Influence of pelvic tilt correction on PJK occurrence after adult spinal deformity surgery.

INTRODUCTION: Many risk factors for proximal junctional kyphosis (PJK) have been reported in the literature, especially sagittal alignment modifications, but studies on pelvic tilt (PT) variations and its influence on PJK are missing. Aim of this study was to analyze the influence of pelvic tilt correction, after long fusion surgery for ASD patients, on PJK occurrence. METHODS: A monocentric retrospective study was conducted on prospectively collected data, including 76 patients, operated with fusion extending from the thoraco-lumbar junction to the ilium. Radiologic parameters were measured on fullspine standing radiographs preoperatively, postoperatively (<6 months) and at latest follow-up (before revision surgery or >2 years). All parameters were analyzed comparing patients with PJK (group "PJK") and without PJK (group "no PJK"). A further analysis compared patients with low (PT/PI<25th percentile, LowPT group) and high (PT/PI>75th percentile, HighPT group) preoperative pelvic tilt. RESULTS: « PJK ¼ patients had a greater lumbar lordosis and thoracic kyphosis correction (p=0,03 et <0,001 respectively) compared to the "no PJK" patients. Pelvic tilt was significantly lower postoperatively in the "PJK" group (p=0,03). Patients from the HighPT PJK group were significantly more corrected than patients from the HighPT noPJK group (p=0,003). CONCLUSION: Through the analysis of 76 patients, we showed that pelvic tilt did not seem to play a role in the setting of PJK after ASD surgery. Decreasing PT after surgery could be an element to watch out for in patients with PJK risk factors.

A comparison of idiopathic scoliosis surgery between teenage years and adulthood.

PURPOSE: Idiopathic scoliosis is an evolutive deformity during patient's life. In case of moderate deformity in a well aligned adolescent, it's a big concern to decide when to do the surgery. Objective of this work was to evaluate and compare clinical, radiological and surgical data of patients with adolescent idiopathic scoliosis operated in childhood (before 20 years) and those operated adults (after 35 years). METHODS: In this retrospective multicenter study, inclusion period extended from 2008 to 2018. Two groups were defined, those operated on before the age of 20 (YAIS), and those operated on after 35 years (OAIS). Demographic, radiographic and surgical data were collected. At follow-up, radiographic data and functional outcomes (VAS, SRS, SF12, Oswestry) were analyzed. Minimum FU was 5 years for young and 2 years for old patients. RESULTS: YAIS group included 364 patients, and OAIS group, 131 patients. In both groups, deformity was important (mean Cobb 63°). Vertebral osteotomies were significantly more frequent, fusions and length of stays were longer for old than young patients. Main Cobb correction was better in young than old (37 ± 10° vs 2 ± 13°, p = 0.03). Functional outcomes were better for young, operated patients than for operated groups after 35 years (SF12 PCS 50 ± 7 vs 39 ± 6, p = 0.02). The same trends were observed at longer follow-up. CONCLUSION: Surgery for idiopathic scoliosis seems to offer a better quality of life and deformity correction when it is performed at adolescence. After 35 years, surgery remains an acceptable therapeutic option, despite higher complication rate.

Optimization of radiation doses for open lumbar spinal fusion using C-arm fluoroscopy and impact on radiation-induced cancer: a pilot study.

