Search

Purpose: Our aim in the study is to measure the area and volume of the tarsal bones and examine the typing of the talus and calcaneus joint surfaces according to sex., Methods: In our study, the area and volume measurements of 630 tarsal bones and the morphology of the talus/calcaneus were analyzed by transferring thin-section Computed Tomography (CT) images to the 3D Slicer program., Results: The volume and area sizes of the foot bones are calcaneus, talus, cuboid, navicular, medial cuneiform, lateral cuneiform, and intermediate cuneiform, respectively. All area and volume values of males were statistically higher than females (p < 0.05). The right side calcaneus area, intermediate cuneiform area, and lateral cuneiform area values were statistically higher than the left side (p < 0.045, p < 0.044, p < 0.030, respectively). There was no statistical relationship between age and area/volume values (p > 0.05). Three different types were seen in the calcaneus and seven in the talus. The most common type in the calcaneus was B1 (40%), and the least common type was A (27.8%). Regardless of the subgroups, the most common type in the talus was type B (37.8%), while the least common type was E2 (1.1%)., Conclusion: Although morphometric measurements of tarsal bones differed according to sex, they did not differ according to age. The frequency of occurrence of the types of articular surfaces of the talus and calcaneus varies according to populations. We think that the morphometry and morphology of tarsal bones will contribute to invasive procedures regarding tarsal bones and surrounding structures, and that three-dimensional bone modeling can be used to create educational materials., (© 2024. The Author(s), under exclusive licence to Springer-Verlag France SAS, part of Springer Nature.)

The human calcaneus is robust and provides a prominent heel for effective bipedal locomotion, although the adjacent talus has no muscle attachments. However, there is incomplete information about the morphological changes in these prominent bones during embryo development. We examined serial histological sections of 23 human embryos and early-term fetuses (approximately 5-10 weeks' gestational age [GA]). At a GA of 5 weeks, the precartilage talus was parallel to and on the medial side of the calcaneus, which had a prolate spheroid shape and consisted of three masses. At a GA of 6 weeks, the cartilaginous talus extended along the proximodistal axis, and the tuber calcanei became long and bulky, with a small sustentaculum talus at the "distal" side. At a GA of 6 to 8 weeks, the sustentaculum had a medial extension below the talus so that the talus "rode over" the calcaneus. In contrast, the talus had a more complex shape, depending on the growth of adjacent bones. At a GA of 9 to 10 weeks, the talus was above the calcaneus, but the medial part still faced the plantar subcutaneous tissue because of the relatively small sustentaculum. Therefore, the final morphology appeared after an additional several weeks. Muscle activity seemed to facilitate growth of the tuber calcanei, but growth of the other parts of calcaneus, including the sustentaculum, seemed to depend on active proliferation at the different sites of cartilage. Multiple tendons and ligaments seemed to fix the talus so that it remained close to the calcaneus., (© 2024 Anatomical Society.)

Maspalomas is one of the most important archaeological sites in Gran Canaria, Canary Islands. The necropolis is one of the few funerary sites on the island where several the skeletons were found in anatomical position. The burials correspond to graves and cists dated between the 12 th and 15 th century CE. These graves and cists are clustered together in different formations across the necropolis, giving rise to a complex composition that denotes the existence of possible interpersonal relationships of the people buried there. A total of 135 calcanei and 118 tali were analysed to find non-metric traits and to test whether the clustered burials share a non-metric trait relationship. Trait combinations were formed using talus and calcaneus non-metric traits separately. The results of this study suggest that the individuals of Maspalomas showed a very high prevalence of lateral and medial talar facets, attributed to prolonged squatting position and/or walking on uneven ground. The calcaneal facet pattern (that may be aetiologically genetic) is more closely related to that observed among North-Africans or Indians than to Western Europeans. Calcaneal facet type Ib, and other genetically-determined traits, such as the extra facet extension of Posterior Facet, or the medial root of the inferior extensor retinaculum trait, either as single traits or as the combination of both traits, were significantly associated with individuals buried in different geographical areas of the necropolis defined by differences in burial structures, a finding that may suggest that genetically-linked individuals were buried in a separate area of the necropolis. The use of trait combination analysis in this study shows that the method can be applied to identify relationships among genetically or professionally related individuals that were subjected to a different burial procedure by their contemporaries.

