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1.
Hum Reprod ; 38(12): 2400-2411, 2023 Dec 04.
Article in English | MEDLINE | ID: mdl-37879843

ABSTRACT

STUDY QUESTION: Is embryo culture in a closed time-lapse system associated with any differences in perinatal and maternal outcomes in comparison to conventional culture and spontaneous conception? SUMMARY ANSWER: There were no significant differences between time-lapse and conventional embryo culture in preterm birth (PTB, <37 weeks), low birth weight (LBW, >2500 g) and hypertensive disorders of pregnancy for singleton deliveries, the primary outcomes of this study. WHAT IS KNOWN ALREADY: Evidence from prospective trials evaluating the safety of time-lapse incubation for clinical use show similar embryo development rates, implantation rates, and ongoing pregnancy and live birth rates when compared to conventional incubation. Few studies have investigated if uninterrupted culture can alter risks of adverse perinatal outcomes presently associated with IVF when compared to conventional culture and spontaneous conceptions. STUDY DESIGN, SIZE, DURATION: This study is a Swedish population-based retrospective registry study, including 7379 singleton deliveries after fresh embryo transfer between 2013 and 2018 from selected IVF clinics. Perinatal outcomes of singletons born from time-lapse-cultured embryos were compared to singletons from embryos cultured in conventional incubators and 71 300 singletons from spontaneous conceptions. Main perinatal outcomes included PTB and LBW. Main maternal outcomes included hypertensive disorders of pregnancy (pregnancy hypertension and preeclampsia). PARTICIPANTS/MATERIALS, SETTING, METHODS: From nine IVF clinics, 2683 singletons born after fresh embryo transfer in a time-lapse system were compared to 4696 singletons born after culture in a conventional incubator and 71 300 singletons born after spontaneous conception matched for year of birth, parity, and maternal age. Patient and treatment characteristics from IVF deliveries were cross-linked with the Swedish Medical Birth Register, Register of Birth Defects, National Patient Register and Statistics Sweden. Children born after sperm and oocyte donation cycles and after Preimplantation Genetic testing cycles were excluded. Odds ratio (OR) and adjusted OR were calculated, adjusting for relevant confounders. MAIN RESULTS AND THE ROLE OF CHANCE: In the adjusted analyses, no significant differences were found for risk of PTB (adjusted OR 1.11, 95% CI 0.87-1.41) and LBW (adjusted OR 0.86, 95% CI 0.66-1.14) or hypertensive disorders of pregnancy; preeclampsia and hypertension (adjusted OR 0.99, 95% CI 0.67-1.45 and adjusted OR 0.98, 95% CI 0.62-1.53, respectively) between time-lapse and conventional incubation systems. A significantly increased risk of PTB (adjusted OR 1.31, 95% CI 1.08-1.60) and LBW (adjusted OR 1.36, 95% CI 1.08-1.72) was found for singletons born after time-lapse incubation compared to singletons born after spontaneous conceptions. In addition, a lower risk for pregnancy hypertension (adjusted OR 0.72 95% CI 0.53-0.99) but no significant difference for preeclampsia (adjusted OR 0.87, 95% CI 0.68-1.12) was found compared to spontaneous conceptions. Subgroup analyses showed that some risks were related to the day of embryo transfer, with more adverse outcomes after blastocyst transfer in comparison to cleavage stage transfer. LIMITATIONS, REASONS FOR CAUTION: This study is retrospective in design and different clinical strategies may have been used to select specific patient groups for time-lapse versus conventional incubation. The number of patients is limited and larger datasets are required to obtain more precise estimates and adjust for possible effect of additional embryo culture variables. WIDER IMPLICATIONS OF THE FINDINGS: Embryo culture in time-lapse systems is not associated with major differences in perinatal and maternal outcomes, compared to conventional embryo culture, suggesting that this technology is an acceptable alternative for embryo incubation. STUDY FUNDING/COMPETING INTEREST(S): The study was financed by a research grant from Gedeon Richter. There are no conflicts of interest for all authors to declare. TRIAL REGISTRATION NUMBER: N/A.


