Biomechanical comparison of a two-level anterior discectomy and a one-level corpectomy, combined with fusion and anterior plate reconstruction in the cervical spine.

BACKGROUND: Common fusion techniques for cervical degenerative diseases include two-level anterior discectomy and fusion and one-level corpectomy and fusion. The aim of the study was to compare via in-vitro biomechanical testing the effects of a two-level anterior discectomy and fusion and a one-level corpectomy and fusion, with anterior plate reconstruction. METHODS: Seven fresh frozen human cadaveric spines (C3-T1) were dissected from posterior musculature, preserving the integrity of ligaments and intervertebral discs. Initial biomechanical testing consisted of no-axial preload and 2Nm in flexion-extension, lateral bending and axial rotation. Thereafter, discectomies were performed at C4-5 and C5-6 levels, then two interbody cages and an anterior C4-C5-C6 plate was implanted. The flexibility tests were repeated and followed by C5 corpectomy and C4-C6 plate reconstruction. Biomechanical testing was performed again and statistical comparisons among the means of range of motion and axial rotation energy loss were investigated. FINDINGS: The two-level cage-plate construct had significantly lower range of motion than the one-level corpectomy-plate construct (P≤0.03). Axial rotation energy loss was significantly (P≤0.03) greater for the corpectomy-plate construct than for the two-level cage-plate construct and the intact condition. INTERPRETATION: A two-level cage-plate construct provides greater stability in flexion, extension and lateral bending motions when compared to a one-level corpectomy-plate construct. A two-level cage-plate is more likely to maintain axial balance by reducing the energy lost in axial rotation.

Vertebrectomy and expandable cage placement via a one-stage, one-position anterolateral retroperitoneal approach in L5 tumors.

Spinal reconstruction of the L5 vertebrae after tumor resection remains a challenge. Complex resection followed by circumferential fixation in the same setting, or in staged fashion, is often employed. The added operative time associated with this method potentially increases morbidity and mortality in an inherently high-risk procedure and anatomy in the lumbosacral area makes reconstruction more challenging. The authors describe a technique involving L5 vertebrectomy, placement of an expandable cage, and anterolateral L4-S1 screw fixation via a one-stage, one-position, anterolateral retroperitoneal approach. Two illustrative cases are presented along with the authors overall experience in L5 tumor operations. We believe that this is a feasible reconstructive option after tumor resection in lower lumbar metastatic spine disease. The approach may be also utilized in combined anteroposterior (two-stage) procedures in primary malignant tumors or oligometastatic disease.

Expandable versus nonexpandable cages for thoracolumbar burst fracture.

BACKGROUND: Burst fractures account for more than half of all thoracolumbar fractures and are frequently associated with spine instability and neurological deficit. The anterior approach is favored when decompression of the spinal canal is necessary. We compare two commonly available struts used for anterior approach after corpectomy: expandable versus nonexpandable titanium cages. METHODS: We retrospectively evaluated 32 patients with acute thoracolumbar burst fractures treated by a single surgeon with a mean follow-up of 13 months. Half of the patients had nonexpandable cages placed (group 1) and the other half had expandable cages placed (group 2). Anterolateral plate/screw supplementation was used in all patients. Radiographs were reviewed to assess kyphosis correction and bony fusion. RESULTS: In group 1, the mean kyphotic angle before surgery was 20.5 degrees. Immediately after surgery, this angle improved to 6 degrees and was 8.5 degrees at final follow-up. In group 2, the mean kyphotic angle before surgery was 21.5 degrees. This angle improved to 4 degrees immediately after surgery and was 6.5 degrees at final follow-up. At the end of follow-up, 2 of 16 patients in group 1 demonstrated pseudoarthrosis, whereas no patients in group 2 showed any evidence of nonunion. No patient in either group experienced hardware failure or new neurological deficit. CONCLUSIONS: Anterior decompression and instrumented stabilization with either an expandable or nonexpandable cage is a safe and reliable surgical treatment option for unstable thoracolumbar burst fractures. Expandable cage enables greater immediate correction of kyphosis with good fusion rate.

Comparison of polymethylmethacrylate versus expandable cage in anterior vertebral column reconstruction after posterior extracavitary corpectomy in lumbar and thoraco-lumbar metastatic spine tumors.