PURPOSE: Intraoperative fluoroscopy use is essential during spinal fusion procedures. The amount of radiation dose should always be minimized. This study aimed to determine the feasibility of halving the frame rate from 12.5 to 6.25 frames per second (fps) and to quantify the reduction in the risk of developing radiation-induced cancer. METHODS: This pilot study included 34 consecutive patients operated for open lumbar posterolateral fusion (PLF) with or without transforaminal lumbar interbody fusion (TLIF). C-arm modes were changed from half-dose (12.5 frames per second (fps), group I) to quarter-dose (6.25 fps, group II). Age, body mass index, surgical procedure, number of treated levels, and complications were collected. Kerma area product (KAP), cumulative air kerma (CAK), and fluoroscopy time were compared. Effective dose and radiation-induced cancer risk were estimated. RESULTS: Eighteen and 16 patients were, respectively, included in group I and II. Demographic, surgical data, and fluoroscopy time were similar in both groups. However, CAK, KAP, and effective dose were significantly lower in group II, respectively, 0.56 versus 0.41 mGy (p = 0.03), 0.09 versus 0.06 Gy cm2 (p = 0.04), and 0.03 versus 0.02 mSv (p = 0.04). Radiation-induced cancer risk decreased by 47.7% from 1.49 × 10-6 to 7.77 × 10-7 after optimization. No complications were recorded in either group. CONCLUSION: This study demonstrates the feasibility of setting 6.25 fps for TLIF with and without PLF. By halving the fps, radiation-induced cancer risk could be almost divided by two, without compromising surgical outcome. Finally, after optimization, the risk of developing radiation-induced cancer was less than one in a million.

Readmission rate after adult scoliosis surgery on primary cases over 45 years-old with long term follow-up.

PURPOSE: Scoliosis surgery is becoming increasingly frequent. Rate of readmission is little discussed in the literature. It is an interesting data for the patient's information and for public authorities to calculate cost-effectiveness. Aim of the study was to evaluate rate and causes of short and long-term readmissions in patients > 45 years old operated on for a scoliosis primary cases, then to look for predictors of these readmissions. METHODS: In this monocentric retrospective cohort study, over 45 years-old scoliosis primary cases operated on between 2015 and 2018 and with a minimum of 2 years follow-up were included. The number of readmissions and their causes were analyzed. Rehospitalized patients (RH) were then compared to non-rehospitalized patients (NRH). Risk factors were sought using a multivariate analysis by logistic regression. RESULTS: 105 patients were included (90% female; 64 ± 8 years). 56% were readmitted at least once. Main cause of readmission as pseudarthrosis (70%). Among the RH patients, fifty-eight required at least one revision. We found no significant difference between RH and NRH, apart from the rate of immediate post-operative medical complications which was significantly higher in RH (17% (n = 11) vs. 4% (n = 2), p = 0.04). According to multivariate analysis, BMI and age were found as predictors of readmission of mechanical origin, and BMI for readmissions of septic origin. CONCLUSION: The readmission rate after scoliosis surgery was 56%. The main cause was pseudarthrosis. Rehospitalized patients had more immediate post-operative medical complications. The elderly and overweight patients are more likely to be readmitted for mechanical or septic reasons.

Sex-dependent evolution of whole-body postural alignment with age.

PURPOSE: The goal of this study was to explore sex-related variations of global alignment parameters and their distinct evolution patterns across age groups. METHODS: This multicentric retrospective study included healthy volunteers with full-body biplanar radiographs in free-standing position. All radiographic data were collected from 3D reconstructions: global and lower limb parameters, pelvic incidence (PI) and sacral slope (SS). Lumbar lordosis (LL), thoracic kyphosis (TK) and cervical lordosis (CL) were also assessed as well as the lumbar and thoracic apex, and thoracolumbar inflexion point. The population was divided into five 5 age groups: Children, Adolescents, Young, Middle-Aged and Seniors. RESULTS: This study included 861 subjects (53% females) with a mean age of 34 ± 17 years. Mean PI was 49.6 ± 11.1 and mean LL was - 57.1 ± 11.6°. Females demonstrated a PI increase between Young and Middle-Aged groups (49 ± 11° vs. 55 ± 12°, p < 0.001) while it remained stable in males. SS and LL increased with age in females while remaining constant in males between Children and Middle-aged and then significantly decreased for both sexes between Middle-Aged and Seniors. On average, lumbar apex, inflexion point, and thoracic apex were located one vertebra higher in females (p < 0.001). After skeletal maturity, males had greater TK than females (64 ± 11° vs. 60 ± 12°, p = 0.04), with significantly larger CL (-13 ± 10° vs. -8 ± 10°, p = 0.03). All global spinal parameters indicated more anterior alignment in males. CONCLUSION: Males present more anteriorly tilted spine with age mainly explained by a PI increase in females between Young and Middle-Aged, which may be attributed to childbirth. Consequently, SS and LL increased before decreasing at senior age.

