Dynamic Photonic Janus Colloids with Axially Stacked Structural Layers.

Diblock copolymer (dBCP) particles capable of dynamic shape and color changes have gained significant attention due to their versatility in programmable shapes and intricate nanostructures. However, their application in photonic systems remains limited due to challenges in achieving a sufficient number of defect-free photonic layers over a tens-of-micrometer scale. In this study, we present a pioneering demonstration of photonic dBCP particles featuring over 300 axially stacked photonic layers with responsive color- and shape-transforming capabilities. Our approach leverages the complex interplay between the macrophase separation of multiple incompatible components and the microphase separation of dBCP from solvent-evaporative microemulsions. Specifically, continuous phase separation of silicone oil from polystyrene-block-poly(2-vinylpyridine) (PS-b-P2VP), triggered by solvent evaporation, promotes the anisotropic growth of PS-b-P2VP layers. This results in the formation of Janus colloids, where an oil droplet merges with a nanostructured polymer cone and lamellar structures align along the long axis of the cone. We highlight the capability to precisely adjust the particle morphology and the corresponding orientation, dispersion, and structural color window by modulating both the molecular weight of PS-b-P2VP and the volume ratio between PS-b-P2VP and silicone oil. Furthermore, reversible swelling/deswelling of photonic colloids is visualized and correlated with their structural colors. Finally, we demonstrate the potential of this study by presenting a multicolor-patterned array of photonic colloids, highlighting the possibilities for applications in smart photonic ink and devices.

Cement Augmented Anterior Reconstruction and Decompression without Posterior Instrumentation: A Less Invasive Surgical Option for Osteoporotic Thoracolumbar Fracture with Cord Compression.

OBJECTIVE: We investigated the clinical and radiological outcomes of a cement augmented anterior reconstruction and decompression without pedicle screw fixation in patients with osteoporotic thoracolumbar vertebral fracture with myelopathy. METHODS: There were 2 male and 6 female patients with thoracolumbar fracture and myelopathy included in the study. The mean follow-up period was more than 1 years. The anterolateral decompression and cement augmented anterior reconstruction with poly(methyl methacrylate) (PMMA) was performed. Demographic data, clinical outcomes, perioperative parameters and radiologic parameter were retrospectively evaluated. RESULTS: The symptoms due to myelopathy were improved in all patients. The preoperative median visual analog scale score for lower back and leg were 8.5 that improved 4.25 and 3 at last follow up. The preoperative function state showed a median Oswestry Disability Index score 61.5 that improved 33. After surgery, preoperative encroachment of the spinal canal (5.12 mm, 37%) was disappeared. The median height of fractured vertebral body significantly increased from 7.83 to 12.63 mm. At the last follow-up point, the median height was 9.91 mm. The median kyphotic deformity was improved from 22.12° to 14.31°. At the final follow-up, the improvement was preserved (median value: 15.03). The acute complication according to PMMA such as leakage and embolization was none, but adjacent compression fracture as late complication according to cement augmentation was. One patient developed surgical site infection. CONCLUSION: On the basis of the preliminary results, we considered that anterolateral decompression and PMMA augmentation might be an optimal method for treating osteoporotic fracture with myelopathy in elderly patients or those with multiple medical comorbidities.

Anterior lumbar interbody fusion with percutaneous pedicle screw fixation for multiple-level isthmic spondylolisthesis.

OBJECTIVE: Multiple-level lumbar isthmic spondylolisthesis is rarely reported. Here, we report 23 consecutive patients who underwent anterior lumbar interbody fusion (ALIF) with percutaneous pedicle screw fixation (PPF) for multiple-level isthmic spondylolisthesis. PATIENTS AND METHODS: From June 2008 through December 2014, multiple-level lumbar isthmic spondylolisthesis was diagnosed in 23 patients (6 men, 17 women) at Wooridul Spine Hospital (Busan, South Korea). Isthmic spondylolisthesis occurred at three spinal levels in 2 patients and at two levels in 21 patients. All patients underwent ALIF with PPF. We used the Oswestry Disability Index (ODI) and visual analog scale scores to evaluate the preoperative and postoperative functional outcome, low back pain, and radicular pain. We also evaluated segmental lordosis and the fusion status using radiographs and data from computed tomography. RESULTS: Isthmic spondylolisthesis occurred from L3 to S1 and mostly occurred at two consecutive spinal levels (i.e., L4-L5 and L5-S1). Significant improvements in the ODI and visual analog scale were observed in patients at final follow up (p<0.05). The mean segmental lordosis significantly increased after operation (from 22.7° to 32.7°). The mean lumbar lordosis significantly increased after operation (from 45.8 to 53.1). Radiographs of all of the patients showed solid fusion at the last follow-up. There was one case of screw fracture at the S1 level; however, in this case the last follow-up radiograph exhibited solid fusion. CONCLUSIONS: Anterior lumbar interbody fusion with PPF can be an effective treatment choice and yield good clinical outcomes in patients with multiple-level isthmic spondylolisthesis.

