Therapeutic Effect of BDNF-Overexpressing Human Neural Stem Cells (F3.BDNF) in a Contusion Model of Spinal Cord Injury in Rats.

The most common type of spinal cord injury is the contusion of the spinal cord, which causes progressive secondary tissue degeneration. In this study, we applied genetically modified human neural stem cells overexpressing BDNF (brain-derived neurotrophic factor) (F3.BDNF) to determine whether they can promote functional recovery in the spinal cord injury (SCI) model in rats. We transplanted F3.BDNF cells via intrathecal catheter delivery after a contusion of the thoracic spinal cord and found that they were migrated toward the injured spinal cord area by MR imaging. Transplanted F3.BDNF cells expressed neural lineage markers, such as NeuN, MBP, and GFAP and were functionally connected to the host neurons. The F3.BDNF-transplanted rats exhibited significantly improved locomotor functions compared with the sham group. This functional recovery was accompanied by an increased volume of spared myelination and decreased area of cystic cavity in the F3.BDNF group. We also observed that the F3.BDNF-transplanted rats showed reduced numbers of Iba1- and iNOS-positive inflammatory cells as well as GFAP-positive astrocytes. These results strongly suggest the transplantation of F3.BDNF cells can modulate inflammatory cells and glia activation and also improve the hyperalgesia following SCI.

Contrast Dispersion on Epidurography May Be Associated with Clinical Outcomes After Percutaneous Epidural Neuroplasty Using an Inflatable Balloon Catheter.

BACKGROUND: Contrast dispersion pattern on epidurography may be associated with clinical improvement after epidural neuroplasty. However, insufficient evidence supports this theory. The current study aims to evaluate the relevance of contrast dispersion and clinical improvement after percutaneous epidural neuroplasty using an inflatable balloon catheter. METHODS: One hundred patients with lumbar spinal stenosis who underwent combined balloon decompression and epidural adhesiolysis between March 2015 to December 2015 participated in the present study. Participants were divided into two groups by contrast dispersion pattern on postprocedural epidurography: the complete contrast dispersion (CCD) and incomplete contrast dispersion (ICCD) groups. The numeric rating scale (NRS), Oswestry Disability Index (ODI), and global perceived effects (GPE) were each assessed before and one, three, six, nine, and 12 months after the intervention. RESULTS: After combined balloon decompression and adhesiolysis, significant pain reduction and functional improvement were maintained up to 12 months in patients with lumbar spinal stenosis. NRS and GPE in the CCD group were significantly lower than in the ICCD group from six to 12 months after the intervention. The ODI in the CCD group was also significantly lower compared with that in the ICCD group from one to 12 months after the intervention. CONCLUSIONS: Combined balloon decompression and adhesiolysis with the inflatable balloon catheter can provide noteworthy pain reduction and improvement of physical function for a long-term period in patients with lumbar spinal stenosis. Because CCD showed better clinical improvement compared with ICCD, a contrast dispersion pattern may be associated with an improved clinical outcome.

Comparison of the effectiveness and safety of bioactive glass ceramic to allograft bone for anterior cervical discectomy and fusion with anterior plate fixation.

Recently, a bioactive glass ceramic (BGC) has been developed for use as intervertebral cages for anterior cervical discectomy and fusion (ACDF). However, the effectiveness and safety of BGC cages remain to be evaluated. We completed a retrospective comparison of the radiological and clinical outcomes of 36 patients (52 levels) who underwent ACDF with a BGC cage and 35 patients (54 levels) using allograft bone. The following variables were compared between the two groups: the visual analog (VAS) neck and arm pain score and the neck disability index (NDI), measured before surgery and 1 year after; the change in Cobb's angle, between the C2 and C7 vertebrae, the global sagittal angle, and disc height compared from before surgery to 1 year after; and the rate of spinal fusion and cage subsidence at 1 and 2 years after surgery. The VAS and NDI scores were not different between the two groups. Similarly, the spinal fusion rate was not different between the BGC and allograft bone group at 1 year (73% and 87%, respectively; p = 0.07) and 2 years (94% and 91%, respectively; p = 0.54) after surgery. However, the rate of cage subsidence was higher in the allograft bone (43%) than the BGC (19%) group (p = 0.03), as was the rate of instrument-related failure (p = 0.028), with a specifically higher incidence of implant fracture or failure in the allograft bone group (p = 0.025). Overall, our findings indicate that BGC cages provide a feasible and safe alternative to allograft bone for ACDF.

