Choice of Rods in Surgical Treatment of Adolescent Idiopathic Scoliosis: What Are the Clinical Implications of Biomechanical Properties? – A Review of the Literature

Søren Ohrt-Nissen,Benny Dahl,Martin Gehrchen 대한척추신경외과학회 2018 Neurospine Vol.15 No.2

The surgical treatment of adolescent idiopathic scoliosis (AIS) involves 3-dimensional curve correction with multisegmental pedicle screws attached to contoured bilateral rods. The substantial corrective forces exert a high level of stress on the rods, and the ability of the rod to withstand these forces without undergoing permanent deformation relies on its biomechanical properties. These properties, in turn, are dependent on the material, diameter, and shape of the rod. The surgical treatment of AIS is characterized by the requirement for a special biomechanical profile that may differ substantially from what is needed for adult deformity surgery. This overview summarizes the current knowledge of rod biomechanics in frequently used rod constructs, with a particular focus on translational research between biomechanical studies and clinical applicability in AIS patients.

Neural Axis Abnormalities in Patients With Adolescent Idiopathic Scoliosis: Is Routine Magnetic Resonance Imaging Indicated Irrespective of Curve Severity?

Sidsel Fruergaard,Søren Ohrt-Nissen,Benny Dahl,Nicolai Kaltoft,Martin Gehrchen 대한척추신경외과학회 2019 Neurospine Vol.16 No.2

Objective: Magnetic resonance imaging (MRI)-verified neural axis abnormalities (NAAs) have been described in adolescent idiopathic scoliosis (AIS), and several risk factors have been associated with the presence of NAAs in AIS patients. However, the clinical significance of these findings is unclear. The purpose of the present study was to determine the prevalence of NAAs in a large consecutive cohort of AIS patients and to evaluate the clinical significance of previously proposed risk factors. Methods: We prospectively included AIS patients referred to a tertiary facility for evaluation. Full-spine MRI scans were performed on all included patients irrespective of curve magnitude or proposed treatment modality. MRI scans were prospectively analyzed by a neuroradiologist and the pathologic findings were confirmed by a second independent radiologist. Results: NAA was observed in 34 of the 381 patients (8.9%): 32 patients had a syrinx, 1 patient had an arachnoid cyst, and 1 patient had a Chiari malformation. Four patients were referred for a neurosurgical evaluation but none received any neurosurgical treatment. No statistically significant difference was observed between the NAA and non-NAA groups in terms of sex, major curve size, thoracic kyphosis, left thoracic curve, curve convexity, curve progression, or level of pain (p>0.05). Conclusion: In this prospective study examining the risk factors for NAA in AIS patients, we found that previously proposed risk factors could not predict the MRI outcomes. The finding of an NAA had no clinical implications and we do not support MRI scans as a routine diagnostic modality in all AIS patients.

Towards Guideline-Based Management of Tethered Cord Syndrome in Spina Bifida: A Global Health Paradigm Shift in the Era of Prenatal Surgery

Viachaslau Bradko,Heidi Castillo,Shruthi Janardhan,Benny Dahl,Kellen Gandy,Jonathan Castillo 대한척추신경외과학회 2019 Neurospine Vol.16 No.4

An estimated 60% of the world’s population lives in Asia, where the incidence of neural tube defects is high. Aware that tethered cord syndrome (TCS) is an important comorbidity, the purpose of this systematic review was to explore the treatment of TCS among individuals living with spina bifida (SB) in Asia. MEDLINE and Embase databases were searched for relevant studies published from January 2000 to June 2018. Search terms such as ‘spinal dysraphism,’ ‘spinabifida,’ ‘diastematomyelia,’ ‘lipomeningocele,’ ‘lypomyelomeningocele,’ ‘meningomyelocele,’ and ‘tethered cord syndrome’ were used in diverse combinations. Of the 1,290 articles that were identified in accordance with PRISMA (Preferred Items for Systematic Reviews and Meta-Analyses) guidelines, 15 Asia-based studies met the inclusion criteria. Significant differences in the diagnostic criteria and management of TCS were documented. As the surgical techniques for prenatal closure of the spinal defect continue to evolve, their adoption internationally is likely to continue. In this setting, a clear and evidence-based approach to the definition and management of TCS is essential. The recent publication by the Spina Bifida Association of America of their updated care guidelines may serve as a tool used to promote a systematized approach to diagnosing and treating TCS among individuals with SB in the region, as well as globally.

Lordosis Distribution Index in Short-Segment Lumbar Spine Fusion – Can Ideal Lordosis Reduce Revision Surgery and Iatrogenic Deformity?

