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1.
J Craniofac Surg ; 26(4): 1234-7, 2015 Jun.
Article in English | MEDLINE | ID: mdl-26080164

ABSTRACT

PURPOSE: Ultrasound activation of resorbable pins directly into drilled holes of the calvarium was introduced to overcome the time-consuming installation in the resorbable osteosynthesis fixation in craniosynostosis surgery. There is paucity in the data comparing the mechanical properties of resorbable screws and ultrasound-activated pins produced by different manufacturers. The aim of this experimental study was to compare the mechanical properties of ultrasound-activated pins and resorbable screws. METHODS: A mechanical testing machine was used to characterize the mechanical performance of screws and ultrasound pins. The screws and pins were tested individually in 2 directions with respect to the longitudinal axis: vertical, that is, axial pull-out strength and horizontal, that is, shear strength. The mean maximum strength of fixation was determined. Broken screws and pinheads were analyzed by a scanning electron microscope to determine the site of fracture. RESULTS: All of the resorbable screws and pins broke at the point where the device enters bone. In pull-out testing, the mean maximum strength of the ultrasound-activated pins was 30.5 ± 5.4 N and that of the resorbable screws was 54.0 ± 0.3 N. In shear testing, the mean maximum strength of ultrasound-activated pins was 57.1 ± 20.1 N and that of the resorbable screws was 53.9 ± 0.4 N. CONCLUSIONS: In their intended configuration, there is no clinically significant difference in fixation strength between ultrasound-activated pins and resorbable screws.


Subject(s)
Absorbable Implants , Bone Plates , Bone Screws , Craniofacial Dysostosis/surgery , Craniosynostoses/surgery , Materials Testing/methods , Skull/surgery , Animals , Disease Models, Animal , High-Energy Shock Waves , Stress, Mechanical , Swine
2.
Int J Comput Assist Radiol Surg ; 8(5): 703-9, 2013 Sep.
Article in English | MEDLINE | ID: mdl-23443983

ABSTRACT

PURPOSE: Craniosynostosis may lead to reduced intracranial volume (ICV) and disturb normal brain growth and development. Thus, ICV is an important parameter with respect to the surgical outcome. Current methods for ICV determination from computed tomography (CT) images have drawbacks. The aim of this study was to investigate the performance of the novel mesh-based method (MBM) for ICV determination with craniosynostosis patients. METHODS: Twenty-two patients operated on for scaphocephaly were included in this study. ICVs from preoperative, one-week postoperative, and one-year postoperative CT images were measured with MBM. The level of agreement with the manual segmentation method (MSM) was determined for the measurements of preoperative and one-year postoperative datasets. Repeatability was determined with re-measurements of six datasets. Measurement time was recorded for MBM. RESULTS: Mean [Formula: see text] preoperative ICV values were 895.0 [Formula: see text] 153.1 [Formula: see text] and 896.4 [Formula: see text] 147.2 [Formula: see text] as measured with MBM and MSM, respectively. Corresponding one-year postoperative values were 1,238.3 [Formula: see text] 118.7 [Formula: see text] and 1,250.1 [Formula: see text] 117.5 [Formula: see text]. The MBM allowed ICV determination from one-week postoperative datasets. Measurement time with MBM was 4 CONCLUSIONS: MBM is an efficient method for determining the ICV of craniosynostosis patients, allowing the measurement of skulls with bony defects. The repeatability and short measurement time of MBM are attributable to the user interference and assessment of the measurement process.


Subject(s)
Craniosynostoses/diagnosis , Imaging, Three-Dimensional , Magnetic Resonance Imaging/methods , Multidetector Computed Tomography/methods , Skull/diagnostic imaging , Craniosynostoses/surgery , Disease Progression , Female , Follow-Up Studies , Humans , Infant , Male , Reproducibility of Results , Retrospective Studies
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