Comparison of degenerative lumbar scoliosis correction and risk for mechanical failure using posterior 2-rod instrumentation versus 4-rod instrumentation and interbody fusion.

PURPOSE: Four-rod instrumentation and interbody fusion may reduce mechanical complications in degenerative scoliosis surgery compared to 2-rod instrumentation. The purpose was to compare clinical results, sagittal alignment and mechanical complications with both techniques. METHODS: Full spine radiographs were analysed in 97 patients instrumented to the pelvis: 58 2-rod constructs (2R) and 39 4-rod constructs (4R). Clinical scores (VAS, ODI, SRS-22, EQ-5D-3L) were assessed preoperatively, at 3 months, 1 year and last follow-up (average 4.2 years). Radiographic measurements were: thoracic kyphosis, lumbar lordosis, spinopelvic parameters, segmental lordosis distribution. The incidence of non-union and PJK were investigated. RESULTS: All clinical scores improved significantly in both groups between preoperative and last follow-up. In the 2R-group, lumbar lordosis increased to 52.8° postoperatively and decreased to 47.0° at follow-up (p = 0.008). In the 4R-group, lumbar lordosis increased from 46.4 to 52.5° postoperatively and remained at 53.4° at follow-up. There were 8 (13.8%) PJK in the 2R-group versus 6 (15.4%) in the 4R-group, with a mismatch between lumbar apex and theoretic lumbar shape according to pelvic incidence. Non-union requiring revision surgery occurred on average at 26.9 months in 28 patients (48.3%) of the 2R-group. No rod fracture was diagnosed in the 4R-group. CONCLUSION: Multi-level interbody fusion combined with 4-rod instrumentation decreased risk for non-union and revision surgery compared to select interbody fusion and 2-rod instrumentation. The role of additional rods on load sharing still needs to be determined when multiple cages are used. Despite revision surgery in the 2R group, final clinical outcomes were similar in both groups. LEVEL OF EVIDENCE: III.

Augmented reality and artificial intelligence-based navigation during percutaneous vertebroplasty: a pilot randomised clinical trial.

PURPOSE: To assess technical feasibility, accuracy, safety and patient radiation exposure of a novel navigational tool integrating augmented reality (AR) and artificial intelligence (AI), during percutaneous vertebroplasty of patients with vertebral compression fractures (VCFs). MATERIAL AND METHODS: This prospective parallel randomised open trial compared the trans-pedicular access phase of percutaneous vertebroplasty across two groups of 10 patients, electronically randomised, with symptomatic single-level VCFs. Trocar insertion was performed using AR/AI-guidance with motion compensation in Group A, and standard fluoroscopy in Group B. The primary endpoint was technical feasibility in Group A. Secondary outcomes included the comparison of Groups A and B in terms of accuracy of trocar placement (distance between planned/actual trajectory on sagittal/coronal fluoroscopic images); complications; time for trocar deployment; and radiation dose/fluoroscopy time. RESULTS: Technical feasibility in Group A was 100%. Accuracy in Group A was 1.68 ± 0.25 mm (skin entry point), and 1.02 ± 0.26 mm (trocar tip) in the sagittal plane, and 1.88 ± 0.28 mm (skin entry point) and 0.86 ± 0.17 mm (trocar tip) in the coronal plane, without any significant difference compared to Group B (p > 0.05). No complications were observed in the entire population. Time for trocar deployment was significantly longer in Group A (642 ± 210 s) than in Group B (336 ± 60 s; p = 0.001). Dose-area product and fluoroscopy time were significantly lower in Group A (182.6 ± 106.7 mGy cm2 and 5.2 ± 2.6 s) than in Group B (367.8 ± 184.7 mGy cm2 and 10.4 ± 4.1 s; p = 0.025 and 0.005), respectively. CONCLUSION: AR/AI-guided percutaneous vertebroplasty appears feasible, accurate and safe, and facilitates lower patient radiation exposure compared to standard fluoroscopic guidance. These slides can be retrieved under Electronic Supplementary Material.

Combined percutaneous and open instrumentation for thoracolumbar kyphosis correction by two-level pedicle subtraction osteotomy in ankylosing spondylitis.