Subject(s)
Hypertension, Pregnancy-Induced , Pre-Eclampsia , Premature Birth , Pregnancy , Female , Child , Infant, Newborn , Humans , Male , Retrospective Studies , Premature Birth/epidemiology , Premature Birth/etiology , Hypertension, Pregnancy-Induced/etiology , Prospective Studies , Time-Lapse Imaging , Semen , Fertilization in Vitro/adverse effects
2.
J Biomech Eng ; 143(6)2021 06 01.
Article in English | MEDLINE | ID: mdl-33537737

ABSTRACT

The cervical spine experiences shear forces during everyday activities and injurious events yet there is a paucity of biomechanical data characterizing the cervical spine under shear loading. This study aimed to (1) characterize load transmission paths and kinematics of the subaxial cervical spine under shear loading, and (2) assess a contemporary finite element cervical spine model using this data. Subaxial functional spinal units (FSUs) were subjected to anterior, posterior, and lateral shear forces (200 N) applied with and without superimposed axial compression preload (200 N) while monitoring spine kinematics. Load transmission paths were identified using strain gauges on the anterior vertebral body and lateral masses and a disc pressure sensor. Experimental conditions were simulated with cervical spine finite element model FSUs (GHBMC M50 version 5.0). The mean kinematics, vertebral strains, and disc pressures were compared to experimental results. The shear force-displacement response typically demonstrated a toe region followed by a linear response, with higher stiffness in anterior shear relative to lateral and posterior shear. Compressive axial preload decreased posterior and lateral shear stiffness and increased initial anterior shear stiffness. Load transmission patterns and kinematics suggest the facet joints play a key role in limiting anterior shear while the disc governs motion in posterior shear. The main cervical spine shear responses and trends are faithfully predicted by the GHBMC cervical spine model. These basic cervical spine biomechanics and the computational model can provide insight into mechanisms for facet dislocation in high severity impacts, and tissue distraction in low severity impacts.


Subject(s)
Cervical Vertebrae
3.
HNO ; 67(Suppl 2): 69-76, 2019 Jun.
Article in English | MEDLINE | ID: mdl-31065762

ABSTRACT

BACKGROUND: In the field of hearing research a variety of imaging techniques are available to study molecular and cellular structures of the cochlea. Most of them are based on decalcifying, embedding, and cutting of the cochlea. By means of scanning laser optical tomography (SLOT), the complete cochlea can be visualized without cutting. The Cav1.3-/- mice have already been extensively characterized and show structural changes in the inner ear. Therefore, they were used in this study as a model to investigate whether SLOT can detect structural differences in the murine cochlea. MATERIALS AND METHODS: Whole undissected cochleae from Cav1.3-/- and wild-type mice of various postnatal stages were immunostained and analyzed by SLOT. The results were compared to cochlea preparations that were immunostained and analyzed by fluorescence microscopy. In addition, cochlea preparations were stained with osmium tetraoxide. RESULTS: Visualization by SLOT showed that the staining of nerve fibers at P27 in Cav1.3-/- mice was almost absent compared to wild-type mice and earlier timepoints (P9). The analysis of cochlea preparations confirmed a reduction of the radial nerve fibers. In addition, a significantly reduced number of ribbon synapses per inner hair cell (IHC) at P20 and P27 in the apical part of the cochlea of Cav1.3-/- mice was detected. CONCLUSION: The visualization of whole non-dissected cochleae by SLOT is a suitable tool for the analysis of gross phenotypic changes, as demonstrated by means of the Cav1.3-/- mouse model. For the analysis of finer structures of the cochlea, however, further methods must be used.


Subject(s)
Cochlea , Hair Cells, Auditory, Inner/ultrastructure , Tomography, Optical , Animals , Disease Models, Animal , Mice , Synapses , Tomography, Optical/methods
4.
HNO ; 67(8): 590-599, 2019 Aug.
Article in German | MEDLINE | ID: mdl-30963223