An optimal cortical bone trajectory technique to prevent early surgical complications.

BACKGROUND: Cortical bone trajectory (CBT) technique has a theoretical benefit for patients with osteoporosis, and leads to reduce screw loosening. However, there are no reports of complications and outcomes of CBT. METHODS: Consecutive patients (n = 34) with degenerative lumbar spines who underwent PLIF between December 2013 and December 2015 and were followed up for at least six months were analyzed in this study. Bone mineral density, fusion rate, cage subsidence, C-arm, screw loosening, screw violation, trajectory angle of the screw, Hounsfield unit and extent of facetectomy were examined. Outcome assessments were obtained in all patients preoperatively and postoperatively. RESULTS: There were 34 patients and 73 screw levels. After the surgery with cortical screw fixation and PLIF, patients had good clinical outcomes. However, ten of the 34 patients had problems with cortical screw fixation such as screw loosening or cage migration. In the patients with screw loosening, two underwent revision surgery due to cage migration, and one had an infection. Incorrect trajectory angles of the screw were significantly related with screw loosening. Low BMD and HU at screw fixation level were associated with screw loosening. Cage subsidence was statistically related with clinical outcomes. CONCLUSION: The cortical screw offers improved clinical outcomes since it requires minimal muscle dissection. However, we have experienced some early complications using this technique. To reduce complications such as screw loosening, an exact insertion angle of the screw and osteoporotic bone quality should be considered carefully.

Treatment outcomes of radiotherapy for primary spinal cord glioma.

PURPOSE: Spinal cord gliomas are rare, and there is no consensus on the optimal radiotherapy (RT) regimen. Herein, we investigated therapeutic outcomes in spinal cord gliomas to obtain clues for the optimal RT regimen. METHODS: We assessed 45 patients who received RT for primary spinal cord non-ependymoma gliomas between 2005 and 2017: 37 (82%) received postoperative RT, 6 (13%) underwent definitive RT without surgery, and 2 (5%) received salvage RT for recurrent tumors. Craniospinal irradiation (CSI; median, 40 Gy) was administered in 4 patients with seeding at diagnosis; all other patients received local RT only (median, 50.4 Gy). RESULTS: In all 23 failures occurred (20 in patients without initial seeding +3 in patients with initial seeding and CSI; median follow-up, 33 months). The 2­year overall survival and progression-free survival rates were 74 and 54%, respectively. Overall, 13 (32%) new seeding events outside the local RT field developed either first or subsequently. Tumor grade was significantly associated with survival endpoints (p = 0.009, 0.028) and overall seeding rates (p = 0.042). In grade II tumors, seeding developed in 23%, with a dismal prognosis (median, 10 months after RT). In grade III tumors, seeding developed in 45% with diverse prognosis. In grade IV tumors, seeding developed in 45%. The survival of patients with newly developed seeding was significantly worse than the others (2-year 50%, p < 0.001). CONCLUSION: To encompass a considerable rate of progressive disease seeding, aggressive treatment such as pre-emptive application of CSI needs to be considered for high-grade spinal cord gliomas with adverse features. Prophylactic CSI could be an option for survival prolongation and requires prospective validation.

Patterns of short-term and long-term surgical outcomes and prognostic factors for cervical ossification of the posterior longitudinal ligament between anterior cervical corpectomy and fusion and posterior laminoplasty.

To compare short-term and long-term surgical outcome patterns between anterior cervical corpectomy and fusion (ACCF) and laminoplasty (LP) in patients diagnosed with cervical ossification of the posterior longitudinal ligament (OPLL) and identify factors affecting surgical outcomes based on follow-up duration. During short-term follow-up period, surgical outcomes between ACCF and LP were similar. However, there were several reports that long-term surgical outcomes were superior in the ACCF compared with LP. Surgical outcomes between ACCF and LP according to follow-up period changed. This study enrolled 70 patients who underwent ACCF and 63 patients who underwent LP between 2005 and 2012. Patterns of surgical outcomes were analyzed in accordance with surgical procedures. Furthermore, these patients were divided into two subgroups in respect of follow-up duration: the short-term group (less than 48 months) and the long-term group (more than 48 months) group. Occupying ratio, type of OPLL, shape of ossified lesion, cervical sagittal alignment, grade of signal intensity on MRI, and Japanese Orthopedic Association (JOA) score were examined. Surgical outcomes of ACCF went into reverse at 48-month follow-up period. In the short-term group, JOA recovery rate had no difference between ACCF and LP. In the long-term group, the ACCF recovery rate (78.5 ± 31.0) was significantly higher than the LP recovery rate (48.4 ± 54.9) (P = 0.008). In the short-term group, old age (p = 0.011), hill shape (p = 0.013), and high grade of MRI signal intensity (p = 0.040) had negative effects on recovery rate. On the other hand, in the long-term group, LP (p = 0.021) and a high grade of MR signal intensity (p = 0.017) independently and negatively affected recovery rate. Long-term surgical outcomes of ACCF became better than those of LP at more than 48-month follow-up period. High-grade MRI signal changes and the LP surgical procedure were independent negative factors for long-term surgical outcomes in patients with OPLL. Direct decompression of the spinal cord with ACCF provides better long-term stable neurologic outcomes than LP.