Scoliosis.

Scoliosis is a three-dimensional spinal deformity that can occur at any age. It may be idiopathic or secondary in children, idiopathic and degenerative in adults. Management of patients with scoliosis is multidisciplinary, involving rheumatologists, radiologists, orthopaedic surgeons, and prosthetists. Imaging plays a central role in diagnosis, including the search for secondary causes, follow-up, and preoperative work-up if surgery is required. Evaluating scoliosis involves obtaining frontal and lateral full-spine radiographs in the standing position, with analysis of coronal and sagittal alignment. For adolescent idiopathic scoliosis, imaging follow-up is often required, accomplished using low-dose stereoradiography such as EOS imaging. For adult degenerative scoliosis, the crucial characteristic is rotatory subluxation, also well detected on radiographs. Magnetic resonance imaging is usually more informative than computed tomography for visualizing associated canal and foraminal stenoses. Radiologists must also have a thorough understanding of postoperative features and complications of scoliosis surgery because aspects can be misleading.

Pedagogy in spine surgery: developing a free and open-access virtual simulator for lumbar pedicle screws placement.

PURPOSE: Simulators for pedicle screws placement range from basic sawbones to virtual reality. Yet, they remain expensive and often require specific devices. No free online virtual simulator has yet been developed. The goal was to design a freely accessible Web-based simulator. METHODS: The computer simulator consisted of a lumbar spine, a red box hiding the pedicles and five pairs of screws. After inserting the screws, the red box was removed to assess their position. A validation study was conducted with 24 medical students randomized into a simulation and a control group. All had a basic course on pedicle screws. The 12 simulation group students performed two sessions on computer. All 24 students then conducted a final common step on sawbones. The number of misplaced screws, types of breaches, and simulation times were analyzed. RESULTS: In the final sawbones simulation, 96 real screws were studied. Control group misplaced 50% of their screws compared with only 20.8% in the simulation group (p < 0.05). More careful, simulation group students were slower to insert their real screws. Over the two computer simulations, the rate of misplaced screws decreased (12.5% vs. 38.3%), showing a good handling of the simulator. Students were able to analyze and correct their pedicle breaches. CONCLUSION: This tool is the first free online lumbar pedicle screws simulator. Simulation helped students to better position the final real screws on sawbones. This project showed it was possible to create a free educational tool with no special equipment. LEVEL OF EVIDENCE: Level 3.

Femoral neck version in the spinopelvic and lower limb 3D alignment: a full-body EOS® study in 400 healthy subjects.

BACKGROUND: The goal of this study was to better understand the variation of femoral neck version according to spinopelvic and lower limb 3D alignment using biplanar X-rays in standing position. METHODS: This multicentric study retrospectively included healthy subjects from previous studies who had free-standing position biplanar radiographs. Subjects were excluded if they presented spinal or any musculo-skeletal deformity, and reported pain in the spine, hip or knee. Age, sex, and the following 3D-reconstructed parameters were collected: spinal curvatures, pelvic parameters, sagittal vertical axis (SVA), T1 pelvic angle (TPA), spino-sacral angle (SSA), femoral torsion angle (FTA), sacro-femoral angle (SFA), knee flexion angle (KA), ankle angle (AA), pelvic shift (PS) and ankle distance. Femoral neck version angle (FVA) was calculated between horizontal plane projection of the bi-coxo-femoral axis and the line passing through the femoral neck barycenter and femoral head center. Analysis according to age subsets was performed. RESULTS: A total of 400 subjects were included (219 females); mean age was 29 ± 18 years (range: 4-83). Subjects with high pelvic tilt values presented significantly higher FVA than average and low-PT individuals, respectively, 7.8 ± 7.1°, 2 ± 9° and 2.1 ± 9.5° (p < 0.001). These subjects also presented lower lumbar lordosis values and higher acetabulum anteversion in the horizontal plane than the two other groups. SVA correlation with FVA was weaker (r = 0.1, p = 0.03) than SSA and TPA (r = - 0.3 and r = 0.3, respectively, p < 0.001). A strong correlation was found with femoral torsion (r = 0.5, p < 0.001). SFA (r = - 0.3, p < 0.001), pelvic shift (r = 0.2, p < 0.001) and ankle distance (r = 0.3, p < 0.001) were also significantly correlated. Multivariate analysis confirmed significant association of age, pelvic tilt, lumbar lordosis, pelvic shift, ankle distance and femoral torsion with FVA. CONCLUSION: Patients with lower lumbar lordosis present pelvic retroversion which induces a higher femoral neck version. This finding may help positioning implants in total hip replacement procedures. Higher pelvic shift, age, male gender and increased femoral torsion were also correlated with higher FVA. LEVEL OF EVIDENCE: II (Diagnostic: individual cross-sectional studies with consistently applied reference standard and blinding).