BACKGROUND: A long global thoracolumbar kyphosis is common in ankylosing spondylitis. Surgical correction of fixed sagittal malalignment by pedicle subtraction osteotomy (PSO) might improve disability and quality of life (QoL). Two-level osteotomies represent major procedures with a risk of hemorrhage. Combined open and minimal invasive surgery has not been described and might be considered. CASE PRESENTATION: A 30-year-old female with ankylosing spondylitis was treated by golimumab and teriparatide. The treatment was stopped during pregnancy which led to vertebral compression fractures and kyphosis of 50° between T11 and L3. A PSO was planned at the kyphotic apex L2. The second PSO was planned at L4 according to the pelvic incidence of 56°, matching with a spinopelvic alignment Roussouly type 3. A derived full balance integrated method was used to calculate the amount of correction. During the first stage surgery, an open approach was performed from L1 to pelvis and combined with percutaneous cement-augmented instrumentation in already fused segments T5-T12, thus reducing perioperative morbidity. A stepwise approach including L2 PSO closure with temporary rods and L4 PSO with final instrumentation was used. Blood loss was estimated around 1100 ml. The patient was able to walk on the second day after surgery. A secondary anterior fusion with LLI cages from L2 to L5 and an ALIF at L5-S1 were performed because of high non-ossified intervertebral disks to reduce the risk for nonunion and rod fractures. At 2-year follow-up, the patient's QoL had significantly improved and full spine radiographs showed stable normalized sagittal parameters. CONCLUSION: The combined open and percutaneous approach was feasible and might be considered as an alternative option to conventional open surgery when planning major deformity correction in ankylosing spondylitis.

Possible factors associated with sagittal malalignment recurrence after pedicle subtraction osteotomy.

PURPOSE: This retrospective study investigates sagittal alignment after pedicle subtraction osteotomy (PSO). The purpose was to investigate factors associated with malalignment recurrence. METHODS: Full spine radiographs were analyzed in 66 patients (average age 54.5 years, follow-up 3.8 years). Measurements were taken preoperatively, 3 months postoperatively, at follow-up: SVA C2 and C7, C2-C7 lordosis, T4-T12 kyphosis, L1-S1 lordosis, PSO lordosis, pelvic incidence, pelvic tilt, sacral slope. Follow-up CTs were screened for pseudarthrosis and gas in sacroiliac joints. RESULTS: PSO lordosis increased from 11.8° to 40.8° (p < 0.0001) and kept stable. Lumbar lordosis increased from 28.6° to 57.7° (p < 0.0001) and decreased to 49.7° (p = 0.0008). Pelvic tilt decreased from 29.2° to 16.5° (p < 0.0001) and increased to 22.5° (p < 0.0001). SVA C7 decreased from 105.1 to 35.5 mm (p < 0.0001) and increased to 64.8 mm (p = 0.0005). Twenty-eight patients (42%) had an SVA C7 increase of more than 70 mm in the postoperative course: recurrence group. These patients were older: 62.8 years versus 52.3 years (p = 0.0031). Loss of lordosis was 11.9° (recurrence group) versus 5.0° (non-recurrence group). Eleven patients (17%) had pseudarthrosis. Pelvic incidence increased by 9.3° (recurrence group) versus 3.8° (non-recurrence group). In 23 patients (35%), pelvic incidence increased > 10°. Gas was evidenced in sacroiliac joints in 22 patients (33%). CONCLUSION: Postoperative anterior malalignment recurrence may occur after PSO. Elderly patients were at risk of recurrence. Loss of lumbar lordosis linked to pseudarthrosis represented another factor. With malalignment recurrence, anterior trunk rotation and pelvic retroversion might additionally have augmented moments across sacroiliac joints with subsequent ligament laxity and pelvic incidence increase. These slides can be retrieved under Electronic Supplementary Material.

Osteoarthritis and spontaneous fusion of facet joints after percutaneous instrumentation in thoracolumbar fractures.

PURPOSE: This retrospective study determined the rate of osteoarthritis and spontaneous facet joint fusion and analyzed risk factors related to patient characteristics, fracture type or surgical technique on pre- and postoperative CT after percutaneous instrumentation in thoracolumbar fractures. METHODS: 1050 facet joints adjacent to screws in 148 patients (15-85 years) with thoracolumbar fractures were analyzed with an average time between CTs of 12.3 months. Screw diameters, lengths and cement augmentation were recorded. Facet joint violation by screw trajectory and by insertion depth was classified in three grades. Pre- and postoperative osteoarthritis was graded as absent, minor or severe and postoperative facet joint fusion as absent, partial or complete. RESULTS: The facet violation rate was moderate in 15.4% and severe in 0.6% according to screw trajectory, and 11.0 and 0.6%, respectively, according to insertion depth. Osteoarthritis was preoperatively rated moderate in 9.6% and severe in 1.2%. A progression was evidenced in 79 facet joints (7.5%). Screw cement augmentation was the main predictive factor (p < 0.0001). Partial fusion was evidenced in 2.6% and complete fusion in 1% of facet joints. Risk factors were: BMI (p = 0.0002), age (p = 0.0013), preoperative osteoarthritis (p = 0.0005), time between 2 CTs (p = 0.0001), B-type fractures (p = 0.0005), concomitant anterior fusion (p = 0.0034). CONCLUSIONS: Occurrence or worsening of osteoarthritis was mainly observed in elderly patients with cement-augmented screws and spontaneous facet fusion in elderly patients with high BMI and preoperative osteoarthritis, or in anteriorly fused B-type injuries. Thus, percutaneous instrumentation can safely be removed after fracture consolidation in younger patients while preserving facet joints.

