A Thesis submitted to The University of Arizona College of Medicine - Phoenix in partial fulfillment of the requirements for the Degree of Doctor of Medicine. / Adolescent Idiopathic Scoliosis (AIS) is typically treated surgically by Posterior Spinal Fusion (PSF) surgery. Intravenous analgesics and oral opioids are commonly used for pain management. Several adjunct therapies are used in addition to the standard treatments. One of these therapies is the use of dexmedetomidine (dex). Though dex has been found to be an effective sedative for post‐operative patients, there are also several adverse effects that are associated with its use. The purpose of this study was to investigate the effectiveness and overall benefit of using dex for pain control for patients undergoing PSF for AIS. IRB approval was obtained. A group of 43 patients with AIS undergoing PSF and using Dex for adjunctive pain control were matched with 43 patients who did not use Dex. The groups were matched based on gender, age, height, weight, and level of spinal fusion. During the patients’ post‐operative hospital stay, the total opioid use and clinical pain scores were compared between the two groups using t‐tests, with significance set at p<0.05. Total opiate use was 239.6 morphine equivalent doses in the non‐Dex (control) group and 246.2 in the group that received Dex (p=0.72). The average pain score in the control group was 2.3, and the group that received Dex was 2.6 (p =0.43). There were no differences in the complication rate between the two groups, specifically the oversedation rates and pulmonary complications. Lastly, the average length of stay for the control group was 4.8 days compared to the dex group, which was 5.0 days (p=0.35). Although adjunctive pain modalities may be very useful in the treatment of postoperative pain after PSF in patients with AIS, the use of Dex in this cohort did not improve pain scores, lower opioid use, or lower the LOS. Based on these results, we do not recommend the routine use of dexmedetomidine as an adjunctive pain control modality. Adjunctive modalities are important in pain control in patients with AIS undergoing PSF, but the use of dexmedotomidine was not effective in improving pain control.

Degenerative conditions of the spine are a major public health problem, leading to severe back pain, reduced quality of life and chronic disablement in a proportion of sufferers. For some of these patients, spinal fusion surgery is a treatment that can alleviate back pain and restore normal function. However, limitations in the availability of graft material mean that alternative grafts are needed and tissue-engineering approaches have been employed. Using a novel self-organising collagen scaffold combined with nano-hydroxyapatite and chondroitin sulphate and by employing the latest materials techniques, I have studied the osteogenic capability of a biomimetic graft for use in spinal fusion surgery. The mineralised collagen scaffold has compressive strength comparable to human cancellous bone and can support the proliferation of viable human mesenchymal stem cells. This porous scaffold can be combined with human mesenchymal stem cells to further promote bone growth, as evidenced by an upregulation in the levels of bone-forming genes and mineralisation of the scaffold. This scaffold can act as a carrier system for BMP-2, with wider application for other growth factors or drugs, providing sustained release when fabricated as a layer-by-layer scaffold. An alternative bone substitute for use in spinal surgery has been designed and characterised, with exciting potential for use in vivo.

