Showing papers in "Journal of Spinal Disorders & Techniques in 2010"

Outcomes of interbody fusion cages used in 1 and 2-levels anterior cervical discectomy and fusion: titanium cages versus polyetheretherketone (PEEK) cages.

Abstract: Study DesignA prospective study was performed in case with cervical spondylosis who underwent anterior cervical discectomy and fusion (ACDF) with titanium or polyetheretherketone (PEEK) cages.ObjectiveTo find out which fusion cage yielded better clinical and radiographic results.Summary of Backgroun

Early complications of extreme lateral interbody fusion in the obese.

Abstract: STUDY DESIGN A retrospective review of prospective data of all patients undergoing extreme lateral interbody fusion (XLIF) for degenerative disease of the lumbar and thoracic spine. OBJECTIVES To compare between obese and nonobese patients, the incidence of early complications and predictive factors affecting complication rate. SUMMARY OF BACKGROUND DATA XLIF is a 90-degree off midline approach that allows for large graft placement, excellent disk height restoration, and indirect decompression at the stenotic motion segment. As the psoas muscle is traversed, the lumbosacral plexus is protected by the use of automated electrophysiology through dynamic discrete evoked electromyogram thresholding. Exposure is achieved with an expandable split-blade retractor, which allows for direct illuminated visualization facilitating discectomy and complete anterior column stabilization by using a large load-bearing implant that rests on the dense ring apophysis bilaterally. METHODS A retrospective chart review of a prospectively compiled database of all patients treated with the XLIF procedure between October 2006 and July 2008 was completed. Early complications were defined as any adverse events occurring within the first 3 months of the index procedure. The National Institute of Health Guidelines for defining obesity relating to body mass index were used. RESULTS Out of 432 patients, 313 have complete data: 156 obese, 157 nonobese. The ages, comorbidities, earlier surgeries, and diagnoses were equivalent. There were no transfusions and no infections. Complications were minimal and about the same in each group. CONCLUSIONS Unlike traditional open lumbar fusion procedures, minimally invasive surgery (XLIF) has no greater risk of complication in the obese patient.

Percutaneous pedicle screw fixation for neurologic intact thoracolumbar burst fractures.

Abstract: Study DesignProspective consecutive series.ObjectiveTo evaluate the efficacy and safety of percutaneous pedicle screw fixation (PPSF) for thoracolumbar AO type A3 fractures with a specially designed surgical instrument system.Summary of Background DataMinimally invasive surgery including PPSF is bec

Lower Incidence of Dysphagia With Cervical Arthroplasty Compared With ACDF in a Prospective Randomized Clinical Trial

Abstract: Study DesignThe current study of 251 consecutive 1-level anterior cervical reconstructions was undertaken to compare the incidence of dysphagia between cervical disk replacement and conventional anterior cervical fusion and instrumentation.ObjectivesThis is a report of 251 patients from 5 investigat

Normal functional range of motion of the cervical spine during 15 activities of daily living.

Abstract: Study DesignProspective clinical study.ObjectiveThe purpose of this investigation was to quantify normal cervical range of motion (ROM) and compare these results to those used to perform 15 simulated activities of daily living (ADLs) in asymptomatic subjects.Summary of Background DataPrevious studie

Impact of Cement Leakage Into Disks on the Development of Adjacent Vertebral Compression Fractures

Abstract: Study DesignA retrospective study assessing new adjacent vertebral compression fracture (VCF) after percutaneous vertebroplasty (PV).ObjectiveTo evaluate the relationship between cement leakage into the disk during initial PV and development of subsequent new adjacent VCF.Summary of Background DataC

Teriparatide may accelerate healing in delayed unions of type III odontoid fractures: a report of 3 cases.

Abstract: Study DesignCase Report.ObjectiveTo report on the treatment of 3 cases of painful delayed unions of type III odontoid fractures with teriparatide.Summary of Background DataFractures of the C2 vertebra, also known as odontoid fractures, are an important subset of cervical spine fractures. Type III od

Trends in epidemiology and management of type II odontoid fractures: 20-year experience at a model system spine injury tertiary referral center.

