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Introduction: Diffuse idiopathic skeletal hyperostosis (DISH) extended to the lumbar segments (L-DISH) reportedly has adverse effects on the surgical outcomes of lumbar spinal stenosis (LSS). However, the risk factors in patients with L-DISH have not been clarified. The purpose of this study was to investigate the long-term risk factors for reoperation at the same level after decompression surgery alone for LSS in patients with L-DISH in a retrospective cohort study. Methods: A postoperative postal survey was sent to 1,150 consecutive patients who underwent decompression surgery alone for LSS from 2002 to 2010. Among all respondents, patients who exhibited L-DISH by preoperative total spine X-ray were included in this study. We investigated risk factors for reoperation at the same level as the initial surgery among various demographic and radiological parameters, including the lumbar ossification condition and computed tomography (CT) or magnetic resonance imaging findings. Results: A total of 57 patients were analyzed. Reoperations at the same level as that of the index surgery were performed in 10 patients (17.5%) and at 11 levels within a mean of 9.2 years. Cox proportional hazard regression analysis indicated that the independent risk factors for reoperation were a sagittal rotation angle 10° (adjusted hazard ratio: 5.17) and facet opening on CT (adjusted hazard ratio: 4.82). Neither sagittal translation nor the ossification condition in the lumbar segments affected reoperations. Conclusions: A sagittal rotation angle 10° and facet opening on preoperative CT were risk factors for reoperation at the same level as that of the index surgery in patients with L-DISH. The surgical strategy should be carefully considered in those patients.

Retrospective longitudinal cohort study.To investigate the association between diffuse idiopathic skeletal hyperostosis (DISH) and reoperation in patients treated surgically for lumbar spinal stenosis (LSS) in long-term results.Few studies have evaluated DISH as a potential risk factor of poor surgical results for LSS.This study included 1063 responders to a postoperative postal survey out of 2363 consecutive patients who underwent surgery for LSS between 2002 and 2010. The survey included questions about reoperations performed at another hospital and the patient-reported outcomes. DISH was evaluated by preoperative standing whole-spine radiographs. We investigated DISH as a predictor of reoperation and characteristics of poor outcomes in patients with DISH. We also assessed selection bias by examining the differences between responders and nonresponders to a postal survey.Reoperations were performed in a total of 115 patients (10.8%) within an average of 8.6 years after the initial surgeries. Patients who only had DISH were not associated with reoperation; however, reoperations were performed significantly more often in patients with DISH extended to the lumbar segment (L-DISH) than in patients without (22% and 7.3%, respectively; P 0.001). Cox analysis showed that L-DISH was one of the significant independent predictors for reoperation (hazard ratio 2.05, P = 0.009). Surgery-free survival was significantly shorter in patients with L-DISH than in those without (P = 0.005). The cause of reoperation did not differ between the patients with and without L-DISH. Several factors, but not L-DISH, were significantly associated with responders to the survey.L-DISH was independently associated with reoperation for LSS. The decreased number of lumbar mobile segments due to L-DISH might lead to unfavorable outcomes. Careful follow-up of patients is needed after surgery for LSS with L-DISH.3.

Study design Matched case-control study. Objective To identify factors other than a multilevel procedure that increase the risk of symptomatic postoperative spinal epidural hematoma (SEH). Summary of background data Postoperative SEH is a potentially devastating complication of spinal surgery. Previous studies that reported risk factors for postoperative SEH all identified a multilevel procedure as a risk factor, but the other risk factors remain unclear. Methods Patients who developed postoperative SEH requiring surgical evacuation were identified from database. Each patient was matched with 3 controls who underwent spinal decompression at the same number of levels in the same part of the spine by the same surgeon during the preceding or following year. Multiple logistic regression analysis was performed to identify the risk factors for postoperative SEH to obtain adjusted odds ratios with 95% confidence intervals. Clinical outcomes after evacuation were investigated separately divided with or without severe paralysis or time until the second surgery. Results Postoperative SEH evacuation was performed after 32 of 8250 (0.39%) spinal decompression procedures. The incidence was significantly higher after thoracic procedures (2.41%) than after cervical (0.21%) or lumbar (0.39%) procedures. Multivariate analysis identified a 50 mm Hg or greater increase in systolic blood pressure after extubation (adjusted odds ratio: 3.22, 95% confidence interval: 1.22-8.51) and higher body mass index (adjusted odds ratio 1.15, 95% confidence interval: 1.01-1.31) as risk factors. Among 14 patients with severe paralysis due to postoperative SEH, those who underwent evacuation within 24 hours of the onset had a significantly better improvement in clinical outcome and Frankel grade than did those after 24 hours. Conclusion A 50 mm Hg or greater increase in systolic blood pressure after extubation and high body mass index were identified as risk factors for SEH. Appropriate blood pressure control especially at the end of surgery is important for the prevention of postoperative SEH, particularly in obese patients. Level of evidence 3.

