day’s knowledge, 76% answered yes 75% (TLIF) and 77 %( PLF).
Conclusions: In a long-term perspective inter body fusion with TLIF does not seem to improve functional outcome in ODI, SF- 36, Dallas pain Questionnaire, Low back pain rating scale compared to a standard Instrumented posterolateral Lumbar fusion (PLF).

69. Is it worthwhile operating geriatric patients with herniated lumbar disc?
Marie Nørgaard Petersen, Christian Støttrup, Mikkel Østerheden Andersen
Rygkirurgisk Sektor, Sygehus Lillebælt, Middelfart

Background: Throughout the modern world the mean age is increasing, making the geriatric population an even greater part of our population. In many aspects, this population differs from the general population, which mandates altered approaches to many issues within the healthcare system. Disc herniation is a significant health issue in our society, which also includes the geriatric population. However limited studies have been conducted on a geriatric-only basis, for what reason we do not know whether surgical intervention have similar effects as is the case with general population.
Purpose / Aim of Study: Does geriatric patients with lumbar disc herniation (LDH) have significant effect following surgical intervention measured using patient reported outcome measures (PROM).
Materials and Methods: 118 (53 male ; 65 female) patients ranging 70-90 years were operated for LDH at Center for Spine Surgery and Research, Middelfart, from June 6th 2010 till April 1st 2014. Using pre-operative and 1-year follow-up data outcome was evaluated in terms of PROMs (ODI, VAS, EQ-5D, SF- 36).
Findings / Results: Patients reported a significant improvement in all measured PROMs at 1-year follow-up. Mean ΔVAS-leg 3.1 (p <0.01), mean ΔVAS- back 2.6 (p <0.01). Mean ΔODI 29.7 (95% CI 25.2 ; 34.1) post- operative mean of 16.0 and a p-value of <0.01. SF-36 Mental Component Score mean improvement 12.0 (p <0.01) and Physical Component Score mean improvement 5.2 (p 0.0001). EQ-5D mean difference of 0.51 (p <0.01).
Conclusions: Geriatric patients have both statistically and clinically significant improvements in multiple PROMs following surgical intervention for LDH. Incidence of surgical complications was not found to be higher when compared to general population. When conservative therapy fails, surgical intervention seems to be a good alternative for geriatric patients suffering from LDH.

70. Comparison of synthetic bone graft ABM/P-15 and allograft on unistrumented posterior lumbar spine fusion in sheep
Martin Glasdam Axelsen, Stig Mindedahl Jespersen, Søren Overgaard, Ming Ding
Department of Orthopedic Surgery, Institute of Clinical Research, Odense University Hospital, University of Southern Denmark; Department of Orthopedic Surgery, Odense University Hospital

Background: Posteriolateral fusion (PLF) is a common used procedure in spinal surgery. New bone graft materials are wanted due to limitations and side effects associated with allo- and autografts. Ifactor flexTM is a commercial available synthetic bone graft material that has gained CE approval in Europe. It consists of a synthetic Anorganic bone matrix (ABM) coated with a 15 amino acid peptide sequence, identical to the biding site for α2-β1 integrin on the surface of bone forming cells. ABM/P15 bone graft has previously shown promising bone formation properties when used in closed devises or bone defects. In PLF the lack of external stability and the large graft size makes it one of the most challenging grafting procedures done in humans
Purpose / Aim of Study: To report fusion rates when using ABM/P15 in uninstrumental posteriolateral fusion in sheep compared with allograft
Materials and Methods: Twelve sheep underwent open two level uninstrumented PLF at L2/L3 and L4/L5. Levels were randomised to allograft of ABM/P15. The sheep were sacrificed after 4.5 months. Levels were harvested and evaluated with Micro-CT 50 scanner and qualitative histology. Fusion rates were assessed with 2D sections and 3D reconstruction images and fusion was defined as intertransverse bridging
Findings / Results: In allograft group we found 68% fusion rates. In ABM/P15 we found extensive migration of the material in all sheep and a fusion rate on 37%. These groups are significant different (P <0,01). Qualitative histology showed good osteointegration of the material and good correlation to scanning results
Conclusions: In this preclinical study we have proved that ABM/p15 has the ability to migrate when lacking external stability as in uninstrumental PLF. This migration causes lower fusion rates. These finding are important for surgeons to make their choice of graft material for PLF