Long-standing tentorial dural arteriovenous fistula presenting as progressively worsening cervical myelopathy by degenerative cervical intervertebral disc: a case report.

We report a rare case of long-standing asymptomatic tentorial dural arteriovenous fistula (DAVF) presenting as symptomatic progressive cervical myelopathy which was caused by the protrusion of degenerative cervical intervertebral discs into the spinal canal and compression of the anterior spinal vein. The cervical spinal canal was narrowed, and the spinal cord was compressed anteriorly by protrusion of cervical intervertebral discs at the C6-7 level. The intervertebral discs compressed the draining vein of the tentorial DAVF (the anterior spinal vein) so venous congestion of the spinal cord resulted in cervical myelopathy only above the C6 level.

Exploring for the optimal structural design for the 3D-printing technology for cranial reconstruction: a biomechanical and histological study comparison of solid vs. porous structure.

PURPOSE: Cranioplasty for recovering skull defects carries the risk for a number of complications. Various materials are used, including autologous bone graft, metallic materials, and non-metallic materials, each of which has advantages and disadvantages. If the use of autologous bone is not feasible, those artificial materials also have constraints in the case of complex anatomy and/or irregular defects. MATERIAL AND METHODS: This study used metal 3D-printing technology to overcome these existing drawbacks and analyze the clinical and mechanical performance requirements. To find an optimal structure that satisfied the structural and mechanical stability requirements, we evaluated biomechanical stability using finite element analysis (FEA) and mechanical testing. To ensure clinical applicability, the model was subjected to histological evaluation. Each specimen was implanted in the femur of a rabbit and was evaluated using histological measurements and push-out test. RESULTS AND CONCLUSION: We believe that our data will provide the basis for future applications of a variety of unit structures and further clinical trials and research, as well as the direction for the study of other patient-specific implants.

An effect comparison of teriparatide and bisphosphonate on posterior lumbar interbody fusion in patients with osteoporosis: a prospective cohort study and preliminary data.

PURPOSE: Our purpose was to evaluate the efficacy of teriparatide for posterior lumbar interbody fusion (PLIF) in osteoporotic women. METHODS: Forty-seven osteoporotic patients underwent PLIF with pedicle screw fixation for degenerative lumbar stenosis and instability. Patients were divided into two groups. The teriparatide group (n = 23) was injected subcutaneously with teriparatide (20 µg daily) for 3-month cycles alternating with 3-month periods of oral sodium alendronate for 12 months. The bisphosphonate group (n = 24) was administered oral sodium alendronate (91.37 mg/week) for ≥1 year. Serial plain radiography, computed tomography, and bone mineral densitometry (BMD) evaluations were performed. Fusion rate, bony fusion duration, and T score changes were evaluated. Clinical data [pain scores, Prolo's functional scale, and Oswestry disability index (ODI)] were also serially evaluated. RESULTS: The teriparatide group showed earlier fusion than the bisphosphonate group. The average period of bone fusion was 6.0 ± 4.8 months in the teriparatide group but 10.4 ± 7.2 months in the bisphosphonate group. The bone fusion rate in the teriparatide group was higher than that in the bisphosphonate group at 6 months; however, there was no difference 12 and 24 months after surgery. Pain scores and ODI were not significantly different between groups. BMD scores in the teriparatide group were significantly improved compared with the bisphosphonate group 2 years after surgery. CONCLUSIONS: There was no significant improvement in overall fusion rate and clinical outcome in our patients after injection of teriparatide, but the teriparatide group showed faster bony union and highly improved BMD scores.

