Indirect spinal canal decompression in burst fractures treated with pedicle screw instrumentation

STUDY DESIGN: Prospective evaluation of spinal canal areas in 67 consecutive burst fractures between T12 and L2 treated by reduction and stabilization with a pedicle fixator. OBJECTIVES: Assessment of the efficacy of "indirect" spinal canal decompression in a large series of burst fractures. SUMMARY OF BACKGROUND DATA: Up to 50% of burst fractures cause neurologic impairment. Reduction and posterior instrumentation is the most common surgical treatment. This also reduces spinal canal encroachment by indirect decompression. No consensus exists as to the consistency and adequacy of such indirect decompression. METHODS: Spinal canal areas were measured on preoperative and postoperative computed tomography scans. The degree of encroachment was compared with clinical and radiographic variables for possible correlation. RESULTS: Spinal canal encroachment was more severe among patients with neurologic deficits than among the neurologically intact. Postoperatively, mean encroachment was reduced from 35% to 12% at T12, from 37% to 17% at L1, and from 52% to 35% at L2. Loss (and postoperative restoration) of anterior vertebral height correlated best with the degree of canal encroachment (and its reduction), especially in Denis Type A burst fractures. In Denis Type B fractures, canal compromise usually was less severe and fragment reduction better in patients older than 40 years of age than in younger patients. CONCLUSIONS: Indirect decompression in burst fractures averages about half of the preexisting encroachment. Results are usually better at T12 and L1 than at L2. Additional or secondary decompression is rarely indicated if these fractures are treated early and by experienced surgeons. Burst Type B fractures in patients older versus younger than 40 years of age differ in many respects.     

Spinal instrumentation with a low complication rate

BACKGROUND: Spinal instrumentation has become an increasing part of the armamentarium of neurosurgery and neurosurgical training. For noncontroversial indications for spine fusion the arthrodesis rate seems to be better. For both noncontroversial and controversial indications, the reported complication rate with spinal instrumentation tends to be greater than that with noninstrumented spine surgeries. These reported complications include a 2-3% neurologic injury rate, 3-45% reoperation rate for implant failure, and inflection rates of 5-10%. Therefore, we report on 299 cases that have undergone spinal instrumentation placed exclusively by neurosurgeons with a very low complication rate. METHODS: Two hundred ninety-nine consecutive spinal instrumentation cases performed exclusively by neurosurgeons at Indiana University Medical Center were analyzed for complications related to spinal instrumentation. The spinal instrumentation placed consisted of 195 anterior cervical locking plates, 22 cases of posterior cervical instrumentation, 9 cases of combined anterior locking plates with posterior cervical instrumentation, 14 anterior thoracolumbar plates, 51 posterior thoraco-lumbar instrumentation cases, and 8 combined anterior/posterior thoracolumbar instrumentation cases. RESULTS: The mean follow-up is 40 months (6-95). There was one perioperative death unrelated to the spinal instrumentation. There were no neurologic injuries and there has been no hardware infection to date. There were two dural tears, three superficial wound infections, and three minor wound breakdowns successfully treated. Hardware complications included three cervical plate/screw extrusions reoperated, one cervical plate fracture reoperated, one posterior cervical screw backout not reoperated, one case of broken pedicle screw not reoperated, one vertebral body failure not reoperated, and one posterior rod case reoperated for excessive rod length and protrusion. The overall complication rate attributable to placement of spinal instrumentation was 10/299 (3%) with a reoperation rate of 2%. The arthrodesis rate was 298/299 (99%). CONCLUSION: The complication rate for using spinal instrumentation can be less than previously reported. Lessons learned and discussed should reduce the rate even more. Spinal instrumentation is a safe and useful adjunct to fusion in treating degenerative, traumatic, infectious, and neoplastic diseases of the spine.     

