BackgroundThe aim was to develop statistical shape models of the main human tarsal bones that would result in novel representations of cuboid, navicular and talus.MethodsFifteen right and 15 left retrospectively collected computed tomography data sets from male individuals, aged from 17 to 63 years, with no known foot pathology were collected. Data were gathered from 30 different subjects. A process of model building includes image segmentation, unifying feature position, mathematical shape description and obtaining statistical shape geometry.ResultsOrthogonal decomposition of bone shapes utilising spherical harmonics was employed providing means for unique parametric representation of each bone. Cross-validated classification results based on parametric spherical harmonics representation showed high sensitivity and high specificity greater than 0.98 for all considered bones.ConclusionsThe statistical shape models of cuboid, navicular and talus created in this work correspond to anatomically accurate atlases that have not been previously considered. The study indicates high clinical potential of statistical shape modelling in the characterisation of tarsal bones. Those novel models can be applied in medical image analysis, orthopaedics and biomechanics in order to provide support for preoperative planning, better diagnosis or implant design.Electronic supplementary materialThe online version of this article (doi:10.1186/s13047-016-0178-x) contains supplementary material, which is available to authorized users.

SummaryBackground:Cherubism is an uncommon hereditary benign fibro-osseous disorder characterized by bilateral enlargement of the mandible and the maxilla that presents with varying degrees of involvement and a tendency toward spontaneous remission. On radiography cherubic lesions appear as cystic multilocular radiolucencies limited to the jaw bones.Case Report:A 5-year-old boy was referred to the Department of Maxillo-Facial Surgery due to deformation of the lower and middle section of the face and displacement or absence of teeth. A panoramic radiograph and a computed tomography revealed extensive multilocular, bilateral radiolucent areas and marked bony expansion in the mandible and maxilla, with sparing of the mandibular condyles. Histopathological evaluation of an incisional biopsy of the left maxilla and genotypic characterization confirmed the diagnosis of cherubism.Conclusions:The radiologic characteristics of cherubism are not pathognomonic but the diagnosis is strongly suggested by bilateral relatively symmetric jaw involvement that is limited to the jaw bones and, together with clinical and histopathologic findings, enables the diagnosis of cherubism. Genotypic characterization confirms the diagnosis.

The aim was to develop a morphometric and anatomically accurate atlas (statistical shape model) of calcaneus. The model is based on 18 left foot and 18 right foot computed tomography studies of 28 male individuals aged from 17 to 62 years, with no known foot pathology. A procedure for automatic atlas included extraction and identification of common features, averaging feature position, obtaining mean geometry, mathematical shape description and variability analysis. Expert manual assistance was included for the model to fulfil the accuracy sought by medical professionals. The proposed for the first time statistical shape model of the calcaneus could be of value in many orthopaedic applications including providing support in diagnosing pathological lesions, pre-operative planning, classification and treatment of calcaneus fractures as well as for the development of future implant procedures.