Delayed-onset radiculopathy caused by a retropulsed bone fragment after percutaneous kyphoplasty: report of four cases and literature review.

BACKGROUND: Vertebral compression fractures caused by osteoporosis are common in elderly patients and are often encountered by clinical physicians. Percutaneous balloon kyphoplasty (PKP) is widely accepted as a minimally invasive procedure for effectively relieving pain and correcting deformities, but complications may occur. Radiculopathy with a delayed onset caused by a retropulsed bone fragment has not been adequately described in the literature. Thus, this article presents a case report of four cases of retropulsed bone fragment-related radiculopathy after PKP. CASE PRESENTATION: In this article, we reported that four out of 251 patients developed radiculopathy after PKP between January 2012 and January 2019 despite experiencing substantial improvements in back pain. All patients with radiculopathy were female and diagnosed with osteoporosis, and their ages ranged from 68 to 89 years. Radiculopathy occurred from 2 to 16 weeks after PKP. All four patients underwent another operation (posterior decompression and instrumentation). Three patients recovered completely, and one died of postoperative intracranial haemorrhage. A detailed imaging study with pre- and postoperative magnetic resonance imaging (MRI) revealed that retropulsed bone fragments that impinged on the corresponding root after PKP were responsible for this complication, and all four patients developed a disrupted posterior vertebral rim preoperatively. No leakage of cement or pedicle track violations were observed. CONCLUSION: Although PKP is a safe and effective treatment for painful osteoporotic vertebral compression fractures, a risk of catastrophic neurological injury remains. Radiculopathy with delayed onset caused by a retropulsed bone fragment after kyphoplasty is rare and challenging to treat, and the integrity of the posterior vertebral cortex should be carefully evaluated preoperatively to prevent this complication.

Finite element analysis after rod fracture of the spinal hybrid elastic rod system.

BACKGROUND: The spinal hybrid elastic (SHE) rod dynamic stabilization system can provide sufficient spine support and less adjacent segment stress. This study aimed to investigate the biomechanical effects after the internal fracture of SHE rods using finite element analysis. METHODS: A three-dimensional nonlinear finite element model was developed. The SHE rod comprises an inner nitinol stick (NS) and an outer polycarbonate urethane (PCU) shell (PS). The fracture was set at the caudal third portion of the NS, where the maximum stress occurred. The resultant intervertebral range of motion (ROM), intervertebral disc stress, facet joint contact force, screw stress, NS stress, and PCU stress were analyzed. RESULTS: When compared with the intact spine model, the overall trend was that the ROM, intervertebral disc stress, and facet joint force decreased in the implanted level and increased in the adjacent level. When compared with the Ns-I, the trend in the Ns-F decreased and remained nearly half effect. Except for torsion, the PS stress of the Ns-F increased because of the sharing of NS stress after the NS fracture. CONCLUSIONS: The study concluded the biomechanical effects still afford nearly sufficient spine support and gentle adjacent segment stress after rod fracture in a worst-case scenario of the thinnest PS of the SHE rod system.

Impact of cervical sagittal parameters and spinal cord morphology in cervical spondylotic myelopathy status post spinous process-splitting laminoplasty.

PURPOSE: No standard strategy exists for managing cervical spondylotic myelopathy (CSM). The efficacy of spinous process-splitting laminoplasty, its impact on cervical alignment change and the incidence of postoperative neck pain remain unclear. We analyzed the parameters of cervical alignment and cord morphology in CSM. METHODS: The radiographic parameters investigated were pre- and postoperative C2-C7 lordosis (CL), C2-C7 sagittal vertical axis (CSVA), T1 slope (TS), TS minus CL (TS - CL) and cervical spinal cord morphology. Myelopathy severity was measured using two different functional scores. Statistical analysis was performed to determine significant differences between preoperative and follow-up radiological findings and change in functional scores. RESULTS: This retrospective study comprised 85 CSM patients from a single institute, with a minimum follow-up of 24 months. Overall, 63.5% (n = 54) of patients had improvement in their postoperative cervical lordotic alignment; 36.5% (n = 31) developed progressive aggravation of the cervical kyphotic alignment. Pearson correlation analysis showed that CSVA, TS and T1-CL were independent predictors of CL curve change. Based on the receiver operating characteristic curve, the cutoff value for CSVA was 2.89 cm with a postoperative visual analog scale (VAS) > 4. The cutoff value of the TS - CL was 20 degrees with a postoperative VAS > 4. CSVA, TS and TS - CL had a significant association with variation in CL. CSVA and TS - CL had a significant association with postoperative neck pain. CONCLUSIONS: CSVA, T1 slope and T1-CL are good predictors of postoperative degenerative kyphotic change and neck pain. Careful consideration of their preoperative cutoff values can improve postoperative outcomes. LEVEL OF EVIDENCE: IV. These slides can be retrieved under Electronic Supplementary Material.