胸腰椎爆裂骨折后路椎弓根钉内固定结合病椎骨水泥强化固定的应用

目的:探讨胸腰椎骨折后路椎弓根钉内固定结合病椎骨水泥强化固定的临床疗效.方法:对2007～7/2010～10收治的22例胸腰段椎体爆裂骨折采用后路减压内固定结合病椎骨水泥强化固定重建脊柱即刻稳定的临床资料进行总结,通过比较术前、术后第3天进行疼痛视觉类比评分(VAS)判断疼痛改善程度,测量椎体前缘、后缘高度的变化判断椎体高度恢复程度,有无脊髓、神经损伤等并发症.所有结果采用SPSS 11.5进行统计分析.结果:22例患者术前、术后第3天的VAS 评分明显改善(P<0.05),手术前后骨折椎体前缘的高度明显增高(P <0.05)经5～12个月随访,无腰部疼痛,椎管无占位,无继发性后凸畸形发生,内固定无断裂及松动移位等并发症.结论:胸腰椎骨折后路椎弓根钉内固定结合病椎骨水泥强化固定术能很早解决疼痛,实现重建脊柱的即刻稳定性,适合于椎体骨折的脊柱稳定性重建和早期功能恢复.     

Adding posterior lumbar interbody fusion to pedicle screw fixation and posterolateral fusion after decompression in spondylolytic spondylolisthesis

STUDY DESIGN: This is a retrospective study analyzing 76 patients treated by decompression, pedicle screw instrumentation, and fusion for spondylolytic spondyiolisthesis with symptomatic spinal stenosis. OBJECTIVES: To verify the advantages of adding posterior lumbar interbody fusion to the usual posterolateral fusion with pedicle screw instrumentation. SUMMARY OF BACKGROUND DATA: Stabilization after decompression of spondylolytic spondylolisthesis is difficult because of a lack of fusional bone bases, gap between the transverse process bases, and incompetent anterior disc support. Posterior lumbar interbody fusion offers anterior support, reduction, and a broad fusion base. METHODS: Forty patients were treated with posterolateral fusion, and 36 were treated with additional posterior lumbar interbody fusion. They were compared for union, reduction of the deformity, and clinical results. RESULTS: The patients were followed up for more than 2 years. Nonunion was observed in three patients who underwent posterolateral fusion (7.5%), and no cases of nonunion was found in patients who underwent posterior lumbar interbody fusion. Reduction of slippage was 28.3% in those who underwent posterolateral fusion and 41.6% in those who had posterior lumbar interbody fusion (P = 0.05). In the posterolateral fusion group, eight patients (20%) had recurrence of deformity, with loss of reduction more than 50%. Hardware failures occurred in two patients who had posterolateral fusion. There was no major neurologic complications in both groups. Both groups had satisfactory results in more than 90% of patients, with marked improvement of claudication. However, subjective improvement of back pain by Kirkaldy-Willis criteria revealed differences in the excellent results. An excellent result was reported by 45% in the posterolateral fusion group and by 75% in posterior lumbar interbody fusion group. CONCLUSIONS: The addition of posterior lumbar interbody fusion to posterolateral fusion after a complete decompression and pedicle screw fixation is a recommended procedure for the treatment of spondylolytic spondylolishesis with spinal stenosis.     

Fatal cardiac tamponade associated with posterior spinal instrumentation. A case report

STUDY DESIGN: Case report of a fatal complication of pedicle screw instrumentation and review of the literature. OBJECTIVE: To describe the clinical and postmortem findings in a 35-year-old man who sustained a T11 burst fracture that was managed by transpedicular posterior instrumentation and who died 12 days after surgery of cardiac tamponade caused by a prick injury of the right coronary artery. SUMMARY OF BACKGROUND DATA: Posterior pedicle screw instrumentation is considered a safe and effective method for stabilizing a spinal motion segment. Nevertheless, there are several rare but significant complications that may occur. This is the first report of a heart tamponade after transpedicular screw insertion. METHODS: A 35-year-old man was treated for a T11 burst fracture with posterior transpedicular stabilization. The surgery was uncomplicated. RESULTS: Twelve days after the intervention, the patient died of cardiogenic shock. Postmortem examination showed a heart tamponade of 350 mL blood originating in a prick injury of the right coronary artery. Histologic findings showed evidence that the injury was caused during surgery by a Kirschner wire. CONCLUSION: There are numerous possible intraoperative complications in posterior pedicle screw fixation, such as nerve root and spinal cord injuries. This case of a fatal heart tamponade after transpedicular screw insertion is rare. It shows that the surgeon must be aware of potential risks associated with such a procedure and have a comprehensive three-dimensional understanding of the anatomic structures involved.     

