51 research outputs found

    Review of Exploration Systems Development (ESD) Integrated Hazard Development Process

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    The Chief Engineer of the Exploration Systems Development (ESD) Office requested that the NASA Engineering and Safety Center (NESC) perform an independent assessment of the ESD's integrated hazard development process. The focus of the assessment was to review the integrated hazard analysis (IHA) process and identify any gaps/improvements in the process (e.g. missed causes, cause tree completeness, missed hazards). This document contains the outcome of the NESC assessment

    Mechanical assessment of two hybrid plate designs for pancarpal canine arthrodesis under cyclic loading

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    Pancarpal canine arthrodesis (PCA) sets immobilization of all three carpal joints via dorsal plating to result in bony fusion. Whereas the first version of the plate uses a round hole (RH) for the radiocarpal (RC) screw region, its modification into an oval hole (OH) in a later version improves versatility in surgical application. The aim of this study was to mechanically investigate the fatigue life of the PCA plate types implementing these two features–PCA-RH and PCA-OH. Ten PCA-RH and 20 PCA-OH stainless steel (316LVM) plates were assigned to three study groups (n = 10). All plates were pre-bent at 20° and fixed to a canine forelimb model with simulated radius, RC bone and third metacarpal bone. The OH plates were fixed with an RC screw inserted either most proximal (OH-P) or most distal (OH-D). All specimens were cyclically tested at 8 Hz under 320 N loading until failure. Fatigue life outcome measures were cycles to failure and failure mode. Cycles to failure were higher for RH plate fixation (695,264 ± 344,023) versus both OH-P (447,900 ± 176,208) and OH-D (391,822 ± 165,116) plate configurations, being significantly different between RH and OH-D, p = 0.03. No significant difference was detected between OH-P and OH-D configurations, p = 0.09. Despite potential surgical advantages, the shorter fatigue life of the PCA-OH plate design may mitigate its benefits compared to the plate design with a round radiocarpal screw hole. Moreover, the failure risk of plates with an oval hole is increased regardless from the screw position in this hole. Based on these findings, the PCA plate with the current oval radiocarpal screw hole configuration cannot be recommended for clinical use

    Wearing Two Hats

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    PLOSONEcomplete data set. (TPLO alignment jig-saw guide)

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    Raw data collected for two groups of clinically performed TPLOs (a crescent osteotomy of the proximal tibia designed to alter the craniotibial shear force as a result of a cranial cruciate deficient knee). Group 1 (2005-2007): freehand osteotomies with jig only; Group 2 (2013-2015): freehand osteotomies with jig only. Group 1 follows recommendation at that time to place proximal jig pin through center of medial collateral ligament (MCL). Group 2 follows the later recommendation to place the jig pin behind the MCL. The objective of the study is to determine if a saw guide attached to the jig can match the positions of the osteotomy performed by experienced surgeons, and also is it can replicate the ideal osteotomy location. The data file are all measurements obtained from these clinical cases that compares guide-to-osteotomy fit and the appropriateness of the osteotomy based upon current published guidelines. All methods are described in the manuscript

    Stifle joint

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    Short-Term Clinical and Radiographical Outcome after Application of Anchored Intervertebral Spacers in Dogs with Disc-Associated Cervical Spondylomyelopathy

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    Objectives The purpose of this study was to assess the short-term outcome of a new intervertebral anchored fusion device (C-LOX) for the treatment of disc associated cervical spondylomyelopathy (DA-CSM) in dogs, based on clinical and radiographical follow-up data. Materials and Methods To be included in the study, dogs had to be clinically affected by DA-CSM treated with surgical distraction/stabilization using the anchored intervertebral spacer (C-LOX). Neurological signs, as well as diagnostic imaging performed pre-, immediately postoperatively, and after 6 weeks and 3 months were assessed. If available, clinical follow-up after 3 months was documented. Results Thirty-seven cases were enrolled in the study. Outcome at 3 months was available in 25 dogs; improvement of neurological status was documented in 25/25 cases. The most common postoperative complication was screw loosening and/or breakage (n = 22), followed by subsidence (n = 15). Four dogs required revision surgery. Clinical Significance Distraction/stabilization of DA-CSM in dogs with the C-LOX device resulted in short-term clinical improvement in 33/37 treated cases. The high incidence of screw loosening was taken into consideration and modification of the implant with a new locking system and new screw dimensions was required. The C-LOX device seems to be a valuable alternative to more complicated distraction–fusion techniques
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