STUDY DESIGN:Experimental study of temperature profiles during vertebroplasty.OBJECTIVES:To define accurate temperature profiles during vertebroplasty in an in vivo animal model.SUMMARY OF BACKGROUND DATA:Controversy still exists whether vertebroplasty achieves its analgesic effect by stabilizing fracture fragments or due to thermal damage of sensory nerves inside the vertebral body. Furthermore, the energy release during cement polymerization may cause thermal injury to the spinal cord or intervertebral discs.METHODS:A total of 4.0 mL PMMA was injected into three lumbar vertebrae of four skeletally mature mixed-bred ewes. Nine separate K-type thermocouples were placed into 12 vertebrae and their adjacent intervertebral discs. Temperature changes were recorded continuously before, during, and after the injection.RESULTS:The highest peak temperatures were measured at the cranial endplate (mean 42.4 +/- 8.8 C) and in the center of the vertebral body (mean 43.3 +/- 6.9 C). Temperatures stayed above 40 C for approximately 2.5 minutes. Peak temperatures in the discs and at the dorsal wall (closest to spinal cord) did not exceed 41 C and 47 C and stayed above 40 C for approximately 1.5 minutes.CONCLUSIONS:The intervertebral discs and the spinal cord do not seem to be in danger of thermal damage during vertebroplasty. The measured energy does not seem to be sufficient for the palliative effect achieved by vertebroplasty.

15 Contributors: 16 29 Abstract: 30

Introduction: Diaphyseal femoral allograft is well suited to anterior column reconstruction of the thoracolumbar spine due to its inherent structural properties and bio-compatibility. The Bridwell system of interbody fusion assessment[1][1] is based on plain x-rays and therefore lacks sensitivity. A new classification system of bony union is proposed using high-speed spiral CT imaging.Methods: Twenty-six patients who underwent anterior thoracolumbar reconstruction for burst fracture using femoral allograft were followed for a minimum of 2 years. Each subject underwent high speed spiral CT scanning through the reconstructed region of the thoracolumbar spine and a classification system of graft to endplate union and central cancellous autograft incorporation was established.The classification system reflects gradually increasing biological stability of the construct. Grade I (complete fusion) implies cortical union of the allograft and central trabecular continuity. Grade II (partial fusion) implies cortical union of the structural allograft with partial trabecular incorporation. Grade III (unipolar pseudarthrosis) denotes superior or inferior cortical non-union of the central allograft with partial trabecular discontinuity centrally and Grade IV (bipolar pseudarthrosis) suggests both superior and inferior cortical non-union with a complete lack of central trabecular continuity. Intra- and inter-observer error studies were carried out involving spinal surgeons, radiologists and trainees to examine reliability of the classificationResults: In this series 84% of cases demonstrated Grade I or Grade II characteristics. 1 case (4%) was identified as Grade IV. The classification showed good reliability with a kappa score of over 0.7Discussion: Plain radiographs have always proved unsatisfactory for the accurate assessment of incorporation of grafts in the thoracolumbar spine. The use of CT imaging in the assessment of graft union has allowed a more accurate assessment of union. The classifi cation system presented allows a reproducible and relevant categorisation of allograft incorporation. [1]: #ref-1

Introduction: Vertebroplasty using polymethylmethacrylate (PMMA) is an established technique in the treatment of osteoporotic fractures of the vertebra. Complications of vertebroplasty associated with PMMA leakage can include damage to the spinal cord. Previous studies have sought to investigate thermal changes in the paravertebral region, but used smaller volumes of cement than are used clinically 1 , or used in vitro experimental techniques. 2 We have designed an in vivo sheep model to investigate the thermal changes after injection of clinically relevant volumes of PMMA, and to measure change in cord function associated with PMMA extrusion. Methods: Five sheep were anaesthetised and 1.0ml of PMMA was injected into the spinal canal at the L1 level, with measurement of the temperature by thermocouple. The L2 to L5 vertebral bodies were then exposed and 9 thermocouples placed at points in and around the vertebra (superior and inferior endplate, disc above and below, central body, posterior wall, and spinal canal) to measure paravertebral temperature for a 10- minute period after injecting 6.0mls of PMMA. All animals were then humanely euthanased, and the T12 to L2 vertebrae harvested to examine the effect of temperature on the vertebral body and spinal cord using light microscopy. Results: The experiments showed significant increases in the paravertebral temperature, especially at the end-plates (mean temperature 51.7°C, mean increase in temperature +16°C). This is contrary to studies using small cement volumes or in vitro conditions. Intradiscal and posterior wall temperature did not significantly rise. Spinal canal temperature reached a mean 75.4°C in the presence of “extruded” cement. Microscopic examination showed thermal damage to the spinal cord. Discussion: The experiments indicate that neurological complications associated with vertebroplasty are likely to be thermally mediated, and that the analgesic effects of vertebroplasty are likely to be, at least in part, due to thermal damage to endplate neurological structures.

2 19 20 Abstract: 21 Biometrics are measurable physical characteristics or personal behavioral traits that can 22 be used to recognize the identity of an individual, or to verify a claimed identity. This 23 specification defines a common set of secure XML encodings for the patron formats 24

This paper describes the work undertaken, and evaluates the results produced, in a project that applied ASN.1 and its newly developed Encoding Control Notation to the Bluetooth Service Discovery Protocol. The use of ASN.1 + ECN was shown to be fully capable of specifying the bits-on-the-line required by the approved Bluetooth specification, and identified some areas where the current Bluetooth specification lacks precision --- noticeably in areas concerned with "extensibility".