Chance fracture after pedicle screw fixation. A case report

STUDY DESIGN: A case of a Chance fracture through an instrumented pedicle is presented. The radiographic and intraoperative findings and management of this complication are reported. OBJECTIVE: To increase awareness of the complications of transpedicular screw fixation and to suggest a form of management of this unusual complication. SUMMARY OF BACKGROUND DATA: To the authors' knowledge, this is the first reported case of such a vertebral fracture occurring after pedicle screw fixation. METHODS: A 44-year-old man with athetoid cerebral palsy and a progressive thoracic kyphosis sustained a Chance fracture at the caudal end of the segmental instrumentation construct. RESULTS: Surgical intervention, including fracture reduction and extension of the instrumented fusion to the pelvis, provided effective restoration of physiologic sagittal alignment. CONCLUSION: Chance fracture after pedicle screw fixation can be successfully managed with surgical intervention.     

Spinal instrumentation in the management of adolescent scoliosis

A multitude of posterior and anterior segmental spinal instrumentation systems are now available for the treatment of idiopathic scoliosis. As a consequence, fixation strategies are more complex than they were with Harrington instrumentation. The newer systems provide better sagittal control and more stable fixation, allowing quicker mobilization of the patient. On thin patients, the bulk of these implants may be a problem. The techniques of fusion and the fusion levels remain constant.     

Restoration of pedicle screw fixation with an in situ setting calcium phosphate cement

STUDY DESIGN: Pedicle screws were pulled out of human cadaveric vertebrae before and after augmentation with polymethylmethacrylate or in situ-setting calcium phosphate cement. The fixation strength of screws augmented with calcium phosphate cement was compared with that of screws augmented with polymethylmethacrylate. OBJECTIVES: To determine whether a new in situ-setting calcium phosphate cement might be suitable for augmenting the fixation of pedicle screws. The principle objective was to compare the pull-out resistance of screws augmented with calcium phosphate cement with the pull-out behavior of screws augmented with polymethylmethacrylate. Polymethylmethacrylate augmentation was chosen as the standard because of its current clinical use. Five types of screws were tested to determine whether screw design had an effect on the efficacy of augmentation. SUMMARY OF BACKGROUND DATA: Although many factors affect the pull-out resistance of pedicle screws, a key determinant of their performance is the strength of their attachment to the spine. In elderly, osteopenic patients, the screw-bone interface is especially at risk for stripping during insertion or pull-out after surgery. In these patients, polymethylmethacrylate has been used to augment pedicle screw fixation, although its use is not without risk. In situ-setting calcium phosphate cements may provide an alternative to polymethylmethacrylate in this application. Like polymethylmethacrylate, calcium phosphate cements can be injected into the prepared screw hole. They have the added advantage of being resorbed and replaced during healing and normal bone remodeling. METHODS: Thirty human lower lumbar vertebrae (L3-L5) were implanted bilaterally with one of five types of pedicle screws (n = 6 for each screw type). The screws were pulled out 3.0 mm at 0.25 mm/sec with a servohydraulic materials testing machine. The 3.0-mm pull-out distance, which was slightly longer than one thread pitch, was designed to strip the screw-bone interface but to leave the pedicle otherwise intact. After the initial testing, the screws in each vertebrae were removed, and the screw tracks were filled with 2.0 cc of polymethylmethacrylate (one side) or calcium phosphate cement (contralateral side). After augmentation, the screws were reinserted, and the cements were allowed to harden for 24 hours. Postaugmentation testing followed the protocols for preaugmentation testing, and the pull-out resistance of screws augmented with calcium phosphate cement was compared with the pull-out resistance of screws augmented with polymethylmethacrylate. RESULTS: Mechanically, calcium phosphate cement compared favorably with polymethylmethacrylate for augmenting pedicle screws. Both restored the strength of the screw-bone interface: across all screw types, the average increase in pull-out strength was 147% with polymethylmethacrylate augmentation and 102% with calcium phosphate cement. There were no significant differences because of screw type with either type of augmentation. CONCLUSIONS: The in situ-setting calcium phosphate cement investigated in this study compared favorably with polymethylmethacrylate in a single-cycle, pull-out test of augmented pedicle screws in senile trabecular bone. With further evaluation, this cement may offer an alternative to polymethylmethacrylate for the enhancement of pedicle screw fixation clinically.     