Abstract: Study DesignA retrospective cohort study of consecutive type II Odontoid fractures presenting to a Level 1 Regional Model Systems Spinal Cord Injury Center between June 1985 and July 2006.ObjectiveTo assess trends in management of type II Odontoid fractures presenting to a Level 1 Model Systems Regi

The relationship of intrapsoas nerves during a transpsoas approach to the lumbar spine: anatomic study.

Abstract: location of these nerves place them at injury risk in a small number of cases. These results suggest that neural monitoring whereas traversing the psoas may be important to enhance the safety of the transpsoas approach. Care is particularly warranted at the L4-5 level.

Safety of anterior cervical discectomy and fusion performed as outpatient surgery

Abstract: Study design Retrospective review of a prospectively collected database. Objective To determine the complications and safety of anterior cervical discectomy and fusion performed on an outpatient basis. Summary of background data Anterior cervical discectomy and fusion performed as outpatient surgery is an appealing alternative and has many potential benefits. The safety of this practice, however, has not been thoroughly investigated. This study aims to examine the frequency of acute complications and rates of unplanned admissions for anterior cervical discectomy and fusions scheduled as outpatient procedures. Methods Data were collected prospectively on 645 consecutive patients undergoing anterior discectomy and fusion by a single surgeon for either stenosis or herniated nucleus pulposus involving 1 level. These data were then retrospectively reviewed for acute complications occurring within 48 hours of surgery. A subset consisting of the last 392 patients were further reviewed to better characterize this population. Complications after surgery as well as procedures requiring postoperative admission for any reason were detailed. Results Two of 645 (0.3%) patients developed acute complications, both of which were epidural hematomas. Both occurred within the protocol's mandatory 4 hours postoperative observation time. Both resolved without permanent neurologic deficit. There were no retropharyngeal hematomas and no deaths. Six percent of patients required an unplanned admission. More than 80% of unplanned admissions were secondary to either pain or nausea. Conclusions One-level anterior cervical discectomy and fusion can be safely performed in an outpatient setting with a 4-hour observation period. There is a low rate (6%) of unplanned admission to the hospital. The number of unplanned admissions can be decreased by more than one-third if autogenous iliac crest bone graft is not harvested. The use of postoperative drains for 1-level anterior discectomy and fusion is called into question.

Implant removal for the management of infection after instrumented spinal fusion.

Abstract: Study DesignWe operated on 21 patients with a postoperative deep wound infection. All the patients underwent implant removal and wide debridement. One patient lost to follow-up was excluded.ObjectiveTo reduce the number of debridements and manage uncontrolled spine infection.Summary of Background Da

Comparison of perioperative oral multimodal analgesia versus IV PCA for spine surgery.

Abstract: Study DesignA preintervention and postintervention design was used to examine a total of 200 patients.ObjectiveAfter successful implementation at our institution of a perioperative oral multimodal analgesia protocol in major joint arthroplasty, a modified regimen was provided to patients undergoing

Successful treatment of thoracolumbar fractures with short-segment pedicle instrumentation.

Abstract: Study design Retrospective radiographic review. Objective To determine whether clinical factors or common classification systems can predict the radiologic outcome of short-segment thoracolumbar fracture fixation. Summary of background data Previous reports have indicated that short-segment thoracolumbar fracture fixation might not be appropriate for highly comminuted fractures or for patients with multiple traumatic injuries. Methods We conducted a retrospective radiographic review of 46 thoracolumbar fractures treated with short-segment posterior instrumentation to determine the rate of correction loss and instrumentation failure in relation to the Load Sharing Classification of Spine Fracture system and the AO Classification of Fractures system. No postoperative bracing was used. Patients with multisystem organ trauma and those with isolated injuries were included. Results An average loss of correction of 7.5 degree was observed. Pedicle screw placement into the fractured vertebra seemed to protect against correction loss: 4 of the 7 patients (57%) in the no intermediate fixation group had >10 degree loss of correction. No relationship was shown between loss of correction and Load Sharing Classification ( or = 7 points), loss of correction and AO Classification, or loss of correction and level of injury (thoracolumbar junction vs. lower lumbar). Conclusions With modern instrumentation and techniques, short-segment thoracolumbar fracture fixation could be used successfully, despite highly comminuted injuries, without anterior column support or supplemental bracing.

