Showing papers in "Journal of Spinal Disorders & Techniques in 2008"

Minimally invasive multilevel percutaneous correction and fusion for adult lumbar degenerative scoliosis: a technique and feasibility study.

Abstract: Study design Prospective evaluation of 12 patients undergoing surgery for lumbar degenerative scoliosis. Objective To assess the feasibility of minimally invasive spine surgery (MIS) techniques in the correction of lumbar degenerative deformity. Summary of background data Patient age, comorbidities, and blood loss may be limiting factors when considering surgical correction of lumbar degenerative scoliosis. MIS may allow for significantly less blood loss and tissue disruption than open surgery. Methods Twelve patients underwent circumferential fusion. The age range of these patients was 50 to 85 years (mean of 72.8 y). Of the 12 patients, 7 were men and 5 were women. All patients underwent direct lateral transpsoas approach for discectomy and fusion with polyetheretherketone cage and rh-BMP2. All fusions to the sacrum included L5-S1 fusion with the Trans1 Axial Lumbar Interbody Fusion technique. Posteriorly, multilevel percutaneous screws were inserted using the CD Horizon Longitude system. Radiographs, visual analog scores (VAS), and treatment intensity scores (TIS) were assessed preoperatively and at last postoperative visit. Operative times and estimated blood loss were recorded. Results Mean number of segments operated on was 3.64 (range: 2 to 8 segments). Mean blood loss for anterior procedures (transpsoas discectomy/fusion and in some cases L5-S1 interbody fusion) was 163.89 mL (SD 105.41) and for posterior percutaneous pedicle screw fixation (and in some cases L5-S1 interbody fusion) was 93.33 mL (SD 101.43). Mean surgical time for anterior procedures was 4.01 hours (SD 1.88) and for posterior procedures was 3.99 hours (SD 1.19). Mean Cobb angle preoperatively was 18.93 degrees (SD 10.48) and postoperatively was 6.19 degrees (SD 7.20). Mean preoperative VAS score was 7.1; mean preoperative TIS score was 56.0. At mean follow-up of 75.5 days, mean VAS was 4.8; TIS was 28.0. Conclusions A combination of 3 MIS techniques allows for correction of lumbar degenerative scoliosis. Multisegment correction can be performed with less blood loss and morbidity than for open correction.

Complications in the use of rhBMP-2 in PEEK cages for interbody spinal fusions.

Abstract: Study design All patients of spinal interbody fusion using polyetheretherketone (PEEK) cages and recombinant human bone morphogenetic protein (rhBMP)-2 performed over a 16-month period were reviewed. Objective To determine the suitability of PEEK cages when used in conjunction with rhBMP-2 in interbody spinal fusion. Summary of background data Bone morphogenetic proteins are increasingly being used in spinal fusion to promote osteogenesis. PEEK is a semicrystalline aromatic polymer that is used as a structural spacer to maintain the disc and foraminal height. Their use has led to increased and predictable rates of fusion. However, not many reports of the adverse effects of their use are available. Methods Fifty-nine consecutive patients of interbody spinal fusion in the cervical or lumbar spine using a PEEK cage and rhBMP-2 were followed for an average of 26 months after surgery. A clinical examination and a record of Oswestry Disability Index, Visual Analog Scale for pain, and a pain diagram were performed preoperatively and at every follow-up visit. All patients had plain radiographs carried out to assess fusion. Ten patients of lumbar spine fusion were additionally evaluated with a computed tomography scan. Results All cases demonstrated an appreciable amount of new bone formation by 6 to 9 months in the cervical spine and by 9 to 12 months in the lumbar spine. End plate resorption was visible radiologically in all cervical spine fusions and majority of lumbar fusions. Cage migration was observed to occur maximally in patients with transforaminal lumbar interbody fusion and posterior lumbar interbody fusion. Disc space subsidence was seen in both cervical and lumbar arthrodesis with the latter showing a lesser incidence, but with a greater degree of collapse. Conclusions PEEK cages and rhBMP-2 when used in spinal fusion give consistently good fusion rates. However, the early role of BMP in the resorptive phase may cause loosening, cage migration, and subsidence.

Minimally invasive sacroiliac arthrodesis: outcomes of a new technique.

