https://orcid.org/0000-0003-0917-9396
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ABSTRACT
Understanding the morphological features characterising a normal femoral head and acetabular cavity is critical for a more comprehensive and updated definition of hip anatomy. Based on anatomical observations, MacConaill introduced the notion that spheroidal articular surfaces are better represented by ovoidal shapes, in comparison with the still well-established spherical shape. This work tests MacConaill’s classification by using a surface-fitting framework to assess the goodness-of-fit regarding the largest assortment of sphere-like shapes presented in a single study (i.e. a total of 10 different shapes: sphere, rotational conchoids, rotational ellipsoid, ellipsoid, superellipsoid, Barr’s superellipsoid, tapered ellipsoid, Barr’s tapered superellipsoid, ovoid, superovoid). Anatomical data of the femoral head and acetabular cavity were obtained from computed tomography scans of a gender-balanced, asymptomatic 15 population of 30 adult subjects. The framework involved image segmentation with active contour methods, mesh smoothing and decimation, and surface fitting to point clouds was performed with genetic algorithms. The statistical analysis of the surface-fitting errors revealed the superior approximation of non-spherical shapes: superovoids provided the best fit for each femoral head and acetabular cavity, whereas spheres presented the worst fitting values. We also addressed gender variability in bony 20 hip geometry as sphericity, ellipticity, conicity and squareness were measured.
Acknowledgments
All authors are thankful for the financial support given by Portuguese Foundation for Science and Technology through national funds with references UID/CEC/50021/2019 and STREACKER UTAP-EXPL/CA/0065/2017.
Disclosure statement
No potential conflict of interest was reported by the authors.
Ethical approval
The data sets used in our study resulted from the approval by the Ethics Research Committee of the Nova Medical School | Faculdade de Ciências Médicas da Universidade Nova de Lisboa (CEFCM) under the Project entitled ‘DEFORMIDADES COXO-FEMURAIS E CONFLITO FEMUROACETABULAR: contributo epidemiológico, diagnóstico e prognóstico’ with reference nr.61/2014/CEFCM, and also by the University of Utah Institutional Review Board #10983.
Notes
2. www.itksnap.org/.
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Notes on contributors
Daniel Simões Lopes
Daniel Simões Lopes is an Assistant Professor of Computer Science & Engineering at Técnico Lisboa, and Head of Biomedical Research at the Visualization and Intelligent Multimodal Interfaces Group at INESC-ID Lisboa, where he carries research in Computer Graphics and Human-Computer Interaction. He holds a degree in biomedical engineering from the University of Lisbon and received his doctoral degree in computational engineering from the same university under the framework of the UT Austin|Portugal Program. His main research interests are virtual reality, augmented reality, collision detection, medical user interfaces, computer-aided design, and graphical user interfaces.
Sara M. Pires
Sara M. Pires has a degree in Biomedical Engineering from the University of Lisbon and was a research member at INESC-ID Lisboa were she carried her M.Sc. studies. Her research focused on shape analysis of the femoral head and acetabular cavity of asymptomatic, displastic and impinged hips.
Carolina D. Barata
Carolina D. Barata is currently studying for a Masters degree in Biomedical Engineering at the University of Lisbon. Her thesis research aims at analyzing longitudinal and survival data for rheumatic disease prognosis. She was also a research member at INESC-ID Lisboa and a collaborator of the IEEE EMBS Portugal Chapter.
Vasco V. Mascarenhas
Vasco V. Mascarenhas MD, MBA, PhD, is a consultant MSK radiologist at Hospital da Luz (Lisbon, Portugal), Head of the Musculoskeletal Imaging Unit (UIME) of Luz-Saúde and the current vice-chair of the arthritis subcommittee of the ESSR. He attended Medical school in Lisbon, Portugal, where he received his MD, and also Finance school where he obtained his MBA from IESE/AESE. Following a residency in radiology at Lisbon University hospital, he trained MSK radiology at the UCLA. Afterwards, he investigated hip impingement disorders obtaining his PhD in Medicine at NOVA Medical School. He has special expertise in non-invasive and invasivehip imaging with CT and MR, with a focus on femoroacetabular impingement and hip preserving imaging. In this capacity, and also as a member of the national MSK committee, he enjoys teaching andpromoting hip and MSK imaging to residents and other radiologists through lectures and workshops at national and international meetings. He was the congress president of the annual ESSR 2019 meeting, held in Lisbon, Portugal, on June 26–29, 2019.
Joaquim A. Jorge
Joaquim A. Jorge received his PhD from Rensselaer Polytechnic Institute, coordinatesthe VIMMI research group at INESC-ID and is Full Professor of Computer Graphicsand Multimedia at Técnico, Universidade de Lisboa. He is Editor-in-Chief of the Computers & Graphics Journal (Elsevier), a Fellow of the Eurographics Association, a Distinguished Speaker and a Distinguished Member of the ACM and IEEE Senior Member. He served on the ACM Europe Council and Chairs the ACM/SIGGGRAPH Specialized Conferences Committee. He has organized 40+ international scientific events, was IEEE 2020 and Eurographics 2016 papers co-chair, served on 200+ program committees and (co-)authored 300+ publications in international peer-refereed venues. His research interests include Augmented and Virtual Reality, Medical Applications, Advanced User Interfaces, 3D Visualization and Modeling.