Robot-assisted versus navigated transpedicular spine fusion: A comparative study.

BACKGROUND: The aim of this study was to compare the intraoperative and postoperative outcomes between a robot-assisted versus a navigated transpedicular fusion technique. METHODS: This retrospective analysis included patients who underwent transpedicular posterior fusion of the spine due to trauma, pyogenic spondylodiscitis and osteoporosis. Surgery was done either with a robot-assisted or a percutaneous navigated transpedicular fusion technique. The outcome analysis included the duration of surgery, the radiation exposure, the postoperative screw position and complications. RESULTS: A total of 60 patients were operated and 491 screws were analysed. No statistical difference was seen in the applied cumulative effective radiation dose per patient. The radiological assessment revealed a more accurate screw placement with robot assistance. A learning curve could be observed in robot-assisted fusion. CONCLUSION: Robot-assisted and navigated transpedicular fusion techniques are both effective and safe. Robot-assisted transpedicular spine fusion goes along with higher placement accuracy but its implementation needs an adequate learning curve.

Cervical spine trauma in diffuse idiopathic skeletal hyperostosis: injury characteristics and outcome with surgical treatment.

STUDY DESIGN: Retrospective study of a consecutive series of operatively managed patients with cervical fractures with diffuse idiopathic skeletal hyperostosis (DISH) presenting to 3 institutions over an 8 year period. OBJECTIVE: Assess demographics, fracture characteristics, outcome and complications in patients managed surgically. SUMMARY OF BACKGROUND DATA: Cervical spine injuries related to DISH represent a difficult subgroup of trauma patients to treat. This subset is fraught with potential complications related to the injury of the ankylosed spine, high rate of co-morbidities, and older demographics. The data in the literature on treatment, outcomes and complications is largely comprised of case reports and small case series. METHODS: All patients with cervical fractures in the setting of DISH between January 2001 and December 2008 were reviewed retrospectively. Charts and radiographs were reviewed assessing demographics, injury characteristics and short-term outcomes. Statistical analysis was performed analyzing the impact of distinct parameters on the incidence of medical and surgical complications. RESULTS: Thirty-three patients with age 73.8 ± 11 years were identified. DISH-affected segments numbered 5.5 ± 2.1. Injury severity as assessed by the Subaxial-Injury-Classification scoring-system (SLIC) averaged 7.2 ± 1.4 points. 7 patients (20.6%) were ASIA-A on admission, 4 (11.8%) ASIA-B, 4 (11.8%) ASIA-C, 10 (29.4%) ASIA-D, and 7 (20.6%) ASIA-E. All but 2 patients (6%) had medical co-morbidities. Inpatient stay was 26.6 ± 23.4 days. 16 patients (47%) had anterior, 12 patients (35.3%) had posterior, and 5 patients (14.7%) had combined anterior-posterior instrumented fusion. 25 patients (73.5%) had medical/surgical complications. 20 patients (58.8%) suffered serious pulmonary complications not related to the neurologic injury (p < 0.05). Nine patients (26.5%) had died. Seven patients (20.6%) showed improved ASIA-scores, 18 patients (52.9%) had no improvement and 2 patients (5.9%) deteriorated. CONCLUSION: The current findings pinpoint the potential for medical and surgical complications in this high risk subgroup. Surgeons should be aware of the unique aspects associated with treatment of these injuries.

Image-based tissue engineering of a total intervertebral disc implant for restoration of function to the rat lumbar spine.

Nonbiological total disc replacement is currently being used for the treatment of intervertebral disc (IVD) disease and injury, but these implants are prone to mechanical wear, tear and possible dislodgement. Recently, tissue-engineered total disc replacement (TE-TDR) has been investigated as a possible alternative to more fully replicate the native IVD properties. However, the performance of TE-TDRs has not been studied in the native disc space. In this study, MRI and microcomputed tomography imaging of the rat spine were used to design a collagen (annulus fibrosus)/alginate (nucleus pulposus) TE-TDR to a high degree of geometric accuracy, with less than 10% difference between TE-TDR and the native disc dimensions. Image-based TE-TDR implants were then inserted into the L4/L5 disc space of athymic rats (n = 5) and maintained for 16 weeks. The disc space was fully or partially maintained in three of five animals and proteoglycan and collagen histology staining was similar in composition to the native disc. In addition, good integration was observed between TE-TDR and the vertebral bodies, as well as remnant native IVD tissue. Overall, this study provides evidence that TE-TDR strategies may yield a clinically viable treatment for diseased or injured IVD.