The shape of the talus, its internal structure, and its mechanical properties are important in determining talar behavior during loading, which may be significant for the design of surgical tools and implants. Although recent studies using statistical shape modeling have described quantitative talar external shape variation, no similar quantitative study exists to describe the density distribution of internal talar structure. The goal of this study is to quantify statistical variation in talar shape and density to benefit the design of talar implants. To this end, weight-bearing computed tomography (CT) scans of the ankle were collected in neutral, bilateral standing posture, and three-dimensional models were generated for each talus. Local density derived from the Hounsfield unit of each CT voxel was extracted. A weighted spherical harmonic analysis was performed to quantify the talar external shape. One hundred and seventy-nine volumes of interest were placed in the same relative position within each talus to quantify the talar density. Additionally, a finite element analysis (FEA) was conducted on a talus with both heterogeneous and homogeneous material properties to observe the effect of these properties on the stress and strain response. Significant differences were found in the talar density in sex and age, as well as in the stress and strain response between homogeneous and heterogeneous FEA. These differences show the importance of considering heterogeneity when examining the load response of tarsal bones., (© 2024 Orthopaedic Research Society.)

Bacground: Morphologic measurements such as body lenght, wither height, heart girth, chest width, body leght, cannon-bone circumference is used to predict carcass weight. For this purpose, estimating carcass weight with measurements of key bones such as ankle bones, which play a significant role in the balance distribution of body weight, seems possible., Objectives: The aim of this study is to create new regression models for effective carcass weight estimation by using the morphometric data of the talus and calcaneus bones of hair goats., Methods: Study materials consisted of talus and calcaneus bones obtained from abattoir products of hair goat kids (12-18 months old, 20 female and 20 male) and adult hair goats (36-48 months old, 20 female and 20 male). Morphometric measurements of the talus and calcaneus of each animal were taken by a digital caliper. Using the morphometric measurements, an index and a factor were calculated for each bone. Regression analysis and correlations were examined in IBM SPSS 21 programme., Results: As a result, statistical analysis of GLc, GLt, Bd, Calfactor and Talfactor were statistically significant on predicting carcass weight., Conclusion: Specific anatomical structures, such as certain bone measurements, such as talus and calnaneus could serve as indicators of growth performance and also carcass weight performance. In addition new anatomical factors and indices may be produced and new regression methods may be applied with these new parameters to predict carcass weight., (© 2024 The Author(s). Veterinary Medicine and Science published by John Wiley & Sons Ltd.)

Background: Cadaver biomechanical testing suggests that the morphology of articulating bones contributes to the stability of the joints and determines their kinematics; however, there are no studies examining the correlation between bone morphology and kinematics of the subtalar joint. The purpose of this study was to investigate the influence of talar and calcaneal morphology on subtalar kinematics during walking in healthy individuals., Methods: Forty ankles (20 healthy subjects, 10 women/10 men) were included. Participants walked at a self-selected pace while synchronized biplane radiographs of the hindfoot were acquired at 100 images per second during stance. Motion of the talus and calcaneus was tracked using a validated volumetric model-based tracking process, and subtalar kinematics were calculated. Talar and calcaneal morphology were evaluated using statistical shape modeling. Pearson correlation coefficients were used to assess the relationship between subtalar kinematics and the morphology features of the talus and calcaneus., Results: This study found that a shallower posterior facet of the talus was correlated with the subtalar joint being in more dorsiflexion, more inversion, and more internal rotation, and higher curvature in the posterior facet was correlated with more inversion and eversion range of motion during stance. In the calcaneus, a gentler slope of the middle facet was correlated with greater subtalar inversion., Conclusion: The morphology of the posterior facet of the talus was found to a primary factor driving multiplanar subtalar joint kinematics during the stance phase of gait., Clinical Relevance: This new knowledge relating form and function in the hindfoot may assist in identifying individuals susceptible to subtalar instability and in improving implant design to achieve desired kinematics after surgery., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article. Disclosure forms for all authors are available online.