In vitro simulation. Early results of stereotaxy for pedicle screw placement

STUDY DESIGN: Frameless stereotaxy with doppler ultrasound and three dimensional computer model registration is assessed in vitro for pedicle screw placement. OBJECTIVE: To identify feasibility of pedicle screw navigation and placement using this technology. SUMMARY OF BACKGROUND DATA: Inaccurate pedicle screw placement can lead to neurovascular injury or suboptimal fixation. Present techniques in pedicle screw placement involve only confirmation of hole orientation. METHOD: Forty-four pedicle screws were placed in lumbosacral models and cadaver specimens. Accuracy was assessed with a computed tomography scan and vertebral cross sectioning. RESULTS: All screws were intrapedicular. Accuracy of anterior cortical fixation was 1.5 mm, with a range of 2.5 mm. CONCLUSION: In vitro frameless stereotaxy is accurate for pedicle screw placement. This technology adds a component of navigation to pedicle screw placement.     

Spinal instrumentation without fusion for progressive scoliosis in young children

This report provides comparative physiological data on the features of the regulatory effects of the neurohormone vasopressin on higher nervous activity in an ascending series of mammals consisting of insectivores, rodents, and primates. Administration of vasopressin to hedgehogs produced a general facilitatory effect on conditioned reflex brain activity. The effects of vasopressin on memory processes in hedgehogs was minor. In rabbits, vasopressin had greater regulatory effects on conditioned reflex memory than in hedgehogs. However, this was transient in nature. In monkeys, administration of vasopressin had complex differential effects on simple conditioned responses and different types of memory. The effects of vasopressin on memory processes were long-lasting and were different for corticalized and noncorticalized forms of nervous activity. The question of changes in the nature of the regulatory effects of vasopressin during phylogenesis is discussed, as is the question of the increases in its level of involvement in the regulation of higher nervous functions and memory processes.     

Correction of unilateral cleft lip nasal deformity with modified Bardach''s technique

Measurements were made of the intake of a WHO/UNICEF glucose-based and a rice cereal-based oral rehydration solution (ORS) by children with diarrhoea. Twenty children who presented to the Children's Outpatient Department at Port Moresby General Hospital with acute diarrhoea and mild dehydration were randomly assigned to an ORS and measurements were taken over the following 3 hours. For data analysis, the patients were paired by weight. Testing the means of the paired samples by t test showed that there was no significant difference between the amount of rice ORS and the amount of glucose ORS taken over 3 hours.     

Structural characteristics of the pedicle and its role in screw stability

STUDY DESIGN: Cross-sectional regional bone mineral density of the pedicle was measured by peripheral quantitative computed tomography. Biomechanical tests were performed to clarify the role of the pedicle in screw stability. OBJECTIVES: To identify the structural characteristics of the pedicle that supports pedicle screw stability and the differences in these characteristics between normal and osteoporotic vertebrae. SUMMARY OF BACKGROUND DATA: The pedicle screw is an essential component of many systems used to align the spine. The contribution of the pedicle to screw stability, however, has not been fully investigated. METHODS: Trabecular, subcortical, and cortical bone mineral density and the area of the pedicle were measured by peripheral quantitative computed tomography. Bone mineral density also was recalculated in four circumferential layers. These parameters were compared between normal and osteoporotic individuals. The relative contribution of the pedicle to screw stability was evaluated by caudocephalad and pull-out loading in a vertebra with or without its body. RESULTS: Inner trabecular, middle subcortical, and outer cortical bone mineral density and cortical bone area in the pedicle were significantly lower in osteoporotic vertebrae than those in normal vertebrae. In the pedicle, bone mineral density increased close to the outer layer. Bone mineral density not as thick even in the outer layer in osteoporotic subjects. Approximately 80% of the caudocephalad stiffness and 60% of the pullout strength of the pedicle screw depended on the pedicle rather than on the vertebral body. CONCLUSION: Screw stability depends on the structural characteristics of the pedicle. The pedicle was denser in the subcortical bone, in which the threads of the screw engage, than in trabecular bone. In osteoporosis, bone mineral density was not as dense even in the outer layer, and the cortex was thinner than normal. A larger screw would not enhance screw stability and may break the thin cortex in osteoporotic vertebrae.     