Reduction of the domino effect in osteoporotic vertebral compression fractures through short-segment fixation with intravertebral expandable pillars compared to percutaneous kyphoplasty: a case control study.

BACKGROUND: Osteoporotic vertebral compression fracture is the leading cause of disability and morbidity in elderly people. Treatment of this condition remains a challenge. Osteoporotic vertebral compression fractures can be managed with various approaches, but each has limitations. In this study, we compared the clinical outcomes obtained using short-segment fixation with intravertebral expandable pillars (I-VEP) to those obtained with percutaneous kyphoplasty in patients who had suffered vertebral compression fractures. METHODS: The study included 46 patients with single-level osteoporotic thoracolumbar fractures. Twenty-two patients in Group I underwent short-segment fixation with I-VEP and 24 patients in Group II underwent kyphoplasty. All patients were evaluated pre- and postoperatively using a visual analogue scale, anterior height of the fractured vertebra, and kyphotic angle of the fractured vertebra. The latter 2 radiological parameters were measured at the adjacent segments as well. RESULTS: There was no significant difference between the groups in terms of gender or fracture level, but the mean age was greater in Group II patients (p = 0.008). At the 1-year follow-up, there were no significant differences in the visual analogue scale scores, anterior height of the fractured vertebra, or the value representing anterior height above the fractured vertebra and kyphotic angle below the fractured vertebra, after adjusting for the patients' gender, fracture level, and age. When considered separately, the anterior height below the fractured vertebra was significantly higher and the kyphotic angle above the fractured vertebra was significantly smaller in Group I than in Group II (p = 0.029 and p = 0.008, respectively). The kyphotic angle of the fractured vertebra was significantly smaller in Group II than in Group I (p < 0.001). CONCLUSIONS: In older individuals with vertebral compression fractures, kyphoplasty restored and maintained the collapsed vertebral body with less kyphotic deformity than that induced by short-segment fixation with I-VEP. Short-segment fixation with I-VEP was more effective in maintaining the integrity of adjacent segments, which prevented the domino effect often observed in patients with osteoporotic kyphotic spines.

Novel Modular Spine Blocks Affect the Lumbar Spine on Finite Element Analysis.

Introduction: There are various surgical interventions to manage osteoporotic vertebral compression fracture. Modular spine block (MSB) is a novel intravertebral fixator that can be assembled. This study aimed to quantitatively investigate the force distribution in vertebrae with the various structural designs and implantation methods by finite element analysis (FEA). Methods: A three-dimensional nonlinear FEA of the L3 implanted with MSB was constructed. Different structural designs (solid vs. hollow) and implantation methods (three-layered vs. six-layered and unilateral vs. bilateral) were studied. The model was preloaded to 150 N-m before the effects of flexion, extension, torsion, and lateral bending were analyzed at the controlled ranges of motion of 20°, 15°, 8°, and 20°, respectively. The resultant intervertebral range of motion (ROM) and disk stress as well as intravertebral force distribution were analyzed at the adjacent segments. Results: The different layers of MSB provided similar stability at the adjacent segments regarding the intervertebral ROM and disk stress. Under stress tests, the force of the solid MSB was shown to be evenly distributed within the vertebrae. The maximum stress value of the unilaterally three-layered hollow MSB was generally lower than that of the bilaterally six-layered solid MSB. Conclusions: The MSB has little stress shielding effect on the intervertebral ROM and creates no additional loading to the adjacent disks. The surgeon can choose the appropriate numbers of MSB to fix vertebrae without worrying about poly(methyl methacrylate) extravasation, implant failure, or adjacent segment disease.