Augmented reality (AR) is an imaging technology by which virtual objects are overlaid onto images of real objects captured in real time by a tracking camera. This study aimed to introduce a novel AR guidance system called virtual protractor with augmented reality (VIPAR) to visualize a needle trajectory in 3D space during percutaneous vertebroplasty (PVP). The AR system used for this study comprised a head-mount display (HMD) with a tracking camera and a marker sheet. An augmented scene was created by overlaying the preoperatively generated needle trajectory path onto a marker detected on the patient using AR software, thereby providing the surgeon with augmented views in real time through the HMD. The accuracy of the system was evaluated by using a computer-generated simulation model in a spine phantom and also evaluated clinically in 5 patients. In the 40 spine phantom trials, the error of the insertion angle (EIA), defined as the difference between the attempted angle and the insertion angle, was evaluated using 3D CT scanning. Computed tomography analysis of the 40 spine phantom trials showed that the EIA in the axial plane significantly improved when VIPAR was used compared with when it was not used (0.96° ± 0.61° vs 4.34° ± 2.36°, respectively). The same held true for EIA in the sagittal plane (0.61° ± 0.70° vs 2.55° ± 1.93°, respectively). In the clinical evaluation of the AR system, 5 patients with osteoporotic vertebral fractures underwent VIPAR-guided PVP from October 2011 to May 2012. The postoperative EIA was evaluated using CT. The clinical results of the 5 patients showed that the EIA in all 10 needle insertions was 2.09° ± 1.3° in the axial plane and 1.98° ± 1.8° in the sagittal plane. There was no pedicle breach or leakage of polymethylmethacrylate. VIPAR was successfully used to assist in needle insertion during PVP by providing the surgeon with an ideal insertion point and needle trajectory through the HMD. The findings indicate that AR guidance technology can become a useful assistive device during spine surgeries requiring percutaneous procedures.

Background Context No previous studies have reported the radiological features of patients requiring surgery in symptomatic lumbar foraminal stenosis (LFS). Purpose This study aims to investigate the diagnostic accuracy of a novel technique, foraminal stenotic ratio (FSR), using three-dimensional magnetic resonance imaging for LFS at L5–S by comparing patients requiring surgery, patients with successful conservative treatment, and asymptomatic patients. Study Design This is a retrospective radiological comparative study. Patient Sample We assessed the magnetic resonance imaging (MRI) results of 84 patients (168 L5–S foramina) aged ≥40 years without L4–L5 lumbar spinal stenosis. The foramina were divided into three groups following standardized treatment: stenosis requiring surgery (20 foramina), stenosis with successful conservative treatment (26 foramina), and asymptomatic stenotic foramen (122 foramina). Outcome Measures Foraminal stenotic ratio was defined as the ratio of the length of the stenosis to the length of the foramen on the reconstructed oblique coronal image, referring to perineural fat obliterations in whole oblique sagittal images. We also evaluated the foraminal nerve angle and the minimum nerve diameter on reconstructed images, and the Lee classification on conventional T1 images. Materials and Methods The differences in each MRI parameter between the groups were investigated. To predict which patients require surgery, receiver operating characteristic (ROC) curves were plotted after calculating the area under the ROC curve. Results The FSR showed a stepwise increase when comparing asymptomatic, conservative, and surgical groups (mean, 8.6%, 38.5%, 54.9%, respectively). Only FSR was significantly different between the surgical and conservative groups (p=.002), whereas all parameters were significantly different comparing the symptomatic and asymptomatic groups. The ROC curve showed that the area under the curve for FSR was 0.742, and the optimal cutoff value for FSR for predicting a surgical requirement in symptomatic patients was 50% (sensitivity, 75%; specificity, 80.7%). Conclusions The FSR determined LFS requiring surgery among symptomatic patients, with moderate accuracy. Foramina occupied ≥50% by fat obliteration were likely to fail conservative treatment, with a positive predictive value of 75%.