ABSTRACT

BACKGROUND: In the field of hearing research a variety of imaging techniques are available to study molecular and cellular structures of the cochlea. Most of them are based on decalcifying, embedding, and cutting of the cochlea. By means of scanning laser optical tomography (SLOT), the complete cochlea can be visualized without cutting. The Cav1.3-/- mice have already been extensively characterized and show structural changes in the inner ear. Therefore, they were used in this study as a model to investigate whether SLOT can detect structural differences in the murine cochlea. MATERIALS AND METHODS: Whole undissected cochleae from Cav1.3-/- and wildtype mice of various postnatal stages were immunostained and analyzed by SLOT. The results were compared to cochlea preparations that were immunostained and analyzed by fluorescence microscopy. In addition, cochlea preparations were stained with osmium tetraoxide. RESULTS: Visualization by SLOT showed that the staining of nerve fibers at P27 in Cav1.3-/- mice was almost absent compared to wildtype mice and earlier timepoints (P9). The analysis of cochlea preparations confirmed a reduction of the radial nerve fibers. In addition, a significantly reduced number of ribbon synapses per inner hair cell (IHC) at P20 and P27 in the apical part of the cochlea of Cav1.3-/- mice was detected. CONCLUSION: The visualization of whole non-dissected cochleae by SLOT is a suitable tool for the analysis of gross phenotypic changes, as demonstrated by means of the Cav1.3-/- mouse model. For the analysis of finer structures of the cochlea, however, further methods must be used.


Subject(s)
Hair Cells, Auditory, Inner , Tomography, Optical , Animals , Cochlea , Disease Models, Animal , Hair Cells, Auditory, Inner/ultrastructure , Mice , Synapses , Tomography, Optical/methods
5.
Eur J Cancer Care (Engl) ; 27(2): e12764, 2018 Mar.
Article in English | MEDLINE | ID: mdl-28921739

ABSTRACT

Relevant, comprehensive and psychometrically rigorous needs assessment tools are needed to ensure appropriate care is delivered to cancer survivors who have completed treatment. The aim of this rapid review was to identify and describe needs assessment tools that are used in cancer survivors post-treatment, assess their psychometric properties and describe their use in clinical care. The electronic databases Medline, Cochrane Library, CINAHL and PsycINFO were searched. Six studies were identified that described five needs assessment tools used in cancer survivors post-treatment. None of these tools covered all domains of unmet need nor demonstrated adequate evidence of all recommended criteria of validity and reliability. Few had been evaluated for use in a clinical environment. Out of the five tools, the Survivor Unmet Needs Survey (SUNS) showed the strongest psychometric properties. There is little empirical evidence available to guide recommendations on the most appropriate process of conducting needs assessment with cancer survivors once they have completed treatment.


Subject(s)
Cancer Survivors , Needs Assessment/standards , Humans , Psychometrics , Quality of Life , Reproducibility of Results
6.
Article in English | MEDLINE | ID: mdl-27726221

ABSTRACT

Cancer survivorship is recognised globally as a key issue. In spite of the key role played by nurses in survivorship care, there is an identified gap in nurse's knowledge in this area. This study reports on the development and evaluation of an educational resource for nurses working with people affected by cancer. The resource was designed using adult learning principles and includes a variety of learning materials and point of care resources. A mixed-methods sequential exploratory design was used to undertake an evaluation of the programme. This included the use of online surveys and semi-structured interviews with pilot participants. A total of 21 participants completed an online survey and 11 participants completed a telephone interview. Overall, the participants found the Cancer Survivorship resource to be engaging, practical and intuitive. A major theme emerging from the survey and interview data was that the resource was applicable to practice and useful in developing survivorship care plans. Respondents requested additional information be included on the role of various health professionals working in survivorship as well as guidelines on when to make referrals. This study provides evidence that the Cancer Survivorship tool may be a promising vehicle for delivering evidence-based education on survivorship care.


Subject(s)
Education, Nursing/methods , Neoplasms/nursing , Oncology Nursing/education , Survivorship , Adult , Aged , Attitude of Health Personnel , Cancer Survivors , Education, Distance/methods , Humans , Internet , Middle Aged , Personal Satisfaction , Pilot Projects , Program Evaluation , Queensland , Surveys and Questionnaires , Victoria , Young Adult
7.
HNO ; 64(9): 625-9, 2016 Sep.
Article in German | MEDLINE | ID: mdl-27138367

ABSTRACT

Over the past years, the multidisciplinary character of the international Computer-Aided Surgery around the Head (CAS-H) symposium has advanced many medical technologies, which were often adopted by industry. In Bern, the synergetic effects of the CAS-H symposium have enabled many experiences and developments in the area of computer-aided surgery. Planning and simulation methods in the areas of craniomaxillofacial surgery and otorhinolaryngology were developed and tested in clinical settings. In the future, further CAS-H symposia should follow, in order to promote the possibilities and applications of computer-assisted surgery around the head.