Percutaneous Image-guided Laser Photocoagulation of Spinal Osteoid Osteoma: A Single-Institution Series.

PURPOSE: To retrospectively evaluate the safety and efficacy of percutaneous image-guided laser photocoagulation for the treatment of spinal osteoid osteoma (OO) in proximity to neural structures. MATERIALS AND METHODS: This study was institutional review board-approved with waivers of informed consent. From January 1994 until October 2014, 58 patients with spinal OO (mean age, 25 years; 40 men, 17 women) were treated in one institution by using laser photocoagulation with combined computed tomographic (CT) and fluoroscopic guidance. One patient was excluded because of less than 3 months of follow-up. All patients had typical clinical and imaging findings. Clinical features, radiologic data, and procedure-related data were reviewed, and limitations, complications, and failure rate were evaluated. All data were expressed as means ± standard deviation. P values of less than .05 were indicative of statistical significance. RESULTS: OO was in the vertebral body for 18 of 57 patients, the neural arch for 21 of 57 patients, and the articular process for 18 of 57 patients. Mean nidal diameter was 8 mm, and the mean distance from the closest neural structure was 6.6 mm (minimum distance, ≤5 mm in 35 of 57 patients). In 35 of 57 patients, no cortical coverage was present between the nidus and neural structure in danger. Mean total energy delivered was 1271 J (2-watt continuous power mode). Thermal insulation (carbon dioxide and/or hydrodissection), temperature monitoring, and electrostimulation were used in 42, 24, and one patient, respectively. Primary clinical success at 1 month was 98.2%. Total recurrence rate was 5.3%. All recurrences were addressed percutaneously. Secondary success rate was 100%. One-year follow-up is available in 54 of 57 patients. No major complications were noted. CONCLUSION: Spinal OO can be safely and effectively treated with percutaneous laser photocoagulation. In cases that are less than 8 mm to 10 mm distance and in the absence of cortical coverage, thermal protection techniques of the neural structures should be used.

Sacroiliac joint luxation after pedicle subtraction osteotomy: report of two cases and analysis of failure mechanism.

BACKGROUND: Sagittal decompensation after pedicle subtraction osteotomy (PSO) is considered as late onset complication. Several mechanisms have been suggested, but little attention has been paid to the caudal end of lumbar instrumented fusion, especially sacral iliac joint (SIJ) deterioration. METHODS: Clinical histories and radiographic sagittal parameters of two patients with SIJ luxation after PSO are presented. The biomechanical failure mechanism and risk factors are analysed. RESULTS: Two patients underwent correction of fixed anterior sagittal imbalance by PSO, followed by pseudarthrosis revision surgery. Both of them sustained persistent sacroiliac pain, progressive recurrence of anterior imbalance and progressive pelvic incidence (PI) increase around 10°. An acute bilateral SIJ luxation occurred in both patients leading to sharp increase or PI around 20°. One patient was treated by SIJ fusion and the other patient was placed on non-weight-bearing crutch ambulation for 1 year. Both patients had a high preoperative PI (95° and 78°). A theoretical match between lumbar lordosis (LL) and PI was not achieved by PSO. Osteopenia was present in both patients. Computed tomography evidenced L5-S1 pseudarthrosis and sacroiliac joint violation by pelvic or sacral ala screws. CONCLUSION: Patients with high PI might seek for further compensation at their SIJ when lacking LL after PSO. Chronic anterior imbalance might lead to progressive weakening of sacroiliac ligaments. Initial circumferential lumbosacral fusion and accurate iliac screw fixation might reduce stress on implants, risk for pseudarthrosis, implant failure and finally SIJ deterioration. Bone mineral density should further be investigated preoperatively.

Treatment of a spinal aneurysmal bone cyst using combined image-guided cryoablation and cementoplasty.

The authors describe the case of a 6.6-cm symptomatic spinal aneurysmal bone cyst (ABC) in a 17-year-old athlete treated percutaneously. Surgical treatment was not considered as the first option owing to its invasiveness and associated morbidity. CT-guided cryoablation of the expansile part of the ABC was performed for tumour shrinkage and nerve decompression. Thermal insulation, temperature monitoring and functional control/electrostimulation of the neural structures at risk were applied. Finally, the bony defect was cemented. No complications occurred during the procedure. Complete resolution of the ABC on imaging and clinical improvement were achieved. Percutaneous cryoablation should be considered as an alternative treatment option, especially when tumour size reduction is desired.