Role of major spine surgery using Kaneda anterior instrumentation for osteoporotic vertebral collapse.

Abstract: Study design A retrospective study. Objectives To investigate the clinical and radiographic results of spinal reconstruction using Kaneda anterior spinal instrumentation for osteoporotic vertebral collapse. Summary of background data Recent advances in osteoporotic vertebral fracture treatment including kyphoplasty changes the role of major surgery for these pathologies. However, osteoporotic vertebral collapse with neurologic compromise remains requiring surgical decompression and reconstruction. Methods Thirty-one consecutive patients who underwent anterior spinal reconstruction for osteoporotic vertebral collapse with neurologic deficits were reviewed retrospectively. Twenty-six patients had single vertebral collapse and 5 had multiple lesions. They were 10 males and 21 females with mean age of 71 years. Mean follow-up period was 57 months. For anterior column support, iliac bone graft was used in 1 patient, cylindrical titanium cages in 12, and bioactive ceramic spacers in 18 patients. Kaneda anterior instrumentation was used in all the patients. Radiographic and clinical assessments were performed preoperatively and at the final follow-up. Results All the patients showed neurologic recovery. Visual analog scales (0 to 10) of low back pain and sciatic pain were 5.8 and 4.2 before surgery, and 2.1 and 0.6 at the final follow-up, respectively. Mean kyphosis of operative levels was 31 degrees before surgery, and improved to 13 degrees immediately after surgery and 21 degrees at the final follow-up. Posterior reinforcement was required in 6 patients (19%), who had severe osteoporosis and/or underwent multilevel corpectomies. Solid fusion was achieved in all patients at the final follow-up. Conclusions The current study demonstrated the advantages of anterior spinal reconstruction in osteoporotic vertebral collapse: (1) safe and reliable decompression could be performed, and (2) 80% of patients were successfully treated with anterior spinal reconstruction alone. However, patients with multilevel corpectomies and/or severe osteoporosis highly required posterior reinforcement.

Clinical outcomes after microendoscopic discectomy for recurrent lumbar disc herniation

Abstract: STUDY DESIGN: Retrospective review of consecutive case series. OBJECTIVE: To assess the safety and efficacy of the microendoscopic approach for treatment of recurrent lumbar disc herniation. SUMMARY OF BACKGROUND DATA: The standard surgical approach for the treatment of recurrent disc herniation uses an open technique with a wide exposure. Many would consider a minimally invasive approach such as microendoscopic discectomy (MED) to be contraindicated in the setting of recurrent disc herniation. METHODS: Sixteen consecutive patients with recurrent lumbar disc herniation who failed conservative management underwent MED. Before surgery and at follow-up, patients completed the Oswestry Disability Index, SF-36, and assessment of leg pain using the Visual Analog Scale. Outcome was also assessed using modified McNab criteria. RESULTS: No case required conversion to an open procedure. Mean operative time was 108 minutes, and mean estimated blood loss was 32 mL. The only surgical complications were 2 durotomies that were treated with dural sealant without sequelae. Mean hospital stay was 23 hours, and mean follow-up was 14.7 months. Approximately 80% of patients had good or excellent outcomes based on modified McNab criteria. The remaining 3 patients had fair outcomes, and no patient had a poor outcome. All standardized measures improved significantly, including mean Visual Analog Scale for leg pain (8.2 to 2.2, P<0.001), mean Oswestry Disability Index (59.3 to 26.7, P<0.001), SF-36 Physical Component Summary score (28.3 to 42.4, P<0.001), and SF-36 Mental Component Summary score (38.2 to 48.3, P<0.001). As of last follow-up no patient has showed recurrence of herniation or evidence of delayed instability. CONCLUSIONS: MED is a safe and effective surgical approach for the treatment of recurrent lumbar disc herniation. Standardized measures of outcome show that MED for recurrent herniation produces improvement in pain, disability, and functional health that is at least comparable with outcomes reported for conventional open microdiscectomy.

Defining "complications" in spine surgery: neurosurgery and orthopedic spine surgeons' survey.

