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.

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.

Purpose The purpose of the study is to assess the displacement of lamina cribrosa (LC) and prelaminar tissue area (PTA) changes following trabeculectomy and non-penetrating deep sclerectomy (NPDS) using spectral-domain optical coherence tomography (SD-OCT) with enhanced depth imaging technology. Methods A total of 30 patients underwent glaucoma surgery. Sixteen patients underwent trabeculectomy, and 14 patients undertook NPDS. Serial horizontal B-scan images of optic nerve head (ONH) were obtained using SD-OCT preoperatively, and at 2-week, 1-, 3-, and 6-month postoperative visit (6 pv). LC displacement magnitude and PTA changes were determined from selected B-scan images. Correspondingly, OCT retinal nerve fiber layer (RNFL) parameters were measured. Results Intraocular pressure (IOP) decreased from 27.4 ± 10.3 mmHg (mean ± standard deviation) to 10.2 ± 4.0 mmHg (P = 0.011) and from 19.9 ± 4.0 mmHg to 11.9 ± 3.6 mmHg (P = 0.012) at 6 pv, for trabeculectomy and NPDS, respectively. There was a significant decrease in the LC depth from a baseline glaucomatous LC displacement of 468.0 ± 142.4 to 397.6 ± 125.2 μm in the trabeculectomy group (P = 0.001) and from 465.2 ± 129.6 to 412.0 ± 122.4 μm in the NPDS group (P = 0.029) at 6 pv. The PTA differed between the procedures at baseline (P = 0.002), but was not statistically significant postoperatively. Multivariate analysis for all patients including age, magnitude of IOP reduction, baseline glaucomatous LC displacement, magnitude of LC displacement, and the type of surgery revealed that only the magnitude of LC displacement was associated with significant RNFL thinning on average (r 2 = 0.162, P = 0.027) and in the following sectors: temporal superior (r 2 = 0.197, P = 0.014), temporal (r 2 = 0.150, P = 0.034), and nasal superior (r 2 = 0.162, P = 0.027). Conclusions Decrease in the LC depth after NPDS surgery can be observed at 6 pv. Regardless of the performed procedure, magnitude of LC displacement is associated with significant, focal RNFL thinning.

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