✓The authors report the case of an 83-year-old woman with refractory sciatica attributable to isthmic spondylolisthesis at L-5. Her symptoms were successfully improved after posterior lumbar interbody fusion (PLIF) at L5–S1; however, notable swelling in her left leg suddenly developed 2 days postoperatively. Anterior migration of a fragment of bone graft was demonstrated on computed tomography scanning, and there was obvious occlusion of the left common iliac vein (CIV) on magnetic resonance venography. Ultrasonography revealed a thrombus in the left CIV at the site of compression. To prevent a pulmonary embolism during manipulation of the affected vein, an inferior vena cava filter was placed just before excision of the migrated bone fragment. The swelling in the patient’s leg subsided quickly after the surgery, and she was treated with heparin and warfarin to prevent recurrent deep vein thrombosis (DVT). Six months after the second surgery, complete restoration of blood flow to the left CIV and no recurrence of DVT were demonstrated on magnetic resonance venography. Especially in elderly patients with degenerative disc disease, excessive curettage and impaction of disc materials during the PLIF procedure may cause migration of bone graft fragments. Surgeons should be aware of the possible vascular complications of PLIF.

✓ The authors report the case of an 87-year-old woman who suffered from T1–2 pyogenic spondylitis resulting in progressive and severe paraplegia. Debridement and anterior manubrium-splitting fusion were difficult because a high-positioned aortic arch was very close to the infectious lesion. Because adequate intravenous antibiotic agents had nearly resolved the inflammation, the authors undertook anterior debridement and posterior fusion that involved costotransversectomy and the placement of a posterior cervical pedicle screw fixation system. At 1.5 years postoperatively, there were no signs of recurrent infection. Solid osseous union was documented, and the patient's paraplegia had improved. A high-positioned aortic arch will likely interfere with an anterior approach to the cervicothoracic junction. If adequate antibiotic therapy has successfully controlled the spinal infection, anterior debridement and posterior fusion can be conducted in cases involving such anatomical limitations.

Study design A retrospective, age- and sex-matched radiographic study. Objectives To investigate the spinopelvic alignment in patients with osteoarthosis of the hip (HOA) and those with low back pain (LBP) and to determine the characteristics and differences in both groups. Summary of background data Hip-spine syndrome, first described by Offierski and MacNab, is quite an important pathology when treating patients with pain in their low back and lower extremities. However, despite it being a well-known entity, few papers have adequately investigated and assessed the spinopelvic alignment in patients with hip-spine syndrome. Methods Sagittal and coronal spinopelvic alignments were investigated in 150 patients with HOA and 150 with LBP using radiographs of the whole spine in both anteroposterior and lateral views. Parameters measured in this study were lumbar lordosis (LL), sacral slope (SS), the shift of the sagittal C7 plumb line, pelvic incidence (PI), and pelvic tilt (PT) on the lateral radiographs. On the anteroposterior (AP) films, lumbar scoliosis, pelvic obliquity, leg length discrepancy, the shift of the coronal C7 plumb line, and Sharp angle were measured. These parameters were compared between the two groups. In patients with HOA, the relationships between Sharp angle and other parameters were also analyzed to clarify the possible influence of sagittal and coronal spinopelvic alignments on HOA without acetabular dysplasia. Results LL, SS, PI, and PO were found to be less in patients with LBP compared with those with HOA, and there was no significant difference in LS between the two groups. PI was significantly greater in HOA patients and strongly correlated to PT, SS, and LL (i.e., as the PI increased so did the PT, SS, and LL). Sharp angles were also significantly greater in HOA patients and strongly correlated to age, LL and SS (i.e., as Sharp angles increased so did LL and SS); however, age decreased in the hip patients. Conclusions These findings suggest that higher PI in the younger individual may contribute to the development of HOA in later life without both lumbar kyphosis and acetabular dysplasia because of the anterior uncovering of the acetabulum. More investigation will be expected to analyze the spinopelvic alignment in patients with hip spine syndrome.