Fusion Rates of Different Anterior Grafts in Thoracolumbar Fractures.

STUDY DESIGN: Retrospective CT analysis of anterior fusion in thoracolumbar trauma. OBJECTIVE: The aim of this study was to compare fusion rates of different bone grafts and to analyze risk factors for pseudarthrosis. SUMMARY OF BACKGROUND DATA: Interbody fusion is indicated in anterior column defects. Different grafts are used: autologous iliac crest, titanium mesh cages filled with cancellous bone, and autologous ribs. It is not clear which graft offers the most reliable fusion. MATERIAL AND METHODS: Radiologic data of 116 patients (71 men, 45 women) operated for type A2, A3, B, or C fractures were analyzed. The average age was 44.6 years (range, 16-75 y) and follow-up was 2.7 years (range, 1-9 y). All patients were treated by posterior instrumentation followed by an anterior graft: 53 cases with iliac crest, 43 cases with mesh cages, and 20 with rib grafts. Fusion was evaluated on CT and classified into complete fusion, partial fusion, unipolar pseudarthrosis, and bipolar pseudarthrosis. RESULTS: Iliac crest fused in 66%, cages in 98%, and rib grafts in 90%. The fusion rate of cages filled with bone was significantly higher as the iliac graft fusion rate (P=0.002). The same was applied to rib grafts compared with iliac crest (P=0.041). Additional bone formation around the main graft, bridging both vertebral bodies, was observed in 31 of the 53 iliac crests grafts. Pseudarthrosis occurred more often in smokers (P=0.042). A relationship between fracture or instrumentation types, sex, age, BMI, and fusion could not be determined. CONCLUSIONS: Tricortical iliac crest grafts showed an unexpected high pseudarthrosis rate in thoracolumbar injuries. Their cortical bone is dense and their fusion surface is small. Rib grafts led to a better fusion when used in combination with the cancellous bone from the fractured vertebral body. Titanium mesh cages filled with cancellous bone led to the highest fusion rate and built a complete bony bridge between vertebral bodies. Smoking seemed to influence fusion. LEVEL OF EVIDENCE: Case control study, Level III.

Clinical Outcomes and Complications After Pedicle-anchored Dynamic or Hybrid Lumbar Spine Stabilization: A Systematic Literature Review.

STUDY DESIGN: A systematic medline review. OBJECTIVE: An overview of pedicle-based dynamic stabilization devices clinical outcomes. SUMMARY OF BACKGROUND DATA: Fusion is the standard instrumentation for many pathologies of the lumbar spine. Worrying rates of failure, including adjacent segment degeneration (ASD), have consistently been reported. The interest for dynamic stabilization came from the need of minimizing the long-term complications related to the restriction of the lumbar motion. However, pedicle-based dynamic stabilization advantages and drawbacks remain controversial. MATERIALS AND METHODS: Articles about the clinical outcomes were identified by a comprehensive Medline search. The inclusion criteria were a minimum follow-up of 12 months, indications for lumbar dynamic stabilization, and assessment of clinical outcomes and adverse events. The studied parameters included self-reported outcomes (pain, disability, and satisfaction) and complications. RESULTS: A total of 46 articles fulfilling the inclusion criteria were reviewed providing results for 2026 patients with a mean follow-up of 33 months. The postoperative improvements in terms of pain and disability were significant. Subjective assessment showed an overall patient satisfaction of 83.4%. Radiographic ASD occurred in 0%-34% of patients. Device breakage occurred in 0%-30%, and device loosening in 0%-72% of patients. The global amount of revision surgeries reached 9.4% mainly for breakage, ASD, or persistent pain, not always associated with screw loosening. CONCLUSIONS: Dynamic stabilization seems as safe and effective but benefits might partly come from decompressive gestures. Reported clinical outcomes seems to be comparable with outcomes published for fusion and no clear evidence of protection of the adjacent segments emerge from this mid-term review. Technical failures are design related but also linked with patient specificities. Relationships between sagittal balance and surgery outcomes are still rarely reported. Dynamic stabilization might display advantages in selected indications, such as moderate degeneration and beginning instability associated with clinical symptoms, but further clinical studies are needed.

Observational, Multicenter Study of the Efficacy and Safety of Cervical Disk Arthroplasty With Mobi-C in the Treatment of Cervical Degenerative Disk Disease. Results at 10 years Follow-Up.