Single-stage posterior corpectomy for the management of spinal tumors has been well described. Anterior column reconstruction has been accomplished using polymethylmethacrylate (PMMA) or expandable cages (EC). The aim of this retrospective study was to compare PMMA versus ECs in anterior vertebral column reconstruction after posterior corpectomy for tumors in the lumbar and thoracolumbar spine. Between 2006 and 2009 we identified 32 patients that underwent a single-stage posterior extracavitary tumor resection and anterior reconstruction, 16 with PMMA and 16 with EC. There were no baseline differences in regards to age (mean: 58.2 years) or performance status. Differences between groups in terms of survival, estimated blood loss (EBL), kyphosis reduction (decrease in Cobb's angle), pain, functional outcomes, and performance status were evaluated. Mean overall survival and EBL were 17 months and 1165 ml, respectively. No differences were noted between the study groups in regards to survival (p = 0.5) or EBL (p = 0.8). There was a trend for better Kyphosis reduction in favor of the EC group (10.04 vs. 5.45, p = 0.16). No difference in performance status or VAS improvements was observed (p > 0.05). Seven patients had complications that led to reoperation (5 infections). PMMA or ECs are viable options for reconstruction of the anterior vertebral column following tumor resection and corpectomy. Both approaches allow for correction of the kyphotic deformity, and stabilization of the anterior vertebral column with similar functional and performance status outcomes in the lumbar and thoracolumbar area.

Balloon kyphoplasty in the treatment of metastatic tumors of the upper thoracic spine.

OBJECT: Balloon kyphoplasty has recently been shown to be effective in providing rapid pain relief and enhancing health-related quality of life in patients with metastatic spinal tumors. When performed to treat lesions of the upper thoracic spine, kyphoplasty poses certain technical challenges because of the smaller size of the pedicle and vertebral bodies. Fluoroscopic visualization is also difficult due to interference of the shoulder. The authors' objective in the present study was to evaluate their approach and the results of balloon kyphoplasty in the upper thoracic spine in patients with metastatic spinal disease. METHODS: Fourteen patients underwent kyphoplasty via an extrapedicular approach to treat metastatic tumors in the upper (T1-5) thoracic spine. Electrodiagnostic monitoring (somatosensory and motor evoked potentials) was used in 5 cases. Three levels were treated in 7 cases, 2 levels in 2 cases, and 1 level in 5 cases. In 3 cases access was bilateral, whereas in 11 cases access was unilateral. The procedure took an average of 25 minutes per treated level, and the mean amount of cement applied was 3 ml per level. Four patients were discharged from the hospital on the day of the procedure, and 10 patients went home after 24 hours. RESULTS: All patients exhibited marked improvement in mean visual analog scale scores (preoperative score 79 vs postoperative score 30, respectively) and Oswestry Disability Index scores (83 vs 33, respectively). The mean kyphotic angle was 25.03° preoperatively, whereas the mean postoperative angle was 22.65° (p > 0.3). At latest follow-up, the mean kyphotic angle did not differ significantly from the postoperative kyphotic angle (26.3°, p > 0.1). No neurological deficits or lung-related complications (pneumothorax or hemothorax) were encountered in any of the patients. Polymethylmethacrylate cement extravasations were observed in 3 (10%) of 30 treated vertebral bodies without any sequelae. By a mean follow-up of 16 months, no patients had experienced an adjacent-level fracture. CONCLUSIONS: Balloon kyphoplasty of the upper thoracic spine via an extrapedicular approach is an efficient and safe minimally invasive procedure that may provide immediate and long-term pain relief and improvement in functional ability. It is technically challenging and has the potential for serious complications. With a fundamental knowledge of anatomy, as well as an ability to interpret fluoroscopy images, one can feasibly and safely perform balloon kyphoplasty in the upper thoracic spine.

Biomechanical comparison of posterior cervicothoracic instrumentation techniques after one-level laminectomy and facetectomy.