The effects of intravenous zoledronic acid in Chinese women with postmenopausal osteoporosis.

The aim of this study was to assess the efficacy and safety of a once-yearly zoledronic acid treatment for Chinese women with postmenopausal osteoporosis in Taiwan and Hong Kong. This post hoc subpopulation analysis, from the Health Outcome and Reduced Incidence with Zoledronic Acid One Yearly Pivotal Fracture Trial, enrolled 323 Chinese women with osteoporosis who were randomly given either annual infusions of zoledronic acid or placebo for 3 consecutive years. The incidence of fractures and changes in bone mineral density (BMD) were measured; adverse events (AEs) and tolerability were recorded and assessed. The results of this study at 36 months demonstrate that there was a significantly reduced risk of morphometric vertebral fracture and clinical vertebral fracture in subjects treated with zoledronic acid (P < 0.05). In addition, there were significant increases of BMD by 4.9%, 4.3%, and 7.0% in the total hip, femoral neck, and trochanter, respectively, in the zoledronic acid group compared with the placebo group (P < 0.001 for all comparisons). The incidences of AEs were comparable between the two groups. Thus, once-yearly zoledronic acid treatment showed bone protection effects by reducing the risk of vertebral fracture and increasing BMD in Chinese women with postmenopausal osteoporosis.

A comparison between pulsed radiofrequency and electro-acupuncture for relieving pain in patients with chronic low back pain.

Many treatment options for chronic low back pain are available, including varied forms of electric stimulation. But little is known about the electricity effect between electro-acupuncture and pulsed radiofrequency. The objective of this study is to assess the difference in effectiveness of pain relief between pulsed radiofrequency and electro-acupuncture. Visual analog score (VAS) pain score, the Oswestry disability index (ODI) to measure a patient's permanent functional disability, and Short form 36 (SF-36) which is a survey used in health assessment to determine the cost-effectiveness of a health treatment, were used as rating systems to measure the pain relief and functional improvement effect of pulsed radiofrequency and electro-acupuncture, based on the methodological quality of the randomized controlled trials, the relevance between the study groups, and the consistency of the outcome evaluation. First, the baseline status before therapy shows no age and gender influence in the SF-36 and VAS score but it is significant in the ODI questionnaire. From ANOVA analyses, it is apparent that radiofrequency therapy is a significant improvement over electro-acupuncture therapy after one month. But electro-acupuncture also showed functional improvement in the lumbar spine from the ODI. This study provides sufficient evidence of the superiority of pulsed radiofrequency (PRF) therapy for low back pain relief compared with both electro-acupuncture (EA) therapy and the control group. But the functional improvement of the lumbar spine was proved under EA therapy only. Both therapies are related to electricity effects.

A Spine Robotic-Assisted Navigation System for Pedicle Screw Placement.

Pedicle screw implantation has excellent treatment effects and is often used by surgeons in spinal fusion surgery. However, due to the complexity of human body anatomy, this surgical procedure is difficult and challenging, especially in minimally invasive surgery or patients with congenital anomalies and kyphoscoliosis deformity. In addition to the abovementioned factors, the surgical experience and technique of the surgeon also affect the recovery rates and complications of the patients after the surgical operation. Therefore, accurately performing pedicle screw implantation has is a constant topic of common concern for surgeons and patients. In recent years, with the technological development, robot-assisted navigation systems have gradually become adopted. These robot-assisted navigation systems provide surgeons with complete preoperative planning before surgery. The system provides 3D reconstructed images of each vertebra, allowing surgeons to understand the patient's physiological characteristics more quickly. It also provides 2D images of sagittal, coronal, axial and oblique planes so that surgeons can accurately perform pedicle screw placement plan. Previous studies have demonstrated the effectiveness of robot-assisted navigation systems for pedicle screw implantation procedures, including accuracy and safety assessments. This step-by-step protocol aims to outline a standardized surgical technique note for robotic-assisted pedicle screw placement.