Although the cervical pedicle screw system is considered the most effective instrumentation for posterior cervical spine surgery, reports on clinical application are limited because of the unresolved and inherent risk of neurovascular complications. The purpose of this study is to retrospectively evaluate the accuracy of placement and clinical effectiveness of the cervical pedicle screw. The cases of 26 patients were investigated. The average followup was 20 months. All but one patient had simultaneous decompression and fusion of various extent. In these cases, screw placement, alignment of the fused segment, fusion rate, neurologic improvement, and complications were assessed. Using an image intensifier, 134 screws were inserted. Five screws (3.7%) completely perforated and 10 (7.4%) partially perforated. The complete perforations occurred in the first 10 patients. Except for two patients with metastasis, bony union was obtained in all patients without loss of correction. Neurologic impairment also was improved in all patients, and no complications associated with the cervical pedicle screw were seen. Clinical results of the cervical pedicle screw system were excellent with few complications. However, there is the possibility of screw perforation, which could cause neurovascular complications. Increased accuracy of screw insertion is needed to make this instrumentation safer.

Cervical pedicle screw is thought to be the most stable instrumentation for reconstructive surgery of the cervical spine. However, because of the unresolved and inherent risk of neurovascular injuries due to screw perforation, it remains not widespread nowadays despite the excellent biomechanical property. Fifty-two consecutive cases having undergone spinal reconstruction using cervical pedicle screw were investigated. There were 24 females and 28 males. The mean follow-up period was 53 months. Those patients were stratified into three groups according to the period of screw insertion. A total of 280 screws were inserted. Ninety-two screws in 19 cases, 100 screws in 18 cases and 88 screws in 15 cases were inserted in the earlier, the middle and the later periods, respectively. Clinical results including complications were recorded in all cases. Screw perforations were evaluated in both plain X-ray and CT. Screw perforations occurred in 11 (12.0%), 7 (7.0%) and 1 (1.1%) screws in each period. There were no complications, such as infection, neurological deterioration and neurovascular injury directly related to screw insertion. The learning curve showed a significant improvement especially in the later period. However, the perforation rates in both the earlier and middle periods must not be underestimated. Surgeons with less experience must insert cervical pedicle screws with the assistance of a senior surgeon to avoid lethal complications.

✓Discal cysts are rare lesions that can result in refractory sciatica. Because they are so rare, their exact origin and details of the clinical manifestations are still unknown. The authors report on five men treated for discal cysts. The mean age of the patients at the time of the surgery was 32 years (range 25–38 years). All patients suffered from lower-extremity pain and the results of the straight leg–raising test were positive in all cases. Three patients reported motor weakness and four had sensory disturbance—symptoms similar to those found in patients with lumbar disc herniation. Magnetic resonance imaging demonstrated spherically shaped extradural lesions of various sizes with low and high signal intensities on T1- and T2-weighted images, respectively. Discography revealed obvious communication between the cyst and the intervertebral disc with reproducible leg pain in all patients. All patients underwent posterior decompression and excision of the cysts either with or without additional discectomy. The radicular symptoms were remarkably improved in all patients immediately after surgery, and no recurrent lesions were noted during follow up.

Objective Recent studies have demonstrated sagittal spinal balance was more important than coronal balance in terms of clinical result of surgery for adult spinal deformity. Notably, Schwab reported one of the target spinopelvic parameters for corrective surgery was that lumbar lordosis (LL) should be within +/10 degrees of pelvic incidence (PI). The present study was aimed to investigate whether the clinical outcome of corrective fusion surgery was really poor for patients who could not be acquired sufficient PI-LL value by the surgery.