OBJECT: Posterior instrumentation is the preferred method of fixation in the unstable cervicothoracic junction (CTJ). Several posterior rod constructs of different diameters and configurations are available for instrumentation across the CTJ. The objective of this study was to compare the biomechanical stability of various posterior instrumentation techniques that cross the CTJ after a 2-column injury through the complete removal of the posterior elements at C-7. METHODS: Eight fresh-frozen human cadaveric spines (C3-T4) were used. After the intact spine analysis, each specimen was destabilized (C-7 laminectomy and bilateral facetectomies) and reconstructed as follows: Group 1, C5-T2 posterior instrumentation with a 3.5-mm rod; Group 2, C5-T2 posterior instrumentation with a transitional rod (3.5-5.5 mm); and Group 3, C5-T2 posterior instrumentation with a side-to-side rod connector (3.5-5.5 mm). All reconstructed groups were tested with posterior instrumentation using the Cervifix system (Synthes, Inc.). The authors hypothesized that Group 2 would be the most stable. RESULTS: Following laminectomy, facetectomy, and the application of instrumentation, there was a decrease in the range of motion in all treatment groups compared with the intact spine. This trend was observed in all 3 planes of motion, but was only significant on right/left lateral bending and flexion (for the transitional rod only). Although the instrumented spines were stiffer than the intact spine in right/left axial rotation, flexion, and extension, these differences did not reach statistical significance. Based on observations during testing, it was evident that in the implanted spines, most of the motion that did occur was localized at the segments adjacent to the instrumented levels. CONCLUSIONS: Based on the results of this investigation, the biomechanical stability of the transitional rod, side-to-side connector ("wedding band"), and 3.5-mm rods appears to be similar.

Diffusion tensor imaging tractography in patients with intramedullary tumors: comparison with intraoperative findings and value for prediction of tumor resectability.

OBJECT: The aim of this retrospective study was to evaluate the predictive value of diffusion tensor (DT) imaging with respect to resectability of intramedullary spinal cord tumors and to determine the concordance of this method with intraoperative surgical findings. METHODS: Diffusion tensor imaging was performed in 14 patients with intramedullary lesions of the spinal cord at different levels using a 3-T magnet. Routine MR imaging scans were also obtained, including unenhanced and enhanced T1-weighted images and T2-weighted images. Patients were classified according to the fiber course with respect to the lesion and their lesions were rated as resectable or nonresectable. These results were compared with the surgical findings (existence vs absence of cleavage plane). The interrater reliability was calculated using the kappa coefficient of Cohen. RESULTS: Of the 14 patients (7 male, 7 female; mean age 49.2 +/- 15.5 years), 13 had tumors (8 ependymomas, 2 lymphomas, and 3 astrocytoma). One lesion was proven to be a multiple sclerosis plaque during further diagnostic workup. The lesions could be classified into 3 types according to the fiber course. In Type 1 (5 cases) fibers did not pass through the solid lesion. In Type 2 (3 cases) some fibers crossed the lesion, but most of the lesion volume did not contain fibers. In Type 3 (6 cases) the fibers were completely encased by tumor. Based on these results, 6 tumors were considered resectable, 7 were not. During surgery, 7 tumors showed a good cleavage plane, 6 did not. The interrater reliability (Cohen kappa) was calculated as 0.83 (p < 0.003), which is considered to represent substantial agreement. The mean duration of follow-up was 12.0 +/- 2.9. The median McCormick grade at the end of follow-up was II. CONCLUSIONS: These preliminary data suggest that DT imaging in patients with spinal cord tumors is capable of predicting the resectability of the lesion. A further prospective study is needed to confirm these results and any effect on patient outcome.

Management of metastatic spine disease.

PURPOSE OF REVIEW: In metastatic spine disease, technologic advancements, neurologic recovery, pain relief, cost-effectiveness, and health-related quality of life have all strengthened surgery's and radiation's role in its management.We evaluated different surgical approaches to the spine and the multimodality treatment in the management of these cases. RECENT FINDINGS: Recently, the survival rate of malignant spinal metastases has rapidly improved because of early detection and multimodality treatment. The goals of surgical intervention are to prolong survival and improve the quality of life of patients.The recent evolution of imaging, radiosurgery, advanced surgical decompressive techniques and instrumentation, as well as percutaneous vertebral body cement augmentation, needs to be considered in the decision-making to optimize patient outcomes. SUMMARY: Management of patients with spine tumors requires a multidisciplinary team that includes a medical and radiation oncologist and a spine surgeon. Newer surgical techniques that address both tumor resection and spinal stabilization offer the best outcome in selected patients. The prognostic parameters suggested for metastatic spine tumors include the general condition of the patient, neurological status number of spinal and extraspinal metastases, primary site of the cancer, visceral metastasis, and severity of spinal cord compression.

Role of motor-evoked potential monitoring in conjunction with temporary clipping of spinal nerve roots in posterior thoracic spine tumor surgery.