Abstract: Study DesignProspective cohort.ObjectiveComparing efficacy and outcomes of a new technique for sacroiliac arthrodesis.BackgroundThe sacroiliac joint has been described as a possible source of chronic low back pain. However, surgical treatment of sacroiliac pain and dysfunction is controversial. Arth

Vertebral artery injuries associated with cervical spine injuries: a review of the literature.

Abstract: Study DesignLiterature review.ObjectiveTo determine the incidence of vertebral artery injuries (VAIs) in association with cervical spine trauma and investigate the optimum diagnostic and treatment protocols.Summary of Background DataVAIs may result from cervical spine trauma and have the potential t

Reliability of a magnetic resonance imaging-based grading system for cervical intervertebral disc degeneration.

Abstract: Study DesignThis was a radiographic reliability study of a novel grading system for cervical intervertebral disc degeneration.ObjectivesThis study aimed to develop and test the reliability of a reproducible grading system for cervical intervertebral disc degeneration on the basis of the routine magn

Subsidence of titanium mesh cage: a study based on 300 cases.

Abstract: Study DesignA cohort study.ObjectiveTo clarify the risk factors for the subsidence of the titanium mesh cage (TMC) after anterior cervical corpectomy and fusion, and to discuss their clinical correlations.Summary of Background DataFusion with TMC after anterior cervical corpectomy has become popular

Early complications of surgical versus conservative treatment of isolated type II odontoid fractures in octogenarians: a retrospective cohort study.

Abstract: Study design A retrospective cohort study of operative versus nonoperative treatment of isolated type II odontoid fractures in patients aged 80 years and more without neurologic deficit admitted to a level 1 spinal cord injury center between June 1985 and July 2006. Objective To assess the presentation and acute complications of operatively and nonoperatively managed type II odontoid fractures in the octogenarian population. Summary of background data Type II odontoid fractures are the most common cervical spine fracture in the elderly. Studies suggest acute in-hospital complication rates in type II odontoid fractures in the elderly exceed 50%. Few studies have examined the acute in-hospital outcomes of isolated type II odontoid fractures in the octogenarian population. Methods The medical records of 223 consecutive C2 fractures from June 1985 to July 2006 over the age of 80 years were reviewed retrospectively. Patients with associated cervical spine fractures were excluded. Eighty neurologically intact patients over age 80 were identified with isolated acute type II odontoid fractures. The charts were reviewed and mechanism of injury, comorbidities, date of injury, date of admission, date of discharge, radiology reports, discharge disposition, associated injuries, fracture management, type of surgical fixation (if any), and documented complications were abstracted. Results Thirty-two patients received operative treatment (10 anterior and 22 posterior) and 40 patients received nonsurgical treatment. Eight patients were excluded because the medical record could not be located. The mean age was 85.5+/-3.5 years in the surgical and 87.3+/-4.7 years in the nonsurgical group (P>0.05); mean length of acute hospital stay was 11.2+/-8.5 days in the nonsurgical and 22.8+/-28.3 days in the surgical group (P 0.5); mean fracture displacement was 4.1+/-3.5 mm in the nonsurgical and 3.9+/-3.4 mm in the surgical group (P>0.5). Acute in-hospital mortality rate was 15% in the nonsurgical group and 12.5% in the surgical group (P>0.05). The percentage of patients experiencing at least one significant complication was higher in the operative group than the nonoperative group (62% vs. 35%, respectively, P Conclusions Type II odontoid fractures in the octogenarian population are associated with substantial morbidity and mortality, irrespective of management method. Prospective studies are needed to better elucidate management strategies for this difficult clinical problem.

Percutaneous sacroiliac joint arthrodesis: a novel technique.

Abstract: Study DesignConsecutive case series.ObjectiveTo report a new percutaneous sacroiliac joint (SIJ) arthrodesis technique utilizing a Hollow Modular Anchorage screw.Summary of Background DataA variety of SIJ arthrodesis techniques have been reported in the established academia to treat intractable SIJ

The clinical characteristics and risk factors for the adjacent segment degeneration in instrumented lumbar fusion.