Abstract: Study design Survey of neurosurgical and orthopedic spine surgeons. Objective To define the "complications of spinal surgery," we surveyed a large group of practicing spine surgeons to establish a preliminary definition of perioperative complications. Summary of background data Although the risk of complications following spinal procedures plays an important role in determining the appropriateness of surgical intervention, there is little consensus among spine surgeons regarding the definition of complications in spine surgery. The relevance of medical complications is also not clearly defined. Methods We surveyed a cohort of practicing spine surgeons via email and a commercially maintained website. Surgeons were presented with various complication scenarios, and asked to assess the presence or absence of a complication, as well as complication severity, with responses limited to "major complication" and "minor complication/adverse event." Results The survey was sent to approximately 2000 practicing surgeons; complete responses were received from 229, giving a response rate of 11.4%. Orthopedic surgeons comprised the majority of respondents (73%); most surgeons reported being in practice for greater than 5 years (83%). Greater than 75% of surgeons agreed on complication presence or absence in 10 of 11 scenarios assessed (91%, P Conclusions We present a practical binary definition of complications in spine surgery based upon a survey of over 200 practicing spine surgeons. Further work is required in critically assessing spine surgery complications.

Transthoracic surgical treatment for centrally located thoracic disc herniations presenting with myelopathy: a 5-year institutional experience.

Abstract: Study design Retrospective review. Objective Review clinical outcomes for myelopathic patients undergoing transthoracic discectomies for central calcified herniations. Summary of background data Ideal surgical treatment for thoracic disc herniation is controversial due to variations in patient presentation, pathology, and possible surgical approach. Although discectomy may lead to improvements in neurologic function, it can be complicated by approach-related morbidity, especially for ventral calcified disc herniations. Review of clinical outcomes for myelopathic patients undergoing transthoracic discectomies for central calcified herniations was completed, paying special attention to neurologic status and procedure-related complications. Methods Between 2002 and 2007, 27 myelopathic patients were treated with 28 transthoracic surgeries for centrally located symptomatic calcified thoracic disc herniations over the last 5 years at a single institution. Demographic data, details of surgery, preoperative and postoperative Nurick and American Spinal Injury Association scores, length of stay, complications, and follow-up data were collected in all patients. Results A total of 27 patients, 8 male (30%) and 19 female (70%) with an average age of 52.3 years (range: 19 to 72) underwent 28 thoracotomies. All had myelopathy whereas 6/27 also had radicular pain syndromes. Fourteen patients had anterior instrumentation alone, 3 had anterior and posterior instrumentation, and 1 had posterior instrumentation alone. Average Nurick grade was 2.5 preoperatively and 1.4 postoperatively. Of note, American Spinal Injury Association scores improved postoperatively in 12/27 patients (10D to 10E; 2C to 2D), remained unchanged in 13/27 (11E to 11E, 2D to 2D), and worsened in 2/27 (2D to 2C). Average length of stay was 7 days (range: 3 to 15). All patients required chest tube placement with average duration of 4 days (range: 1 to 7). Major complications occurred in 6 cases (21.4%) over an average follow-up of 12 months (range: 1 to 40 mo). Conclusions Thoracotomy for treatment of centrally located thoracic disc herniations is associated with improvement in or stabilization of myelopathic symptoms in the majority of patients with an acceptable rate of complications. Interestingly, most patients with weakness improved in strength (12/16, 75%), no patients with normal strength developed new weakness (10/10, 100%), and only 2 patients had new weakness noted postoperatively (7.4%).

Correlative factor analysis on the complications resulting from cement leakage after percutaneous kyphoplasty in the treatment of osteoporotic vertebral compression fracture.

Abstract: Study DesignThe correlative factors for complications resulting from cement leakage were retrospectively reviewed in 71 patients who underwent percutaneous kyphoplasty.ObjectiveTo explore the correlative factors affecting the complications of percutaneous kyphoplasty in the treatment of osteoporotic

Surgical outcome of 2-stage (posterior and anterior) surgical treatment using spinal instrumentation for tuberculous spondylitis.

Abstract: Study DesignA prospective study on the clinical outcomes in patients with tuberculous spondylitis treated by a 2-stage operation (posterior and anterior) using posterior spinal instrumentation.ObjectiveTo evaluate the clinical outcomes of the 2-stage surgical treatment (first stage: placement of pos

Transpedicular bivertebrae wedge osteotomy and discectomy in lumbar spine for severe ankylosing spondylitis.