Percutaneous Endoscopic Cervical Discectomy (PECD): An Analysis of Outcome, Causes of Reoperation.

OBJECTIVE: Percutaneous endoscopic cervical discectomy (PECD) is regarded as an effective treatment modality in cervical disc herniation, including radicular pain and lateral location of disc herniation. This study aimed to evaluate the clinical and radiologic outcomes of PECD along with the causes of reoperation and the technique itself. METHODS: Between January 2007 and November 2012, 101 patients underwent PECD at the Busan Wooridul Hospital. Three patients underwent a 2-level PECD. The mean follow-up period was 34 months (range, 18-72 months). The mean age was 46.1 years; the most common operation was at the C5-C6 level (n = 45), followed by C6-C7 (n = 35), C4-C5 (n = 16), and C3-C4 (n = 8). The clinical outcomes were evaluated via the visual analog scale of the neck and arm according to the Neck Disability Index and the modified Macnab criteria. Among 101 patients, 12 underwent an additional operation at the index level. Five patients had aggravated stenosis by disc height narrowing, 4 had recurred disc, 2 had remained disc, and 1 had sustained symptoms. RESULTS: After PECD, there was a significant improvement in the visual analog scale and Neck Disability Index scores (P < 0.001). According to the modified Macnab criteria, excellent concordance was achieved in 65 patients, good in 22, fair in 2, and poor in 12. The reoperation performed on 12 patients improved their clinical outcomes. The mean duration was 4.8 months (2 days to 18 months) until reoperation. There were 3 PECD revisions, 3 artificial disc replacements, 2 corpectomies, 2 anterior cervical discectomies and fusion with cages, and 2 transfers to another hospital. The common feature was older age (P = 0.016) and male sex (P = 0.031). Preoperative radiologic findings were characterized by the foraminal disc (P = 0.04), disc degeneration at the index level (P = 0.05), combined bony spur (P = 0.001), concomitant adjacent level degeneration (P = 0.019), cervical kyphosis (P = 0.015), and segmental angle deterioration after PECD (P = 0.038). No statistical correlation was seen between the operation level and herniation size (P > 0.05). CONCLUSIONS: In total, 87% patients showed successful clinical outcome. Poor and fair outcomes at initial PECD were overcome by revision surgery, which improved outcomes. Although PECD is a promising minimally invasive procedure for cervical disc treatment, the indications for PECD should be considered carefully.

Use of a Zero-Profile Device for Contiguous 2-Level Anterior Cervical Diskectomy and Fusion: Comparison with Cage with Plate Construct.

BACKGROUND: A new zero-profile, standalone device (Zero P) was recently developed and has shown a lower incidence rate of complications and competitive clinical outcomes compared with anterior cervical cage with plate construct (CP) in single and multilevel anterior cervical diskectomy and fusion (ACDF). However, there is still concern whether Zero P is appropriate for multilevel ACDF. In addition, there have been few reports of contiguous 2-level ACDF used in conjunction with Zero P. METHODS: We reviewed contiguous 2-level ACDF performed from December 2006 to February 2015. A total of 63 patients met inclusion criteria for the study (CP group = 32 cases; Zero P group = 31 cases). All preoperative and postoperative clinical and radiologic parameters were recorded. These parameters were compared between both groups. RESULTS: The postoperative change of Cobb S over time in the Zero P group was significantly different from that in the CP group. The maintenance of Cobb S in the Zero P group was better than that in the CP group (P < 0.05). The maintenance of anterior intervertebral disk height (IDH) at postoperative assessment for the Zero P group was significantly better than that in the CP group (P < 0.05). Within-group comparison of the postoperative change of anterior and posterior IDH over time revealed that the anterior IDH was significantly lower than the posterior IDH in the Zero P group (P < 0.05). CONCLUSION: For 2-level contiguous ACDF, the use of a zero-profile device has the capacity to show compatible outcomes in correction and maintenance of segmental angle if the anterior titanium alloy plate is properly positioned at the anterior vertebral line.