BACKGROUND: Cervical disk arthroplasty replacement (CDA) was developed to avoid specific disadvantages of cervical fusion. The purpose of this paper is to provide 10-year follow-up results of an ongoing prospective study after CDA. METHODS: Three hundred eighty-four patients treated using the Mobi-C (ZimVie, Troyes, France) were included in a prospective multicenter study. Routine clinical and radiologic examinations were reported preoperatively and postoperatively with up to 10-year follow-up. Complications and revision surgeries were also documented. RESULTS: At 10 years showed significant improvement in all clinical outcomes [Neck Disability Index, visual analog scale (VAS) for arm and neck pain, physical component summary of SF36, and mental component summary of SF36). Motion at the index level increased significantly over baseline (mean range of motion=7.6 vs. 8 degrees at five years and 6.0 degrees preoperatively; P <0.001) and 71.3% of the implanted segments remained mobile (range of motion>3 degrees). Adjacent disks were also mobile at 10 years with the same mobility as preoperatively. At 10 years, 20.9% of the implanted segments demonstrated no heterotopic ossification. Thirty-four patients (8.9%) experienced 41 adverse events, with or without reoperation during the first five years. We found only two additional surgeries after five years. We observed an increased percentage of working patients and a decrease in medication consumption. Regarding the overall outcome, 94% of patients were satisfied. CONCLUSIONS: Our 10-year results showed significant improvement in all clinical outcomes, with low rates of revision or failure. This experience in patients with long-term follow-up after CDA endorses durable, favorable outcomes in properly selected patients.

Sagittal balance correction of idiopathic scoliosis using the in situ contouring technique.

PURPOSE: Idiopathic scoliosis can lead to sagittal imbalance. The relationship between thoracic hyper- and hypo-kyphotic segments, vertebral rotation and coronal curve was determined. The effect of segmental sagittal correction by in situ contouring was analyzed. METHODS: Pre- and post-operative radiographs of 54 scoliosis patients (Lenke 1 and 3) were analyzed at 8 years follow-up. Cobb angles and vertebral rotation were determined. Sagittal measurements were: kyphosis T4-T12, T4-T8 and T9-T12, lordosis L1-S1, T12-L2 and L3-S1, pelvic incidence, pelvic tilt, sacral slope, T1 and T9 tilt. RESULTS: Thoracic and lumbar curves were significantly reduced (p = 0.0001). Spino-pelvic parameters, T1 and T9 tilt were not modified. The global T4-T12 kyphosis decreased by 2.1° on average (p = 0.066). Segmental analysis evidenced a significant decrease of T4-T8 hyperkyphosis by 6.6° (p = 0.0001) and an increase of segmental hypokyphosis T9-T12 by 5.0° (p = 0.0001). Maximal vertebral rotation was located at T7, T8 or T9 and correlated (r = 0.422) with the cranial level of the hypokyphotic zone (p = 0.003). This vertebra or its adjacent levels corresponded to the coronal apex in 79.6 % of thoracic curves. CONCLUSIONS: Lenke 1 and 3 curves can show normal global kyphosis, divided in cranial hyperkyphosis and caudal hypokyphosis. The cranial end of hypokyphosis corresponds to maximal rotation. These vertebrae have most migrated anteriorly and laterally. The sagittal apex between segmental hypo- and hyper-kyphosis corresponds to the coronal thoracic apex. A segmental sagittal imbalance correction is achieved by in situ contouring. The concept of segmental imbalance is useful when determining the levels on which surgical detorsion may be focused.

Thoracolumbar fracture reduction by percutaneous in situ contouring.

PURPOSE: Percutaneous in situ contouring is based on bilateral bending of rods on the spine, thus increasing lordosis at the fracture. It was analyzed if this technique would provide a better reduction than prone positioning and how sagittal alignment would behave. METHODS: Twenty-nine patients were operated using in situ contouring and selective anterior fusion for non-neurologic A2, A3 or B2 fractures. Clinical results were assessed prospectively using visual analog scale (VAS) and Oswestry Disability Index (ODI). The radiographic deformity correction was measured by sagittal index and regional kyphosis. Sagittal balance was assessed using kyphosis, lordosis, T9 tilt, pelvic incidence, pelvic tilt and sacral slope. Posterior wall fragment reduction was evaluated by computed tomography. RESULTS: After 2 years, VAS and ODI were comparable to the status prior to the accident. The sagittal index was 19.7° preoperatively, 5.3° after prone positioning and -1.1° after in situ contouring (p < 0.001). The loss of correction was 2.4°, mainly during the first 3 months. Similar observations were made for regional kyphosis. The sagittal spino-pelvic alignment was stable postoperatively. A preoperative canal obstruction ≥50 % was observed in 16 patients, and the fragments migrated anteriorly in all patients. CONCLUSIONS: Percutaneous instrumentation and anterior fusion provides good clinical results. In situ contouring increases lordosis obtained by prone positioning. Anterior column lengthening and ligamentotaxis reduce posterior wall fragments, which decompress the canal without laminectomy. The fusion of anterior defects prevents the loss of correction and provides a stable sagittal profile. The instrumentation may be removed without damaging the paravertebral muscles and loss of correction.