71. Pharmacokinetics of Single Dose Cefuroxime in Porcine Intervertebral Disc and Vertebra Determined by Microdialysis
Pelle Hanberg
Ortopædkirurgisk Forskning i Aarhus, Aarhus Universitetshospital

Background: Pyogenic spondylodiscitis is associated with prolonged antimicrobial therapy and high relapse rates. Nevertheless, tissue pharmacokinetic studies of relevant antimicrobials are still sparse. Previous approaches based on bone biopsy and discectomy exhibit important methodological limitations.
Purpose / Aim of Study: Microdialysis (MD) was used to assess intervertebral disc (IVD), vertebral and subcutaneous tissue (SCT) pharmacokinetics of cefuroxime in a large animal model.
Materials and Methods: Ten female pigs were assigned to receive 1,500 mg of cefuroxime intravenously over 15 min. Measurements of cefuroxime were obtained from plasma, SCT, the vertebra and the IVD for 8 hours thereafter. MD was applied for sampling in solid tissues.
Findings / Results: For both the IVD and the vertebra, the area under the concentration-curve from zero to the last measured value was significantly lower than that of free plasma. Tissue penetration of cefuroxime was incomplete for the IVD, while vertebral cefuroxime penetration only just failed to be significantly incomplete. Furthermore, the penetration of cefuroxime from plasma to IVD was delayed. Additionally, a noticeable prolonged elimination rate of cefuroxime in the IVD was found. The maximal concentration and the elimination of cefuroxime were reduced in IVD compared to both SCT and vertebra. Due to this delay in elimination of cefuroxime, the time with concentrations above the minimal inhibitory concentration (T>MIC) was significantly higher in IVD than in SCT, vertebra and free plasma for MICs up to 6 μg/ml.
Conclusions: MD was successfully applied for serial assessment of the concentration of cefuroxime in the IVD and the vertebral bone. Penetration of cefuroxime from plasma to IVD was found to be incomplete and delayed, but due to a prolonged elimination, the best results regarding T>MIC was found in IVD.

72. Can supine lateral bending radiographs predict the initial in-brace correction of the Providence orthosis in patients treated for adolescent idiopathic scoliosis?
Søren Ohrt-Nissen
Spine Unit, Department of Orthopaedic Surgery, Rigshospitalet, University of Copenhagen

Background: Supine lateral bending radiographs (SLBR) are used to assess curve flexibility in patients undergoing surgical treatment of Adolescent Idiopathic Scoliosis (AIS) but to what extent SLBR can be used to predict in-brace correction (IBC) before initiating bracing treatment is unknown. The Providence orthosis is a part-time bracing system that has been shown to provide substantial curve correction.
Purpose / Aim of Study: To determine the association between SLBR and initial IBC in patients treated with Providence orthosis.
Materials and Methods: A retrospective cross-sectional study was conducted on all patients with AIS treated with Providence orthosis from January 1st 2006 to December 31st 2013. Only patients with a major curve of 25-45° were included. Cobb angles on SLBR before treatment and on initial standing, in- brace radiograph (IBR) were measured twice for each patient by one observer 30 days apart. Using a repeated measures mixed effect model, mean difference and 95% limits of agreement (LOA) between Cobb angles on each type of radiograph were estimated.
Findings / Results: A total of 127 patients were included. Median Cobb angle on “pre-treatment” standing radiographs was 35° (IQR: 31-39°), which was reduced to 14° (IQR: 7-19°) on IBR. 52% of curves were thoracic (T), 30% were thoracolumbar/lumbar (TL/L) and 18% were double curves (DC). Overall mean difference between SLBR and IBR was 0.2° (LOA, ±10 degrees), for T curves it was 0.16° (LOA: ±8.4°), for TL/L 0.9° (LOA: ±9.8°) and for DC 0.4° (LOA: ±16°).
Conclusions: Major curve measurements on SBLR and IBR are within ±10° in T and TL/L curves with a mean difference of less than one degree. These findings could indicate that SBLR are not necessary prior to brace treatment. This may reduce the number of radiographs in patients with AIS.