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Bicortical screw fixation is an established technique to increase screw strength in vertebral bodies, although it is associated with several complications, for example screw-loosening. Cement augmentation can increase stability of screw-fixation but can also cause various complications, such as cement-leakage or cement embolism. In this study, we tested a new, multicortical screw fixation technique in the sacrum. Four fresh-frozen sacrums were used. In group 1, standard screw insertion, with sagittal parallel and axial convergent screw-drive was performed. In group 2, the screw-drive of the first screw was similar to the screw-drive in group 1. In addition, a second screw was inserted descending into the intended hole in the head of the screw and at a stable angle. Therefore, the screws of the multiloc humerus nail-system (Synthes) were used. The specimens were connected to a testing-machine and underwent cyclic axial loading with an increase in the load after each completed stage. Multicortical screw fixation leads to a significant increase in the number of completed cycles and a significantly increased load until failure. Multicortical screw fixation in the sacrum offers a stronger attachment of the screws. In the future, multicortical implants, which fulfil the criteria demanded in spine surgery, can offer higher stability and may decrease the loosening rates of the implanted screws. • Sacral bicortical screw fixation is commonly used for strength and stability. • This study tested a new, multicortical screw fixation technique. • Fresh-frozen sacrums were used to compare bicortical and multicortical techniques. • Multicortical screw fixation resulted in more strength, stability and load bearing. [ABSTRACT FROM AUTHOR]

Abstract Severe spinal cord injuries cause permanent neurological deficits and are still considered as inaccessible to efficient therapy. Injured spinal cord axons are unable to spontaneously regenerate. Re-establishing functional activity especially in the lower limbs by reinnervation of the caudal infra-lesional territories might represent an effective therapeutic strategy. Numerous surgical neurotizations have been developed to bridge the spinal cord lesion site and connect the intact supra-lesional portions of the spinal cord to peripheral nerves (spinal nerves, intercostal nerves) and muscles. The major disadvantage of these techniques is the increased hypersensitivity, spasticity and pathologic pain in the spinal cord injured patients, which occur due to the vigorous sprouting of injured afferent sensory fibers after reconstructive surgery. Using micro-surgical instruments and an operation microscope we performed detailed anatomical preparation of the vertebral canal and its content in five human cadavers. Our observations allow us to put forward the possibility to develop a more precise surgical approach, the so called "ventral root bypass" that avoids lesion of the dorsal roots and eliminates sensitivity complications. The proposed kind of neurotization has been neither used, nor put forward. The general opinion is that radix ventralis and radix dorsalis unite to form the spinal nerve inside the dural sac. This assumption is not accurate, because both radices leave the dural sac separately. This neglected anatomical feature allows a reliable intravertebral exposure of the dura-mater ensheathed ventral roots and their damage-preventing end-to-side neurorrhaphy by interpositional nerve grafts. [ABSTRACT FROM AUTHOR]

Abstract: The goal of this study was to investigate the effect of plasma treatment on the wettability and dissolution of fenofibrate compacts. Contact angle measurements and intrinsic dissolution rate studies of untreated and plasma-treated fenofibrate compacts were conducted. The contact angle data clearly show that the wettability of the tablet surface increased with the duration of plasma treatment. Analyses of stability revealed that the surfaces which were plasma-treated for more than 1min regained some degree of hydrophobicity after storage in air. Since their hydrophobic recovery finally reached the level observed with 1min plasma-treated fenofibrate compacts it was deduced that permanent incorporation of hydrophilic groups had already attained saturation upon plasma irradiation for 1min. Dissolution studies revealed the advantages of the hydrophilized surface of plasma-treated fenofibrate compacts. Due to the improved wettability of plasma-treated fenofibrate its intrinsic dissolution rate was vastly increased compared to untreated fenofibrate. This study thus demonstrates the potential of plasma treatment to enhance the wettability and dissolution behavior of poorly water-soluble drugs. [Copyright &y& Elsevier]

Screw loosening is a major complication following spondylodesis. While several modifications increase screw stability, some, such as screw augmentation, are associated with potential complications; new techniques are needed to minimize the risk of screw loosening without increasing complication rates. 13 fresh-frozen human lumbar vertebral bodies (L1 to L5) were dissected. In group 1 (n = 7), pedicle screws were implanted conventionally, while in group 2 (n = 6), the screws were positioned divergent in the sagittal pathway. Screw stability was tested under cyclic axial load; one testing-cycle included 1000 repetitions. The first cycle started with a load of 100 N while the load was increased by +20 N in each following cycle until failure. Failure was defined by either a >5 mm movement of the screw heads or triggering of the switch-off threshold. Average number of cycles until failure was increased in group 2 compared with group 1 (12,046 vs 9761 cycles), as was the average load to failure (Fmax 313 N vs 260 N). Overall, in group 2, the number of cycles until screw loosening or failure increased by 23% (p = 0.28), while the required force increased by 20% (p = 0.3). Statistically significant correlation between BMD and increased number of cycles completed as well as with increased load (p < 0.01) could be observed. The results demonstrate, that divergent screw-drift of pairs of screws in the sagittal plane tends to increase stability, especially in vertebral bodies with lower bone density. Moreover, we could demonstrate a correlation between BMD and stability of screw-fixation. • Lumbar parallel screw fixation is commonly used for strength and stability. • This study tested a new, diverging screw fixation technique. • Fresh-frozen vertebral bodies were used to compare parallel and diverging screw fixation. • Diverging screw fixation tends to offer more strength and stability in poor bone-quality. [ABSTRACT FROM AUTHOR]

• Biomechanical simulation of axial force induction testing C1/2 Harms Construct. • Lateral Mass screws construct resulted from 142.04 µm/m to 188.54 µm/m. • Pedicle screws construct resulted from 165.98 µm/m to 195.95 µm/m. • Pedicle screws in a C1/2 Harms Construct were not superior compared to lateral mass screws. The use of the posterior arch of C1 as pedicle has shown beneficial stability regarding screw loosening, however, the C1 pedicle screw placement is challenging. Therefore, the study aimed to analyse the bending forces of the Harms construct used in fixation of C1/C2 when using pedicle screws compared to lateral mass screws. Five cadaveric specimens with a mean age of 72 years at death and bone mineral density measuring for 512.4 Hounsfield Units (HU) on average were used. A custom-made biomechanical setup was used to test the specimens with a C1/C2 Harms construct each with the use of lateral mass screws and pedicle screws in sequence. Strain gauges were used to analyse the bending forces from C1 to C2 in cyclic axial compression (μm/m). All underwent cyclic biomechanical testing using 50, 75 and 100 N. In all specimens, placement of lateral mass screws and pedicle screws was feasible. All underwent cyclic biomechanical testing. For the lateral mass screw, a bending of 142.04 µm/m at 50 N, 166.56 µm/m at 75 N and 188.54 µm/m at 100 N was measured. For the pedicle screws, bending force was slightly elevated with 165.98 µm/m at 50 N, 190.58 µm/m at 75 N and 195.95 µm/m at 100 N. However, bending forces did not vary significantly. In all measurements, no statistical significance was found when comparing pedicle screws and lateral mass screws. The lateral mass screw used in the Harms Construct to stabilize C1/2 showed less bending forces, therefore the construct with lateral mass screws appears more stable in axial compression compared to the one with pedicle screws. However, bending forces did not vary significantly. [ABSTRACT FROM AUTHOR]