Meningioma surgery in the elderly: outcome and validation of 2 proposed grading score systems.

BACKGROUND: Although population age increases, published evidence on meningioma treatment in the elderly is scarce. OBJECTIVE: In order to improve selection for surgery, we investigated our patients' collective, using 2 proposed risk assessment systems, the Clinical-Radiological Grading System (CRGS) and the SKALE score (sex, Karnofsky, American Society of Anesthesiology [ASA] score, location, edema). METHODS: We retrospectively assessed morbidity and mortality in 164 patients aged ≥ 65, operated on for an intracranial meningioma. Medical and surgical records were reviewed and analyzed. CRGS and SKALE scores were calculated. The ability of both CRGS and SKALE and all single factors to predict death within 12 months was analyzed by the use of multivariate logistic regression modeling. RESULTS: Eleven patients died (6.7%). Logistic regression for CRGS/SKALE showed a significant relationship with 12 months mortality. Age, Simpson resection grade, and sex were not significant predictors when investigated alone. In multivariate logistic regression, including all proposed factors, only concomitant disease and edema (CRGS) as well as ASA score and preoperative Karnofsky Performance Scale (SKALE) showed a significant relationship to mortality. After stepwise reduction of the full multivariate regression model to its significant terms, only concomitant disease and ASA remained significant for CRGS (P < .001) and SKALE (P = .003), respectively. CONCLUSION: Meningioma resection in the elderly is possible with some mortality. We were unable to reproduce the utility of 2 proposed grading systems for mortality prediction when extending to younger patients. In single-factor analysis, only concomitant disease and ASA score remained significant. The decision whether to operate should be taken individually. Patients with severe concomitant disease or high ASA score should be advised not to undergo surgical therapy independently from other factors.

Modern management of rare brain metastases in adults.

Brain metastases (BM) represent the main cause of intracranial neoplasms in adults, while being relatively less common in children. Today, better treatment options of the primary malignancy lead to higher remission rates as well as prolonged stable clinical conditions. This may in part explain the increased incidence of BM. Morbidity and mortality rates in patients with malignancies deteriorate significantly in cases of metastatic involvement of the central nervous system. Nowadays, especially modern management using surgical, medical, and radiotherapeutic options for treatment of BM tends to improve survival rates and enhance quality of life. Nonetheless, almost all treatment options are considered as palliative. In this review, we outline current knowledge of the incidence, diagnostic facilities, and therapeutic management of rare BM, with consideration of the basic aspects of the primary malignancy.

The vertebral artery and the cervical pedicle: morphometric analysis of a critical neighborhood.

OBJECT The purpose of this retrospective study was to quantify the anatomical relationship between the vertebral artery (VA), the cervical pedicle, and its surrounding structures, including the incidence of irregularities. Additionally, data delineating a "safe zone," and these data's application during instrumentation with transpedicular cervical screw fixation were considered. The anatomical proximity of the VA to the cervical pedicle prevents spine surgeons from preferring cervical pedicle screws (CPSs) over lateral mass screws at levels C3-6. Accurate placement of CPSs is often difficult to determine, because this definition can vary between 1 and 4 mm of lateral "noncritical" and "critical" pedicle breaches. No previous study in a western population has investigated the VA's proximity to the cervical pedicle, its percentage of occupancy in the transverse foramen (TF), and the incidence of irregular VA pathways. METHODS One hundred twenty-seven consecutive patients who underwent CT angiography of the neck were enrolled in this study. The measurements included the following: medial pedicle border to VA; lateral pedicle border to VA; pedicle diameter (PD); sagittal diameter of the VA; coronal diameter of the VA; sagittal diameter of the TF; and coronal diameter of the TF. The cross-sections of the VA and the TF were measured to determine the occupation ratio of the VA. In addition, a safe zone was defined based on all lateral pedicle border to VA measurements in which the VA was within the TF. The level of entry of the VA into the TF as well as irregularities of the VA and the cervical pedicles were recorded. RESULTS Vertebral artery dominance on the left side was seen in 69.3% of cases. The mean PD increased from 4.9 to 6.5 mm (from C-3 to C-7, respectively). Statistically significantly bigger PDs were seen in males. The mean PD at C-2 was 5.6 mm. Entry of the VA at C-6 was seen in approximately 80% of cases. The TF occupation ratio of the VA was found to be the greatest in C-4 and C-7 (37.1 and 74.2%, respectively). The safe zone increased from C-2 to C-6 (1.1 to 1.7 mm, respectively), but was only 0.65 mm at C-7. In 23.6% of cases, an irregular pathway of the VA or irregular anatomy of a cervical pedicle was seen, with the highest incidence of irregularities found at C-2. CONCLUSIONS Computed tomography angiography is a valuable tool that can help determine the relationships between cervical pedicles and the VA as well as irregular VA pathways. Pedicle diameter, safe zone, and occupational ratio of the VA in the foramen determine the risk associated with instrumentation and should be assessed individually. Based on the authors' measurements, C-4 and C-7 can be considered critical levels for CPS placement. Because of this and the high incidence of irregular VA pathways and different entry points, it may be helpful to review neck CT angiography studies before considering posterior instrumentation procedures in the cervical spine.