Tanvir Johanning Bari,Martin Heegaard,Rachid Bech-Azeddine,Benny Dahl,Martin Gehrchen 대한척추신경외과학회 2021 Neurospine Vol.18 No.3

Objective: The demand for spinal fusion is increasing, with concurrent reports of iatrogenic adult spinal deformity (flatback deformity) possibly due to inappropriate lordosis distribution. This distribution is assessed using the lordosis distribution index (LDI) which describes the upper and lower arc lordosis ratio. Maldistributed LDI has been associated to adjacent segment disease following interbody fusion, although correlation to later-stage deformity is yet to be assessed. We therefore aimed to investigate if hypolordotic lordosis maldistribution was associated to radiographic deformity-surrogates or revision surgery following instrumented lumbar fusion. Methods: All patients undergoing fusion surgery (≤4 vertebra) for degenerative lumbar diseases were retrospectively included at a single center. Patients were categorized according to their postoperative LDI as: “normal” (LDI 50–80), “hypolordotic” (LDI<50), or “hyperlordotic” (LDI>80). Results: We included 149 patients who were followed for 21±14 months. Most attained a normally distributed lordosis (62%). The hypolordotic group had increased postoperative pelvic tilt (PT) (p<0.001), pelvic incidence minus lumbar lordosis (PI–LL) mismatch (p<0.001) and decreased global lordosis (p=0.007) compared to the normal group. Survival analyses revealed a significant difference in revision surgery (p=0.03), and subsequent multivariable logistic regression showed increased odds of 1-year revision in the hypolordotic group (p=0.04). There was also a negative, linear correlation between preoperative pelvic incidence (PI) and postoperative LDI (p<0.001). Conclusion: In patients undergoing instrumented lumbar fusion surgery, hypolordotic lordosis maldistribution (LDI<50) was associated to increased risk of revision surgery, increased postoperative PT and PI–LL mismatch. Lordosis distribution should be considered prior to spinal fusion, especially in high PI patients.

A Comparison of Mortality and Morbidity Between Complex and Degenerative Spine Surgery in Prospectively Collected Data From 2,280 Procedures

Stian Solumsmoen,Tanvir Johanning Bari,Sarah Woldu,Oliver Bremerskov Zielinski,Martin Gehrchen,Benny Dahl,Rachid Bech-Azeddine 대한척추신경외과학회 2021 Neurospine Vol.18 No.3

Objective: The reported incidence of complications and/or adverse events (AEs) following spine surgery varies greatly. A validated, systematic, reproducible reporting system to quantify AEs was used in 2 prospective cohorts, from 2 spine surgery centers, conducting either complex or purely degenerative spine surgery; in a comparative fashion. The aim was to highlight the differences between 2 distinctly different prospective cohorts with patients from the same background population. Methods: AEs were registered according to the predefined AE variables in the SAVES (Spine AdVerse Events Severity) system which was used to record all intra- and perioperative AEs. Additional outcomes, including mortality, length of stay, wound infection requiring revision, readmission, and unplanned revision surgery during the index admission, were also registered. Results: A total of 593 complex and 1,687 degenerative procedures were consecutively included with 100% data completion. There was a significant difference in morbidity when comparing the total number of AEs between the 2 groups (p<0.001): with a mean number of 1.42 AEs per patient (n=845) in the complex cohort, and 0.97 AEs per patient (n=1,630) in the degenerative cohort. Conclusion: In this prospective study comparing 2 cohorts, we report the rates of AEs related to spine surgery using a validated reproducible grading system for registration. The rates of morbidity and mortality were significantly higher following complex spine surgery compared to surgery for degenerative spine disease.

Use of Opioids and Other Analgesics Before and After Primary Surgery for Adult Spinal Deformity: A 10-Year Nationwide Study

Frederik Taylor Pitter,Matt Sikora,Martin Lindberg-Larsen,Alma Becic Pedersen,Benny Dahl,Martin Gehrchen 대한척추신경외과학회 2020 Neurospine Vol.17 No.1

Objective: To report the 1-year pre and postoperative analgesic use in patients undergoing primary surgery for adult spinal deformity (ASD) and assess risk factors for chronic postoperative opioid use. Methods: Patients >18 years undergoing primary instrumented surgery for ASD in Denmark between 2006 and 2016 were identified in the Danish National Patient Registry. Information on analgesic use were obtained from the Danish National Health Service Prescription Database. Use of analgesics was calculated one year before and after surgery for each patient, per quarter (-Q4 to -Q1 before and Q1 to Q4 after). Users were defined as patient with one or more prescriptions in the given quarter. Results: We identified 892 patients. Preoperatively, 28% (n=246) of patients were opioid users in -Q4 and 33% (n=295) in -Q1. Postoperatively, 85% (n=756) of patients were opioid users in Q1 and 31% (n=280) in Q4. Proportions of users of other analgesics (paracetamol, antidepressants, and anticonvulsants) were stable before and after surgery. Use of nonsteroidal anti-inflammatory drug decreased postoperatively by 40% (-Q1 vs. Q4). 26% of patients had chronic preoperative opioid use (one or more prescriptions in each -Q2 and -Q1) and 24% had chronic postoperative use (prescription each of Q1–Q4). Multivariate logistic regression analysis showed age increment per 10 years and preoperative chronic opioid use as risk factors for chronic postoperative opioid use. Conclusion: One year after ASD surgery, opioid use was not reduced compared to preoperative usage.