Background: To analyze the curvature characteristics of the talus trochlea in people from northern China in different sex and age groups., Methods: Computed tomography scanning data of talus from 61 specimens were collected and constructed as a three-dimensional model by Materialise's Interactive Medical Image Control System(MIMICS) software, anteromedial(AM), posteromedial(PM), anterolateral(AL), and posterolateral(PL) edge, anterior edge of medial trochlea, posterior edge of medial trochlea and anterior edge of lateral trochlea were defined according to the anatomical landmarks on trochlear surface. The curvature radii for different areas were measured using the fitting radius and measure module., Results: There were significant differences among the talus curvatures in the six areas (F = 54.905, P = 0.000), and more trends in the analytical results were as follows: PM > PL > MP > AL > MA > AM. The average PL radius from specimens aged > 38 years old was larger than that from specimens aged < = 38 years (t=-2.303, P = 0.038). The talus curvature of the AM for males was significantly larger than that for females (t = 4.25, P = 0.000), and the curvature of the AL for males was larger than that for females (t = 2.629, P = 0.010). For observers aged < = 38 years, the AM curvature of the right talus in the male group was significantly larger than that in the female group (P < 0.01). In age < = 38years group, the MA curvature of right talus in male was significantly larger than in female group(P < 0.01), fitting radius of talus for male (21.90 ± 1.97 mm) was significantly greater than female of this(19.57 ± 1.26 mm)(t = 6.894, P = 000). The average radius of the talus in the male population was larger than that in the female population., Conclusion: There was no significant relationship between age and talus curvature for males and females. The radius of curvature in the posterior area was significantly larger than that in the anterior area. We recommend that this characteristic of the talus trochlea should be considered when designing the talus component in total ankle replacement (TAR)., (© 2024. The Author(s).)

Background: When lateral ankle sprains progress into chronic lateral ankle instability (CLAI), restoring precise anatomic relationships of the lateral ankle ligament complex (LALC) surgically is complex. This study quantifies the radiographic relationships between the anterior talofibular ligament (ATFL), calcaneofibular ligament (CFL), and prominent osseous landmarks visible under fluoroscopy to assist in perioperative practices for minimally invasive surgery for CLAI., Methods: Ten fresh frozen ankle specimens were dissected to expose the LALC and prepared by threading a radiopaque filament through the ligamentous footprints of the ATFL and CFL. Fluoroscopic images were digitally analyzed to define dimensional characteristics of the ATFL and CFL. Directional measurements of the ligamentous footprints relative to the lateral process of the talus and the apex of the posterior facet of the calcaneus were calculated., Results: Dimensional measurements of the ATFL were a mean length of 9.3 mm, fibular footprint of 9.4 mm, and talar footprint of 9.1 mm. Dimensional measurements of the CFL were a mean length of 19.4 mm, fibular footprint of 8.2 mm, and calcaneal footprint of 7.3 mm. From the radiographic apparent tip of the lateral process of the talus, the fibular attachment of the ATFL was found 13.3 mm superior and 4.4 mm posterior, whereas the talar attachment was found 11.5 mm superior and 4.8 mm anterior. From the radiographic apparent posterior apex of the posterior facet of the calcaneus, the fibular attachment of the CFL was found 0.2 mm inferior and 6.8 mm anterior, whereas the calcaneal attachment was found 14.3 mm inferior and 5.9 mm posterior., Conclusion: The ATFL and CFL were radiographically analyzed using radiopaque filaments to outline the ligamentous footprints in their native locations. These ligaments were also localized with reference to 2 prominent osseous landmarks. These findings may assist in perioperative practices for keyhole incision placement and arthroscopic guidance. Perfect lateral ankle joint imaging with talar domes superimposed is required to be able to do this., Clinical Relevance: Radiographic evaluation of the ATFL and CFL with reference to prominent osseous landmarks identified under fluoroscopy may assist in perioperative practices for minimally invasive surgery to address CLAI for keyhole incision placement and arthroscopic guidance., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article. ICMJE forms for all authors are available online.