Effectiveness and tolerability of transdermal buprenorphine patches: a multicenter, prospective, open-label study in Asian patients with moderate to severe chronic musculoskeletal pain.

BACKGROUND: We examined the effectiveness and tolerability of transdermal buprenorphine (TDB) treatment in real-world setting in Asian patients with musculoskeletal pain. METHODS: This was an open-label study conducted in Hong Kong, Korea, and the Philippines between June 2013 and April 2015. Eligible patients fulfilled the following criteria: 18 to 80 years of age; clinical diagnosis of osteoarthritis, rheumatoid arthritis, low back pain, or joint/muscle pain; chronic non-malignant pain of moderate to severe intensity (Box-Scale-11 [BS-11] pain score ≥ 4), not adequately controlled with non-opioid analgesics and requiring an opioid for adequate analgesia; and no prior history of opioid treatment. Patients started with a 5 µg/h buprenorphine patch and were titrated as necessary to a maximum of 40 µg/h over a 6-week period to achieve optimal pain control. Patients continued treatment with the titrated dose for 11 weeks. The primary efficacy endpoint was the change in BS-11 pain scores. Other endpoints included patients' sleep quality and quality of life as assessed by the 8-item Global Sleep Quality Assessment Scale (GSQA) questionnaire and the EuroQol Group 5-Dimension Self-Report Questionnaire-3 Level version (EQ-5D-3 L), respectively. Tolerability was assessed by collecting adverse events. RESULTS: A total of 114 eligible patients were included in the analysis. The mean BS-11 score at baseline was 6.2 (SD 1.6). Following initiation of TDB, there was a statistically significant improvement in BS-11 score from baseline to visit 3 (least squares [LS] mean change: -2.27 [95% CI -2.66 to -1.87]), which was maintained till the end of the study (visit 7) (LS mean change: -2.64 [95% -3.05 to -2.23]) (p < 0.0001 for both). The proportion of patients who rated sleep quality as 'good' increased from 14.0% at baseline to 26.9% at visit 6. By visit 6, the mean EQ VAS score increased by 7.7 units (SD 17.9). There were also significant improvements in patients' levels of functioning for all EQ-5D-3 L dimensions from baseline at visit 6 (p < 0.05 for all). Seventy-eight percent of patients reported TEAEs and 22.8% of patients discontinued due to TEAEs. TEAEs were generally mild to moderate in intensity (96.5%). CONCLUSIONS: TDB provides effective pain relief with an acceptable tolerability profile over the 11-week treatment period in Asian patients with chronic musculoskeletal pain. More studies are needed to examine the long-term efficacy and safety of TBD treatment in this patient population. TRIAL REGISTRATION: ClinicalTrials.gov NCT01961271 . Registered 7 October 2013 (retrospectively registered; first patient was enrolled on 28 June 2013 and last patient last visit date was 26 Apr 2015).

Early neuroprotective effect with lack of long-term cell replacement effect on experimental stroke after intra-arterial transplantation of adipose-derived mesenchymal stromal cells.

BACKGROUND AIMS: Adipose-derived mesenchymal stromal cells (AD-MSCs) have high proliferative capacity and ability to secrete trophic factors. Although intra-arterial (IA) transplantation of stem cells induces efficient engraftment to the host brain, it is unclear whether engrafted cells exert their long-term therapeutic effects through a bystander mechanism or a cell replacement mechanism. METHODS: After induction of ischemia in rats by middle cerebral artery occlusion, we transplanted human AD-MSCs into their carotid arteries with the use of a micro-needle, and we then investigated the therapeutic effects during the early and late phases of ischemia by means of in vivo magnetic resonance imaging, functional and histological analyses. RESULTS: During the early phase of cerebral ischemia, IA transplantation of AD-MSCs attenuated inflammation and enhanced endogenous neurogenesis. Transplanted animals showed a marked improvement in functional tests during the early phase of cerebral ischemia that was less prominent but still significant during the late phase of cerebral ischemia. Although the transplanted cells effectively migrated to the infarct area, only a small number of engrafted cells survived at 8 weeks after transplantation and differentiated into neuronal, glial and endothelial cells. CONCLUSIONS: IA transplantation of human AD-MSCs provides an effective therapeutic modality in a rodent model of stroke, of which the main effects are mediated by a bystander mechanism at the early phase of ischemia.