Effects of lumbar artificial disc design on intervertebral mobility: in vivo comparison between mobile-core and fixed-core.

Although in theory, the differences in design between fixed-core and mobile-core prostheses should influence motion restoration, in vivo kinematic differences linked with prosthesis design remained unclear. The aim of this study was to investigate the rationale that the mobile-core design seems more likely to restore physiological motion since the translation of the core could help to mimic the kinematic effects of the natural nucleus. In vivo intervertebral motion characteristics of levels implanted with the mobile-core prosthesis were compared with untreated levels of the same population, levels treated by a fixed-core prosthesis, and normal levels (data from literature). Patients had a single-level implantation at L4L5 or L5S1 including 72 levels with a mobile-core prosthesis and 33 levels with a fixed-core prosthesis. Intervertebral mobility characteristics included the range of motion (ROM), the motion distribution between flexion and extension, the prosthesis core translation (CT), and the intervertebral translation (VT). A method adapted to the implanted segments was developed to measure the VT: metal landmarks were used instead of the bony landmarks. The reliability assessment of the VT measurement method showed no difference between three observers (p < 0.001), a high level of agreement (ICC = 0.908) and an interobserver precision of 0.2 mm. Based on this accurate method, this in vivo study demonstrated that the mobile-core prosthesis replicated physiological VT at L4L5 levels but not at L5S1 levels, and that the fixed-core prosthesis did not replicate physiological VT at any level by increasing VT. As the VT decreased when the CT increased (p < 0.001) it was proven that the core mobility minimized the VT. Furthermore, some physiologic mechanical behaviors seemed to be maintained: the VT was higher at implanted the L4L5 level than at the implanted L5S1 level, and the CT appeared lower at the L4L5 level than at the L5S1 level. ROM and motion distribution were not different between the mobile-core prosthesis and the fixed-core prosthesis implanted levels. This study validated in vivo the concept that a mobile-core helps to restore some physiological mechanical characteristics of the VT at the implanted L4L5 level, but also showed that the minimizing effect of core mobility on the VT was not sufficient at the L5S1 level.

Bacteriology of degenerated lumbar intervertebral disks.

STUDY DESIGN: A prospective microbiological analysis of intervertebral disk material in surgically treated patients presenting lumbar disk degeneration. OBJECTIVE: To determine the prevalence and species of bacteria in degenerated lumbar disks, their eventual role in the pathophysiology, and the possible influence of risk factors. SUMMARY OF BACKGROUND DATA: Intervertebral disk degeneration results from biochemical, mechanical, genetic, and toxic factors. The hypothesis of low-grade infection has been raised but not elucidated to date. METHODS: Eighty-three patients (34 males, 49 females, 41 y) were treated by lumbar disk replacement at L3-L4, L4-L5, or L5-S1. An intraoperative biopsy and microbiological culture were performed for each disk to determine if intradiskal bacteria were present. Magnetic resonance stages were Pfirrmann IV or V, with Modic I in 32, and Modic II in 25 cases. A preoperative discography was performed in 49 patients, 24 had previous nucleotomy. RESULTS: Bacteria were found in 40 disks, 43 cultures were sterile. The following bacteria were evidenced: Propionibacterium acnes 18, coagulase-negative staphylococci 16, gram-negative bacilli 3, Micrococcus 3, Corynebacterium 3, others 5. Ten biopsies presented 2 different species. Multinucleated cells were evidenced histologically in 33% of positive biopsies. Bacteria were predominantly found in males (P=0.012). The mostly positive level was L4-L5 (P=0.075). There was no significant relationship between bacterial evidence and Modic sign. A preoperative discography or previous nucleotomy did not represent significant contamination sources. None of the patients presented infectious symptoms. CONCLUSIONS: Although the hypothesis of biopsy contamination cannot be excluded, intradiskal bacteria might play a role in the pathophysiology of disk degeneration. However, the histologic presence of multinucleated cells may indicate an inflammatory process that could sustain the hypothesis of low-grade spondylodiscitis at 1 stage of the cascade of lumbar disk degeneration. These microbiological and histologic findings would need to be compared with nondegenerated disks. LEVEL OF EVIDENCE: : Diagnostic level III.

Comparison of open versus minimally invasive surgery in the treatment of thoracolumbar metastases.