Bioabsorbable instrumentation for single-level cervical degenerative disc disease: a radiological and clinical outcome study.

OBJECT: The authors present the radiological and clinical outcome data obtained in patients who underwent single-level anterior cervical discectomy and fusion (ACDF) for cervical spondylosis and/or disc herniation; bioabsorbable plates were used for instrumentation. The use of metallic plates in ACDF has gained acceptance as a stabilizing part of the procedure to increase fusion rates, but when complications occur with these devices, the overall effectiveness of the procedure is compromised. As a possible solution, bioabsorbable implants for ACDF have been developed. This study investigates the feasibility and radiological and clinical outcomes of the bioabsorbable plates for ACDF. METHODS: The radiological and clinical outcomes of 30 patients were investigated retrospectively. All patients presented with cervical radiculopathy or myelopathy and underwent single-level ACDF in which a bioabsorbable anterior cervical plate and an allograft bone spacer were placed at a level between C-3 and C-7. Radiological outcome was assessed based on the fusion rate, subsidence, and Cobb angle of the surgical level. Clinical outcome was determined by using a visual analog scale, the Neck Disability Index, and the Odom criteria. RESULTS: There were no intraoperative complications, and no hardware failure was observed. No signs or symptoms of adverse tissue reaction caused by the implant were seen. Two reoperations were necessary due to postoperative blood collections. The overall complication rate was 16.7%. After 6 months, radiographic fusion was seen in 92.3% of patients. Subsidence at 11.3 +/- 7.2 months was 3.1 +/- 5.8 mm (an 8.2% change over the immediately postoperative results), and the change in the sagittal curvature was -2.7 +/- 2.7 degrees . The visual analog scale score for neck and arm pain and Neck Disability Index improved significantly after surgery (p < 0.001). Overall at 19.5 months postoperatively, 83% of the patients had favorable outcomes based on the Odom criteria. CONCLUSIONS: Absorbable instrumentation provides better stability than the absence of a plate but graft subsidence and deformity rates may be higher than those associated with metal implants. There were no device-related complications, but adverse late effects cannot be excluded. The fusion rate and outcome are comparable to the results achieved with metallic plates. The authors were satisfied with the use of bioabsorbable plates as a reasonable alternative to metal, avoiding the need for lifelong metallic implants.

Tubular microsurgery for lumbar discectomies and laminectomies in obese patients: operative results and outcome.

STUDY DESIGN: This is a retrospective single-center case study involving 115 obese and nonobese patients who underwent minimally invasive lumbar surgery between 2004 and 2007. OBJECTIVE: The purpose of this study was to evaluate the effect of minimally invasive spinal surgery in obese and nonobese patients by operative results and patient outcomes. SUMMARY OF BACKGROUND DATA: Spinal surgery in obese patients is associated with increased complications, blood loss, and operative times. The potential benefits of minimally invasive lumbar surgery in obese patients are discussed. METHODS: All patients underwent 1-level lumbar microdiscectomy or laminectomy using tubular retractors. Data were collected on patient demographics, comorbidities, smoking habits, operative results, and clinical outcomes, and compared for obese and nonobese patients. Operative results included operative times, blood loss, length of stay, and perioperative complications. Clinical outcomes were assessed by using pre- and postoperative visual analog scale and Macnab outcome criteria at most recent follow-up. RESULTS: In this study, 31% of 115 patients were classified as obese. Obese patients tended to undergo surgery at a younger age. Obesity, comorbidities, and age did not have an impact on patient outcome at a mean follow-up of 15.9 months. No significant differences were seen between obese versus nonobese patients in terms of incision lengths, operative time, blood loss, and complication rates. In obese patients, all parameters and operative results compared favorably to reported historical results of patients undergoing open lumbar surgery. Overall, favorable outcome was seen in 92% and 84% of obese and nonobese lumbar microdiscectomy patients, respectively, and in 75% of laminectomy patients. Postoperative visual analog scale did not show any significant difference. CONCLUSION: This is the first study comparing operative results from tubular microsurgery between obese and nonobese patients. No major differences were detected in outcome, operative and perioperative data including complication rates. With tubular microsurgery, obese patients experienced the same or equally beneficial outcome, compared to nonobese patients, while incision lengths, blood loss, operative times, and length of stay were less when compared to open procedures. Other comorbidities and age had no significant impact on perioperative complications and clinical outcome.