Subject(s)
Head/surgery , High Fidelity Simulation Training/trends , Otorhinolaryngologic Surgical Procedures/trends , Preoperative Care/trends , Robotic Surgical Procedures/trends , Surgery, Computer-Assisted/trends , Humans , Switzerland
8.
Med Image Anal ; 18(3): 487-99, 2014 Apr.
Article in English | MEDLINE | ID: mdl-24561486

ABSTRACT

In this paper, we propose a new method for fully-automatic landmark detection and shape segmentation in X-ray images. To detect landmarks, we estimate the displacements from some randomly sampled image patches to the (unknown) landmark positions, and then we integrate these predictions via a voting scheme. Our key contribution is a new algorithm for estimating these displacements. Different from other methods where each image patch independently predicts its displacement, we jointly estimate the displacements from all patches together in a data driven way, by considering not only the training data but also geometric constraints on the test image. The displacements estimation is formulated as a convex optimization problem that can be solved efficiently. Finally, we use the sparse shape composition model as the a priori information to regularize the landmark positions and thus generate the segmented shape contour. We validate our method on X-ray image datasets of three different anatomical structures: complete femur, proximal femur and pelvis. Experiments show that our method is accurate and robust in landmark detection, and, combined with the shape model, gives a better or comparable performance in shape segmentation compared to state-of-the art methods. Finally, a preliminary study using CT data shows the extensibility of our method to 3D data.


Subject(s)
Algorithms , Anatomic Landmarks/diagnostic imaging , Artificial Intelligence , Imaging, Three-Dimensional/methods , Pattern Recognition, Automated/methods , Radiographic Image Interpretation, Computer-Assisted/methods , Tomography, X-Ray Computed/methods , Femur/diagnostic imaging , Humans , Pelvis/diagnostic imaging , Radiographic Image Enhancement/methods , Reproducibility of Results , Sensitivity and Specificity
9.
J Dent Res ; 92(12 Suppl): 195S-201S, 2013 Dec.
Article in English | MEDLINE | ID: mdl-24158340

ABSTRACT

Dimensional alterations of the facial bone wall following tooth extractions in the esthetic zone have a profound effect on treatment outcomes. This prospective study in 39 patients is the first to investigate three-dimensional (3D) alterations of facial bone in the esthetic zone during the initial 8 wks following flapless tooth extraction. A novel 3D analysis was carried out, based on 2 consecutive cone beam computed tomographies (CBCTs). A risk zone for significant bone resorption was identified in central areas, whereas proximal areas yielded only minor changes. Correlation analysis identified a facial bone wall thickness of ≤ 1 mm as a critical factor associated with the extent of bone resorption. Thin-wall phenotypes displayed pronounced vertical bone resorption, with a median bone loss of 7.5 mm, as compared with thick-wall phenotypes, which decreased by only 1.1 mm. For the first time, 3D analysis has allowed for documentation of dimensional alterations of the facial bone wall in the esthetic zone of humans following extraction. It also characterized a risk zone prone to pronounced bone resorption in thin-wall phenotypes. Vertical bone loss was 3.5 times more severe than findings reported in the existing literature.


Subject(s)
Alveolar Process/diagnostic imaging , Cone-Beam Computed Tomography/methods , Esthetics, Dental , Imaging, Three-Dimensional/methods , Tooth Extraction , Tooth Socket/diagnostic imaging , Adult , Aged , Alveolar Bone Loss/diagnostic imaging , Anatomic Landmarks/diagnostic imaging , Bone Resorption/diagnostic imaging , Collagen/therapeutic use , Cuspid/surgery , Female , Follow-Up Studies , Humans , Incisor/surgery , Male , Middle Aged , Phenotype , Prospective Studies , Radiography, Dental, Digital/methods , Young Adult
10.
Lab Chip ; 12(18): 3413-8, 2012 Sep 21.
Article in English | MEDLINE | ID: mdl-22801572