Abstract The first part of this research was focused on the relationship between injury severity and cell death mechanisms after spinal cord ischemia-reperfusion injury. The major blood supply to the thoracolumbar spinal cord comes from the segmental arteries originating from the thoracoabdominal aorta. Paraplegia cause by spinal cord ischemia is a devastating complication of thoracoabdominal aortic surgery. Previous studies indicated that ischemia-reperfusion injury of the central nervous system causes two distinct types of cell death, necrosis and apoptosis. It was also implicated that the intensity of injury can somehow affect the cell death mechanisms. In the first series of our experiments, by occluding the descending thoracic aorta with or without simultaneously inducing hypovolemic hypotension in rats, we established a model of experimental spinal cord ischemia-reperfusion (SCIR) in which the injury severity can be controlled. Recordings of carotid blood pressure (CBP) and spinal cord blood flow (SCBF) showed that aortic occlusion induced dramatic CBP elevation but SCBF drop in both the normotensive (NT) and hypotensive (HT) groups. However, the HT group demonstrated significantly lower SCBF during aortic occlusion, and much slower elevation of SCBF after reperfusion, and extremely poor neurological performance. Spinal cord lesions were characterized by infarction associated with extensive necrotic cell death, but little apoptosis and caspase-3 activity. In contrast, in the NT group, SCIR resulted in minor tissue destruction associated with persistently abundant apoptosis, augmented caspase-3 activity, and favorable functional outcome. The relative sparing of motoneurons in the ventral horns from apoptosis might have accounted for the minor functional impairment in the NT group. The severity of ischemia-reperfusion (I/R) injury was found to have substantial impact on the histopathological changes and cell death mechanisms, which correlated with neurological performance. These findings implicate that injury severity and duration after injury are two critical factors to be considered in therapeutic intervention. Based on the knowledge that bPrevious studies have implicated both excitotoxicity and apoptosis are involved in the pathogenesis of SCIR injury, we proposedtested the possibility that the N-methyl-D-aspartate (NMDA) receptor antagonist (dizocilpine maleate: (MK801) and the protein synthesis inhibitor (cycloheximide) would produce a synergic effect in the treatment of SCIR injury. In the second series of experiments, I/R iSpinal cord ischemia-reperfusion injury was induced by a thoracic aortic occlusion and blood volume reduction, followed by reperfusion and volume restoration. ischemia-reperfusion Rats were treated with vehicle, MK801, cycloheximide, or combination of MK801 and cycloheximide in combination. The MK801 and combined therapy group got a better recovery of hHind limb motor function recovery was better in the MK801 and combined-therapy groups than in the control and cycloheximide groups. On the 7th day after ischemia-reperfusion injury, all three treated groups showed significantly higher neuronal survival rates (NSR) than that of the control group. Among the three treated groups, the combined-treatment group showed the highest NSR. In addition, the Ttherapeutic effect of the combined-treatment group (27.4% increase of NSR) iwas better than the anticipated by the addition of MK801 and cycloheximide based on NSR data group. The number of apoptotic cells of was significantly reduced in the cycloheximide group and the combined-treatment group, as compared to that of the control group. It was unchanged in the MK-801 group. These results suggest that combined treatments directed at blocking both NMDA receptor-mediated excitotoxic necrosis and caspase-mediated apoptosis might have synergic therapeutic potential in reducing SCIR injury. Mitogen-activated protein kinases (MAPKs) including c-Jun N-terminal kinases (JNK), p38, and extracellular signal-regulated kinases (ERK), play important roles in the transduction of stressful signals and the integration of cellular responses. Although it has been generally held that the JNK and p38 pathways are related to cell death and degeneration, while the ERK pathway, cell proliferation and survival, controversy still exists. The roles of the ERK pathway in I/R injury of the CNS, in particular, remain to be clarified, because contradictory data have been reported by different investigators. Given this controversy, in the third series of experiments, we examined in injured spinal cords the temporal and spatial profiles of ERK1/2 activation following SCIR, and the effects of inhibiting the kinase that phosphorylates ERK1/2, MEK. The results showed that I/R injury induced an immediate phosphorylation of ERK1/2 in the spinal cord, which was alleviated by a MEK inhibitor, U0126. The control group was characterized by poorer neurological outcome, more severe tissue destruction, pronounced apoptosis, and lower neuronal survival. In contrast, the U0126-treated group demonstrated more apparent improvement of hind limb motor function, less tissue destruction, lack of