Abstract: Study Design: A prospective study was performed in 8 patientswith severe ankylosing spondylitis.Objectives: To observe the feasibility, reliability, and complica-tions of a method of transpedicular bivertebrae wedge osteo-tomy and discectomy to manage the sagittal plane deformity inankylosing spondylitis with chin-brow vertical angles beyond 90degrees.Summary of Background Data: In ankylosing spondylitis, thecorrection of sagittal plane deformity can be achieved bylengthening the anterior elements, shortening the posteriorelements, or a combination of the 2. Neither Smith-Petersenosteotomy, nor pedicle subtraction osteotomy in 1 segment canachieve adequate correction for cases of severe ankylosingspondylitis kyphosis.Methods: From January 2003 to May 2007, 8 patients (3 malesand 5 females) with severe ankylosing spondylitis in ourinstitution underwent a single stage transpedicular bivertebraewedge osteotomy and discectomy. The operation techniqueincludes resection of the posterior elements of 2 adjacentvertebrae, resection of the inferior-posterior aspect of proximalvertebra, and the superior-posterior aspect of the distal vertebra,followed by posterior instrumentation with pedicle screws andspinal fusion. Preoperative and postoperative height, chin-browvertical angle, sagittal balance, and sagittal Cobb angle of thevertebral osteotomy segment were documented. Intraoperative,postoperative, and general complications were registered.Results: The mean follow-up was 18.7±6.1 months (range: 14to 54mo). The mean duration of surgery was 236 minutes(range: 198 to 310min), and the average volume of intraopera-tive blood loss was 2200mL (range: 1600 to 3860mL). Thepatients’ height increased from 120.5±12.0cm to 159.6±12.4cm(P=0.000). The mean chin-brow vertical angle was improvedfrom 102.8±9.7 to 19.3±13.9 degrees (P=0.000). The spinalsagittal Cobb angle of the vertebral osteotomy segment wascorrected from kyphosis 38.6±16.5 degrees to lordosis26.6±10.1 degrees (P=0.000). One patient with the involve-ment of the cervical spine suffered an extension spinal fracture atC5/6 as the operating table was extended. Translation at theosteotomy site occurred in 1 patient during the correction.Fusion of the osteotomy was achieved in all patients, and noloosening or breakage of pedicle screws was found.Conclusions: In cases of severe ankylosing spondylitis kyphosiswith chin-brow vertical angles beyond 90 degrees, a single stagetranspedicular bivertebrae wedge osteotomy and discectomy isan effective corrected method of correction.Key Words: ankylosing spondylitis, kyphosis, osteotomy,discectomy(J Spinal Disord Tech 2010;23:186–191)

A computer-aided Cobb angle measurement method and its reliability.

Abstract: Study design Development of a computer-aided Cobb measurement method and evaluation of its reliability. Objectives To reduce the variability of Cobb angle measurement by developing the computer-aided method and to investigate if the developed method is sensitive to observer skill levels or experiences. Summary of background data Therapeutic decisions for scoliosis heavily rely on the Cobb angle measured from consecutive radiographs. The manual Cobb measurement is subject to human errors. The observer error is 3 to 10 degrees resulted from different end-vertebrae selection and/or manually drawing variable best-fit lines to the endplates of the end-vertebrae. Methods A fussy Hough transform technique was used to develop a computer-aided method to detect the vertebral endplates. The Cobb angle, upper end-vertebra, and lower end-vertebra were then measured automatically. The computer-aided method was tested twice by each of 3 observers in 84 posteroanterior radiographs from patients with adolescent idiopathic scoliosis. The intraobserver and interobserver errors were analyzed. Results Both the intraobserver and interobserver reliability analyses resulted in the intraclass correlation coefficients higher than 0.9 for the Cobb angle. The average intraobserver and interobserver errors were less than 3 degree for the Cobb angle, and less than 0.3 levels for both the upper and lower end-vertebral identification. There were no significant differences in the measurement variability between groups of curve location (thoracic, thoracolumbar, and lumbar), curve direction (right and left), curve magnitude (curves less than 25 degree, between 25 and 45 degrees, and more than 45 degree), and observer experience (experienced observer and inexperienced observers). Conclusions Compared with the documented results, variability of the Cobb measurement is reduced by using the developed computer-aided method. This method can help orthopedic surgeons measure the Cobb angle more reliably during scoliosis clinics.