Sagittal correction after short percutaneous fixation for thoracolumbar compression fractures: comparison of the combination of SpineJack® kyphoplasty and fractured vertebra screw fixation.

PURPOSE: The aim of this study was to compare two percutaneous pedicle fixations for the treatment of thoracolumbar fractures: one associating a jack kyphoplasty (SpineCut) and the other using intermediate screws (Trident). METHODS: All adult patients treated for single-level Magerl/AO type A thoracolumbar traumatic fractures in four orthopaedic departments, with SpineCut or Trident, with a one year minimum follow-up, were retrospectively included. Neurological disorders and osteoporotic fractures were not included. The following data were collected: age, sex, Magerl/AO type, type of surgery, and complications. Radiological parameters were analyzed on pre-operative CT scan, and on standing X-rays before discharge, at three months and one year post-operative: vertebral wedge angle (VWA), regional kyphosis angle (RKA), and traumatic regional angulation (TRA: difference between RKA and physiological values for each vertebra). RESULTS: Eighty patients were included, with 42 patients in SpineCut group and 38 in Trident group. Mean age was 41 ± 15.7 years. TRA correction did not differ between the groups: respectively 11.2 ± 8.1° in SpineCut versus 10.2 ± 9.1° in Trident group (p = 0.52). TRA loss of correction between early post-operative and three months was statistically higher in Trident group: -4 ± 5.1° versus -1.5 ± 3.8° (p = 0.03). After 3 months, TRA correction loss was comparable between the groups. Multivariate analysis demonstrated that pre-operative VWA was the only factor significantly associated with early TRA correction loss (p = 0.01). VWA correction and loss of correction did not differ significantly between the groups. No complications were observed. CONCLUSION: Percutaneous pedicle fixations of traumatic thoracolumbar fractures associating jack kyphoplasty and intermediate screws are both safe and efficient techniques.

Implant removal after short percutaneous pedicle fixation associated with SpineJack® kyphoplasty: is correction sustained?

PURPOSE: This study objective was to evaluate sagittal correction loss after instrumentation removal in patients treated for thoracic or lumbar compression fractures treated with SpineJack® kyphoplasty associated with short percutaneous pedicle screw fixation. METHODS: This retrospective multicenter study was carried out in three major French trauma centers. All patients with a single type A thoracic or lumbar fracture, treated by the studied technique between 2017 and 2020, have been included. Demographic data, fracture type, removal procedure achievement and term were collected. Radiological parameters were measured at five timepoints: pre-operative, intra-operative, immediate post-operative, early post-operative (< 3 months) and at follow-up (1 year). Vertebral wedge angle (angle between the two endplates of the fractured vertebra) and traumatic regional angulation (TRA-calculated by subtracting regional kyphosis from the physiological reference values). RESULTS: 150 patients were included. Mean age was 48.6 ± 17.8 years. Average follow-up was 14.4 ± 3 months. 82 patients had secondary instrumentation removal. Mean time to removal was 6.4 ± 2.4 months. TRA correction loss between immediate post-operative and last follow-up was greater in removal group: 5.1 ± 5.6° versus 2.7 ± 4.7° (p = 0.01). Material was removed earlier in younger patients (p = 0.002). TRA correction loss was similar in the early and late removal groups (p = 0.83). Multivariate analysis identified only Magerl/AO A3 fractures as risk factor for loss of TRA correction (p = 0.007). CONCLUSION: Instrumentation removal was associated with good radiological outcomes with a non-significant loss of vertebral wedge angle and tolerable loss of traumatic regional angulation (+ 2.4° compared to the no-removal group), even if performed early.