Abstract: Study design A retrospective study. Objective The aims of this study were to evaluate the clinical significance of, characteristics of, and risk factors for adjacent segment degeneration (ASD) in patients who have undergone instrumented lumbar fusion. Summary of background data ASD has been considered a potential long-term complication of spinal arthrodesis. However, the exact mechanisms and risk factors related to ASD are not completely understood. Methods A total of 48 patients who underwent instrumented lumbar fusion at L4-5 and had minimal ASD preoperatively were evaluated. The patients were divided into 2 groups at follow-up according to the development of ASD defined by radiologic criteria. Through review of their medical records and the radiologic files, the following variables were evaluated in the 2 groups: basic demographic data, body weight, body height, body mass index, bone mineral density, types of surgical approaches, preoperative and postoperative segmental and lumbar lordosis, and clinical outcomes. Results ASD was found in 30 (62.5%) patients. The variables that showed statistical intergroup differences were the mean age at surgery, the mean difference in the degree of preoperative from postoperative lumbar lordosis, and the proportion of patients who underwent anterior lumbar interbody fusion. However, there were no statistically significant intergroup differences in the Japanese Orthopedic Association score at 1-year postoperatively or at the final follow-up, or in the recovery rate, success rate, and complication rate. Conclusions Radiographic ASD is relatively common long-term finding associated with instrumented lumbar fusion. However, radiographic evidence of ASD does not necessarily correlate with a poor outcome. Our results suggest that advanced age, anterior lumbar interbody fusion, and the restoration of the preoperative standing lumbar lordosis may have a protective effect against the development of ASD.

Increasing bending strength and pullout strength in conical pedicle screws: biomechanical tests and finite element analyses.

Abstract: Study Design: Comparative in vitro biomechanical study and finite element analysis. Objectives: To investigate the bending strength and pullout strength of conical pedicle screws, as compared with conventional cylindrical screws. Summary of Background Data: Transpedicle screw fixation, the gold standard of spinal fixation, is threatened by screw failure. Conical screws can resist screw breakage and loosening. However, biomechanical studies of bending strength have been lacking, and the results of pullout studies have varied widely. Methods: Ten types of pedicle screws with different patterns of core tapering and core diameter were specially manufactured with good control of all other design factors. The stiffness, yielding strength, and fatigue life of the pedicle screws were assessed by cantilever bending tests using high-molecular-weight polyethylene. The pullout strength was assessed by pullout tests using polyurethane foam. Concurrently, 3-dimensional finite element models simulating these mechanical tests were created, and the results were correlated to those of the mechanical tests. Results: In bending tests, conical screws had substantially higher stiffness, yielding strength, and fatigue life than cylindrical screws (P<0.01), especially when there was no step at the thread-shank junction. In pullout tests, pullout strength was higher in screws with a conical core and smaller core diameter and also in situations with higher foam density (P<0.01). In finite element analysis, the maximal deflection and maximal tensile stress were closely related to yielding strength (r = 0.91) and fatigue life (r = 0.95), respectively, in the bending analyses. The total reaction force was closely related to the pullout strength in pullout analyses (r = 0.84 and 0.91 for different foam densities). Conclusions: Conical screws effectively increased the bending strength and pullout strength simultaneously. The finite element analyses reliably predicted the results of the mechanical tests.

Motion analysis of bryan cervical disc arthroplasty versus anterior discectomy and fusion: results from a prospective, randomized, multicenter, clinical trial.

Abstract: Study Design Prospective, randomized, multicenter clinical trial. Objective Kinematic analysis of target level and adjacent motion segments after Bryan artificial cervical disc replacement versus anterior cervical fusion. Summary of Background Data Disc arthroplasty has been shown to provide short-term clinical results that are comparable or better than those attained with traditional anterior cervical discectomy and fusion. One purported benefit of arthroplasty is the ability to prevent or delay adjacent level operations. Methods All patients received either a single-level anterior cervical discectomy and fusion with an anterior cervical plate (Atlantis anterior cervical plate, n=221) or a single-level artificial cervical disc replacement (Bryan cervical disc prosthesis, n=242) at C3 to C7. Flexion, extension, and neutral lateral radiographs were obtained preoperatively, and at regular intervals of 24 months. Cervical vertebral bodies were tracked to calculate the functional spinal unit motion parameters, including flexion/extension range of motion and translation. If visible, the functional spinal unit parameters were obtained at the operative level as well as the level above and below. Results Significantly more motion was retained in the disc replacement group than the plated group at the index level. The disc replacement group retained an average of 7.95 degrees at 24 months. The preoperative motion was 6.43 degrees and there was no evidence of degradation of motion over 24 months. In contrast, the average range of motion in the fusion group was 1.11 degrees at 3-month follow-up and gradually decreased to 0.87 degrees at 24 months. The preoperative motion was 8.39 degrees. The Bryan disc did not migrate. At 24-month follow-up, there was no case of subsidence of the Bryan disc. There was no evidence of bridging bone across any of the Bryan implant disc spaces. Conclusions The Bryan disc treatment, on average, maintained flexion/extension range of motion without degradation over 24 months. No ectopic bridging ossification was seen in any of the Bryan discs and no subsidence or displacement of the Bryan disc occurred.

