C2 prosthesis: anterior upper cervical fixation device to reconstruct the second cervical vertebra

Destruction of the second cervical vertebra leads to a highly unstable situation. Reconstruction is difficult because the axis plays a central role in rotatory movements and has a unique function in redistributing axial loads. The axis transfers the axial load of the two lateral masses of the atlas to three surfaces on the third cervical vertebra: the two articular facets and the vertebral body. As reconstruction is difficult and the instability in this region is life threatening, pathological processes are often treated less radically compared to other areas of the cervical spine. However, this more moderate approach may result in worse outcomes and prognoses. This paper presents the development of a new implant (C2 prosthesis) and two illustrative cases describing the implementation of this new implant. The C2 prosthesis provides anterior support and therefore allows a more radical surgical approach

Interior pathways of the North Atlantic meridional overturning circulation

To understand how our global climate will change in response to natural and anthropogenic forcing, it is essential to determine how quickly and by what pathways climate change signals are transported throughout the global ocean, a vast reservoir for heat and carbon dioxide. Labrador Sea Water (LSW), formed by open ocean convection in the subpolar North Atlantic, is a particularly sensitive indicator of climate change on interannual to decadal timescales. Hydrographic observations made anywhere along the western boundary of the North Atlantic reveal a core of LSW at intermediate depths advected southward within the Deep Western Boundary Current (DWBC). These observations have led to the widely held view that the DWBC is the dominant pathway for the export of LSW from its formation site in the northern North Atlantic towards the Equator. Here we show that most of the recently ventilated LSW entering the subtropics follows interior, not DWBC, pathways. The interior pathways are revealed by trajectories of subsurface RAFOS floats released during the period 2003-2005 that recorded once-daily temperature, pressure and acoustically determined position for two years, and by model-simulated 'e-floats' released in the subpolar DWBC. The evidence points to a few specific locations around the Grand Banks where LSW is most often injected into the interior. These results have implications for deep ocean ventilation and suggest that the interior subtropical gyre should not be ignored when considering the Atlantic meridional overturning circulation.Dissertatio

Multilevel en bloc spondylectomy and chest wall excision via a simultaneous anterior and posterior approach for Ewing sarcoma

Study Design. A case study of a patient with Ewing sarcoma of T8 and T9 with paravertebral and chest wall involvement, who underwent neoadjuvant chemotherapy and subsequent multilevel en bloc spondylectomy and chest wall excision using a simultaneous anterior and posterior approach. Objective. To show the feasibility of treating Ewing sarcoma of the thoracic spine with paravertebral and chest wall extension by multiagent chemotherapy followed by a multilevel en bloc spondylectomy and chest wall excision using a simultaneous anterior and posterior approach. Summary of Background Data. Ewing sarcoma is a primary malignant bone tumor that occasionally involves the spinal column. Most patients with Ewing sarcoma of the spine are treated with systemic chemotherapy followed by definitive local control. Radiation therapy is the usual mode of local control in these patients because the spinal column has historically been considered a surgically inaccessible site where wide surgical margins are difficult to obtain. However, en bloc spondylectomy techniques have been described that can probably further decrease the risk of local recurrence, thereby minimizing or even eliminating the need for radiation therapy. To our knowledge, a combined en bloc spondylectomy and chest wall excision in a patient with Ewing sarcoma in the spine has not been previously reported. Methods. Neoadjuvant chemotherapy consisting of vincristine, doxorubicin, and cyclophosphamide was administered. After completion of the chemotherapy, an en bloc spondylectomy of T8 and T9 with removal of the chest wall was achieved using a simultaneous anterior and posterior approach to the spine. A stackable carbon fiber cage filled with autograft and allograft bone was inserted between T7 and T10. The spine was stabilized with anterior and posterior instrumentation. The chest wall was reconstructed with contoured polymethylmethacrylate and polypropylene (Marlex, Textile Development Associates, Inc., Franklin Square, NY) mesh. Results. The patient maintained normal neurologic function, and pain was lessened. The margins were free of tumor, and tumor necrosis was 100%. After surgery, radiotherapy was not administered. No local tumor recurrence or distant metastases were evident at the last follow-up. Balance in the coronal and sagittal planes was maintained. The patient has returned to work and resumed normal activities of daily living. Conclusions. Multilevel en bloc spondylectomy and chest wall excision performed using a simultaneous anterior and posterior approach is a safe and effective technique that may be used to achieve adequate margins in select patients with malignant tumors involving the thoracic spine and chest wall. This technique can eliminate the need for radiation therapy in patients with Ewing sarcoma and probably decreases the risk of local recurrence compared with radiation therapy alone. © 2005, Lippincott Williams & Wilkins, Inc.link_to_subscribed_fulltex