Clinical outcomes of microendoscopic decompressive laminotomy for degenerative lumbar spinal stenosis.

The goal of surgical treatment for degenerative lumbar spinal stenosis (LSS) is to effectively relieve the neural structures by various decompressive techniques. Microendoscopic decompressive laminotomy (MEDL) is an attractive option because of its minimally invasive nature. The aim of prospective study was to investigate the effectiveness of MEDL by evaluating the clinical outcomes with patient-oriented scoring systems. Sixty consecutive patients receiving MEDL between December 2005 and April 2007 were enrolled. The indications of surgery were moderate to severe stenosis, persistent neurological symptoms, and failure of conservative treatment. The patients with mechanical back pain, more than grade I spondylolisthesis, or radiographic signs of instability were not included. A total of 53 patients (36 women and 17 men, mean age 62.0) were included. Forty-five patients (84.9%) were satisfied with the treatment result after a follow-up period of 15.7 months (12-24). The clinical outcomes were evaluated with the Oswestry disability index (ODI) and the Japanese Orthopedic Association (JOA) score. Of the 50 patients providing sufficient data for analysis, the ODI improved from 64.3 +/- 20.0 to 16.7 +/- 20.0. The JOA score improved from 9.4 +/- 6.1 to 24.2 +/- 6.0. The improvement rate was 73.9 +/- 30.7% and 40 patients (80%) had good or excellent results. There were 11 surgical complications: dural tear in 5, wrong level operation in 2, and transient neuralgia in 4 patients. No wound-related complication was noted. Although the prevalence of pre-operative comorbidities was very high (69.8%), there was no serious medical complication. There was no post-operative instability at the operated segment as evaluated with dynamic radiographs at final follow-up. We concluded that MEDL is a safe and very effective minimally invasive technique for degenerative LSS. With an appropriate patient selection, the risk of post-operative instability is minimal.

Vitamin-D binding protein does not enhance healing in rat bone defects: a pilot study.

Vitamin D-binding protein (DBP) has an anabolic effect on the skeleton and reportedly enhances bone ingrowth. We used an in vivo critical bone defect model to determine whether local administration of DBP promotes bone defect healing. We created a 5-mm segmental bone defect in the radial shaft in a rat model. Forty-eight rats were assigned to eight groups: local application of 1 microg, 5 microg, 10 microg, or 50 microg DBP (DBP-1, DBP-5, DBP-10, DBP-50), autogenous bone marrow mononuclear cells with or without 10 microg DBP (BM-DBP-10, BM), 80 microg BMP-2 delivered in gelatin sponge (BMP-2), and the sham operated group. Radiographic evaluation, histological stains, and epifluorescence microscopy were performed. Grossly, all bone gaps of the BMP-2 group were solidly bridged by callus, while all those in the sham operated group remained unhealed by 9 weeks. Only one specimen of the BM-DBP-10 and DBP-50 groups and three specimens of the BM group were solidly healed; pseudarthroses occurred in all of the other specimens. Histological study and radiographs of the specimens showed similar results. We did not observe the enhanced bone healing reported in a previous study.

Comparison and prediction of pullout strength of conical and cylindrical pedicle screws within synthetic bone.

BACKGROUND: This study was designed to derive the theoretical formulae to predict the pullout strength of pedicle screws with an inconstant outer and/or inner diameter distribution (conical screws). For the transpedicular fixation, one of the failure modes is the screw loosening from the vertebral bone. Hence, various kinds of pedicle screws have been evaluated to measure the pullout strength using synthetic and cadaveric bone as specimens. In the literature, the Chapman's formula has been widely proposed to predict the pullout strength of screws with constant outer and inner diameters (cylindrical screws). METHODS: This study formulated the pullout strength of the conical and cylindrical screws as the functions of material, screw, and surgery factors. The predicted pullout strength of each screw was compared to the experimentally measured data. Synthetic bones were used to standardize the material properties of the specimen and provide observation of the loosening mechanism of the bone/screw construct. RESULTS: The predicted data from the new formulae were better correlated with the mean pullout strength of both the cylindrical and conical screws within an average error of 5.0% and R2 = 0.93. On the other hand, the average error and R2 value of the literature formula were as high as -32.3% and -0.26, respectively. CONCLUSION: The pullout strength of the pedicle screws was the functions of bone strength, screw design, and pilot hole. The close correlation between the measured and predicted pullout strength validated the value of the new formulae, so as avoid repeating experimental tests.

