PEEK Cages versus Titanium-Coated PEEK Cages in Single-Level Anterior Cervical Fusion: A Randomized Controlled Study.

BACKGROUND: The implantation of a spacer is a common practice after anterior diskectomy in cervical spine. Polyether ether ketone (PEEK) cages have replaced titanium implants due to their better radiologic visibility and appearance in postoperative magnetic resonance imaging (MRI) scans. However, PEEK showed apparently higher nonunion rates than titanium cages. The aim of the study was to evaluate the fusion behavior of plain PEEK cages in comparison to titanium-coated PEEK (TiPEEK) cages. METHOD: We randomized 104 patients with single-level cervical radiculopathy or mild myelopathy. They were divided into two groups of 52 patients each, receiving either a PEEK cage or the titanium-coated variant of the same cage type. The 1- and 2-year follow-ups were completed by 43 patients in the PEEK group and by 50 patients in the TiPEEK group. Fusion was determined by plain X-ray and lateral functional X-ray. RESULTS: Two years after surgery, a complete fusion was observed in 37 patients of the PEEK group (86%). Six cases were considered as nonunions. In the TiPEEK group, we found 41 fusions (82%) and 9 nonunions at this time. The difference was not considered significant (p = 0.59). The clinical evaluation of the two groups showed no difference in the neurologic examination as well in the pain scores over the time period. CONCLUSIONS: Despite some assumptions about an advantage of TiPEEK over PEEK cages for fusion in cervical spine surgery, this prospective randomized controlled study did not find an accelerated or improved fusion using TiPEEK for anterior cervical diskectomy.

Effects of the COVID-19 Pandemic on the Management of Spinal Disorders - Results of a National Survey. / Auswirkungen der COVID-19-Pandemie auf die Behandlung von Wirbelsäulenerkrankungen ­ Ergebnisse einer nationalen Umfrage.

INTRODUCTION: Far-reaching political steps to contain the COVID-19 pandemic have been undertaken in recent weeks. These also impact on surgical specialties not directly involved in the management of patients infected with the coronavirus. The Spine Section, the interdisciplinary professional political arm of the German Spine Society (DWG), the Professional Association for Orthopedic and Trauma Surgery (BVOU), and the Federal Association of German Neurosurgeons (BDNC) conducted a survey on the collateral effects of the pandemic on spine surgery in Germany. METHOD: This cross-sectional study included outpatient, day-patient and inpatient facilities caring for patients with spinal disorders during the COVID-19 pandemic. The survey was designed to analyse the impact of the COVID-19 pandemic on the management of inpatients and outpatients with spinal disorders and to assess the economic ramifications in the various settings. RESULTS: All members of the Spine Section (n = 134) were invited to participate in the questionnaire consented by BVOU and BDNC. The questions were answered anonymously, and the personal data entered did not permit any de-anonymisation. All in all, 68% (n = 91) of the respondents completed the survey in full. Based on the type of employment (practice 30%, practice/staff: 45% and staff: 25%) and range of activities (conservative: 5%, conservative/operative: 75%, operative: 20%) the survey by the Spine Section can be regarded as representative. 95% of the practices/outpatient clinics reported a decline in their number of patients. In addition, the number of operations performed fell by 36% (SD 17%). The percentage of elective procedures declined from approximately 78% to 6%. As a result, more than half of the physicians anticipated moderate (20 - 40%) economic challenges and 25% major (> 50%) financial problems. CONCLUSION: In order to cushion collateral damage in the wake of future pandemic management, any implications in the interdisciplinary management of patients with spinal disorders should be based on these results.

Optimized Screw Trajectory for Lumbar Cortical Bone Trajectory Pedicle Screws Based on Clinical Outcome: Evidence Favoring the Buttress Effect Theory.