ABSTRACT

In the last few decades, micro-models have become popular experimental tools for two-phase flow studies. In this work, the design and fabrication of an innovative, elongated, glass-etched micro-model with dimensions of 5 × 35 mm(2) and constant depth of 43 microns is described. This is the first time that a micro-model with such depth and dimensions has been etched in glass by using a dry etching technique. The micro-model was visualized by a novel setup that allowed us to monitor and record the distribution of fluids throughout the length of the micro-model continuously. Quasi-static drainage experiments were conducted in order to obtain equilibrium data points that relate capillary pressure to phase saturation. By measuring the flow rate of water through the flow network for known pressure gradients, the intrinsic permeability of the micro-model's flow network was also calculated. The experimental results were used to calibrate a pore-network model and test its validity. Finally, we show that glass-etched micro-models can be valuable tools in single and/or multi-phase flow studies and their applications.

11.
Int J Comput Assist Radiol Surg ; 7(2): 225-31, 2012 Mar.
Article in English | MEDLINE | ID: mdl-21792672

ABSTRACT

PURPOSE: The aim of this study was to validate the accuracy and reproducibility of a statistical shape model-based 2D/3D reconstruction method for determining cup orientation after total hip arthroplasty. With a statistical shape model, this method allows reconstructing a patient-specific 3D-model of the pelvis from a standard AP X-ray radiograph. Cup orientation (inclination and anteversion) is then calculated with respect to the anterior pelvic plane that is derived from the reconstructed model. MATERIALS AND METHODS: The validation study was conducted retrospectively on datasets of 29 patients (31 hips). Among them, there were 15 men (15 hips) and 14 women (16 hips). The average age of the patients was 69.4±8.5 (49-82) years. Each dataset has one postoperative X-ray radiograph and one postoperative CT scan. The postoperative CT scan for each patient was used to establish the ground truth for the cup orientation. The cup anteversion and inclination that were calculated from the 2D/3D reconstruction method were compared to the associated ground truth. To validate reproducibility and reliability, two observers performed measurements for each dataset twice in order to measure the reproducibility and the reliability of the 2D/3D reconstruction method. RESULTS: Our validation study demonstrated a mean accuracy of 0.4 ± 1.8° (-2.6° to 3.3°) for inclination and a mean accuracy of 0.6±1.5° (-2.0° to 3.9°) for anteversion. Through the Bland-Altman analysis, no systematic errors in accuracy were detected. The method showed very good consistency for both parameters. CONCLUSIONS: Our validation results demonstrate that the statistical shape model-based 2D/3D reconstruction-based method is an accurate, consistent, and reproducible technique to measure cup orientation from postoperative X-ray radiographs. The best results were achieved with radiographs including the bilateral anterior superior iliac spines and the cranial part of non-fractured pelvises.


Subject(s)
Acetabulum/diagnostic imaging , Arthroplasty, Replacement, Hip/methods , Hip Joint/diagnostic imaging , Imaging, Three-Dimensional/methods , Radiographic Image Interpretation, Computer-Assisted , Acetabulum/surgery , Aged , Aged, 80 and over , Confidence Intervals , Databases, Factual , Female , Hip Joint/surgery , Humans , Male , Middle Aged , Models, Statistical , Observer Variation , Reoperation/methods , Reproducibility of Results , Retrospective Studies , Risk Assessment , Statistics, Nonparametric , Tomography, X-Ray Computed/methods
12.
J Laryngol Otol ; 125(3): 262-70, 2011 Mar.
Article in English | MEDLINE | ID: mdl-21078217

ABSTRACT

OBJECTIVE: To present the auditory implant manipulator, a navigation-controlled mechanical and electronic system which enables minimally invasive ('keyhole') transmastoid access to the tympanic cavity. MATERIALS AND METHODS: The auditory implant manipulator is a miniaturised robotic system with five axes of movement and an integrated drill. It can be mounted on the operating table. We evaluated the surgical work field provided by the system, and the work sequence involved, using an anatomical whole head specimen. RESULTS: The work field provided by the auditory implant manipulator is considerably greater than required for conventional mastoidectomy. The work sequence for a keyhole procedure included pre-operative planning, arrangement of equipment, the procedure itself and post-operative analysis. CONCLUSION: Although system improvements are necessary, our preliminary results indicate that the auditory implant manipulator has the potential to perform keyhole insertion of implantable hearing devices.