Pedicle screw placement with a free hand technique in thoracolumbar spine: is it safe?

Abstract: Study DesignComputerized tomography (CT) analysis of in vivo pedicle screw placement to determine their exact position in relation to the pedicle in thoracolumbar region (T10-L3).ObjectiveTo evaluate the clinical accuracy of the placement of thoracolumbar pedicle screws with a free hand technique af

Segmental pedicle screwing for idiopathic scoliosis using computer-assisted surgery.

Abstract: Study DesignRetrospective clinical study.ObjectivesTo evaluate the accuracy of computer-assisted surgery for idiopathic scoliosis.Summary of Background DataSegmental pedicle screw fixation has been proven to enable enhanced correction of scoliotic deformities. However, both neurovascular and viscera

Cervical Kinematics After Fusion and Bryan Disc Arthroplasty

Abstract: INTRODUCTION Disc arthroplasty has been shown to provide short-term clinical results that are comparable with those attained with traditional anterior cervical discectomy and fusion. One proposed benefit of arthroplasty is the ability to prevent or delay adjacent level operations by retaining motion at the target level and eliminating abnormal adjacent activity. This paper compares motion parameters for single-level anterior cervical discectomy and fusion and disc replacement patients at the index level and adjacent segments. METHODS Radiographic data from patients enrolled in a prospective, randomized clinical trial were selected for kinematic assessment of cervical motion. All patients received either a single-level fusion with allograft and anterior cervical plate (Atlantis anterior cervical plate, n=13) or a single-level artificial cervical disc (Bryan Cervical Disc prosthesis, n=9) at either C5/C6 or C6/C7. Flexion, extension, and neutral lateral radiographs were obtained preoperatively, immediately postoperatively, and at regular intervals up to 24-month time points. Cervical vertebral bodies were tracked on the digital radiographs using quantitative motion analysis software (QMA, Medical Metrics) to calculate the functional spinal unit motion parameters including range of motion (ROM), translation, and center of rotation. If visible, the functional spinal unit parameters were obtained at the operative level, and also the level above and the level below. RESULTS As expected, significantly (P<0.006 at 3, 6, 12, and 24 mo) more flexion/extension motion was retained in the disc replacement group than the plated group at the index level. The disc replacement group retained an average of 6.7 degrees at 24 months. In contrast, the average ROM in the fusion group was 2.0 degrees at the 3-month follow-up and gradually decreased to 0.6 degrees at 24 months. The flexion/extension ROM both above and below the operative level was not statistically different for the disc-replaced and fusion patients, however, mobility increased for both groups over time. The anterior/posterior translation that occurs with flexion/extension motion remained unchanged for the disc replacement group at the level above the target disc preoperatively and postoperatively. In contrast, the translation increased for the level above the fusion. At the 6-month follow-up, the increase in translation was significantly greater for patients that were fused (P<0.02) than for patients that received a disc replacement. This change was not significant at 12 months. DISCUSSION Previous studies have shown the Bryan disc to maintain mobility at the level of the prosthesis. The long-term clinical benefit of maintenance of motion is postulated to be the ability to delay or avoid adjacent level operations. This study reveals that there is no difference in flexion/extension ROM at the level above and below either a fusion or Bryan arthroplasty. There is, however, an increase in anterior/posterior translation at the cephalad adjacent level in patients with arthrodesis while the Bryan arthroplasty retains normal translation for the same amount of flexion/extension at the adjacent level. CONCLUSION The Bryan disc may delay adjacent level degeneration by preserving preoperative kinematics at adjacent levels.