A morphometric analysis of contralateral neural foramen in TLIF.

STUDY DESIGN: A retrospective review PURPOSE: This study was designed to compare postoperative changes in neural foramen between transforaminal lumbar interbody fusion (TLIF) and posterior lumbar interbody fusion (PLIF). METHODS: A retrospective analysis of 67 patients was compared to the change of neural foraminal morphometry of the two techniques. 33 patients (40 levels) had TLIF and 34 patients (39 levels) had PLIF. The two groups had similar demographic profiles. Radiological parameters including anterior and posterior disc height, foraminal height (FH), and segmental Cobb angle (SCA) were measured by sagittally reconstructed computed tomography images before and after surgery. Cage position was designated as contralateral, middle, and ipsilateral in the TLIF group. Surgical results were assessed by Odom criteria, visual analog scale (VAS), and Oswestry disability index (ODI) scores. RESULTS: The TLIF and PLIF group showed no bilateral difference in FH. The TLIF group had increased contralateral SCA compared to the ipsilateral side postoperatively. FH differed according to cage position in the TLIF group. When a cage was inserted deeply into the contralateral side, contralateral FH increased significantly. However, when a cage was inserted into the ipsilateral side, contralateral FH decreased significantly. Back pain was significantly lower in the TLIF group at 1 and 6 months than in the PLIF group. However, ODI and Odom scale scores were not different between the groups. CONCLUSIONS: TLIF may induce uneven changes in foraminal morphometry. Cage position may be the major determinant of this result.

Bone loss of the superior adjacent vertebral body immediately posterior to the anterior flange of Bryan cervical disc.

BACKGROUND: No previous reports have mentioned bone loss of the superior adjacent vertebra immediately posterior to the anterior flange of Bryan cervical disc (Medtronic Sofamor Danek, Memphis, TN, USA), which plays a central role to prevent posterior migration of the device. The purpose of this study is to describe a new potential complication, bone loss immediately posterior to the anterior total disc replacement (TDR) flange on the superior adjacent vertebra following the Bryan cervical TDR and to discuss the possible mechanism. METHODS: The authors retrospectively reviewed 37 patients undergoing cervical TDR with the Bryan cervical disc. The clinical and radiological outcome data were collected at 1, 3, 6, 12, 24, and 36 months postoperatively, and at last follow-up, which ranged from 42 to 113 moths (average, 60.1 months). Clinical evaluation included the visual analog scale and neck disability index, and the radiographic evaluation included measurements of the functional spinal unit range of motion on flexion and extension and identification of radiographic changes such as bone loss. RESULTS: The Bryan TDR showed good mid-term clinical and radiological outcomes. Interestingly, however, bone loss was noted immediately posterior to the TDR flange on superior adjacent vertebra in 3 total patients; at 3 months (n = 2) and 6 months (n = 1). Although the bone loss was increased up to 6 months, this did not progress and no degradation of clinical and radiological outcomes occurred at last follow-up. CONCLUSIONS: Bone loss immediately posterior to the anterior TDR flange on the superior adjacent vertebra can occur in the early postoperative period due to possibly stress shielding effect. However, it did not result in clinical changes or increased rates of graft failure at last follow-up. A long-term follow-up study is mandatory to evaluate the long-term effects of the bone loss.

Stand-alone Cervical Cages Versus Anterior Cervical Plates in 2-Level Cervical Anterior Interbody Fusion Patients: Analysis of Adjacent Segment Degeneration.

STUDY DESIGN: A retrospective study. OBJECTIVE: To analyze adjacent segment degeneration (ASD) in 2-level anterior cervical discectomy, comparing fusion with stand-alone cages [anterior cervical discectomy and fusion (ACDF)-CA] and fusion with cage and plate constructs (ACDF-CPC) with respect to clinical outcomes and radiologic changes. SUMMARY OF BACKGROUND DATA: ACDF using a stand-alone cage or a cage and plate construct is a popular procedure. However, there is lack of knowledge concerning ASD between the 2 procedures. METHODS: A total of 42 consecutive patients who underwent 2-level ACDF-CA or ACDF-CPC for 2-level cervical disk disease and who completed 2 years of follow-up were included in this study. The patients were divided into 2 groups: ACDF-CA group (n=22) and ACDF-CPC group (n=20). The following parameters were assessed using radiographs: disk space narrowing, anterior osteophyte formation, calcification of the anterior longitudinal ligament, and fusion status. Clinical outcomes were assessed using the Robinson criteria. RESULTS: No difference in clinical outcomes was observed between the 2 groups. Moreover, the ACDF-CPC group showed a similar fusion rate compared with the ACDF-CA group (100% vs. 95%, P=0.335). There was also no statistical significance in anterior osteophyte formation and calcification of the anterior longitudinal ligament. However, mean intervertebral disk height change of an adjacent segment was significantly lower in the ACDF-CA group than the ACDF-CPC group (upper level: 0.08±0.24 vs. 0.49±0.35; lower level: 0.06±0.41 vs. 0.49±0.28; P<0.01). CONCLUSIONS: The use of a cage with or without plate constructs in 2-level ACDF provides similar clinical results and fusion rates. Notwithstanding, ACDF-CPC showed a higher incidence of ASD than ACDF-CA over the 2-year follow-up.