The morphological adaptations of euprimates have been linked to their origin and early evolution in an arboreal environment. However, the ancestral and early locomotor repertoire of this group remains contentious. Although some tarsal bones like the astragalus and the calcaneus have been thoroughly studied, the navicular remains poorly studied despite its potential implications for foot mobility. Here, we evaluate early euprimate locomotion by assessing the shape of the navicular-an important component of the midtarsal region of the foot-using three-dimensional geometric morphometrics in relation to quantified locomotor repertoire in a wide data set of extant primates. We also reconstruct the locomotor repertoire of representatives of the major early primate lineages with a novel phylogenetically informed discriminant analysis and characterize the changes that occurred in the navicular during the archaic primate-euprimate transition. To do so, we included in our study an extensive sample of naviculars (36 specimens) belonging to different species of adapiforms, omomyiforms, and plesiadapiforms. Our results indicate that navicular shape embeds a strong functional signal, allowing us to infer the type of locomotion of extinct primates. We demonstrate that early euprimates displayed a diverse locomotor behavior, although they did not reach the level of specialization of some living forms. Finally, we show that the navicular bone experienced substantial reorganization throughout the archaic primate-euprimate transition, supporting the major functional role of the tarsus during early primate evolution. This study demonstrates that navicular shape can be used as a reliable proxy for primate locomotor behavior. In addition, it sheds light on the diverse locomotor behavior of early primates as well as on the archaic primate-euprimate transition, which involved profound morphological changes within the tarsus, including the navicular bone., (Copyright © 2023 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Talus is a pivotal bone that assists in easy and correct locomotion and transfers body weight from the shin to the foot. Despite its small size, it is implicated in many clinical disorders. Familiarity with the anatomy of the talus and its anatomical variations is essential for the diagnosis of any disorder related to these variations. Furthermore, orthopedic surgeons must be fully aware by this anatomy during podiatry procedures. In this review, we attempt to present its anatomy in a simple, updated and comprehensive manner. We have also added the anatomical variations and some clinical points relevant to the unique and complex anatomy of talus. The talus has no muscle attachment. However, it does have many ligaments attached to it and others around it to keep it in place. Moreover, the bone plays a pig role in movements due to its involvement in many joints. Most of its surface is covered with articular cartilage. Therefore, its blood supply is relatively poor. This puts the talus at greater risk for poor healing as well as more complications in the event of injury than any other bone. We hope this review will make it easier for clinicians to pursue and understand the updated essential knowledge of one of the most complex bone anatomies that they need in their clinical practice., (© 2023. The Author(s), under exclusive licence to Japanese Association of Anatomists.)

Background: The present study aimed to clarify the morphological patterns of the calcaneus and talus that are associated with hallux valgus angle (HVA) by quantifying the differences in the hindfoot bone morphology between left and right sides in HV patients with clear bilateral difference of HVA., Methods: Three-dimensional (3D) computed tomography scans of 32 feet of 16 patients with HV who had right-to-left HVA differences of more than 5 degrees (68.8 ± 8.6 years) were enrolled, and 3D surface models of the calcaneus and talus were generated. A total of 556 and 430 landmarks were placed on the calcaneal and talar surfaces, respectively, to calculate the principal components (PCs) of shape variations. The PC scores were compared between the small and large HVA sides within an individual., Results: The calcaneus in patients with a larger HVA (mean, 43.2 degrees) possessed slender calcaneal tuberosity, more medially oriented posterior articular surface in the coronal plane, and narrower and more concave anterior-middle articular surfaces compared to those with a small HVA (mean, 33.7 degrees). The talus with a larger HVA exhibited more medially oriented talar head in the transverse plane and more anteriorly protruded lateral region of the talar head compared to the small HVA., Conclusions: The morphological patterns of the calcaneus in patients with a larger HVA allows the hindfoot bones to easily rotate in the everting direction, while those of the talus could induce a larger internal rotation of the first metatarsal. These morphological patterns of the calcaneus and talus could be structural factors affecting the HV., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier GmbH.)