Results of using robotic-assisted navigational system in pedicle screw placement.

Recent technical developments have resulted in robotic-assisted pedicle screw placement techniques. However, the use of robotic-assisted navigational techniques is still subject to controversy. This study aims to assess the accuracy and safety of a self-developed navigation system, the point spine navigation system (PSNS), for robotic-assisted pedicle screw placement surgery. Fifty-nine pedicle screws were implanted in three porcine vertebrae at the T6-T10 and L1-L5 levels, with the assistance of the PSNS. The navigation and planning system provides virtual surgical guide images, including sagittal, coronal, axial, oblique planes, and customized three-dimensional reconstructions for each vertebra to establish accurate pedicle screw trajectories and placement tracts. After pedicle screw placement, post-operative spiral computer tomographic scans were performed and screws were evaluated using the Gertzbein-Robbins classification. Differences between the actual pedicle screw position and pre-operative planning paths, including the angle, shortest distance, and entry trajectory were recorded. The 59 pedicle screw placements were all within a safe zone, and there was no spinal canal perforation or any other damage under postoperative computed tomography image data. Fifty-one screws were categorized as group A, seven screws were noted as group B, and one screw was identified as group E under the Gertzbein-Robbins classification. The mean entry point deviation was 2.71 ± 1.72°, mean trajectory distance was 1.56 ± 0.66 mm, and average shortest distance between two paths was 0.96 ± 0.73 mm. Pedicle placement remains a challenging procedure with high reported incidences of nerve and vascular injuries. The implementation of a robotic-assisted navigational system yields an acceptable level of accuracy and safety for the pedicle screw placement surgery.

Three-dimensional culture of human nucleus pulposus cells in fibrin clot: comparisons on cellular proliferation and matrix synthesis with cells in alginate.

Regeneration of nucleus pulposus (NP) tissue may stop or reverse early intervertebral disk (IVD) degeneration. Cellular proliferation and matrix synthesis can be promoted by incorporation of cells and bioscaffolds. However, insertion of preshaped solid bioscaffolds may damage remaining IVD integrity. Fibrin clots can be introduced in a minimally invasive manner with polymerization in desired three-dimensional shape and retention of cells. In this study, we investigated the cellular proliferation and matrix synthesis of human NP cells in the fibrin clots in vitro. Monolayer-expanded cells were embedded in fibrin clot or alginate and were cultivated in vitro for 2 weeks. Increased DNA content and decreased expression of apoptosis stimulating fragment (Fas)-associated death-domain protein in fibrin scaffolds suggested higher cellular proliferation and reduced apoptosis. Superior proteoglycan synthesis was found in fibrin scaffolds. As expression of collagens I and X increased and SOX9 expression decreased, fibrin scaffolds tended to promote fibrotic transformation and inhibit chondrogenesis. Adjustments of fibrin preparations are needed to make it more suitable for IVD regeneration.

Instrumented posterior lumbar interbody fusion in adult spondylolisthesis.

UNLABELLED: It is unclear whether using artificial cages increases fusion rates compared with use of bone chips alone in posterior lumbar interbody fusion for patients with lumbar spondylolisthesis. We hypothesized artificial cages for posterior lumbar interbody fusion would provide better clinical and radiographic outcomes than bone chips alone. We assumed solid fusion would provide good clinical outcomes. We clinically and radiographically followed 34 patients with spondylolisthesis having posterior lumbar interbody fusion with mixed autogenous and allogeneic bone chips alone and 42 patients having posterior lumbar interbody fusion with implantation of artificial cages packed with morselized bone graft. Patients with the artificial cage had better functional improvement in the Oswestry disability index than those with bone chips alone, whereas pain score, patient satisfaction, and fusion rate were similar in the two groups. Postoperative disc height ratio, slip ratio, and segmental lordosis all decreased at final followup in the patients with bone chips alone but remained unchanged in the artificial cage group. The functional outcome correlated with radiographic fusion status. We conclude artificial cages provide better functional outcomes and radiographic improvement than bone chips alone in posterior lumbar interbody fusion for lumbar spondylolisthesis, although both techniques achieved comparable fusion rates. LEVEL OF EVIDENCE: Level III, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Surgical removal of extravasated epidural and neuroforaminal polymethylmethacrylate after percutaneous vertebroplasty in the thoracic spine.