apoptosis, and higher neuronal survival. In addition, administration of U0126 also significantly increased the activation of nuclear factor-£eB (NF-£eB) and the expression of cellular inhibitor of apoptosis protein 2 (c-IAP2). These findings implicate that the mechanisms underlying the neuroprotection afforded by ERK1/2 inhibition may be through the NF-£eB-c-IAP2 axis. The activation of the MEK-ERK signaling pathway appeared to be harmful in SCIR injury. Strategies aimed at blocking this pathway may bear potential therapeutic benefits in the treatment of SCIR injury. The second part of the research was focused on the pathophysiology of surgery-associated paraspinal muscle injury and measures to protect surgically violated paraspinal muscles. The wide dissection and forceful retraction of paraspinal muscles which are often required for posterior spinal sugery may severely jeopardize the muscles structurally and functionally. Immediate posteoperative pathological changes in the surgically violated paraspinal muscles may cause severe pain and a delay of patient ambulation. Long-term sequelae of surgical injury of paraspinal muscles include chronic back pain and impaired back muscle strength. Ironically, being a common complication of posterior spinal surgery, paraspinal muscle injury is so often neglected. Limited previous data indicate that the underlying pathophysiology of muscle damage involve both mechanical and ischemic mechanisms. We hypothesized that surgical dissection and retraction may produce oxidative stress within the paraspinal muscles. Meanwhile, we also proposed that the oxidative stress may trigger certain protective mechanisms within the insulted muscles. The first part of our study was a human study conducted to assess the significance of oxidative stress, and the relationship between it and the stress response mediated by heat shock protein 70 (HSP70) induction within paraspinal muscles under intraoperative retraction. A group of patients with lumbar spondylolisthesis treated with posterolateral lumbar spinal fusion, pedicle fixation and laminectomy were enrolled. Multifidus muscle specimens were harvested intraoperatively before, at designated time points during, and after surgical retraction. Muscle samples were analyzed for HSP70 and malondialdehyde (MDA) levels. Both HSP70 expression and MDA production within multifidus muscle cells were increased significantly by retraction. HSP70 expression then dropped after a peak at 1.5 hr of retraction, whereas MDA levels remained elevated even after release of retractors for reperfusion of the muscles. Histopathological and immunohistochemical evidence indicated that the decline of HSP70 synthesis within muscle cells after prolonged retraction was the result of severe muscle damage. These results highlighted the noxious impact of intraoperative retraction on human paraspinal muscles, and the significance of oxidative stress at the cellular and molecular levels. It is also implicated that intraoperative maneuvers aimed at reducing the oxidative stress within the paraspinal muscles may help attenuating surgery-associated paraspinal muscle damage. Given the findings of the first part of our study, and the knowledge that inflammation is a major postoperative pathological finding in surgically injured paraspinal muscles, we proceeded to examine the roles of two important inflammatory mediators, cyclooxygenase (COX)-2 and nuclear factor (NF)-£eB, in the pathogenesis of retraction-associated paraspinal muscle injury. A rat model of paraspinal muscle dissection and retraction that mimicks the conditions in human posterior spinal surgery was established. In the control group, paraspinal muscles were dissected from the spine through a dorsal incision, and then laterally retracted. Paraspinal muscle specimens were harvested before, and at designated time points during and after persistent retraction. The time course of NF-£eB activation as well as the expression of COX-2 were examined. Severity of inflammation was evaluated based on histopathology and myeloperoxidase (MPO) activity. NF-£eB activation was inhibited by the administration of pyrrolidine dithiolcarbamate (PDTC) in the PDTC-treated group. In the control group, retraction induced an early increase of NF-£eB/DNA binding activity in paraspinal muscle cells, which persited throughout the whole course of retraction. COX-2 expression was not detectable until 1 day after surgery, and reached a peak at 3 days. The time course of COX-2 expression correlated with that of inflammatory pathology and MPO activity. Extensive muscle fiber loss and collagen fiber replacement were observed at 7 days after surgery. Pretreatment with PDTC inhibited intraoperative NF-£eB activation and greatly downregulated postoperative COX-2 expression and inflammation in the muscles. Fibrosis following inflammation was also significantly abolished by PDTC administration. These findings indicate that NF-£eB-regulated COX-2 expression and inflammation play an important role in the pathogenesis of surgery-associated paraspinal muscle injury. Therapeutic strategies involving NF-£eB inhibition may be applicable to the prevention of such injury.