BACKGROUND: Cortical bone trajectory (CBT) is a relatively new technique for pedicle screw insertion in the field of spine surgery. Previous studies have demonstrated the significantly better pullout and toggle characteristics the new method offers, and it appears to have certain advantages over the widely used traditional trajectory. The mechanism of the pullout and toggle characteristics still remains unknown. PURPOSE: To report the medium- to long-term follow-up findings of patients who underwent posterior lumbar interbody fusion or posterior lumbar fusion (PLIF/PLF) at our institution and to discuss the ideal screw trajectory when using this technique. STUDY DESIGN: Retrospective radiologic study. METHODS: Fifty-five patients who underwent PLIF/PLF for lumbar spondylosis using the new technique between January 2011 and January 2016 were included. Clinical outcome was assessed using the Japanese Orthopaedic Association scores for low back pain and visual analog scale scores. Screw loosening was evaluated via the presence of a translucent zone surrounding the pedicle screw using plain X-radiography (Xp). The screw trajectory was evaluated by measuring the rostral range (RR) and the lateral range score (LRS). The RR is the angle between the line drawn along the distal end plate of the vertebra and the line drawn along the screw on the lateral view. The LRS is the score given depending on the position of the tip of the screw seen on the Xp taken in the anteroposterior (AP) view. The pedicle ring is equally divided into the medial third (zone A), central third (zone B), and the lateral third (zone C) by four vertical lines. A score of 0 to 3 points is given depending on the position of the tip of the screw: 0, outside the pedicle ring; 1, zone A; 2, zone B; and 3, zone C. RESULTS: Bone fusion was recorded in 49 patients (49/55 patients). The total number of screws with a visible translucent zone on Xp was 26 (26/242 screws). When the screws are inserted at a more acute angle in the lateral view (low RR) or when the screws are directed more medially (low LRS), the risk of developing a translucent zone around the pedicle screw increased. CONCLUSION: With CBT, the pedicle screws are inserted from the pars interarticularis that is rich in cortical bone, strong enough to withstand the substantial forces usually encountered in the region. Our clinical data suggest that the optimal screw trajectory is one where the screw is inserted at an angle > 22.55 degrees (high RR) on the lateral view Xp and where the tip of the screw is directed toward the lateral third of the pedicle on the AP Xp. We believe the naturally occurring buttress effect that exists in the vertebra may give CBT a mechanical and anatomical advantage over the traditional screw trajectory.

Burden of disease of reoperations in instrumental spinal surgeries in Germany.

PURPOSE: To estimate the incidence of instrumental spinal surgeries (ISS) and consecutive reoperations and to calculate the related resource utilization and costs. METHODS: ISS and subsequent reoperations were identified retrospectively using surgery codes in claims data. The study period included January 01, 2009 to December 31, 2011. The reoperation rate was calculated for 1 year after the primary ISS. Resource utilization and costs were analyzed by group comparison. RESULTS: A total of 3316 incident ISS patients were identified in 2010 with an annual reoperation rate of 9.98% (95% CI 8.98-11.02%). Mean costs per patient were €11,331 per ISS and €11,370 per reoperation, with €8432 directly attributed to the reoperation and €2938 to additional resources. CONCLUSIONS: Costs of ISS and subsequent reoperations have a significant impact on health insurances budgets. The annual cost of reoperations exceeds the direct cost of the primary surgery driven by the need for further inpatient and outpatient care.

Lateral mass lesions of the C1 vertebra: a modified "far lateral" approach.

PURPOSE: The surgical removal of lateral mass lesions is demanding due to their close anatomical relationship with the vertebral artery, upper spinal cord as well as overlying muscular structures. Usually a dorsal approach will be performed to reach the lateral mass. The disadvantage of this approach is the extensive mobilization of the neck muscles required to allow exposure of the lateral mass, which can be accompanied by severe muscular atrophy due to the damage of the local innervation. Additionally, management of the exposure of the vertebral artery is hindered by the dorsal approach. METHODS: A modified "far lateral" approach with complete resection of the lateral mass of C1 followed by a substitute with a Harms cage is presented. RESULTS: A 54-year-old woman was suffering from severe neck pain accompanied by a progressive sliding of her head and the visual axis to the right hand side. MRI as well as CT scans showed an osteolytic destruction of the right lateral mass of C1. After occipito-cervical fusion the osteolytic lateral mass was removed using a far lateral approach to the upper cervical spine. The patient recovered immediately after surgery, the neck pain improved and the lateral bending of the head was balanced. CONCLUSIONS: This far lateral approach offers the advantage of direct visualization of the lateral aspect of the upper cervical spine with the opportunity for local stabilization at the center of rotation.

