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.

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.

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.

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.

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.

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.

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.

Segmental correction of adolescent idiopathic scoliosis by all-screw fixation method in adolescents and young adults. minimum 5 years follow-up with SF-36 questionnaire.

BACKGROUND: In our institution, the fixation technique in treating idiopathic scoliosis was shifted from hybrid fixation to the all-screw method beginning in 2000. We conducted this study to assess the intermediate -term outcome of all-screw method in treating adolescent idiopathic scoliosis (AIS). METHODS: Forty-nine consecutive patients were retrospectively included with minimum of 5-year follow-up (mean, 6.1; range, 5.1-7.3 years). The average age of surgery was 18.5 ± 5.0 years. We assessed radiographic measurements at preoperative (Preop), postoperative (PO) and final follow-up (FFU) period. Curve correction rate, correction loss rate, complications, accuracy of pedicle screws and SF-36 scores were analyzed. RESULTS: The average major curve was corrected from 58.0 ± 13.0° Preop to 16.0 ± 9.0° PO(p < 0.0001), and increased to 18.4 ± 8.6°(p = 0.12) FFU. This revealed a 72.7% correction rate and a correction loss of 2.4° (3.92%). The thoracic kyphosis decreased little at FFU (22 ± 12° to 20 ± 6°, (p = 0.25)). Apical vertebral rotation decreased from 2.1 ± 0.8 PreOP to 0.8 ± 0.8 at FFU (Nash-Moe grading, p < 0.01). Among total 831 pedicle screws, 56 (6.7%) were found to be malpositioned. Compared with 2069 age-matched Taiwanese, SF-36 scores showed inferior result in 2 variables: physical function and role physical. CONCLUSION: Follow-up more than 5 years, the authors suggest that all-screw method is an efficient and safe method.

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.

Alteration in shoulder kinematics and associated muscle activity in people with idiopathic scoliosis.

STUDY DESIGN: A cross-sectional control-matched study in adolescents with idiopathic scoliosis (IS). OBJECTIVE: To evaluate whether subjects with IS had shoulder dysfunction and associated impairment in shoulder kinematics and muscular activation. SUMMARY OF BACKGROUND DATA: Evidence indicates that shoulder kinematics are related to shoulder pain and dysfunction. Despite the degree of morbidity associated with altered shoulder kinematics likely to occur in subjects with IS, no report has been published to address this hypothesis. METHODS: In this investigation, shoulder kinematics (scapular tipping, scapular upward rotation, and scapulohumeral rhythm) and associated muscular activities [upper trapezius (UT), lower trapezius (LT), serrantus anterior (SA), and middle deltoid (MD)] were evaluated with a 3-dimensional electromagnetic tracking device and electromyography during arm elevations in 13 female subjects with IS and 13 age-gender-dominant hand-matched controls. Additionally, self-reported Flexilevel Scale of Shoulder Function (FLEX-SF) was evaluated between the 2 groups. RESULTS: Subjects with IS demonstrated lower FLEX-SF scores than the controls (P = 0.01). For the convex side, more anterior tilt of the scapula in resting position was identified (P = 0.006). For the concave side, more scapular upward rotation in resting position was identified (P = 0.01). For the EMG amplitude, higher LT contraction activity on the convex side and lower LT and SA contraction activity on the concave side were established (P = 0.007 and less than 0.01, respectively). A moderate positive association was found between scapular posterior tipping during movement and FLEX-SF functional score (R = 0.51). A moderate negative association was found between LT muscular activity and FLEX-SF functional score (R = -0.54). CONCLUSION: Given the progressive nature of IS and kinematic linkage among the thoracic spine, scapula, and arm, inadequate posterior tipping movement and high LT muscular activity on the convex side of IS are important to consider in rehabilitation programs for subjects with IS.

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.

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.

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.

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.

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.

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.

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.

All pedicle screw fixation technique in correcting severe kyphoscoliosis in an osteogenesis imperfecta patient: a case report.

Spinal deformity in patients with osteogenesis imperfecta demonstrates a high prevalence. The surgical treatment of this problem had numerous difficulties, which included breakage of bone, dislodgement of implants, and late loss of correction. We reported the correction of severe kyphoscoliosis in a patient with osteogenesis imperfecta using 3-rod all pedicle screw fixation technique. In this case, the 2 main goals of spinal operation, stabilization and correction of spinal curvatures, were achieved. The Cobb angles of scoliosis and thoracic kyphosis were corrected from 110 degrees to 68 degrees and from 107 degrees to 39 degrees, respectively. One and a half years after the operation, spinal radiographs showed no loss of correction, either on coronal or sagittal planes. The predicted forced vital capacity, predicted forced expiratory volume in 1 second and vital capacity of the lung of the patient had improved 2-fold. The usage of pedicle screw, with its conical core and cylindrical thread design, and 3-rod technique in fixation, together with cyclic intravenous bisphosphonate administration and halo-gravity traction preoperatively, contributed to the success in this case.

Prognosis of operative treatment for metastatic hepatocellular carcinoma of the spine.

UNLABELLED: Developing and developed countries have been reported increasing numbers of hepatocellular carcinoma and increased rates of distant metastasis from hepatocellular carcinoma. Data regarding operative treatments and prognoses of hepatocellular carcinoma metastasis to the spine are lacking in the literature. We retrospectively reviewed 12 patients with hepatocellular carcinoma and metastasis to the spine who had spinal surgery between 1986 and 1996. All 12 patients had severe back pain preoperatively. Posterior surgery alone was performed on two patients, anterior surgery alone in six patients, and combined anterior and posterior surgery in four. Ten of the 12 patients experienced pain relief and their neurologic status was preserved or improved. We designed a new outcome assessment, a modified Prolo scale, to evaluate surgical outcome. Seven of the 12 patients had good or excellent results. Our sample size was limited and we could draw no definite conclusions regarding the prognoses of these patients or the value of surgical intervention; however, we think that operative treatment for spinal metastatic hepatocellular carcinoma lesions may improve quality of life, regardless whether the survival time is prolonged. LEVEL OF EVIDENCE: Therapeutic study, Level IV (case series--no, or historical, control group). See the Guidelines for Authors for a complete description of levels of evidence.