Long-term surgical outcomes of cervical myelopathy with athetoid cerebral palsy.

PURPOSE: To understand the long-term surgical outcomes and prognostic factors for the operative treatment of cervical myelopathy (CM) in patients with athetoid cerebral palsy (ACP). METHODS: We retrospectively reviewed 24 patients with ACP who underwent surgery for CM at our hospital between March 2002 and June 2008. All patients had more than 5 years follow-up. Anterior fusion (11 patients), posterior fusion (1 patient), or combined anterior and posterior (AP) fusion (7 patients) and C1-2 fusion (5 patients) surgeries were performed. Surgical outcomes (average follow-up 102 months), as assessed using modified JOA (mJOA) scores, the Neck Disability Index (NDI), and a visual analog scale (VAS) were compared between the preoperative and postoperative states. RESULTS: Preoperatvie cervical kyphosis decreased mJOA scores significantly. Long-term follow-up clinical outcomes demonstrated that 10 patients showed favorable (excellent and good) outcomes and 11 patients had non-favorable (fair and worse) outcomes. According to the mJOA scores, patients showed postoperative improvement (7.10-10.45). NDI decreased from 68.46 to 31.66. A second operation was done in seven cases due to instrument failure, progressive kyphotic deformities and adjacent segment degeneration. A preoperative botulinum toxin injection significantly decreased (p < 0.05) the incidence of a second operation. CONCLUSIONS: Patients with ACP have high incidence of instrument failure. Strong surgical fixation, bone fusion and perioperative immobilizations using botulinum toxin injection should be carefully planned preoperatively.

Co-transplantation of bone marrow-derived mesenchymal stem cells and nanospheres containing FGF-2 improve cell survival and neurological function in the injured rat spinal cord.

BACKGROUND: Spinal cord injury (SCI) is a devastating and irreversible event, and much research using fibroblast growth factor-2 (FGF-2) has been performed to test its capacity to blunt the effects of SCI as well as to provide an environment conducive for SCI repair. METHODS: We tested how the in vitro release of FGF-2 from heparin-conjugated poly(L-lactide-co-glycolide) (PLGA)-conjugated nanospheres (HCPNs) affected the growth of human bone marrow-derived mesenchymal stem cells (hBMSCs), as well as the effects of their co-transplantation in an animal model of SCI. RESULTS: Our results showed that sustained, long-term release of FGF-2 from HCPNs significantly increased hBMSCs proliferation in vitro, and that their co-transplantation following rat SCI lead to increased functional improvement, a greater amount of hBMSCs surviving transplantation, and a greater density of neurofilament-positive cells in the injury epicenter. CONCLUSION: These results suggest a proliferative, protective, and neural inductive potential of FGF-2 for transplanted hBMSCs, as well as a possible role for sustained FGF-2 delivery along with hBMSCs transplantation in the injured spinal cord. Future studies will be required to ascertain the safety FGF-2-containing HCPNs before clinical application.

Finite Element Analysis of Stress Distribution and Range of Motion in Discogenic Back Pain.