INTRODUCTION: Minimally invasive surgery (MIS) techniques have been developed for the surgical treatment of thoracolumbar spinal metastases to reduce the morbidity associated with the operation. The purpose of our study was to compare the mean length of stay, change in pain levels, neurological symptoms, complications and survival after open versus MIS surgery. MATERIAL AND METHODS: This is a single-center retrospective study based on a register of patients treated for vertebral metastases between January 2014 and October 2016. The collection included demographic data, cancer-related data, clinical data, the characteristics of the surgery, the length of stay, assessment of pain and the occurrence of death. These data were compared between open and MIS surgery groups. RESULTS: Out of 59 patients, 35 were treated with open surgery and 24 were treated with MIS surgery. The two groups were comparable in terms of age, gender and body mass index. Breast, kidney, prostate and lung cancers were the most frequent primary tumors. Prognostic and instability scores were comparable. Short- and medium-term pain assessment showed comparable results. Median survival was 208 days in the open surgery group and 224days in the MIS group (p=0.5299). CONCLUSION: MIS techniques aim to limit the surgical approach and allow a faster introduction of adjuvant treatments than after open surgery. Our study did not find any differences between open and MIS surgery in terms of pain, neurological evolution or survival time in patients treated for thoracolumbar spinal metastases. LEVEL OF EVIDENCE: IV; retrospective study.

The influence of total disc arthroplasty with Mobidisc prosthesis on lumbar spine and pelvic parameters: a prospective in vivo biomechanical study with a minimum 3 year of follow-up.

BACKGROUND: This study examined the impact of Mobidisc implant on spinopelvic parameters, with particular focus on the preservation of the lumbar lordosis (LL) and on the segmental lordosis (SL) of the treated and adjacent segments. METHODS: A prospective study was conducted on 63 consecutive patients with symptomatic degenerative disc disease who underwent Mobidisc implantation at the Clinic for Spinal Diseases in Strasbourg, France. Based on the profile images of the whole, the following static spinopelvic parameters were measured and analysed: lumbar lordosis L1-S1 (LL), SL for L3-L4, L4-L5 and L5-S1, sacral slope (SS), pelvic tilt (PT) and pelvic incidence. In the lumbar spine images, the anterior (ADH) and posterior disc height (PDH) were measured prior to surgery and at the different follow-up appointments. The preoperative and postoperative values were compared and statistically analysed at different time intervals. RESULTS: Sixty-three patients were included in the study. The average age of the patients was 41.4 years (range 27-59 years). The mean follow-up was 44 months (range 36-71 months). Overall, total disc replacement (TDR) led to an increase in LL which increased TED over time. The preoperative LL measured 48.9° ± 10.1° and 53.4° ± 9.9° at 3 years follow-up (p < 0.0001). In the cohort of patients who underwent TDR at L4-5, the LL increased from 51.6° ± 10° to 56.2° ± 9.2° at the last FU (p = 0.006). All other spinopelvic parameters remained stable between the preoperative values and the last follow-up. In the patients who underwent L5-S1 TDR, a significant increase in LL was also observed between preoperative data and at the last FU (from 47.8° ± 10.1° to 53.3° ± 10.1°, p < 0.0001). Following L5-S1 TDR, the SS increased from 32.9° ± 8.3° to 35.6° ± 7.4° (p = 0.05) and the PT decreased from 15.4° ± 6.2° to 11.6° ± 5.7° between preoperative values and the last follow-up. Considering the entire cohort, the SL L5-S1 increased significantly from 5.9° ± 4.2° preoperatively to 8.1° ± 4.4° (p < 0.01) at the last FU, while at the L4-L5 level, the SL remained stable from 9.9 ± 4.5° to 10.7° ± 3.8° (p = 0.3). After L4-5 TDR, an increase in ADH and PDH at the treated level was observed, while these parameters progressively decreased in the adjacent segment. In patients who underwent L5-S1 TDR, a significant increase in L5-S1 ADH and PDH was observed from 18.8 ± 9.1 to 28.4 ± 11.1 and from 9.5 ± 3.8 to 17.6 ± 9.5 pixels, respectively. ADH and PDH at the proximal adjacent levels L3-4 and L4-5 were reduced. We did not observe any case of implant failure or damage to the bone/implant interface. CONCLUSION: TDR with Mobidisc allows for an improvement of LL and SL at the treated level. An increase in both anterior and posterior disc height was observed at the treated level. While disc height decreased at the adjacent level, further studies are required to investigate whether these changes are clinically relevant.

Sagittal spinopelvic alignment and body mass index in patients with degenerative spondylolisthesis.