Operative results and learning curve: microscope-assisted tubular microsurgery for 1- and 2-level discectomies and laminectomies.

OBJECT: The authors present their clinical results and the learning curve associated with the use of tubular retractors for 1- and 2-level lumbar microscope-assisted discectomies and laminectomies. METHODS: The study involves a retrospective and prospective analysis of 230 patients who underwent noninstrumented minimally invasive procedures for degenerative lumbar spinal disease between 2004 and 2007. Data on patient demographic characteristics and operative results, including length of stay, blood loss, operative times, and surgical complications were collected. Clinical outcomes were assessed based on pre- and postoperative Visual Analog Scale scores, Oswestry Disability Index values, and the Macnab outcome scale scores. RESULTS: The results showed characteristic differences in blood loss and operating times between 1- and 2-level procedures and between discectomies and laminectomies. A significant learning curve was seen by a decrease in operating time for 1-level discectomies and 2-level laminectomies. Major complications were not observed. CONCLUSIONS: The use of tubular retractors for microsurgical decompression of degenerative spinal disease is a safe and effective treatment modality. As with other techniques, minimally invasive procedures are associated with a significant learning curve. As surgeons become more comfortable with the procedure, its applications can be expanded to include, for example, spinal instrumentation and deformity correction.

The N-end rule ubiquitin-conjugating enzyme, HR6B, is up-regulated by nerve growth factor and required for neurite outgrowth.

Neurite outgrowth is accompanied by increased levels of high molecular weight ubiquitin conjugates and decreased levels of free ubiquitin. The search for enzymes responsible for increased utilization of ubiquitin revealed the ubiquitin-conjugating enzyme, HR6B (yeast UBC2/RAD6), increased on mRNA and protein level in rat pheochromocytoma (PC12) cells after treatment with nerve growth factor (NGF). HR6B participates in 'N-end rule degradation' that is implicated in the cleavage of proteins with destabilizing N-terminal residues (bulky hydrophobic or basic amino acids) and requires UBR1, the ubiquitin ligase binding N-end rule target proteins. Down-regulation of HR6B or UBR1 mRNA by small interfering RNA and treatment with Leu--Ala, a dipeptide-inhibitor of UBR1, inhibit neurite outgrowth of PC12 cells. Furthermore, axonal regeneration of adult sensory neurons, which express prominent nuclear and membrane-associated HR6 immunoreactivity, is reduced by Leu--Ala in vitro. Therefore, N-end rule ubiquitination is required for neuronal differentiation of PC12 cells and may be involved in axonal regeneration of peripheral neurons.

Tissue distribution of the "N-end rule" ubiquitin-conjugating enzyme, HR6, in the rat.

The conjugation of multiple ubiquitin molecules is required for recognition and degradation of a protein by the proteasome. The ubiquitination pathway responsible for the bulk of constitutive protein degradation targets proteins carrying basic or large hydrophobic amino acids at the N-terminus. In mammalian cells, this "N-end rule" pathway requires the ubiquitin-conjugating enzyme HR6. Until now, it has not been known which mammalian tissues and cell types predominantly utilize this pathway for degradation. Therefore, the distribution and intracellular localization of HR6 was determined by indirect immunofluorescence techniques and protein blotting of adult rat tissues. Intense immunoreactivity against HR6 was detected in various epithelia, muscle, testis, peripheral neurons, chromaffin cells and macrophages, whereas lower HR6 protein levels were found in the gut or in the kidney. Autonomic and sensory neurons, glandular cells and spermatocytes revealed prominent nuclear HR6 immunoreactivity. Plasma membrane labeling was observed in peripheral neurons, spermatocytes and skeletal muscle cells. Smooth muscle cells, macrophages, endothelial and epithelial cells exhibited primarily cytoplasmic staining. The clear differences in the regional and intracellular distribution of HR6 are suggestive for the involvement of N-end rule protein degradation in various physiological processes dependent on cell type and subcellular structure.