Investigation of the Average Shape and Principal Variations of the Human Talus Bone Using Statistic Shape Model

Abstract

Due to the complexity of articular interconnections and tenuous blood supply to the talus, talus fractures are often associated with complications (e.g., avascular necrosis). Currently, surgically fusing the talus to adjacent bones is widely used as treatment to talus fractures, but this procedure can greatly reduce mobility in the ankle and hindfoot. Alternatively, customized talus implants have shown an overall satisfactory patient feedback but with the limitation of high expenses and time-consuming manufacturing process. In order to circumvent these disadvantages, universal talus implants have been proposed as a potential solution. In our study, we aimed to develop a methodology using Statistical Shape Model (SSM) to simulate the talus, and then evaluate the feasibility of the model to obtain the mean shape needed for universal implant design. In order to achieve this, we registered 98 tali (41 females and 57 males) and used the registered dataset to train our SSM. We used the mean shape derived from the SSM as the basis for our talus implant template, and compared our template with that of previous works. We found that our SSM mean shape talus implant was geometrically similar to implants from other works, which used a different method for the mean shape. This suggests the feasibility of SSM as a method of finding mean shape information for the development of universal implants. A second aim of our study was to investigate if one scalable talus implant can accommodate all patients. In our study, we focused on addressing this from a geometric perspective as there are multiple factors impacting this (e.g., articular surface contact characteristics, implant material properties). Our initial findings are that the first two principal components should be afforded consideration for the geometrical accuracy of talus implant design. Additional factors would need to be further evaluated for their role in informing universal talus implant design.

A feature‐based statistical shape model for geometric analysis of the human talus and development of universal talar prostheses

“…Figure13demonstrates the magnitude fields of shape deviations between our mean shape and the best talar shape found byTrovato et al (2017), and the mean shapes obtained byLiu et al (2020) andLenz et al (2021). The deviation fields indicated that the best talar shape presented by Trovato et al was more deviated from our predicted mean shape than the mean shapes predicted byLiu et al and …”

“…Shape deviations of the best talar shape presented by Trovato et al (2017), and the mean shapes obtained by Liu et al (2020) and Lenz et al (2021) from the mean shape predicted in this study [Colour figure can be viewed at wileyonlinelibrary.com]…”

“…By the comparison, we attempted to demonstrate instances of methodological and sample effects on the calculated mean shapes. The mean shapes obtained by the works of Liu et al (2020), Trovato et al (2017), and Lenz et al (2021) were available to us. The data set of our study intersected with the data set used by Liu et al and Trovato et al, however, they utilized different shape registration methods to establish correspondence and obtain the mean shape.…”

“…Besides few treatment methods being available for total/partial loss of talus (Taniguchi et al, 2012), a more recent and so far promising approach is implantation of talar body or total talar prostheses (Ando et al, 2016; Angthong, 2014; Bowes et al, 2019; Harnroongroj & Harnroongroj, 2014; Harnroongroj & Vanadurongwan, 1997; Islam et al, 2014; Magnan et al, 2004; Regauer et al, 2017; Ruatti et al, 2017; Stevens et al, 2007; Taniguchi et al, 2012; Trovato et al, 2017; Tsukamoto et al, 2010). Designing talar prostheses, particularly non‐custom‐made or universal prostheses for total talar replacement, requires understanding of anatomic variations of the talus (Bowes et al, 2019; Islam et al, 2014; Lenz et al, 2021; Liu et al, 2020; Trovato et al, 2017; Tümer, Arbabi, et al, 2019).…”

Statistical shape modelling to analyse the talus in paediatric clubfoot

“…The contribution of third, fourth, and fifth PC modes can be considered as a local variation among most areas of articulations (Talar neck angle 2, talar neck angle 3, talar neck depth 2, talar neck depth 3 in geometric measurements). Similar observations are found by Liu et al 22 on adult talus with less variation in each mode as their samples are all healthy and intact.…”