Lumbar Spine Posttherapeutic Imaging.

Management of patients after lumbar spine surgery or interventional radiology can be complex, and postoperative imaging patterns are often poorly understood by nonspecialized radiologists. This article focuses on postoperative imaging features of the lumbar spine in five clinical settings (with corresponding interventions): vertebral osteoporotic fractures (percutaneous vertebroplasty and vertebral augmentation), lumbar disk herniation (surgical diskectomy and percutaneous interventional radiology), lumbar spinal stenosis (surgical decompression), lumbar spondylolisthesis (surgical decompression and fusion), and degenerative scoliosis (techniques of osteotomies).For each intervention, we discuss imaging indications, depending if the patient is asymptomatic or if there are suspected complications, describe normal and pathologic imaging features, and present key points.

The rib cage: a new element in the spinopelvic chain.

INTRODUCTION: This study analyzes anatomical variations of the thoracic cage (TC) according to spinopelvic alignment, age and gender using stereoradiography in erect position. METHODS: This retrospective multicentric study analyzed computed parameters collected from free-standing position bi-planar radiographs, among healthy subjects. Collected data were: age, gender, pelvic parameters (Pelvic Incidence, Pelvic Tilt (PT) and Sacral Slope), T1-T12 Kyphosis (TK), L1-S1 Lordosis (LL), curvilinear spinal length, global TC parameters (maximum thickness and width, rib cage volume, mean Spinal Penetration Index (SPI)), 1st-10th rib parameters (absolute and relative (to the corresponding vertebra) sagittal angles). RESULTS: Totally, 256 subjects were included (140 females). Mean age was 34 (range: 8-83). Significant correlations were found between TK and TC thickness (0.3, p < 0.001) and with TC Volume (0.3, p = 0.04), as well as rib absolute sagittal angle for upper and middle ribs (0.2, p = 0.02). Conversely, a -0.3 correlation has been exhibited between SPI and TK. Similar correlations were found with LL. PT significantly correlated with TC thickness (0.4, p = 0.003), SPI (-0.3, p = 0.03), and all rib relative sagittal angles. Among global TC parameters, only thickness and SPI significantly changed after 20 years (respectively, 0.39 and -0.52, p < 0.001). Ribs relative sagittal angle showed negative correlation with age in skeletally mature subjects (p < 0.001). CONCLUSION: This study demonstrates the correlation between TC anatomy and spinopelvic parameters, confirming its part of the spinopelvic chain of balance. Indeed, higher spinal curvatures were associated with lower SPI and higher TC thickness, TC volume and rib absolute sagittal angles.

Variation of cervical sagittal alignment parameters according to gender, pelvic incidence and age.

PURPOSE: The aim was to describe radiographic cervical sagittal alignment variations according to age, gender and pelvic incidence (PI) and to investigate relationships with thoracic alignment. METHODS: A total of 2599 individuals (5-93 years) without spinal deformity were studied. Cranial cervical parameters were: McGregor slope, occipita-C2 angle, McGregor-C2 lordosis and C1-C2 lordosis. Caudal cervical parameters were: C2-C7, cranial arch and caudal arch lordosis and C7- and T1-slope. A Bayesian inference compared parameter distributions. Correlations with spinopelvic and global alignment parameters were investigated. RESULTS: Among cranial cervical parameters, variations of McGregor slope were non-significant. McGregor-C2 lordosis and C1-C2 lordosis were smaller in males and increased significantly during growth, whereas the occipito-C2 angle decreased (Pr > 0.95). The occipito-C2 angle was larger and McGregor-C2 lordosis was smaller in low PI (Pr > 0.95). Among caudal cervical parameters, C2-C7 lordosis and C7- and T1-slope were larger in males and increased after 50 years (Pr > 0.95). Lordosis changes were non-significant in the cranial arch, whereas values increased in the caudal arch after 35 years (Pr > 0.95). Caudal parameter differences were non-significant between PI groups. Strong correlations existed between C2-C7, caudal arch lordosis, C7-slope, T1-slope and thoracic kyphosis. The sagittal vertical axis C2 correlated with caudal arch lordosis and T1-slope (ρ > 0.5; Pr > 0.95). CONCLUSION: Cervical alignment parameters vary according to age, gender and PI. In the cranial cervical spine, changes occur mainly during growth. In the caudal cervical spine, lordosis increases in the caudal arch, which is related to thoracic kyphosis increase with age. The caudal cervical arch acts as a compensatory segment by progressive extension, allowing horizontal gaze.