Radiation exposure to the surgeon and the patient during kyphoplasty.

Abstract: STUDY DESIGN Prospective study of patients who underwent single or multilevel kyphoplasty for vertebral fractures. OBJECTIVE To quantify the radiation exposure to the surgeon and to the patient during kyphoplasty, and also to provide a procedural algorithm that effectively minimizes the radiation exposure to the surgeon during any fluoroscopic-guided procedure. SUMMARY OF BACKGROUND DATA Spine surgeons who perform minimally invasive procedures often employ fluoroscopy for intraoperative navigation. METHODS Twenty-seven patients were enrolled. Two fluoroscopes (1 anterior/posterior and 1 lateral) were used for localization, navigation, and monitoring cement flow. All surgeons wore thyroid shields and lead aprons. The dose of radiation exposure was measured by dosimeter badges. One badge was attached to each patient. The surgeons wore 3 badges: under the thyroid shield (protected), under the lead apron over the left chest (protected), and outside the lead apron over the left chest (unprotected). A thermoluminescent ring dosimeter was worn on the right hand for 18 cases, and on the left hand for 9 cases. RESULTS The exposure time was 5.7+/-2.0 minutes/vertebra for a single level (n=10), 3.9+/-0.8 minutes/vertebra for a 2 level (n=9), 2.9+/-1.2 minutes/vertebra for a 3 level kypholasty (n=8). The exposure time of single level kyphoplasy was significantly different from that of multilevel kyphoplasy (2 level, P=0.040; 3 level, P=0.002). Surgeon exposure as measured by the protected dosimeter was less than the minimum reportable dose (<0.010 mSv). Exposure as measured by the unprotected dosimeter, which is equivalent to deep whole body exposure was 0.248+/-0.170 mSv/vertebra. The eye exposure was 0.271+/-0.200 mSv/vertebra, and the shallow exposure (hand/skin) was 0.273+/-0.200 mSv/vertebra. The hand exposure was 1.744+/-1.173 mSv/vertebra. CONCLUSIONS Without eye or hand protection, the total radiation exposure dose to these areas would exceed the occupational exposure limit after 300 cases per year. Surgeons should wear lead lined glasses and keep their hands out of the radiation beam.

Comparison of posterolateral fusion with and without additional posterior lumbar interbody fusion for degenerative lumbar spondylolisthesis.

Abstract: ObjectivesThe surgical approach that should be used for degenerative spondylolisthesis (DS) is a controversial issue. Decompression and posterolateral fusion (PLF) with or without lumbar interbody fusion is widely used. Many studies have compared the outcomes of these 2 approaches, but the appropria

The radiation exposure associated with cervical and lumbar spine radiographs.

Abstract: Study designCross-sectional study.ObjectiveTo calculate the effective radiation doses of routine anteroposterior (AP) and lateral radiographs of the cervical and lumbar spines.Summary of Background DataAlthough plain radiographs are generally used as the initial imaging modality for the evaluation o

Raster stereography versus radiography in the long-term follow-up of idiopathic scoliosis.

Abstract: Study DesignRaster-stereographic and radiographic evaluation of idiopathic scoliosis without braces in a retrospective longitudinal long-term follow-up study.ObjectiveTo investigate the reliability and accuracy of raster stereography in comparison with radiography as the gold standard, using a longi

C5 nerve root palsy after cervical laminoplasty and posterior fusion with instrumentation.

Abstract: Study DesignConsecutive case series.ObjectiveTo compare the incidence and clinical characteristics of postoperative fifth cervical nerve root palsy (C5 palsy) in patients with cervical myelopathy treated by laminoplasty alone and laminoplasty with posterior instrumentation.Summary of Background Data

Feasibility of occipital condyle screw placement for occipitocervical fixation: a cadaveric study and description of a novel technique.