Subject(s)
Cochlear Implantation/instrumentation , Cochlear Implants , Robotics/instrumentation , Surgery, Computer-Assisted/instrumentation , Cochlear Implantation/methods , Equipment Design , Equipment Failure , Humans , Mastoid/surgery , Minimally Invasive Surgical Procedures/instrumentation , Minimally Invasive Surgical Procedures/methods , Surgery, Computer-Assisted/methods , Tomography, X-Ray Computed
13.
Article in English | MEDLINE | ID: mdl-21097234

ABSTRACT

Cranioplasty is a commonly performed procedure. Outcomes can be improved by the use of patient specific implants, however, high costs limit their accessibility. This paper presents a low cost alternative technique to create patient specific polymethylmethacrylate (PMMA) implants using rapid prototyped mold template. We used available patient's CT-scans, one dataset without craniotomy and one with craniotomy, for computer-assisted design of a 3D mold template, which itself can be brought into the operating room and be used for fast and easy building of a PMMA implant. We applied our solution to three patients with positive outcomes and no complications.


Subject(s)
Biocompatible Materials/chemistry , Bone Cements/therapeutic use , Plastic Surgery Procedures/instrumentation , Polymethyl Methacrylate/chemistry , Skull/surgery , Equipment Failure Analysis , Humans , Prosthesis Design
14.
HNO ; 57(10): 975-82, 2009 Oct.
Article in German | MEDLINE | ID: mdl-19777172

ABSTRACT

Computer-aided microscopic surgery of the lateral skull base is a rare intervention in daily practice. It is often a delicate and difficult minimally invasive intervention, since orientation between the petrous bone and the petrous bone apex is often challenging. In the case of aural atresia or tumors the normal anatomical landmarks are often absent, making orientation more difficult. Navigation support, together with imaging techniques such as CT, MR and angiography, enable the surgeon in such cases to perform the operation more accurately and, in some cases, also in a shorter time. However, there are no internationally standardised indications for navigated surgery on the lateral skull base. Miniaturised robotic systems are still in the initial validation phase.


Subject(s)
Diagnostic Imaging/trends , Osteotomy/trends , Otorhinolaryngologic Surgical Procedures/trends , Robotics/trends , Skull Base/surgery , Surgery, Computer-Assisted/trends , Humans
15.
HNO ; 56(4): 376-8, 780-2, 2008 Apr.
Article in German | MEDLINE | ID: mdl-18345525

ABSTRACT

Endoscopic or microscopic surgery for chronic rhinosinusitis with or without nasal polyps is a routine intervention in daily practice. It is often a delicate and difficult minimally invasive intervention in a narrow space, with a tunnel view of 4 mm in the case of endoscopy and frequent bleeding in chronically inflamed tissue. Therefore, orientation in such a "labyrinth" is often difficult. In the case of polyp recurrence or tumors, the normal anatomical landmarks are often missing, which renders orientation even more difficult. In such cases, computer-aided navigation together with images such as those from computed tomography or magnetic resonance imaging can support the surgeon to make the operation more accurate and, in some cases, faster. Computer-aided surgery also has great potential for education.


Subject(s)
Endoscopy/methods , Otorhinolaryngologic Surgical Procedures/methods , Paranasal Sinuses/surgery , Robotics/methods , Skull Base/surgery , Surgery, Computer-Assisted/methods , Humans
16.
J Orthop Res ; 26(6): 860-4, 2008 Jun.
Article in English | MEDLINE | ID: mdl-18240332