Global alignment taking into account the cervical spine with odontoid hip axis angle (OD-HA).

INTRODUCTION: Global alignment analysis is of upmost importance in adult spinal deformity patients (ASD). Numerous parameters exist in the literature to measure global alignment based upon C7 or T1. One common limitation of these parameters is that they neglect the cervical segment which is essential in spinal compensatory mechanisms and in horizontal gaze preservation. A recent stereoradiography analysis of asymptomatic subjects introduced a new 3D parameter (ODHA), defined as the angle between the vertical reference line and the line joining the odontoid tip (OD) to hip axis center (HA). Thus, the goal of this study was to analyze 3D global alignment of ASD patients using the new parameter odontoid hip axis angle and its relationship to other spinal parameters. METHODS: In this prospective study, 90 adult patients with lumbar scoliosis (Cobb > 20°) were included. All subjects underwent low dose biplanar X-rays with 3D spinal reconstructions. Based on published normative values of ODHA, we defined abnormally high value as mean ODHA of asymptomatic subject + 2SD (i.e., ODHA > 6.1°). Values of 3D radiographic parameters and ODI were compared between patients with ODHA > 6.1° and < 6.1°. RESULTS: Mean ODHA was 5+/- 3.6° (0.4° to 18.6°). 22 patients had abnormally high ODHA. They were older than the 68 other patients (68+/- 9y vs 53+/- 14y, p = 0.001), without any significant difference in terms of sex, BMI and rate of rotatory subluxation (54% vs 62%, p = 0.06). However, coronal and sagittal deformity was more important in patients with abnormal ODHA (larger Cobb angle, coronal malalignment, pelvic tilt and lower lumbar lordosis). Patients with abnormal ODHA had significantly worst ODI (50+/- 23 vs 30+/- 18, p = 0.0005). CONCLUSION: Extreme values of ODHA are observed in significantly older patients with significant functional impairment. In addition, in these patients with sagittal malalignment with loss of lumbar lordosis, who recruit compensatory mechanisms such as pelvic retroversion, the cervical area is also involved with a posture in cervical hyperlordosis to maintain the head over the pelvis. Thus, ODHA is an interesting parameter allowing a more comprehensive alignment measurement taking into account the mechanisms of compensation of the cervical spine to the pelvis.

Pseudarthrosis in adult spine deformity surgery: risk factors and treatment options.

PURPOSE: Highlight risk factors for pseudarthrosis in long-segment spinal fusions, collect the approaches carried to address this complication. METHODS: Patients with ASD and fusion of ≥ 4 levels with minimum follow-up (FU) of ≥ 2 years were included. Full-body X-rays were done preoperatively, < 3 months and ≥ 2 years. Oswestry disability index (ODI), Scoliosis Research Society-22 and SF36 assessed pre- and postoperatively. The relationship between demographic, surgical and radiological variables with the development of pseudarthrosis was evaluated. RESULTS: Out of 524 patients included, 65 patients (12.4%) developed pseudarthrosis and 53 underwent revision surgery. Notably, 88% of pseudarthrosis cases are associated with fusion length (OR = 1.17, 95% CI = 1.05-1.292, p = 0.004), osteotomy requirement (OR = 0.28, 95% CI = 0.09-0.85, p = 0.025), pelvic fixation (OR = 0.34, 95% CI = 0.13-0.88, p = 0.026) and combined approaches (OR = 3.29, 95% CI = 1.09-9.91, p = 0.034). Sagittal alignment is not related to the rate of pseudarthrosis. Health related and quality of life scores were comparable at last FU between patients revised for pseudarthrosis and those that didn't require revision surgery (ODI = 28% no revision and 30% revision group). CONCLUSIONS: Pseudarthrosis is not related to malalignment, but with the surgical techniques employed for its treatment. Anterior approaches with anterior support decrease the rate by 30%, while long fusions, osteotomies and pelvic fixation increase its rate.