Degenerative disease of the lumbar spine (DDLS) is a common condition for which surgery is beneficial in selected patients. Wide variation in surgical referral and rates of surgery has been observed contributing to unequal access to care. Our objectives were to examine (1) the variation in preferences for referral and surgery among surgeons, family physicians (FPs) and patients, (2) how FP referral practices compare with preferences and guideline recommendations, and (3) how the ‘enthusiasm’ of patients and physicians influence regional variation in surgical rates. We used conjoint analysis in a mailed survey to elicit preferences based on clinical vignettes from surgeons, FPs and patients. A Delphi expert panel provided consensus guideline recommendations for surgical referral to compare with actual FP referral practices. Rates of surgery for DDLS, obtained from Ontario hospital discharge data, were used to quantify regional variation and regression models assessed the relationship with patient and physician enthusiasm. We identified significant differences in preferences for referral and surgery between patients, FPs and surgeons. Surgeons placed high importance on leg-dominant symptoms while patients had high importance for quality of life symptoms (i.e. severity, duration, walking tolerance). Surgical referral practices were poorly predicted by individual FP preferences and guideline recommendations based on clinical factors alone. Variation in Ontario surgical rates was higher than that of hip or knee replacements and was highly associated with the enthusiasm of surgeons (p<0.008), rather than FPs or patients. By appreciating the variation in preferences between patients and physicians, and exploring other non-clinical factors that influence referrals, we may be able to improve the efficiency of referrals and enhance the shared decision making process. With an understanding of the influence that surgeons have in driving variation in surgical rates, further research may allow us to direct strategies to improve access and allow for a more equitable delivery of care for patients suffering from DDLS.

Degenerative disease of the lumbar spine (DDLS) is a common condition for which surgery is beneficial in selected patients. Wide variation in surgical referral and rates of surgery has been observed contributing to unequal access to care. Our objectives were to examine (1) the variation in preferences for referral and surgery among surgeons, family physicians (FPs) and patients, (2) how FP referral practices compare with preferences and guideline recommendations, and (3) how the ‘enthusiasm’ of patients and physicians influence regional variation in surgical rates. We used conjoint analysis in a mailed survey to elicit preferences based on clinical vignettes from surgeons, FPs and patients. A Delphi expert panel provided consensus guideline recommendations for surgical referral to compare with actual FP referral practices. Rates of surgery for DDLS, obtained from Ontario hospital discharge data, were used to quantify regional variation and regression models assessed the relationship with patient and physician enthusiasm. We identified significant differences in preferences for referral and surgery between patients, FPs and surgeons. Surgeons placed high importance on leg-dominant symptoms while patients had high importance for quality of life symptoms (i.e. severity, duration, walking tolerance). Surgical referral practices were poorly predicted by individual FP preferences and guideline recommendations based on clinical factors alone. Variation in Ontario surgical rates was higher than that of hip or knee replacements and was highly associated with the enthusiasm of surgeons (p<0.008), rather than FPs or patients. By appreciating the variation in preferences between patients and physicians, and exploring other non-clinical factors that influence referrals, we may be able to improve the efficiency of referrals and enhance the shared decision making process. With an understanding of the influence that surgeons have in driving variation in surgical rates, further research may allow us to direct strategies to improve access and allow for a more equitable delivery of care for patients suffering from DDLS.

The purpose of this work was to determine the possible effects of isolated spinal ligament transection on the biomechanics of the lumbar spine. A finite element model of a lumbar spine was developed and validated against experimental data. The model was tested in the primary modes of spinal motion in the intact condition, followed by comparative analysis of isolated removal of each spinal ligament. Results showed that stress increased in the remaining ligaments once a ligament was removed, potentially leading to ligament damage. Results also showed changes in bone remodeling "stimulus" which could lead to changes in bone density. Isolated ligament transection had little effect on intervertebral disc pressures. All major biomechanical changes occurred at the same spinal level as the transected ligament, with minor changes at adjacent levels. The results of this work demonstrate that iatrogenic damage of spinal ligaments disturbs the load sharing within spinal-ligament complex and may induce significant clinical changes in the spinal motion segment.