Tumor necrosis alpha-blocking agent (etanercept): a triple blind randomized controlled trial of its use in treatment of sciatica.

Abstract: Study DesignTriple blind randomized controlled study.ObjectiveTo establish the treatment effect of etanercept in acute sciatica secondary to lumbar disc herniation.Summary of Background DataEtanercept is a selective competitor of tumor necrosis factor-α which is a proinflammatory cytokine. It is cur

Long-term Results of Iliac Wing Fixation Below Extensive Fusions in Ambulatory Adult Patients With Spinal Disorders

Abstract: Study design Case series, level of evidence therapeutic IV. Objective Examine the results of bilateral iliac wing fixation in long fusions to the pelvis in ambulatory adult patients. Summary of background data Adult spinal deformity surgery is an endeavor often fraught with complications. One particularly debilitating problem with long fusions of the spine in adults with spinal diseases such as degenerative scoliosis and spondylolysis is failure of the lumbosacral (spinal-pelvic) junction owing to nonunion, implant failure, or sacral fracture. This can result in continued pain, continued curve progression and deformity, progressive sagittal imbalance, and the need for reoperation. Some deformity surgeons have speculated fusion rates at the caudal end of long constructs to the sacrum could be improved by the addition of spinopelvic fixation. Iliac wing screws have been successfully used in nonambulatory patients for the treatment of neuromuscular scoliosis, but concerns exist over use in ambulatory patients. Prominence, local irritation of the screws, screw breakage, infection, and sacroiliac joint pathology are all concerns. The purpose of this study was to examine the results of long fusions to the sacrum using bilateral iliac wing screw fixation in ambulatory adults with spinal deformities. Methods This case series consisted of 78 patients followed for at least 2 years (average 3.7 y, range: 2 to 8 y). All patients were ambulatory adults who received bilateral iliac wing fixation below long fusion constructs (average 9 levels fused). All but 3 patients were above 50 years old and the average age in the study was 67.6 years. There were 66 females and 12 males in the study. The operative indications for posterior spinal fusion were fixed sagittal imbalance spondylolysis (23 patients), idiopathic scoliosis (22 patients), degenerative scoliosis (15 patients), pseudarthrosis below long fusions (13 patients), and traumatic kyphosis (5 patients). Patients were analyzed clinically and radiographically and all complications were noted. Correction of coronal deformity and correction of fixed sagittal imbalance were measured by comparing preoperative and postoperative radiographic measurements. All patients completed the Zuckerman written questionnaire to assess patient's subjective clinical result. Results Twelve of 78 patients (15.3%) developed pseudarthrosis with broken implants; however only 5 of 78 (6.4%) nonunions occurred at the lumbosacral junction. Six of 78 patients (7.7%) required removal of the iliac screws for pain or painful prominence. Forty-two patients had one or more complications with an overall complication rate of 54%. Despite the overall complication and revision rate, 78% of patients reported good or excellent results with the Zuckerman questionnaire. Excellent correction of sagittal balance and coronal deformity was achieved. Average sagittal balance preoperatively was+10 and improved to an average of+2.5 postoperatively. Average major curve coronal plane deformity preoperatively was 61 degree and improved to an average of 29 degree postoperatively. There were no sacral fractures, sacral screw failures, or significant sacroiliac joint degeneration on follow-up radiographs. Conclusions In this series, nonunions continue to be a problem, with a rate of 15.3%, however only 6.4% of nonunions were at the lumbosacral junction. Complications specific to iliac screw placement were minimal. These difficult surgeries are known to be plagued with problems and our complication rate is consistent with what is present in the current literature. The use of iliac wing fixation seems to dramatically improve lumbosacral fusion rates with an acceptable complication rate; in addition there seems to be a protective effect in preventing sacral fractures, sacral screw failure, and sacroiliac arthritis.