Although extravasations of polymethylmetharylate during percutaneous vertebroplasty are usually of little clinical consequence, surgical decompression is occasionally required if resultant neurologic deficits are severe. Surgical removal of epidural polymethylmetharylate is usually necessary to achieve good neurologic recovery. Because mobilizing the squeezed spinal cord in a compromised canal can cause further deterioration, attempts to remove epidural polymethylmetharylate in the thoracic region need special consideration. A 66-year-old man had incomplete paraparesis and radicular pain on the chest wall after percutaneous vertebroplasty for osteoporotic compression fracture of T7. Radiological studies revealed polymethylmetharylate extravasations into the right lateral aspect of spinal canal that caused marked encroachment of the thecal sac and right neuroforamina. Progressive neurologic deficit and poor responses to medical managements were observed; therefore, surgical decompression was performed 4 months later. After laminectomy and removal of facet joints and T7 pedicle on the affected side, extravasated polymethylmetharylate posterior and anterior to the thecal sac was completely removed without retracting the dura mater. Spinal stability was reconstructed by supplemental spinal instrumentation and intertransverse arthrodesis with banked cancellous allografts. Myelopathy and radicular pain gradually resolved after decompression surgery. The patient was free of sensory abnormality and regained satisfactory ambulation two years after surgical decompression.

Superior mesenteric artery syndrome complicating staged corrective surgery for scoliosis.

Superior mesenteric artery syndrome (SMAS) is a rare complication following correction of scoliosis with either nonoperative or operative methods. If the patient diagnosed with this syndrome is not managed timely and adequately, mortality may result. We report two cases of SMAS complicating staged corrective surgery for scoliosis using modern segmental derotation instrumentation system. The aim of this report is to highlight the clinical presentations, laboratory findings, radiologic features, and management of the syndrome. The first patient had the syndrome after two-staged scoliosis surgery with halo traction between two stages, and the second patient after three-staged scoliosis surgery with halo traction between the first and second surgeries. The first patient responded well to conservative treatment. However, the second patient failed to respond to conservative treatment and needed a gastrojejunostomy operation to bypass the duodenal obstruction. Clinicians treating post scoliosis surgery patients should always have a high index of suspicion for this potential life-threatening condition. Early diagnosis will enable a multidisciplinary team approach to be initiated early to provide optimal care for the patient. Nutritional and fluid supplementation is mandatory during conservative treatment. The duration for trial of conservative treatment should not exceed 1 week.

Estimated prevalence of osteoporosis from a Nationwide Health Insurance database in Taiwan.

Approximately 9.24% of the Taiwanese population is aged 65 years or older. Among them, osteoporosis is a major problem, along with it associated age-related fractures. We investigated the prevalence of osteoporosis in 1996-2001 by sampling Taiwan's National Health Insurance (NHI) database. Data from 102,763 men (51.27%) and 97,654 women (48.73%) were evaluated. In this cohort, osteoporosis was recorded in each yearly dataset if the codes 733.0 or 733.00-733.09 were found on a search of the administrative or outpatient sub-databanks. A stable estimated prevalence of osteoporosis was calculated according to Taiwan's NHI sampling data from 1999 to 2001. The results showed a trend toward increasing proportions of coded osteoporosis with age, more predominantly in the female population. The averaged prevalence of osteoporosis, between 1999 and 2001, in those aged > or = 50 years was 1.63% for men and 11.35% for women. These estimates were lower than those reported elsewhere for Taiwan and for Japan but more equal to that in the Mexican American sub-population of the United States. In conclusion, the prevalence of osteoporosis is underestimated in the NHI database. Policymakers should be aware of this finding and allocate resources accordingly.