Dynesys® dynamic stabilization outcomes in degenerative spine surgery.

Dynesys® is a dynamic device used for posterior stabilization of the lumbar spine. The objective of this study was to analyze the clinical and radiological outcomes at a 2-year minimum follow-up. In this retrospective study, patients operated between 2009 and 2016 with Dynesys® stabilization were included. 5 different etiologies were included: disc herniation, lumbar stenosis, revision for adjacent seg- ment disease (ASD), spondylolisthesis, and scoliosis. Clinical and radiological evaluations were performed. Postoperative complications and revisions were recorded. 136 patients were included: 34 for lumbar spinal stenosis, 19 for disc herniation, 29 degenerative spon- dylolisthesis, 41 revisions for ASD, and 13 scoliosis. Mean age was 64.8. Average clinical follow-up was 46 months. Postoperative clinical results showed a mean lumbar VAS of 3.07, a mean radicular VAS of 3.01 and an ODI score of 31.8%. The ASD rate was 16.2%, and overall revision rate was 11.8%. 2 cases (1.5%) of screw loosening were identified. Clinical outcomes, ASD rate and revision rate were more favorable in the spondylolisthesis and disc herniation groups. This study has one of the largest Dynesys® cohort in literature. Spinal dynamic stabilization by Dynesys® presents good long-term clinical and radiological out- comes with a lower rate of complications than pre- viously published cohorts and lumbar fusions. Best indications seem to be degenerative spondylolisthesis.

Relationships between radiographic parameters and spinopelvic muscles in adult spinal deformity patients.

INTRODUCTION: While the clinical impact of coronal and sagittal alignment in adult spinal deformity (ASD) patients (pts) is established, there is a paucity of data in terms of axial plane deformity and potential association between muscle degeneration and 3D deformity. The purpose of this study was to analyze spinopelvic muscles characteristics in association with the 3D deformity of ASD patients. METHODS: This is a prospective cohort study; primary lumbar scoliosis patients (Cobb > 20°) were enrolled and sustained a low-dose X-rays with 3D spinal reconstructions and a fat/water separation MRI (from C7 to the knee). Volumetric 3D reconstructions and fat infiltration (FI) of 6 muscles groups were performed. Relationships between muscular data, radiographic parameters and health-related quality of life were investigated. Patients were stratified and compared based on the SRS classification, the odontoid-hip axis (ODHA) angle (> or < 6.1°) and occurrence of rotatory subluxation. RESULTS AND DISCUSSION: Twenty-eight patients were enrolled with a mean age of 60 ± 16yo and mean body mass index of 26 ± 4 kg/m2 without differences between groups. There were a moderate sagittal malalignment and a Cobb angle of 45 ± 11° (table). Muscular volume was smaller in patients with more severe deformity (p > 0.05). Pts with ODHA > 6.1° or pelvic incidence minus lumbar lordosis > 10° had significantly higher FI for the 6 muscular groups, patients with pelvic tilt > 20° had significantly higher FI for erector spinae, hip flexors and extensors (p < 0.05). SF36-PCS significantly correlated with the muscular volume; SRS and Oswestry disability index correlated with the erectors spinae volume (p < 0.05). CONCLUSION: This study analyzed for the first time the relationship between 3D radiographic parameters and muscular characteristics in ASD. Sagittal malalignment is associated with increased FI and decreased muscle volumes with poor outcomes. These slides can be retrieved under Electronic Supplementary Material.