Intra-vital ultrasonographic monitoring of intra-cerebral tumor growth in a rat glioma model: technical note.

The assessment of therapeutic effects in rodent glioma models by comparison of post mortem tumor sizes has to deal with differing individual growth kinetics and the possibility of spontaneous tumor regression. This technical note describes the intravital ultrasonographical monitoring of cerebral tumor growth in individual animals. In the experiments C6 lacZ glioma cells were injected intracerebrally into female Wistar rats. Extended craniectomy allowed for transcutaneous sonographic examination of the tumor growth. Four animals were followed ultrasonographically, the volumes of the tumors were calculated and plotted graphically, and on day 21 histological evaluation was performed. Our results show that ultrasonography is an easy and reliable imaging modality for frequent assessment of tumor growth kinetics in the intra-cerebral rat glioma model. It allows for the intravital monitoring of treatment with new therapeutic strategies and increases the reliability of the model by visualization of the tumor size before initiation of treatment.

PMMA vertebroplasty in patients with malignant vertebral destruction of the thoracic and lumbar spine.

OBJECT: Patients with osteolytic metastases frequently suffer from serious local and radicular pain. Pathophysiologically, local pain arises from skeletal instability, whereas radicular pain originates from compression of nerve roots by local tumor growth. Causal treatment of osteolytic metastases in disseminated malignant disease is very difficult. Resection of vertebrae, in combination with ventro-dorsal stabilization, is a complex treatment for patients with a limited life expectancy. Percutaneous polymethylmethacrylate (PMMA) vertebroplasty is a new and easy method of relieving patients' pain. In addition, it is both cost effective and safe. Pain is reduced immediately after treatment. Due to the regained vertebral stability, early mobilization of the patients is possible. METHODS: A total of 22 patients with osteolytic malignancies of the thoracic and lumbar spine were treated with PMMA vertebroplasty. Prior to and after surgery, then six weeks and six months after discharge from hospital, patients answered the Oswestry Low Back Pain Disability (OLBPD) Questionnaire for assessment of treatment-related change in disability. Percutaneous vertebroplasty was performed in a total of 19 patients. In three patients with tumor related compression of nerve roots an open neurolysis was performed followed by vertebroplasty. RESULTS: A total of 86% of patients reported a significant pain reduction. Vertebroplasty was highly beneficial for patients with pain related to local instability of the spine, but less so in patients with additional nerve root compression. Extravasation of PMMA beyond the vertebral margins was observed in 23% of the cases. No treatment-related clinical or neurological complications were seen. CONCLUSIONS: PMMA vertebroplasty is a useful and safe method of pain relief for patients with malignant osteolytic diseases of the thoracic and lumbar spine.

The tissue level of dexamethasone in human brain tumors is about 1000 times lower than the cytotoxic concentration in cell culture.

In glioblastoma patients dexamethasone is routinely administered as an antiedematous drug. In contrast to its empirically proven effect, the biochemical way of action remains poorly understood. In order to assess whether a direct cytotoxic effect is present in vivo we compared dexamethasone levels in brain tumor specimens with its cytotoxic concentrations in cell culture. Biopsy specimens were taken during microsurgical tumor removal, homogenized and dexamethasone levels were measured by high pressure liquid chromatography. In cell culture we tested different concentrations of dexamethasone on A172, U87, U373 cells and on eleven primary glioblastoma cell lines. Furthermore a pilocytic astrocytoma I, an astrocytoma II and an oligodendroglioma III and a meningioma were examined. Cell viability was assessed using the Alamar Blue assay and the concentrations resulting in loss of 50% of the cell population were calculated (LD50). The average brain tumor tissue concentration of dexamethasone was 225 nanogram g(-1). The mean LD50 in cell culture ranged at 222 microgram ml(-1). We conclude that a direct cytotoxic effect of dexamethasone on brain tumor cells is not present in vivo because the tissue levels of the drug are about 1000 times lower than the LD50 in cell culture.