Abstract: STUDY DESIGN Occipital-cervical (OC) stabilization using occipital condyle fixation with a polyaxial screw-rod construct is described. OBJECTIVES To describe a novel technique and initial radiographic results for posterior OC fixation using the occipital condyles for cranial fixation. SUMMARY OF BACKGROUND DATA Stabilization of the OC junction remains a challenge. Owing to the regional anatomy and the poor occipital bone purchase, multiple attachment points to the occipital bone are required to increase construct rigidity. To address these issues, we propose a novel OC fixation technique using polyaxial occipital condyle screws for cranial purchase. METHODS The OC junction was exposed posteriorly in silicone-injected cadaver heads. Polyaxial titanium screws (3.5 mm) were inserted bicortically solely into the occipital condyles; C1 lateral masses and C2 pedicles, or transarticularly through C1-C2, followed by fixation to a 3-mm rod. Drilling was guided by anatomic landmarks and fluoroscopy. Computerized tomography scans were obtained. Condylar screw angles and lengths were analyzed with respect to historical morphometric condyle measurements and with respect to neurovascular structures. RESULTS The condylar entry point was 4 to 5-mm lateral to the foramen magnum on the axial plane, and 1 to 2-mm rostral to the atlantooccipital joint. The mean angle of medialization was 17 degrees (range: 12 to 22 degrees). In the sagittal plane, the maximal superior screw angulation was 5 degrees. The mean screw length to obtain bicortical purchase was 22 mm (range: 20 to 24 mm). The hypoglossal canal was uninterrupted during its full course. The jugular bulb, carotid, and vertebral arteries were not injured by condyle screw placement. No fractures were identified. CONCLUSION Condyle screws can be placed without injury to neurovascular structures. OC junction fixation using polyaxial occipital condyle screws is feasible and can be considered a salvage technique or an alternative where other fixation techniques are not available.

Higher risk of adjacent segment degeneration after floating fusions: long-term outcome after low lumbar spine fusions.

Abstract: STUDY DESIGN We report the long-term outcome after mono-segmental and bisegmental fusions at the lumbar L4-S1 region of the spine. OBJECTIVE Long-term clinical and radiologic outcome measures were used to determine a lumbar fusion's contribution to degenerative changes in adjacent motion segments (ASD). SUMMARY OF BACKGROUND DATA The role of low lumbar spinal fusions and their long-term contribution to accelerated degenerative changes in the adjacent motion segments continues to be a subject of controversy. PATIENTS AND METHODS We followed-up 102 patients with an average age of 54 (22 to 78) years and a follow-up time of 14 (3 to 22) years. RESULTS Overall results in patients were good, the Oswestry-Disability Index (ODI) showed an average of 26% (0% to 70%) at follow-up, the Visual Analog Scale rose from 2.7 (postoperative) and 2.9 (12 wk follow-up) to 3.6 (latest follow-up) points, respectively. Patient satisfaction with their health-related situation at follow-up was 69% (15% to 100%). Patients who underwent fusions of the segment L5/S1 showed a significant (P<0.05) lower risk for ASD than patients with fusions L4/5 (20% vs. 46%). Compared with L4/5 fusions, bisegmental L4-S1 fusions showed a similar trend (P=0.06) with a lower risk for ASD (24%). Objective and subjective clinical results showed no differences between these groups. Patients suffering from ASD showed significant (P<0.05) reduced sacral inclination and lumbar lordosis angles and also significant (P<0.05) higher ODI values compared with non-ASD patients. CONCLUSIONS We conclude that floating fusions of single low lumbar segments are more likely to result in ASD and are negatively influenced by sagittal plane abnormalities.

Therapy of spinal wound infections using vacuum-assisted wound closure: Risk factors leading to resistance to treatment