Study Design. A prospective, randomized, single-blinded study. Objectives. To prospectively compare the anesthesia for posterior lumbar spinal fusion between the age- and gender-matched groups with and without preoperative epidural anesthesia with morphine. Summary of Background Data. To reduce the blood loss, hypotensive anesthesia is frequently used in the spinal fusion. However, in spite of administration of the hypotensive agents, inadequate analgesia during operation often causes unfavorable and unexpected elevation of blood pressure resulting in excessive bleeding. As well, intractable wound pain sometimes occurs after spinal fusion due to inadequate analgesia during surgery. Methods. Forty cases of posterior lumbar spinal fusion were investigated prospectively. Twenty patients underwent preoperative epidural anesthesia with morphine and sedation by continuous intravenous administration of propofol but without administration of any kind of anesthetics, including intraoperative and/or postoperative epidural anesthesia (Group E). Another 20 patients underwent inhalation general anesthesia with sevoflurane and intermittent intravenous administration of fentanyl without any regional block (Group F). In these groups, dynamics and average mean blood pressure during surgery, blood loss during surgery, postoperative requirement of analgesics, the visual analogue scale, and accuracy of neurologic evaluation immediately after surgery were analyzed. Results. The average mean blood pressure during surgery was significantly lower in Group E than Group F: 57.1 mm Hg and 72.8 mm Hg, respectively. In addition, the dynamics of blood pressure were more stable in Group E than Group F. The blood loss during surgery was significantly less in Group E than in Group F: 546 g and 631 g, respectively. The patients of Group E required analgesics after surgery less frequently, and the rating on the visual analogue scale was significantly lower in Group F on the first, second, and third days after surgery. It was difficult to evaluate the neurologic status accurately in 5 patientsof Group F because of the inadequate emergence immediately after surgery. There were no patients in Group E whose neurologic status was unclear because of the paralysis caused by epidural anesthesia. Conclusions. To combine preoperative epidural anesthesia with other anesthetic procedure for spinal fusion contributes to maintain more stable hypotension during surgery. As a result, it will be possible to lessen the bleeding during surgery. In addition, the postoperative pain was easily controlled with administration of fewer analgesic agents in patients who underwent the epidural anesthesia. The effectiveness of pre-emptive analgesia should be emphasized to diminish the postoperative pain.

Background Recent studies have demonstrated sagittal spinal balance was more important than coronal balance in terms of clinical result of surgery for adult spinal deformity. Notably, Schwab reported that one of the target spinopelvic parameters for corrective surgery was that pelvic incidence (PI) minus lumbar lordosis (LL) should be within +/- 10 °. The present study aimed to investigate whether the clinical outcome of corrective fusion surgery was really poor for patients who could not acquire sufficient PI-LL value through the surgery. Methods The present study included 13 patients (mean 68.5 yrs old) with adult spinal deformity. Inclusion criteria were corrective fusion surgery more than 4 intervertebral levels, PI-LL ≥10° on the whole spine X-ray immediately after surgery, and follow-up period ≥3 years. All surgeries were performed by posterior approach. Parameters using SRS-Schwab classification, proximal junctional kyphosis (PJK) of ≥15°, implants loosening, and non-union were investigated using the total standing spinal X-ray. Clinical outcomes were evaluated by Japanese Orthopaedic Association scores (JOA score), Oswestry Disability Index, SF-36, Visual Analog Scale for low back pain, and satisfaction for surgery using SRS-22 questionnaire. Results All patients showed the PI-LL ≥20° before surgery. Although the LL were acquired mean 23.6° after surgery, significant loss of correction was observed at final follow up. The acquired coronal spinal alignment was maintained within the follow-up period. However, sagittal vertical axis (SVA) was shifted forward significantly, from mean 4.5cm immediately after surgery to 11.1cm at final follow-up. Five patients showed PJK, 10 patients showed implants loosening, 8 patients showed non-union at final follow-up. The JOA score and mental health summary measures of SF-36 were significantly improved at final follow-up. The satisfaction score was mean 3.3 points, including 3 patients with ≥4 points, at final follow-up. The satisfaction score correlated negatively with SVA at final follow-up (ρ=-0.58 p=0.03). Conclusions The forward shift of SVA was frequently observed, and SVA at final follow-up related to the patient’s satisfaction of surgery. This study indicated the importance of postoperative PI-LL value, but also noted 23% of patients acquired good SVA and satisfaction nevertheless they had inadequate postoperative LL.