Salvage Percutaneous Vertebral Augmentation Using Polymethyl Methacrylate in Patients with Failed Interbody Fusion.

BACKGROUND: Percutaneous vertebral augmentation with cement is used as a salvage procedure for failed instrumentation. Few studies have reported the use of this procedure for failed anterior lumbar fusion in elderly patients with osteoporosis and other complicated diseases who have undergone a previous major operation. METHODS: Between January 2007 and December 2015, the clinical and radiographic results of 8 patients with osteoporosis who showed subsidence and migration of the implant after an initial operation were examined. After the development of implant failure, the patients underwent vertebral augmentation with polymethyl methacrylate. RESULTS: Mean patient age was 73.4 years (range, 67-78 years), and mean bone mineral density was -2.96 (range, -2.1 to -3.8). The mean radiologic follow-up period between augmentation and the last follow-up examination was 16 months (range, 3-38 months). Although the subjective clinical outcome was not satisfying to the patients, no loss of correction, fractures, or screw loosening occurred during the follow-up period. CONCLUSIONS: The injection of cement around the instrument might help to stabilize it by providing strength to the axis and preventing further loosening. This salvage procedure could be an alternative in the management of cases with failed interbody fusion.

Anterior dislodgement of a fusion cage after transforaminal lumbar interbody fusion for the treatment of isthmic spondylolisthesis.

Transforaminal lumbar interbody fusion (TLIF) is commonly used procedure for spinal fusion. However, there are no reports describing anterior cage dislodgement after surgery. This report is a rare case of anterior dislodgement of fusion cage after TLIF for the treatment of isthmic spondylolisthesis with lumbosacral transitional vertebra (LSTV). A 51-year-old man underwent TLIF at L4-5 with posterior instrumentation for the treatment of grade 1 isthmic spondylolisthesis with LSTV. At 7 weeks postoperatively, imaging studies demonstrated that banana-shaped cage migrated anteriorly and anterolisthesis recurred at the index level with pseudoarthrosis. The cage was removed and exchanged by new cage through anterior approach, and screws were replaced with larger size ones and cement augmentation was added. At postoperative 2 days of revision surgery, computed tomography (CT) showed fracture on lateral pedicle and body wall of L5 vertebra. He underwent surgery again for paraspinal decompression at L4-5 and extension of instrumentation to S1 vertebra. His back and leg pains improved significantly after final revision surgery and symptom relief was maintained during follow-up period. At 6 months follow-up, CT images showed solid fusion at L4-5 level. Careful cage selection for TLIF must be done for treatment of spondylolisthesis accompanied with deformed LSTV, especially when reduction will be attempted. Banana-shaped cage should be positioned anteriorly, but anterior dislodgement of cage and reduction failure may occur in case of a highly unstable spine. Revision surgery for the treatment of an anteriorly dislodged cage may be effectively performed using an anterior approach.

Comparison between the accuracy of percutaneous and open pedicle screw fixations in lumbosacral fusion.