Postoperative spinal patients were randomly assigned to one of three treatment conditions and were taught five adaptive movements by occupational therapists. The Control group received routine hospital occupational therapy; the Placebo group participated in an imagery relaxation task unrelated to the mental practice task of the Imagery group, which was shown line drawings of the adaptive movements under study, provided movement instructions, and asked to mentally practice each movement in a familiar, daily living situation. Thirty-five patients returned for follow-up, and a measure of outcome was obtained through the use of a quantified movement assessment instrument. Subjective ratings for anxiety, rumination, and imagery were made by the occupational therapists. An occupational motoric-symbolic rating scale was developed to assess the symbolic portion of the patient's job experience. Statistical procedures including chi square, analysis of variance, and Pearson correlation were performed. Results were in the predicted direction although statistical significance was not achieved. Possible explanations for the obtained results were discussed.

La presente Tesis Doctoral se titula "Obtención y caracterización de nuevos cementos óseos de fosfatos de calcio en el sistema DCP&#8213;alfa-TCP". Los cementos de fosfatos de calcio (CFC) son materiales biocompatibles que tienen la propiedad de endurecer en condiciones fisiológicas formando una estructura porosa de cristales interconectados de hidroxiapatita, i.e. la fase mineral de los tejidos óseos. Estos materiales pueden ser diseñados para que sean inyectables y tengan distintos porcentajes de porosidad. Este hecho permite obtener cementos con distintas tasas de reabsorción ósea que pueden aplicarse con técnicas de mínima invasión. En general, estas propiedades otorgan a estos biomateriales un excelente interés en campos de aplicación de prevención, reconstrucción o estabilización ósea (p.e.: osteoporosis, cirugía craneofacial, vertebroplastia, cifoplastia).Esta Tesis Doctoral consta de 6 capítulos. El Capítulo 1 (Cementos óseos de fosfatos de calcio) recoge el estado del arte de los CFC. Se realiza una revisión bibliográfica crítica de toda la información de interés. Se concluye la necesidad de realizar estudios cinéticos que expliquen adecuadamente las propiedades de fraguado de estos cementos y permitan diseñar cementos con mejores propiedades. El Capítulo 2 (Materiales y métodos utilizados en la fabricación y caracterización de cementos óseos de fosfatos de calcio) describe el protocolo de trabajo seguido para caracterizar los CFC física y químicamente. Este protocolo permite establecer correlaciones entre la microestructura y las propiedades macroscópicas. El Capítulo 3 (Estudio de la cinética de la reacción de fraguado de un cemento óseo de fosfato de calcio) investiga la cinética de fraguado de un cemento octocálcico en el sistema DCP&#8213;alfa-TCP. Los resultados mostraron que: (a) sólo el alfa-TCP reaccionó para dar una hidroxiapatita deficiente en calcio (CDHA); (b) el porcentaje de reacción y la resistencia mecánica a compresión estaban correlacionadas; (c) el cemento presentó una estructura de cristales interconectados con distinto grado de compacidad. El Capítulo 4 (Estudio de nuevas formulaciones de cementos de fosfatos de calcio en el sistema DCP&#8213;alfa-TCP) investiga las propiedades de fraguado y de resistencia mecánica de cementos del sistema DCP&#8213;alfa-TCP en el intervalo de relaciones Calcio/Fósforo (Ca/P) 1.26<Ca/P<1.50. Se estudia cómo varían la trabajabilidad, los tiempos de fraguado y la resistencia a la compresión. También se estudia el efecto de la adición de carbonato cálcico (CC) sobre las propiedades de fraguado ya que se espera obtener como producto final de la reacción de fraguado una hidroxiapatita deficiente en calcio carbonatada y, por lo tanto, más semejante a la apatita de la fase mineral ósea. Los resultados mostraron que la adición de un 10 % de CC produjo un efecto fluidificante sobre los cementos con un incremento en los valores de los tiempos de fraguado. El análisis de la evolución de la resistencia a la compresión con el tiempo demostró que el CC actúa como un retardador. Sin embargo, la resistencia final alcanzada representa en muchos casos un incremento de más del 40 %. El Capítulo 5 (Discusión general) discute los resultados más relevantes analizados a lo largo de los Capítulos 3 y 4 