ABSTRACT

Computer-aided surgery (CAS) allows for real-time intraoperative feedback resulting in increased accuracy, while reducing intraoperative radiation. CAS is especially useful for the treatment of certain pelvic ring fractures, which necessitate the precise placement of screws. Flouroscopy-based CAS modules have been developed for many orthopedic applications. The integration of the isocentric flouroscope even enables navigation using intraoperatively acquired three-dimensional (3D) data, though the scan volume and imaging quality are limited. Complicated and comprehensive pathologies in regions like the pelvis can necessitate a CT-based navigation system because of its larger field of view. To be accurate, the patient's anatomy must be registered and matched with the virtual object (CT data). The actual precision within the region of interest depends on the area of the bone where surface matching is performed. Conventional surface matching with a solid pointer requires extensive soft tissue dissection. This contradicts the primary purpose of CAS as a minimally invasive alternative to conventional surgical techniques. We therefore integrated an a-mode ultrasound pointer into the process of surface matching for pelvic surgery and compared it to the conventional method. Accuracy measurements were made in two pelvic models: a foam model submerged in water and one with attached porcine muscle tissue. Three different tissue depths were selected based on CT scans of 30 human pelves. The ultrasound pointer allowed for registration of virtually any point on the pelvis. This method of surface matching could be successfully integrated into CAS of the pelvis.


Subject(s)
Pelvis/diagnostic imaging , Pelvis/surgery , Surgery, Computer-Assisted/instrumentation , Surgery, Computer-Assisted/standards , Ultrasonography/standards , Animals , Humans , Models, Anatomic , Monitoring, Intraoperative/instrumentation , Monitoring, Intraoperative/standards , Muscle, Skeletal/diagnostic imaging , Reproducibility of Results , Swine , Tomography, X-Ray Computed , Water
17.
Unfallchirurg ; 111(2): 126-31, 2008 Feb.
Article in German | MEDLINE | ID: mdl-18239902

ABSTRACT

According to the literature, differences in torsion of 15 degrees and more develop in 20-30% of cases after intramedullary nailing of femoral shaft fractures. A computer-assisted method makes it possible to determine the antetorsion angle during surgery. In this experimental study, the precision of the measurements obtained with the navigation system were checked with a femur model and compared with a CT reference method. The measurements are carried out on a femur model that is equipped with a rotation device in the middle of the shaft. Nine reproducible angles can be set. Two investigators each conduct the measurements of the antetorsion angle ten times. A comparison is drawn between the absolute values of the antetorsion angle measured and the difference values of the adjoining positions. When comparing the absolute values of the navigation and reference systems, the mean deviations of both methods are around 1 degrees (0.35; 1.75) and comparing the differences 0.5 degrees (-0.2; 1.17). The maximum deviation of the absolute values of the CT reference method amounts to 6.4 degrees . Under experimental conditions, measurement of the femoral antetorsion angle proved to be sufficiently precise for clinical specifications in comparison to a CT reference method.


Subject(s)
Bone Malalignment/surgery , Femoral Fractures/surgery , Fluoroscopy/instrumentation , Fracture Fixation, Intramedullary/instrumentation , Range of Motion, Articular/physiology , Surgery, Computer-Assisted/instrumentation , Humans , Sensitivity and Specificity , Tomography, X-Ray Computed
18.
Unfallchirurg ; 111(3): 162-6, 2008 Mar.
Article in German | MEDLINE | ID: mdl-18214413

ABSTRACT

Surgical navigation has proven to be a minimally invasive procedure that enables precise surgical interventions with reduced exposure to irradiation for patient and personnel. Fluoroscopy-based modules have prevailed on the market. For certain operations of the pelvis computed tomography is necessary with its high imaging quality and considerably larger scan volume. To enable navigation in these cases, matching of the CT data set and the patient's real pelvic bone is essential. The common pair point-matching algorithm is complemented by the surface-matching algorithm to achieve an even higher overall precision of the system. For conventional surface matching with a solid pointer, the bone has to be exposed from soft tissue quite extensively, using a solid pointer. This conflicts with the claim of computer-assisted surgery to be minimally invasive. We integrated an A-mode ultrasonic pointer with the intention to perform extended surface matching on the pelvic bone noninvasively. Related to the conventional method, comparable and to some extent even improved precision conditions could be established.