OBJECTIVE: Precise knowledge regarding the mechanical stress applied to the intervertebral disc following each individual spine motion enables physicians and patients to understand how people with discogenic back pain should be guided in their exercises and which spine motions to specifically avoid. We created an intervertebral disc degeneration model and conducted a finite element (FE) analysis of loaded stresses following each spinal posture or motion. METHODS: A 3-dimensional FE model of intervertebral disc degeneration at L4-5 was constructed. The intervertebral disc degeneration model was created according to the modified Dallas discogram scale. The von Mises stress and range of motion (ROM) regarding the intervertebral discs and the endplates were analyzed. RESULTS: We observed that mechanical stresses loaded onto the intervertebral discs were similar during flexion, extension, and lateral bending, which were greater than those occurring during torsion. Based on the comparison among the grades divided by the modified Dallas discogram scale, the mechanical stress during extension was greater in grades 3-5 than it was during the others. During extension, the mechanical stress loaded onto the intervertebral disc and endplate was greatest in the posterior portion. Mechanical stresses loaded onto the intervertebral disc were greater in grades 3-5 compared to those in grades 0-2. CONCLUSION: Our findings suggest that it might be beneficial for patients experiencing discogenic back pain to maintain a neutral posture in their lumbar spine when engaging in daily activities and exercises, especially those suffering from significant intravertebral disc degeneration.

Feasibility and safety report on robotic assistance for cervical pedicle screw fixation: a cadaveric study.

This cadaveric study aimed to evaluate the safety and usability of a novel robotic system for posterior cervical pedicle screw fixation. Three human cadaveric specimens and C2-T3 were included. Freshly frozen human cadaver specimens were prepared and subjected to robot-assisted posterior cervical pedicle screw fixation using the robotic system. The accuracy of screw placement, breach rate, and critical structure violations were evaluated. The results were statistically compared with those of previous studies that used different robotic systems for cervical pedicle screw fixation. The robotic system demonstrated a high accuracy rate in screw placement. A significant number of screws were placed within predetermined safe zones. The total entry offset was 1.08 ± 0.83 mm, the target offset was 1.86 ± 0.50 mm, and the angle offset was 2.14 ± 0.77°. Accuracy rates comparable with those of previous studies using different robotic systems were achieved. The system was also feasible, allowing precise navigation and real-time feedback during the procedure. This cadaveric study validated the safety and usability of the novel robotic system for posterior cervical pedicle screw fixation. The system exhibited high precision in screw placement, and the results support the extension of the indications for robot-assisted pedicle screw fixation from the lumbar spine to the cervical spine.

Differential effects of sevoflurane and desflurane on frontal intraoperative electroencephalogram dynamics associated with postoperative delirium.

STUDY OBJECTIVE: Intraoperative electroencephalogram (EEG) patterns associated with postoperative delirium (POD) development have been studied, but the differences in EEG recordings between sevoflurane- and desflurane-induced anesthesia have not been clarified. We aimed to distinguish the EEG characteristics of sevoflurane and desflurane in relation to POD development. DESIGN AND PATIENTS: We collected frontal four-channel EEG data during the maintenance of anesthesia from 148 elderly patients who received sevoflurane (n = 77) or desflurane (n = 71); 30 patients were diagnosed with delirium postoperatively. The patients were divided into four subgroups based on anesthetics and delirium status: sevoflurane delirium (n = 17), sevoflurane non-delirium (n = 60), desflurane delirium (n = 13), and desflurane non-delirium (n = 58). We compared spectral power, coherence, and pairwise phase consistency (PPC) between sevoflurane and desflurane, and between non-delirium and delirium groups for each anesthetic. MAIN RESULTS: In patients without POD, the sevoflurane non-delirium group exhibited higher EEG spectral power across 8.5-35 Hz (99.5% CI bootstrap analysis) and higher PPC from alpha to gamma bands (p < 0.005) compared to the desflurane non-delirium group. Conversely, in patients with POD, no significant EEG differences were observed between the sevoflurane and desflurane delirium groups. For the sevoflurane-induced patients, the sevoflurane delirium group had significantly lower power within 7.5-31.5 Hz (99.5% CI bootstrap analysis), reduced coherence over 8.9-23.8 Hz (99.5% CI bootstrap analysis), and lower PPC values in the alpha band (p < 0.005) compared with the sevoflurane non-delirium group. For the desflurane-induced patients, there were no significant differences in the EEG patterns between delirium and non-delirium groups. CONCLUSIONS: In normal patients without POD, sevoflurane demonstrates a higher power spectrum and prefrontal connectivity than desflurane. Furthermore, reduced frontal alpha power, coherence, and connectivity of intraoperative EEG could be associated with an increased risk of POD. These intraoperative EEG characteristics associated with POD are more noticeable in sevoflurane-induced anesthesia than in desflurane-induced anesthesia.