para comprender las posibilidades clínicas que este tipo de materiales nos ofrece. El Capítulo 6 (Conclusiones) presenta una serie de conclusiones obtenidas a partir de los resultados de los Capítulos 3 y 4. Son conclusiones extraídas a partir del análisis de los resultados de determinadas poblaciones de muestras. Como los intervalos de variabilidad de los parámetros de cada población son diferentes, muchas de las conclusiones no son generalizables a todo el sistema DCP&#8213;alfa-TCP, sino que se han de leer dentro de este sistema y en las condiciones experimentales estudiadas. Finalmente, la Tesis Doctoral lista el conjunto de referencias bibliográficas utilizadas en este trabajo de investigación.

Aims This study examines the effects of surgery for chronic low back pain (CLBP) as well as fear avoidance, disability and levels of rated physical activity in patients treated in 2011. An additional aim was to assess patient’s experience of physiotherapy in primary care following the surgery as well the effect of physiotherapy on above mentioned outcome measures. Method A cross-sectional study design was used and a stratified random sample from 189 patients who were treated surgically in a hospital setting. This resulted in a sample of 112 respondents, half of whom where female. Ages ranged between 25-78 years. Questionnaires were sent by mail and data from 79 patients was collected. Non-parametric statistics were used. Outcome measures used were Tampa Scale for Kinesiophobia, Roland Morris Disability Questionnaire and the physical activity scale. Results More than one in four patients reported high levels of kinesiophobia, more than one in three experienced disability and less than a third were physically active. Patients with total disc replacement had better outcome than patients with lumbar fusion. A higher degree of kinesiophobia correlated significantly to experiencing more disability (rs=0.53, p&lt;0.001) and being less physically active (rs=-0.48, p&lt;0.001), and there were significant negative correlations between disability and levels of rated physical activity (rs=-0.37, p&lt;0.001). Rehabilitation in primary care did not affect the results significantly. Conclusions The results of this study hint that the fear avoidance model is relevant in patients treated surgically for chronic low back pain. Physiotherapists and other health care professionals should screen for these beliefs and try to target them. This may assist patients to pursue health promoting activities and activities in daily life. / Syfte och frågeställningar Denna studie undersöker effekterna av kirurgi för kronisk ländryggssmärta liksom kinesiofobi, funktionsnedsättning och skattade fysiska aktivitetsnivåer hos patienter som behandlats under 2011. Ett annat syfte var att utvärdera patienternas upplevelser av sjukgymnastik i primärvård samt effekten av sjukgymnastik på ovannämnda utfallsmått postoperativt. Metod Tvärnsittsstudie med stratifierat randomiserat urval från 189 patienter som behandlats kirurgiskt i sjukhusmiljö. Detta resulterade i 112 respondenter, varav hälften var kvinnor. Åldrarna sträckte sig från 25-78 år. Enkäter från 79 patienter kunde analyseras. Icke-parametrisk statistik användes för analys. De utfallsmått som användes var Tampaskalan för kinsiofobi, Roland Morris funktionsnedsättningsskala och en skala för fysisk aktivitet. Resultat Mer än en fjärdedel av alla patienter rapporterade höga nivåer av kinesiofobi, mer än en tredjedel upplevde funktionsnedsättning och mindre än en tredjedel skattade sig som fysiskt aktiva. Patienter som opererats med diskprotes hade bättre resultat än patienter som opererats med steloperation. En högre grad av kinesiofobi korrelerade signifikant med att uppleva en större funktionsnedsättning (rs=0.53, p&lt;0.001)  och lägre skattad fysisk aktivitet (rs=-0.48, p&lt;0.001). Det fanns även en signifikant negativ correlation mellan funktionsnedsättning och skattad fysisk aktivitet (rs=-0.37, p&lt;0.001). Rehabilitering i primärvård påverka inte resultatet signifikant. Slutsats Resultaten i denna studie pekar mot att rädsla-undvikande-modellen är relevant hos patienter som behandlats kirurgiskt för kronisk ländryggssmärta. Sjukgymnaster och annan häslo- och sjukvårdspersonal bör undersöka om dessa tankar finns hos denna patientgrupp och behandla dem. Detta för att underlätta för patienter att delta i aktiviteter för förbättrad hälsa och aktivitet i dagliga livet.