Posttraumatic kyphosis: current state of diagnosis and treatment: results of a multinational survey of spine trauma surgeons.

Abstract: Study DesignMultinational survey of spine trauma surgeons.ObjectivesTo survey a multinational group of spine trauma surgeons and develop an updated consensus definition of posttraumatic kyphosis (PTK), and the most current methods for diagnosis and treatment.Summary of Background DataPTK remains a p

Microdecompressive laminatomy with a 5-year follow-up period for severe lumbar spinal stenosis.

Abstract: Study design The 2 groups of patients with severe lumbar spinal stenosis were prospectively compared as a case control study. Objectives This prospective case control study sought to evaluate bilateral microdecompressive laminatomy (MDL) for treatment of severe lumbar spinal stenosis. Summary of background data Total laminectomy is a general consensus on the therapy of severe spinal stenosis. The authors tried to investigate a new minimal invasive approach. Methods Patients were randomly divided into 2 groups. In first group, 34 patients underwent total laminectomy (TL) for severe lumbar spinal stenosis. In the second group, 37 patients with the same diagnosis underwent bilateral MDL. The groups were compared for disability, walking distance, degree of postoperative back and leg pain, perioperative complications, and postoperative instability. Radiographic analyses were performed at regular intervals to demonstrate satisfactory decompression. Results Mean follow-up was 5 years. Postoperative computerized tomography and magnetic resonance imaging demonstrated adequate decompressions in both groups. The walking distance, pain control, and disability scores were slightly higher among patients in the MDL group, although these results did not achieve statistical significance. Perioperative complications and postoperative instability were significantly higher in the TL group (P Conclusions Compared with classic approaches, bilateral MDL provides adequate and safe decompression in lumbar spinal stenosis. It significantly reduces clinical symptoms and disability. However, TL shows higher perioperative complications and postoperative instability. To the best of our knowledge, this is the first study to define a bilateral MDL approach to treat the stenotic lumbar spine without a herniated disc.

The effect of differing spinal fusion instrumentation on the occurrence of postoperative crankshaft phenomenon in adolescent idiopathic scoliosis.

Abstract: STUDY DESIGN: Retrospective. OBJECTIVE: To compare the occurrence of the crankshaft phenomenon in patients with adolescent idiopathic scoliosis (AIS) who underwent hybrid, consecutive pedicle screw or interval pedicle screw instrumentation for posterior spinal fusion. SUMMARY OF BACKGROUND DATA: Scoliosis may progress after posterior spinal fusion in skeletally immature patients with AIS. The crankshaft phenomenon occurs when the anterior column continues to grow in the face of posterior fusion causing characteristic twisting of the fused segment. The optimal surgical method for preventing the occurrence of this complication has not been determined. METHODS: Sixty seven patients with AIS who underwent posterior fusion over a 6-year period were divided into groups according to fixation method: hybrid instrumentation, interval pedicle screw placement, or consecutive pedicle screw placement. Preoperative, postoperative, and follow-up radiographic measures, including Cobb angle, apical vertebral rotation (AVR), apical vertebral transposition (AVT), rib vertebral angle difference (RVAD) and trunk shift (TS) were assessed. The occurrence of the crankshaft phenomenon was determined. RESULTS: The mean follow-up duration was 36 months. There were no between-the-group differences in demographics or preoperative or immediate postoperative measures. At the last follow-up, significant differences among the groups were apparent for Cobb angle, AVR, AVT, RVAD, and TS (all P<0.05). Cobb angle, AVR, AVT, RVAD, and TS significantly increased between the postsurgery and the last follow-up in the hybrid instrumentation group (all P<0.0167). Only TS increased significantly in the 2 other groups. There were 7 cases of crankshaft phenomenon occurrence in the hybrid instrumentation group (33%), but none in the other 2 groups. CONCLUSIONS: These findings suggest that in skeletally immature patients with AIS, hybrid instrumentation cannot effectively prevent occurrence of the crankshaft phenomenon, whereas interval and consecutive pedicle screw instrumentation may be more (and equally) efficacious in this regard.

Preoperative radiographic factors and surgeon experience are associated with cortical breach of C2 pedicle screws.