Efficacy of the Game Ready® cooling device on postoperative analgesia after scoliosis surgery in children.

PURPOSE: The aim of this study was to investigate the opioid-sparing effect of a cooling brace after surgical correction of idiopathic surgery in children. METHODS: We compared two consecutive cohorts of patients before and after introducing this technique in our institution. Management of patients was standardized. The primary objective of the study was to investigate the morphine consumption during the first postoperative day. Secondary outcomes were opioid consumption at day 3, pain intensity (at days 1 and 3), the mobilization in the standing position and duration of hospitalization. RESULTS: This study included 23 and 22 patients in the control and the cooling cohorts. Cooling brace was associated with a significant decrease in morphine consumption at day 1 (1.7 [0.9, 3.3] versus 1.2 [0.5, 3.2] mg kg-1, P = 0.02) and day 3 (2.5 [0.5, 6.7] versus 1.2 [0.9, 2.5] mg kg-1, P = 0.003), and a reduction in duration of hospitalization (4 [3, 6] versus 3 [3, 4] days, P = 0.004). However, no difference was found on the pain intensity or the percentage of patient mobilized in the standing position. Number of level fused and intraoperative opioid consumption were also different between the two cohorts. However, multivariate analysis found only the use of the cooling brace as significantly associated with opioid consumption at day 1. CONCLUSION: The use of this cooling brace allows decreasing the opioid use after surgical correction of idiopathic surgery in children. The current results strongly suggest an interest of this technique in the postoperative management of patients. These slides can be retrieved under Electronic Supplementary Material.

Correction to: Efficacy of the Game Ready® cooling device on postoperative analgesia after scoliosis surgery in children.

Unfortunately, one co-author name was incorrectly published in the original publication. The complete correct name of the co-author is given below.

Preliminary experience with SpineEOS, a new software for 3D planning in AIS surgery.

PURPOSE: Preoperative planning of scoliosis surgery is essential in the effective treatment of spine pathology. Thus, precontoured rods have been recently developed to avoid iatrogenic sagittal misalignment and rod breakage. Some specific issues exist in adolescent idiopathic scoliosis (AIS), such as a less distal lower instrumented level, a great variability in the location of inflection point (transition from lumbar lordosis to thoracic kyphosis), and sagittal correction is limited by both bone-implant interface. Since 2007, stereoradiographic imaging system is used and allows for 3D reconstructions. Therefore, a software was developed to perform preoperative 3D surgical planning and to provide rod's shape and length. The goal of this preliminary study was to assess the feasibility, reliability, and the clinical relevance of this new software. METHODS: Retrospective study on 47 AIS patients operated with the same surgical technique: posteromedial translation through posterior approach with lumbar screws and thoracic sublaminar bands. Pre- and postoperatively, 3D reconstructions were performed on stereoradiographic images (EOS system, Paris, France) and compared. Then, the software was used to plan the surgical correction and determine rod's shape and length. Simulated spine and rods were compared to postoperative real 3D reconstructions. 3D reconstructions and planning were performed by an independent observer. RESULTS: 3D simulations were performed on the 47 patients. No difference was found between the simulated model and the postoperative 3D reconstructions in terms of sagittal parameters. Postoperatively, 21% of LL were not within reference values. Postoperative SVA was 20 mm anterior in 2/3 of the cases. Postoperative rods were significantly longer than precontoured rods planned with the software (mean 10 mm). Inflection points were different on the rods used and the planned rods (2.3 levels on average). CONCLUSION: In this preliminary study, the software based on 3D stereoradiography low-dose system used to plan AIS surgery seems reliable for preoperative planning and precontoured rods. It is an interesting tool to improve surgeons' practice, since 3D planning is expected to reduce complications such as iatrogenic malalignment and to help for a better understanding of the complications, choosing the location of the transitional vertebra. However, further work is needed to improve thoracic kyphosis planning. These slides can be retrieved under Electronic Supplementary Material.