Correction of a dystrophic cervicothoracic spine deformity in Recklinghausen's disease

A case is presented of a 14-year-old boy with neurofibromatosis who had a 92 degrees dystrophic kyphosis (as measured on radiographs between C3 and C7) of the cervical spine. He was treated successfully by posterior stabilization and anterior fusion using a free vascularized fibula graft. This method appears to be an attractive alternative to an avascular fibula graft and avoids the risk of graft resorption (creeping substitution), weakening (fracture), or nonunion during the process of bony consolidation. It provides a stable and longstanding anterior strut, essential in the management of high grades of kyphosis. At 1-year followup the patient has no symptoms, is fully mobile, and shows radiographically complete incorporation of the graft with no loss of correction.     

Correction of the secondary nasal deformity in bilateral cleft lip with a new technique

Bilateral cleft lip often has nasal deformities of various degrees. It is not enough to elongate the nasal columella for such deformities. Based on the thoughts that secondary deformities of the nose and lip should be treated as a whole, the authors introduced a new technique, in which five aspects of the deformities were considered and treated at the same time. Thirteen patients have undergone surgical correction with satisfactory results.     

Carbonated apatite cement augmentation of pedicle screw fixation in the lumbar spine

STUDY DESIGN: Biomechanical testing with human cadaveric lumbar vertebral bodies was used to determine the utility of an injectable carbonated apatite cancellous bone cement for improving the structural performance of pedicle screws subjected to axial pull-out or transverse cyclic loading. OBJECTIVES: To ascertain whether augmentation with a carbonated apatite cement can enhance pedicle screw fixation in the lumbar spine. SUMMARY OF BACKGROUND DATA: The beneficial effects of polymethylmethacrylate augmentation on pedicle screw pull-out strength have been demonstrated. Cancellous bone cement, however, may provide an attractive alternative in this application, as it is remodelable, biocompatible, and nonexothermic. METHODS: Forty-three cadaveric lumbar vertebral bodies were instrumented with pedicle screws. In 20 of these specimens, axial pull-out strength was compared between the control screws and those augmented with cancellous bone cement. In the remaining 23 specimens, the screws were loaded in the superior-inferior direction with a peak displacement of +/- 1 mm at a frequency of 3 Hz for 5000 cycles. Three parameters were calculated from the force-versus-time data: 1) the energy dissipated, 2) the peak force at the start of the test, and 3) the peak force at the end of 5000 cycles. RESULTS: The pull-out strength of the augmented pedicles averaged 68% greater than that of the control side. In response to cyclic loading, all measures of bio-mechanical performance improved 30-63%. CONCLUSIONS: The data suggest that augmentation with this carbonated apatite cancellous bone cement can enhance immediate screw fixation.     

Possibilities of ambulation in children with myelodysplasia]

This article reviews four reports that have addressed the efficacy of spinal instrumentation to enhance spinal fusion in patients with degenerative spondylolisthesis. These papers serve to highlight some of the common problems with interpreting and applying the clinical findings of such studies: small, nonuniform patient selection; variable instrumentation techniques; relatively brief follow-up periods (usually less than 5 years); lack of a uniform scale for clinical assessment of patients; and lack of consensus on the definition and clinical documentation of motion segment instability.     

Surgery of the spine in myelodysplasia. An overview

Significant spinal deformity is particularly common in nonambulatory patients with myelodysplasia. Progressive deformity may be caused by congenital anomalies, paralytic collapse, hip contractures, or spinal cord tethering. Existing or projected functional impairment should be the principle indication for treatment. Surgical treatment is complicated by poor soft tissue coverage, associated contractures, lack of sensation, weak bone, and absence of posterior elements. Successful fusion can be achieved by circumferential (anterior and posterior) fusion and current rigid segmental instrumentation. The unique deformities and bony anatomy require individualized techniques to achieve fixation.     