The sagittal orientation and osteoarthritis of facet joints, paravertebral muscular dystrophy and loss of ligament strength represent mechanical factors leading to degenerative spondylolisthesis. The importance of sagittal spinopelvic imbalance has been described for the developmental spondylolisthesis with isthmic lysis. However, it remains unclear if these mechanisms play a role in the pathogenesis of degenerative spondylolisthesis. The purpose of this study was to analyze the sagittal spinopelvic alignment, the body mass index (BMI) and facet joint degeneration in degenerative spondylolisthesis. A group of 49 patients with L4-L5 degenerative spondylolisthesis (12 males, 37 females, average age 65.9 years) was compared to a reference group of 77 patients with low back pain without spondylolisthesis (41 males, 36 females, average age 65.5 years). The patient's height and weight were assessed to calculate the BMI. The following parameters were measured on lateral lumbar radiographs in standing position: L1-S1 lordosis, segmental lordosis from L1-L2 to L5-S1, pelvic tilt, pelvic incidence and sacral slope. The sagittal orientation and the presence of osteoarthritis of the facet joints were determined from transversal plane computed tomography (CT). The average BMI was significantly higher (P=0.030) in the spondylolisthesis group compared to the reference group (28.2 vs. 24.8) and 71.4% of the spondylolisthesis patients had a BMI>25. The radiographic analysis showed a significant increase of the following parameters in spondylolisthesis: pelvic tilt (25.6° vs. 21.0°; P=0.046), sacral slope (42.3° vs. 33.4°; P=0.002), pelvic incidence (66.2° vs. 54.2°; P=0.001), L1-S1 lordosis (57.2° vs. 49.6°; P=0.045). The segmental lumbar lordosis was significantly higher (P<0.05) at L1-L2 and L2-L3 in spondylolisthesis. The CT analysis of L4-L5 facet joints showed a sagittal orientation in the spondylolisthesis group (36.5° vs. 44.4°; P=0.001). The anatomic orientation of the pelvis with a high incidence and sacral slope seems to represent a predisposing factor for degenerative spondylolisthesis. Although the L1-S1 lordosis keeps comparable to the reference group, the increase of pelvic tilt suggests a posterior tilt of the pelvis as a compensation mechanism in patients with high pelvic incidence. The detailed analysis of segmental lordosis revealed that the lordosis increased at the levels above the spondylolisthesis, which might subsequently increase posterior stress on facet joints. The association of overweight and a relatively vertical inclination of the S1 endplate is predisposing for an anterior translation of L4 on L5. Furthermore, the sagittally oriented facet joints do not retain this anterior vertebral displacement.

Influence of 2 different dynamic stabilization systems on sagittal spinopelvic alignment.

STUDY DESIGN: A retrospective study. OBJECTIVE: To analyze and compare the sagittal spinopelvic alignment variation after implantation of purely dynamic and hybrid pedicle screw-based stabilization systems, seeking for its clinical implication. SUMMARY OF BACKGROUND DATA: Numerous studies have investigated the kinematic features of pedicle screw-based dynamic stabilization systems since their clinical application. However, there is a lack of literature concerning their influence on the sagittal spinopelvic alignment, which has been proved to be important in the development of future adjacent segment degeneration (ASD). METHODS: Lateral standing lumbar radiographs of 29 patients (17 males, 12 females, 27 to 64 y) who were implanted with purely dynamic (Dynesys: group A, n=15) or hybrid (FlexPLUS: group B, n=14) stabilization systems, and with a minimum follow-up of 1 year, have been reviewed. These parameters were measured using Spineview software and were compared within and between groups: L1 to S1 lordosis, lordosis of instrumented segments (ISL), cranial adjacent segment lordosis (CASL) next to the instrumentation, highest instrumented segment lordosis (HISL), pelvic incidence, sacral slope, and pelvic tilt. RESULTS: Preoperative lordosis parameters were not significantly different between group A and B. The average L1 to S1 lordosis decreased from 55.3 degrees preoperatively to 52.6 degrees postoperatively in group A (P=0.007) and from 60.2 degrees to 59.3 degrees in group B (P=0.054). There was no significant difference between both groups (P=0.083). The average ISL decreased from 25.9 degrees preoperatively to 21.7 degrees postoperatively (P=0.00002) in group A and from 30.0 degrees to 28.6 degrees in group B (P=0.153). The prepostoperative ISL variation was significantly different between group A and B (P=0.015). The average HISL decreased from 9.5 degrees to 6.2 degrees in group A (P=0.0007) and from 13.1 degrees to 12.4 degrees in group B (P=0.295). The loss of HISL was significantly greater (P=0.010) in group A than in group B. The average CASL increased from 6.9 degrees to 9.2 degrees (P=0.013) in group A. The CASL variation from 10.6 degrees to 10.4 degrees was not significant (P=0.763) in group B. When comparing both groups, the difference of CASL variation was statistically significant (P=0.043). The pelvic incidence, sacral slope, and pelvic tilt did not change significantly before and after instrumentation in both groups. CONCLUSIONS: On the basis of the result of this study, the hybrid stabilization system could better preserve the lordosis of instrumented segments and subsequently reduce the extent of compensatory lordosis increase at the cranial adjacent segment. This could theoretically prevent the development of an ASD. The long-term outcome and the correlation between lordosis-preserving capacity and ASD need to be further prospectively analyzed.