Subject(s)
Image Processing, Computer-Assisted/instrumentation , Imaging, Three-Dimensional/instrumentation , Minimally Invasive Surgical Procedures/instrumentation , Pelvic Bones/diagnostic imaging , Pelvic Bones/surgery , Phantoms, Imaging , Surgery, Computer-Assisted/instrumentation , Transducers , Ultrasonography/instrumentation , Bone Screws , Equipment Design , Fracture Fixation, Internal/instrumentation , Humans , Sensitivity and Specificity , Tomography, X-Ray Computed/instrumentation , User-Computer Interface
19.
Proc Inst Mech Eng H ; 221(7): 739-53, 2007 Oct.
Article in English | MEDLINE | ID: mdl-18019461

ABSTRACT

Computer assisted orthopaedic surgery (CAOS) technology has recently been introduced to overcome problems resulting from acetabular component malpositioning in total hip arthroplasty. Available navigation modules can conceptually be categorized as computer tomography (CT) based, fluoroscopy based, or image-free. The current study presents a comprehensive accuracy analysis on the computer assisted placement accuracy of acetabular cups. It combines analyses using mathematical approaches, in vitro testing environments, and an in vivo clinical trial. A hybrid navigation approach combining image-free with fluoroscopic technology was chosen as the best compromise to CT-based systems. It introduces pointer-based digitization for easily assessable points and bi-planar fluoroscopy for deep-seated landmarks. From the in vitro data maximum deviations were found to be 3.6 degrees for inclination and 3.8 degrees for anteversion relative to a pre-defined test position. The maximum difference between intraoperatively calculated cup inclination and anteversion with the postoperatively measured position was 4 degrees and 5 degrees, respectively. These data coincide with worst cases scenario predictions applying a statistical simulation model. The proper use of navigation technology can reduce variability of cup placement well within the surgical safe zone. Surgeons have to concentrate on a variety of error sources during the procedure, which may explain the reported strong learning curves for CAOS technologies.


Subject(s)
Arthroplasty, Replacement, Hip/methods , Hip Joint/physiopathology , Hip Joint/surgery , Image Interpretation, Computer-Assisted/methods , Software , Surgery, Computer-Assisted/methods , User-Computer Interface , Computer Graphics , Computer Simulation , Hip Joint/pathology , Humans , Models, Biological , Reproducibility of Results , Robotics/methods , Sensitivity and Specificity
20.
Eur J Vasc Endovasc Surg ; 34(6): 702-8, 2007 Dec.
Article in English | MEDLINE | ID: mdl-17920306

ABSTRACT

PURPOSE: Since long-term patency and device integrity of nitinol stents in SFA lesions are not well studied, we examined clinical outcome, patency and device integrity after stenting long lesions using a standardized implantation technique. METHODS: Between 2001 and 2006, 59 patients (74 lesions) were treated with the same nitinol self-expandable stent (Zilver, Cook, USA) and technique for SFA recanalization. Clinical charts and imaging were retrospectively reviewed for patency (primary and assisted-primary), and device integrity. RESULTS: Patients were 74.5 (10.9) years old (range 49 to 93), 64% male, 42% diabetic, 62% hypertensive and 67% current or former smokers. Lesions were 23% TASC B, 16% TASC C, or 61% TASC D. Mean recanalization length was 19 cm (range 3 to 53). Mean number of stents per patient was 2.8 (total 210). Mean follow-up time was 2.4 years (range 3 days to 4.8 years). Kaplan-Meier estimates for primary patency rates were 90%, 78%, 74%, 69%, and 69% at 1, 2, 3, 4 and 4.8 years, respectively. Ten restenoses at a mean of 500 (388) days (1-1251 days) were successfully recanalized. The assisted primary patency rates were 96%, 90%, 90%, 90% and 90% at 1, 2, 3, 4 and 5 years, respectively. Six complete occlusions could not be reverted by a second recanalization procedure, and were treated by surgical bypass (1 case), amputation (3 cases), or medical management (2 cases). One (1.04%) Class II stent fracture was noted. CONCLUSIONS: SFA recanalization with a standardized implantation technique and nitinol stents provides good long-term primary and assisted-primary patency.


Subject(s)
Alloys , Angioplasty, Balloon/methods , Arterial Occlusive Diseases/therapy , Femoral Artery , Ischemia/therapy , Leg/blood supply , Stents , Aged , Aged, 80 and over , Equipment Failure , Female , Follow-Up Studies , Humans , Male , Middle Aged , Retreatment , Retrospective Studies
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