Abstract: Study design This study retrospectively reviewed spine surgical procedures complicated by wound infection and managed by a protocol including the use of vacuum-assisted wound closure (VAC). Objective To define factors influencing the number of debridements needed before the final wound closure by applying VAC for patients with postoperative spinal wound infections. Summary of background data VAC has been suggested as a safe and probably effective method for the treatment of spinal wound infections. The risk factors for infection resistance and need for debridement revisions after VAC placement are unknown. Methods Seventy-three consecutive patients with 79 wound infections after undergoing spine surgery were studied (6 of them had recurrence of infection). All patients were taken to the operating room for irrigation and debridement under general anesthesia followed by placement of the VAC with subsequent delayed closure of the wound. Linear regression and t test were used to identify if the following variables were risk factors for the resistance of infection to VAC treatment: timing of clinical appearance of infection, depth of infection (deep or superficial), presence of instrumentation, positive culture for methicillin-resistant Staphylococcus aureus (MRSA) or more than 1 microorganism, age of the patient, and presence of other comorbidities. Results There were 34 males and 39 females with an average age of 58.4 years (21 to 82). Once the VAC was initiated, there was an average of 1.4 procedures until and including closure of the wound. The wound was closed an average of 7 days (range 5 to 14) after the placement of the initial VAC on the wound. The average follow-up was 14 months (range 12 to 28). All of the patients but 2 achieved a clean, closed wound without removal of instrumentation at a minimum follow-up of 1 year. Sixty patients had implants (instrumentation or allograft) within the site of wound infection. Thirteen patients had a decompression with exposed dura. Sixty-four infections (81%) presented with a draining wound within the first 6 weeks postoperatively. Sixty-nine infections (87.3%) were deep below the fascia. There was no statistical significance (P>0.05) of all tested risk factors for the resistance of infection to treatment with the VAC system. The parameter more related to repeat VAC procedures was the culture of MRSA or multiple bacteria. Conclusions VAC therapy may be an effective adjunct in closing spinal wounds even after the repeat procedures. The MRSA or multibacterial infections seem to be most likely to need repeat debridements and VAC treatment before final wound closure.

Instrumented posterior lumbar interbody fusion for patients with degenerative lumbar scoliosis.

Abstract: ObjectiveSurgery for degenerative lumbar scoliosis remains challenging for spine surgeons even with the application of pedicle screw instrumentation. This retrospective study assesses the outcomes of instrumented posterior lumbar interbody fusion (PLIF) for degenerative lumbar scoliosis.MethodsFrom

Minimally invasive transpedicular vertebrectomy for metastatic disease to the thoracic spine.

Abstract: Study design and objective We present a series of 8 patients with thoracic metastatic disease causing acute neurologic decline. We present minimally invasive posterolateral vertebrectomy and decompression as an effective approach in patients with significant comorbidities and as palliative care. Background Metastatic disease to the spine is common and frequently occurs in the thoracic vertebrae. Posterior laminectomy alone has generally been found to be ineffective in the management of spinal metastatic disease with neurologic compromise as most compression occurs ventrally. Patients with significant comorbidities are often unable to tolerate extensive surgery involving a thoracotomy. Limited life expectancy and quality of life issues also often argue against extensive surgery. Methods Eight patients (mean age 74 y) with thoracic metastatic disease and acute neurologic compromise underwent a minimally invasive posterolateral vertebrectomy and partial tumor resection. Patients were considered unsuitable for an open anterior approach owing to age, comorbidities, and limited life expectancies. In the operating room, patients were positioned prone. A paramedian incision measuring 3 cm allowed the introduction of sequential dilators and the placement of a 22-mm diameter tubular retractor. Dorsal decompression was accomplished and partial vertebrectomy was performed for ventral decompression. Radiation was used postoperatively in all patients. Results There were no complications due to the procedure. Improvement of at least 1 grade on the Nurick scale was noted in 5 of 8 (62.5%) patients. Two patients were able to ambulate independently immediately after surgery despite having significant paraparesis preoperatively. Pain improved in 5 of 8 (62.5%) patients postoperatively according to the numerical pain score. Average inpatient length of stay was 4 days after the procedure. Mean blood loss was 227 mL and mean length of the procedure was 2.2 hours. Conclusions Minimally invasive transpedicular vertebrectomy is an effective palliative treatment option for thoracic metastatic disease in patients not eligible for more extensive anterior transthoracic surgery and stabilization.

In vitro analysis of anterior and posterior fixation in an experimental unstable burst fracture model.

Abstract: Study DesignA biomechanical comparison of fixation constructs in an experimental fracture model.ObjectiveTo determine the relative postoperative stability of anterior graft and plating with that of posterior or combined fixation constructs in an unstable thoracolumbar burst fracture model.Summary of

Long-term biomechanical stability and clinical improvement after extended multilevel corpectomy and circumferential reconstruction of the cervical spine using titanium mesh cages.

Abstract: Study DesignRetrospective review of clinical case series.ObjectiveWe present our experience with extended (≥3 levels) anterior cervical corpectomy (EACC) and reconstruction.Summary of Background DataMultilevel cervical corpectomy has traditionally been associated with increased graft-related complic

Intraoperative localization of thoracic spine level with preoperative percutaneous placement of intravertebral polymethylmethacrylate.