Soft tissue and bone defect management in total sacrectomy for primary sacral tumors: A systematic review with expert recommendations

Study Design. Systematic review and expert consensus. Objective. To address the following two questions: (A) Is there a difference in outcomes after spino-pelvic reconstruction of total sacrectomy defects compared with no reconstruction? (B) What constitutes best surgical technique for soft tissue and bony reconstruction after total sacrectomy? Summary of Background Data. The management of the soft tissue and bony defect after total sacrectomy for primary sacral tumors remains a challenge due to the complex anatomical relationships and biomechanical requirements. The scarcity of evidence-based literature in this specialized field makes it difficult for the treating surgeon to make an informed choice. Methods. A systematic literature review was performed (1950–2015), followed by a meeting of an international expert panel. Medline, Embase, and CINAHL databases and Cochrane Libraries were searched. Using the GRADE guidelines, the panel of experts formulated recommendations based on the available evidence. Results. Three hundred fifty-three studies were identified. Of these, 17 studies were included and were case series. Seven were evaluated as high quality of evidence and nine were of low quality. There were a total of 116 participants. Three studies included patients (n = 24) with no spino-pelvic reconstruction. One study included patients (n = 3) with vascularized bone reconstruction. Twelve studies included patients (n = 80) with no soft tissue reconstruction, three studies described patients with a local flap (n = 20), and four studies with patients having regional flap reconstruction (n = 16). Patients with or without spino-pelvic reconstruction had similar outcomes with regards to walking; however, most patients in the nonreconstructed group had some ilio-lumbar ligamentous stability preserved. The wound dehiscence and return to theater rates were higher in patients with no soft tissue reconstruction. Conclusion. We recommend spino-pelvic reconstruction be undertaken with soft tissue reconstruction after total sacrectomy

Feasibility of achieving the 2025 WHO global tuberculosis targets in South Africa, China, and India: a combined analysis of 11 mathematical models

BACKGROUND: The post-2015 End TB Strategy proposes targets of 50% reduction in tuberculosis incidence and 75% reduction in mortality from tuberculosis by 2025. We aimed to assess whether these targets are feasible in three high-burden countries with contrasting epidemiology and previous programmatic achievements. METHODS: 11 independently developed mathematical models of tuberculosis transmission projected the epidemiological impact of currently available tuberculosis interventions for prevention, diagnosis, and treatment in China, India, and South Africa. Models were calibrated with data on tuberculosis incidence and mortality in 2012. Representatives from national tuberculosis programmes and the advocacy community provided distinct country-specific intervention scenarios, which included screening for symptoms, active case finding, and preventive therapy. FINDINGS: Aggressive scale-up of any single intervention scenario could not achieve the post-2015 End TB Strategy targets in any country. However, the models projected that, in the South Africa national tuberculosis programme scenario, a combination of continuous isoniazid preventive therapy for individuals on antiretroviral therapy, expanded facility-based screening for symptoms of tuberculosis at health centres, and improved tuberculosis care could achieve a 55% reduction in incidence (range 31-62%) and a 72% reduction in mortality (range 64-82%) compared with 2015 levels. For India, and particularly for China, full scale-up of all interventions in tuberculosis-programme performance fell short of the 2025 targets, despite preventing a cumulative 3·4 million cases. The advocacy scenarios illustrated the high impact of detecting and treating latent tuberculosis. INTERPRETATION: Major reductions in tuberculosis burden seem possible with current interventions. However, additional interventions, adapted to country-specific tuberculosis epidemiology and health systems, are needed to reach the post-2015 End TB Strategy targets at country level. FUNDING: Bill and Melinda Gates Foundation

Image-guided multilevel vertebral osteotomies for en bloc resection of giant cell tumor of the thoracic spine: case report and description of operative technique

The use of frameless stereotactic navigation is gaining popularity in spinal surgery. Although initially used in the spine for placement of lumbar pedicle screws, this technology has expanded to facilitate placement of spinal instrumentation at virtually all spinal levels. While previous reports have described the utility of image guidance for placement of spinal instrumentation, its use in assisting with resection of complex spine tumors has not been extensively reported. Here we describe the use of frameless stereotaxy to guide a complex, four-level sagittal vertebral osteotomy for en bloc resection of a giant cell tumor involving the chest wall and thoracic spine