BACKGROUND CONTEXT: The vascular supply of the thoracic spinal cord depends on the thoracolumbar segmental arteries. Because of the small size and ventral course of these arteries in relation to the dorsal root ganglion and ventral root, they cannot be reliably identified during surgery by anatomic or morphologic criteria. Sacrificing them will most likely result in paraplegia. PURPOSE: The goal of this study was to evaluate a novel method of intraoperative testing of a nerve root's contribution to the blood supply of the thoracic spinal cord. STUDY DESIGN/SETTING: This is a clinical retrospective study of 49 patients diagnosed with thoracic spine tumors. Temporary nerve root clipping combined with motor-evoked potential (MEP) and somatosensory-evoked potential (SSEP) monitoring was performed; additionally, postoperative clinical evaluation was done and reported in all cases. METHODS: All cases were monitored by SSEP and MEPs. The nerve root to be sacrificed was temporarily clipped using standard aneurysm clips, and SSEP/MEP were assessed before and after clipping. Four nerve roots were sacrificed in four cases, three nerve roots in eight cases, and two nerve roots in 22 cases. Nerve roots were sacrificed bilaterally in 12 cases. RESULTS: Most patients (47/49) had no changes in MEP/SSEP and had no neurological deficit postoperatively. One case of a spinal sarcoma demonstrated changes in MEP after temporary clipping of the left T11 nerve root. The nerve was not sacrificed, and the patient was neurologically intact after surgery. In another case of a sarcoma, MEPs changed in the lower limbs after ligation of left T9 nerve root. It was felt that it was a global event because of anesthesia. Postoperatively, the patient had complete paraplegia but recovered almost completely after 6 months. CONCLUSIONS: Temporary nerve root clipping combined with MEP and SSEP monitoring may enhance the impact of neuromonitoring in the intraoperative management of patients with thoracic spine tumors and favorably influence neurological outcome.

Posterior transpedicular corpectomy for malignant cervical spine tumors.

The goal of this study was to assess surgical clinical and radiographic outcomes of using a posterior transpedicular approach (posterolateral) for ventral malignant tumors of the cervical spine. Access to ventral lesions of the cervical spine can be challenging in patients with malignant tumors. Anterior approaches are the gold standard for ventral pathology in the cervical spine, however, there are cases, where a posterior approach is indicated due to multilevel disease, previous radiation, swallowing difficulty with difficulty in retraction of trachea and esophagus, and in cases where circumferential fusion cannot be done due to patients' poor medical condition. A single approach could provide spinal stabilization and removal of tumor. Eight cases of ventral cervical spine malignant tumors (7 metastatic and 1 chordoma) underwent corpectomy through a posterior transpedicular (posterolateral) approach. Tumors involved C2 (5), C3 (1), C5 (1), and C7 (1). Six cases had anterior reconstruction and three column fusion, and two cases had posterior fusion alone. Gross total resection was achieved in all cases. No hardware failure or worsening of neurological condition was seen (4 patient were neurologically intact and remained intact after surgery and 4 patients improved in their Frankel grade). Pain improved in all patients, mean visual analog scale preoperative was 86 and improved to 22 after surgery. In two patients the vertebral artery was ligated without sequelae. We conclude that cervical spine transpedicular (posterolateral) approach is useful in cases where an anterior approach or a circumferential approach is not an option. It avoids the morbidity of anterior transcervical, transternal, and transoral procedures while providing decompression of neural elements and allowing three column stabilization when needed.

Traumatic central cord syndrome: results of surgical management.

OBJECT: The authors compare clinical outcomes demonstrated in patients with traumatic central cord syndrome (CCS) who underwent early (< or = 24 hours after injury) or late (> 24 hours after injury) surgery. METHODS: The clinical characteristics, radiographic findings, surgery-related results, length of hospital stay (LOS), and clinical outcomes obtained in 50 patients with surgically treated traumatic CCS were reviewed retrospectively. Shorter intensive care unit (ICU) stay and LOS were observed in all patients who underwent early surgery compared with those who underwent late surgery. In patients with CCS secondary to acute disc herniation or fracture/dislocation who underwent early surgery significantly greater overall motor improvement was observed than in those who underwent late surgery (p = 0.04). Overall motor outcome in patients with CCS secondary to spinal stenosis or spondylosis who underwent early surgery was not significantly different from that in those who underwent late surgery (p = 0.51). Worse motor outcomes were found in patients who were older than 60 years of age and in whom initial bladder dysfunction was present (p = 0.03 and 0.02, respectively) compared with younger patients without bladder dysfunction. CONCLUSIONS: Early surgery is safe and more cost effective than late surgery for the treatment of traumatic CCS, based on ICU stay and LOS and improved overall motor recovery, in patients whose CCS was related to acute disc herniation or fracture. In the setting of spinal stenosis or spondylosis, early surgery was safe but did not improve motor outcome compared with late surgery.