Endoscopic treatment of vesicoureteral reflux in patients with myelodysplasia

PURPOSE: We assessed the usefulness of and indications for endoscopic treatment of vesicoureteral reflux in myelodysplasia patients. MATERIALS AND METHODS: A total of 26 patients treated with intermittent catheterization was divided into 11 (16 ureters) with and 15 without vesicoureteral reflux. In 9 patients (13 ureters) endoscopic correction was performed with 3% atelo-collagen and without anesthesia at the outpatient clinic. In each ureter we obtained the sum of scores for 4 risk factors for upper urinary tract deterioration: bladder compliance less than 10 ml./cm. water, grade 2 to 3 bladder deformity, detrusor-sphincter dyssynergia and urethral closure pressure 50 cm. water or greater. RESULTS: No reflux was demonstrated immediately after the initial collagen injection but cystography 3 to 6 months later showed recurrent reflux in 5 ureters (38%). Repeat injection cured the reflux, with results persisting for an average of 17 months. Mean risk factor score for patients without vesicoureteral reflux was significantly lower than that for patients with reflux. In patients treated with intermittent catheterization and anticholinergic agents the mean score for ureters with an increased or unchanged reflux grade was significantly greater than for those with a decreased grade. CONCLUSIONS: Endoscopic treatment of reflux appears to be safe and useful in patients with myelodysplasia. The treatment is preferable in those with high risk factor scores due to the possibility of increased reflux grade in such patients.     

Long-term intravesical oxybutynin chloride therapy in children with myelodysplasia

PURPOSE: We evaluated the clinical use of long-term intravesical oxybutynin chloride in the treatment of neurogenic bladder dysfunction in children with myelodysplasia who could not tolerate oral anticholinergics. MATERIALS AND METHODS: We retrospectively reviewed the records of all patients recommended for intravesical oxybutynin chloride therapy. A total of 12 girls and 18 boys 1 to 17 years old was recruited for study. Oxybutynin chloride (5 mg.) was instilled 2 times daily and pretreatment cystograms were compared to followup urodynamic studies. Duration of therapy was 2 to 26 months (mean 13, median 12). RESULTS: Mean total capacity plus or minus standard deviation increased from 209 +/- 103 to 282 +/- 148 ml. (p < 0.01), mean safe capacity increased from 157 +/- 105 to 234 +/- 147 ml. (p < 0.01) and mean age adjusted safe capacity increased from 76 +/- 36 to 115 +/- 62%. Of the 29 patients who were incontinent 3 (10%) achieved continence and 19 (65%) reported a decreased use of sanitary pads. None of the patients had systemic side effects related to intravesical treatment. CONCLUSIONS: We believe that intravesical oxybutynin chloride is a viable treatment option for patients with myelodysplasia in whom oral therapy fails.     

Outcome analysis of vesicoureteral reflux in children with myelodysplasia

PURPOSE: Vesicoureteral reflux in children with myelodysplasia is usually secondary to abnormal bladder storage. The purpose of this study was to assess the outcome of vesicoureteral reflux in children with myelodysplasia. MATERIALS AND METHODS: We retrospectively analyzed the records of 319 children with myelodysplasia who presented to our institution between 1978 and 1985. Of these children 95 presented with or had reflux during followup and they were treated with prophylactic antibiotics. Clean intermittent catheterization and anticholinergic medication were added to the regimen when indicated. RESULTS: Reflux resolved in 63% of these patients with nonsurgical management. Temporary cutaneous vesicostomy was performed in 23 children (24%) with persistent high grade reflux or evidence of upper tract deterioration. Ureteral reimplantation and augmentation cystoplasty were performed in 18 (20%) and 8 (8%) patients, respectively. No patient had progression to chronic renal failure and scars developed in only 14 kidneys (10%). CONCLUSIONS: In the majority of cases (63%) reflux resolved with nonsurgical management. Reflux in these patients should not be treated in isolation. The management of reflux is primarily aimed at improving bladder storage. The combination of aggressive nonsurgical therapy and close observation is recommended. This regimen leads to the satisfactory resolution of reflux with minimal renal morbidity.