BACKGROUND CONTEXT: In pedicle screw fixation, accurate insertion is essential to avoid neurological injury or weak stability. The percutaneous pedicle screw system was developed for minimally invasive spine surgery, and its safety has already been reported. However, the accuracy of percutaneous pedicle screw fixation (PPF) has not been compared with that of the open system to date. PURPOSE: To compare the accuracy of PPF with that of open pedicle screw fixation (open PF) and to investigate the risk factors associated with pedicle wall penetration. STUDY DESIGN/SETTING: A retrospective case series. PATIENT SAMPLE: The study group included 237 patients who underwent posterior pedicle screw fixation between January 2008 and October 2010 at a single institute with a total of 1,056 pedicle screw fixations completed. One hundred and twenty-six patients with 558 screws underwent open PF and 111 patients with 498 screws underwent PPF. OUTCOME MEASURES: Postoperative computerized tomography, including sagittal and coronal reformatted images. METHODS: Consecutive surgeries with either conventional open PF or PPF for anterior lumbar interbody fusion or transforaminal lumbar interbody fusion were performed. The open pedicle screw employed was from the WSH system (Winova, Seoul, Korea), and the two percutaneous pedicle screw systems were the Sextant (Medtronics, Minneapolis, MN, USA) and the Viper systems (DePuy Spine, Raynham, MA, USA). Computed tomography images were evaluated to determine pedicle wall penetration after operation. Severity was classified as mild (<3 mm), moderate (3-6 mm), and severe (≥6 mm), and the direction was assessed as medial, lateral, inferior, and superior. RESULTS: Pedicle wall penetration occurred in 75 patients (13.4%) in the open PF group and 71 patients (14.3%) in the PPF group and was not statistically different between the groups (p=.695). Assessment of the severity of the pedicle wall penetration revealed that minor penetration was the most common (open PF group, 9.7%; PPF group, 10.6%), although the distribution of the degree of severity was not statistically different between the groups (p=.863). A relatively higher incidence of lateral penetration was observed in the open PF group (66.7% vs. 43.7%), whereas medial, superior, and inferior penetrations were higher in the PPF group (p=.033). Other parameters such as age, sex, surgical method, and surgeon factors did not influence the penetration rate, but bone mineral densitometry negatively correlated with the penetration. CONCLUSIONS: Pedicle wall penetration during screw fixation was not different between the open PF and PPF groups. The lateral, paraspinal, muscle-splitting approach seems to lessen medial wall penetration, especially in the S1 vertebra. Distribution of the direction of penetration differs between the groups, with lateral wall penetration being more prominent in the open PF group. Careful placement of pedicle screws is necessary for a stronger construct because of the high incidence of penetration.

Clinical and radiological comparison of femur and fibular allografts for the treatment of cervical degenerative disc diseases.

OBJECTIVE: This consecutive retrospective study was designed to analyze and to compare the efficacy and outcomes of anterior cervical discectomy and fusion (ACDF) using a fibular and femur allograft with anterior cervical plating. METHODS: A total of 88 consecutive patients suffering from cervical degenerative disc disease (DDD) who were treated with ACDF from September 2007 to August 2010 were enrolled in this study. Thirty-seven patients (58 segments) underwent anterior interbody fusion with a femur allograft, and 51 patients (64 segments) were treated with a fibular allograft. The mean follow-up period was 16.0 (range, 12-25) months in the femur group and 19.5 (range, 14-39) months in the fibular group. Cage fracture and breakage, subsidence rate, fusion rate, segmental angle and height and disc height were assessed by using radiography. Clinical outcomes were assessed using a visual analog scale and neck disability index. RESULTS: At 12 months postoperatively, cage fracture and breakage had occurred in 3.4% (2/58) and 7.4% (4/58) of the patients in the femur group, respectively, and 21.9% (14/64) and 31.3% (20/64) of the patients in the fibular group, respectively (p<0.05). Subsidence was noted in 43.1% (25/58) of the femur group and in 50.5% (32/64) of the fibular group. No difference in improvements in the clinical outcome between the two groups was observed. CONCLUSION: The femur allograft showed good results in subsidence and radiologic parameters, and sustained the original cage shape more effectively than the fibular allograft. The present study suggests that the femur allograft may be a good choice as a fusion substitute for the treatment of cervical DDD.

Usefulness of carbon dioxide laser for recurrent lumbar disc herniation.

OBJECTIVE: During revision microdiscectomy for recurrent lumbar disc herniation (rLDH), the major concerns are approach-related complications, including dural tear and nerve root injury, because of adhesion scars and granulation tissue along the previous laminotomy site. In revision microdiscectomy of rLDH, carbon dioxide (CO2) laser can enable precise dissection and removal of adhesion scar. The purpose of this study was to evaluate the clinical usefulness of CO2 laser dissection in patients who had undergone revision microdisectomy of rLDH. METHODS: Clinical and radiologic data were reviewed from 21 patients who underwent single lumbar level CO2 laser dissection followed by removal of rLDH between October 2006 and July 2010. They were followed up with plain radiographs, and their mean follow-up period was 30 months. RESULTS: Patients' mean hospital stay after operation was 5.1 days. Pain scores on a visual analogue scale (VAS) for back and leg pain were improved from a preoperative mean of 4.7 and 7.6 to a postoperative mean of 3.5 and 3.0, respectively (p<0.001). Clinical outcomes based on the Oswestry Disability Index (ODI) were improved from a preoperative mean of 57.4-22.2% postoperatively (p<0.001). CONCLUSIONS: Our results demonstrate that CO2 laser could be a useful surgical tool during revision microdisectomy of rLDH.