Abstract: Objective To evaluate the safety and utility of preoperative vertebroplasty for intraoperative localization of thoracic spinal levels. Summary of background data Intraoperative fluoroscopy or plain radiographs are traditionally used to localize thoracic spine levels during thoracic spine operations. Unfortunately, such localization can occasionally be difficult in the midthoracic levels due to lack of landmarks, scapular shadows, and the body habitus of the morbidly obese. There are multiple techniques described in the literature that allow for preoperative localization of thoracic spinal levels during approaches to the posterior thoracic spine. For efficient and accurate intraoperative localization of thoracic spinal levels during anterior thoracic spine procedures, we describe a method that uses preoperative percutaneous placement of polymethylmethacrylate (PMMA) into the vertebral body using standard vertebroplasty technique. Methods Four patients with morbid obesity and symptomatic thoracic disc herniations underwent preoperative vertebroplasty procedures using standard percutaneous techniques. The PMMA cement was used to expeditiously identify thoracic spinal levels of interest using intraoperative fluoroscopy. Results All 4 patients underwent successful vertebroplasty procedures without complications. The PMMA cement was easily identified intraoperatively and led to the correct identification of the thoracic spinal levels of interest. Conclusions Preoperative placement of PMMA into thoracic vertebral bodies using standard vertebroplasty technique provides a safe, efficient, and reliable method of localizing thoracic spine levels intraoperatively. Such procedures can be performed in the outpatient setting and can be associated with extremely low morbidity when done by experienced practitioners. This procedure should be reserved for patients in whom a surgeon anticipates difficulty using standard radiographs or fluoroscopy to localize thoracic spinal levels intraoperatively.

Clinical results of ossification of the posterior longitudinal ligament (OPLL) of the thoracic spine treated by anterior decompression.

Abstract: Study DesignA retrospective study.ObjectiveTo evaluate surgical outcomes and prognostic factors of thoracic ossification of the posterior longitudinal ligament (OPLL) treated by anterior decompression.Summary of Background DataThe results of surgery for thoracic myelopathy caused by OPLL have been r

Validity of serum creatine kinase as a measure of muscle injury produced by lumbar surgery.

Abstract: BACKGROUND AND PURPOSE Serum creatine kinase (CK) concentrations have historically been used to investigate muscle disease and serious muscle damage, and there is a growing interest in the potential for a biochemical approach to quantifying skeletal muscle injury occurring in orthopedic surgeries and spinal injuries. The wide availability of CK measurement could foster spinal muscle injury research. However, measurement validity has never been systematically demonstrated in clinical settings. In this study, the validity of serum CK concentration elevation as an index of muscle injury was investigated using lumbar decompression surgery (LDS) as a model. SUBJECTS AND METHODS Blood samples were obtained from 18 research volunteers drawn from the clinical population undergoing LDS. A baseline sample was taken in the preoperative waiting area. Each subject's highest CK concentration between 12 and 48 hours after surgery was used as the biochemical injury response. The surface area of muscle isolated (incision lengthxdepth) and strained by retraction was obtained for concurrent validity testing against biochemical measurement. RESULTS The correlation between highest total CK concentration and muscle surface area was moderate (r=0.60) and significant (P<0.01). Correlations between surface area and CK at specific time points, revealed minimal loss of association at 12 hours (r=0.57) and 24 hours (r=0.58), but weaker correlations at 6 hours (r=0.45) and 48 hours (r=0.28) after injury. Analyses for proportions of each isoenzyme making up the total CK revealed that baseline and peak CK consisted almost exclusively of skeletal muscle CK (CK-MM), with minimal representation by heart muscle (CK-MB), and brain (CK-BB). CONCLUSIONS The findings provide support for the validity of serum CK measurement as an index of skeletal muscle injury caused by LDS, and demonstrate that LDS provides a useful model for measurement testing and development studies.

Transvertebral Transsacral strut grafting for high-grade isthmic spondylolisthesis L5-S1 with fibular allograft.

Abstract: Study DesignA clinical retrospective study was conducted.ObjectiveTo evaluate the clinical and radiographic outcomes of 25 consecutive patients with symptomatic high-grade isthmic spondylolisthesis at L5-S1 treated by decompression and transvertebral, transsacral strut grafting with fibular allograf