Le délai optimal entre une lésion médullaire traumatique (LMT) et la chirurgie demeure indéterminé. Cependant, la relation entre la prévention de complications et le délai chirurgical n’a jamais été spécifiquement étudiée. L’objectif principal de ce travail était de détecter si les taux de complications chez des LMT étaient associés avec le délai chirurgical. L’objectif secondaire était d’identifier si le délai chirurgical est un prédicteur indépendant de la survenue de complications. Un premier article présente l’analyse d’une cohorte rétrospective de 431 LMTs. Une chirurgie réalisée dans un délai inférieur à 24h (ou inférieur à 72h si un délai de 24h ne peut être respecté) prédisait une diminution du taux de l’ensemble des complications, du taux de pneumonies et du taux de plaies de pression. Les autres facteurs prédictifs de complications identifiés étaient : l’âge, la sévérité de l’atteinte neurologique de la lésion selon l’échelle ASIA, un traumatisme cervical plutôt que thoracique, la présence de comorbidités, la sévérité du traumatisme selon l’échelle ISS et la complexité de la chirurgie. Les connaissances actuelles suggèrent qu’une opération chirurgicale rapide n’a que peu d’effet sur la récupération neurologique chez les LMTs complètes (interruption complète des fonctions sensorimotrices). Pour cette raison, notre second article analyse l’impact du délai chirurgical sur la survenue des complications à partir d’une sous-population de 197 LMTs complètes de notre cohorte. Un délai chirurgical supérieur à 24h prédisait une augmentation des complications, notamment les pneumonies et les infections urinaires. Bien que des études prospectives randomisées sont nécessaires pour confirmer nos conclusions, nos études supportent un délai chirurgical rapide afin de diminuer le taux de complications non neurologiques chez les LMTs. / Optimal timing of surgery after traumatic spinal cord injury (SCI) is one of the most controversial subjects in spine surgery. However, the relationship between prevention of peri-operative complications and timing of surgical decompression was never specifically studied. The primary goal of our study was to evaluate if the peri-operative complication rate was associated with surgical timing. The secondary goal of our study was to identify if surgical timing is an independent predictor of complications. A first publication presents the analysis of a retrospective cohort of 431 cases of traumatic SCI. A reduction in the global rate of complications as well as the incidence of pneumonia and pressure ulcer were predicted by surgery performed earlier than 24 hours (or earlier than 72 hours if the surgery could not be performed within 24 hours following the SCI). Other predictors where statistically related to the occurrence of complications: increasing age, severity of neurological injury, a cervical rather than a thoracic lesion, medical comorbidities, the severity of trauma, and the complexity of surgery. Previous studies suggest that early surgery is of little benefit for neurological recovery in complete traumatic SCI (with complete interruption of sensorimotor function). Therefore our second publication analyzed the impact of early surgical intervention in the sub-population of 197 complete SCI. Surgical timing later than 24 h was a predictor of complications, specifically pneumonia and UTI. Although a randomized controlled trial is needed to confirm our findings, our studies support that early surgical timing after traumatic SCI (typically within 24 hours) could decrease the rate of non neurological complications.