Abstract: Study design A retrospective review study. Objective In this study, we attempt to identify radiographic variables associated with likelihood of intraoperative breach during C2 pedicle screw placement. In addition, we attempt to correlate surgeon experience with breach rate. Summary of background data Pedicle screws have emerged as an effective approach for obtaining fixation of the axis, yet placement of C2 pedicle screws is technically demanding and poses the risk of injury to the vertebral artery. Given the evidence for substantial variation in C2 anatomy, preoperative assessment of computed tomography (CT) scans may indicate, which patients are at increased risk for cortical breach during the pedicle screw placement. Materials and methods A retrospective review of all patients undergoing C2 pedicle screw fixation at a single institution over the last 6 years was conducted. Radiographic cortical breaches were defined on postoperative CT scans as visualization of the screw beyond the cortical edge. Radiographic measurements were determined from preoperative CT scans and were then correlated with breaches via Student t test. The association of breach rate with surgeon experience was evaluated using univariate linear regression. Results Ninety-three patients underwent placement of 170 screws. Cortical breach was detected on postoperative CT scans in 43 screws (25.3%). One clinically significant breach occurred with damage to the left vertebral artery intraoperatively. On axial CT sections, mean pedicle isthmus diameter was significantly smaller in patients with breach than in patients without breach for both left and right sides, P=0.006 and P=0.010, respectively. Specifically, a diameter of less than 6 mm was associated with a nearly 2-fold increase in risk of cortical breach (37% vs. 21%). Surgeons with greater experience in placing C2 pedicle screws were noted to have a lower breach incidence (P=0.004). Conclusions During placement of C2 pedicle screws, likelihood of cortical breach may be associated with size of pedicle and surgeon experience. Extensive preoperative evaluation of CT scans and consideration of technical demands of procedure may help avoid complications with such internal fixation.

Segmental percentage contributions of cervical spine during different motion ranges of flexion and extension.

Abstract: STUDY DESIGN A blind, repeated-measure design was employed in the study. OBJECTIVE To quantitatively measure the percentage contribution of segmental angular motion during different motion ranges of cervical flexion-extension for clinical applications and better understanding of cervical biomechanics. SUMMARY OF BACKGROUND DATA Restriction of cervical motion is a major symptom in patients suffering from neck injuries or pathologies. Although segmental angular motion alternation is a criterion for the detection of neck related impairments, the percentage contribution throughout cervical movements is not well understood. METHODS A total of 384 image sequences during cervical flexion-extension obtained from 48 healthy adult subjects were analyzed with a precise image protocol using dynamic videofluoroscopic techniques. RESULTS The middle cervical spines demonstrated significantly greater angular percentage contributions at C3/4 (29.89%) and C4/5 (37.14%) angles during the initial 1/3 flexion movement; whereas the lower cervical spines revealed statistically greater angular contributions (C5/6: 22.57% to 29.45%; C6/7: 28.80% to 37.42%) from the middle to final 1/3 ranges of flexion movement (P<0.001). With regard to cervical extension motion, the majority of segmental percentage contributions statistically shifted initially from C5/6 level (30.21%) to C4/5 (24.96%) and C5/6 (26.12%) levels, and finally to the C3/4 (27.55%) and C4/5 (29.77%) segments (P<0.001). CONCLUSIONS The segmental percentage contributions in this study might imply that the cervical flexion movement initially relied more on the middle cervical segments and later on the lower ones, whereas a motion pattern trend from lower to middle segments was observed during cervical extension.

Neck muscle strength before and after cervical laminoplasty: relation to axial symptoms.

Abstract: Study DesignA prospective study to investigate serial changes in neck muscle strength before and after cervical laminoplasty.ObjectivesTo examine the correlation between neck muscle strength and axial symptoms, and to clarify the risk factors for axial symptoms.Summary of Background DataAxial sympto

Influence of Dynesys system screw profile on adjacent segment and screw.

Abstract: Study DesignDisplacement-controlled finite element analysis was used to evaluate the mechanical behavior of the lumbar spine after insertion of the Dynesys dynamic stabilization system.ObjectiveThis study aimed to investigate whether different depths of screw placement of Dynesys would affect load s