Gelatin/chondroitin-6-sulfate copolymer scaffold for culturing human nucleus pulposus cells in vitro with production of extracellular matrix.

Tissue-engineering approaches for treating degenerative intervertebral discs aim to regenerate intervertebral disc tissues in order to retard or even reverse the degenerative process. This study was designed to investigate the feasibility of the glutaraldehyde crosslinked gelatin/chondroitin-6-sulfate copolymer scaffold to serve as a bioactive scaffold for culturing human nucleus pulposus (NP) cells in vitro with preservation of the cell viability, cell proliferation, and production of important extracellular matrix, including glycoaminoglycans (GAG) and Type II collagen. Each experimental sample was seeded with 1 x 10(6) human NP cells, and then the cell-scaffold hybrids were cultured in vitro for 6 or 12 weeks. SEM showed a highly porous structure with an average pore size of 100 microm in the copolymer scaffold. Immediately after cell seeding, SEM showed that the seeded cells penetrated deeply and distributed evenly in the copolymer scaffold. Water-soluble tetrazolium salt-1 (WST-1) assay showed good viability and active proliferation of cultured human NP cells in the copolymer scaffolds up to 12 weeks. The cell-scaffold hybrids contained significantly higher levels of sulfated GAG than the control samples (41.29 mug vs 6.04 mug per scaffold). Immunohistochemical study showed Type II collagen fibrils on the surface of scaffold substrate after 6 weeks of cultivation. More abundant deposition of Type II collagen could be detected after 12 weeks. The results achieved in this study indicate that the gelatin/chondroitin-6-sulfate copolymer scaffold is a promising bioactive scaffold for regeneration of nucleus pulposus tissue.

Multiple parallel skin markers for minimal incision lumbar disc surgery; a technical note.

BACKGROUND: Spinal surgery depends on accurate localization to prevent incorrect surgical approaches. The trend towards minimally invasive surgery that minimizes surgical exposure and reduces postoperative pain increasingly requires surgeons to accurately determine the operative level before an incision is made. Preoperative localization with a C-arm image intensifier is popular, but the exposure of both patients and theatre staff to radiation is a disadvantage, as well as being time-consuming. METHODS: We describe a simple surgical tool developed to help localize exact spinal levels in conjunction with a simple AP X-ray film immediately before surgery. Multiple parallel skin markers were made using a circular oven rack comprising multiple 1.5 cm spaced parallel wires attached to a circular outside rim. The longest line was placed on the line of the postero-superior iliac spine (PSIS) over the junction of the L5-S1 region. RESULTS AND CONCLUSIONS: Based on the film taken, the incision can be accurately made at the intended level. The incision wound can be minimized to 3.0 cm even when using conventional disc surgery instruments.

Management of scoliosis.

The etiology and nature of truncal deformity in idiopathic scoliosis remains unclear. Only 2 methods are effective to halt or correct the spinal deformity. The first is bracing in young patients and the second is surgical correction for severe curve. Bracing is feasible for children with a Cobb angle between 20 degrees to 35 degrees, while surgical correction is the only choice if the Cobb angle is greater than 40 degrees. Recent surgical developments have led to good correction results with reduced operative scale through continuous spinal cord monitoring, evolution of spinal implants, and better perioperative and postoperative care. The newer spinal systems can produce 3-dimensional reconstruction of the deformity and maintain truncal balance afterwards. The newer implants are user-friendly and low-profile. The combined hook/screw application (hybrid) and the all-screw placement methods have become quite popular. With these methods, the correction rate is increased with reduced loss of correction at follow-up. Navigation systems facilitate accurate insertion of pedicle screws into the vertebral bodies, while video-assisted endoscopic instruments allow early ambulation. These methods are useful in cases of thoracic scoliosis. In the future, in order to minimize the operative scale and prevent deformity, important goals are elucidation of the real nature and the causes of scoliosis and restriction of the number of fusion levels by use of emerging technologies.