The addition of information regarding obesity status to the forensic anthropological biological profile could significantly contribute to the identification of human skeletal remains since over 40% of the U.S. adult population is currently obese. This study examines the differences in talar shape and trabecular bone structure between obese and non-obese individuals. A sample of 20 obese and 20 non-obese divided evenly by sex was selected from the Texas State University Donated Skeletal Collection. Tali were imaged using x-ray computed tomography (voxel size: 28-38.7 μm). Image stacks were processed to produce binary images as well as trabecular thickness and spacing maps. Landmark-based geometric morphometric analyses were conducted to quantify shape variation. Shape coordinates were used to locate 100 geometrically homologous volumes of interest within each talus. Bone volume fraction, trabecular thickness, and trabecular spacing were extracted at each volume of interest. Within each sex, a one-way ANCOVA was used to determine if significant differences exist between obese and non-obese individuals in trabecular bone after controlling for age. The size of the talus as well as subtle aspects of shape were found to distinguish the sexes. The results further indicate that bone volume fraction significantly differs between obese and non-obese males. In females, bone volume fraction is correlated with age but does not differ between obese and non-obese. The study demonstrates that bone microstructure is a promising approach to estimating body mass or body mass index category but age effects diminish the potential for the talus to be used alone., (© 2023 The Authors. Journal of Forensic Sciences published by Wiley Periodicals LLC on behalf of American Academy of Forensic Sciences.)

Since both the talocrural and subtalar joints can be involved in chronic ankle instability, the present study assessed the talar morphology as this bone is the key player between both joint levels. The 3D orientation and curvature of the superior and the posteroinferior facet between subjects with chronic ankle instability and healthy controls were compared. Hereto, the talus was segmented in the computed tomography images of a control group and a chronic ankle instability group, after which they were reconstructed to 3D surface models. A cylinder was fitted to the subchondral articulating surfaces. The axis of a cylinder represented the facet orientation, which was expressed by an inclination and deviation angle in a coordinate system based on the cylinder of the superior talar facet and the geometric principal axes of the subject's talus. The curvature of the surface was expressed as the radius of the cylinder. The results demonstrated no significant differences in the radius or deviation angle. However, the inclination angle of the posteroinferior talar facet was significantly more plantarly orientated (by 3.5°) in the chronic instability group (14.7 ± 3.1°) compared to the control group (11.2 ± 4.9°) (p < 0.05). In the coronal plane this corresponds to a valgus orientation of the posteroinferior talar facet relative to the talar dome. In conclusion, a more plantarly and valgus orientated posteroinferior talar facet may be associated to chronic ankle instability., (© 2021 The Authors. Journal of Orthopaedic Research® published by Wiley Periodicals LLC on behalf of Orthopaedic Research Society.)

The implant design of the talar component for total ankle replacement (TAR) should match the surface morphology of the talus so that the replaced ankle can restore the natural motion of the tibiotalar joint and may reduce postoperative complications. The purpose of this study was to introduce a new 3D fitting method (the two-sphere fitting method of the talar trochlea with three fitting resection planes) to approximate the shape of the upper part of the talus for the Chinese population. 90 models of the tali from CT images of healthy volunteers were used in this study. Geometrical fitting and morphological measurements were performed for the surface morphology of the upper part of the talus. The accuracy of the two-sphere fitting method of the talar trochlea was assessed by a comparison of previously reported data. Parameters of the fitting geometries with different sizes were recorded and compared. Results showed that compared with previously reported one-sphere, cylinder, and bitruncated cone fitting methods, the two-sphere fitting method presented the smallest maximum distance difference, indicating that talar trochlea can be approximated well as two spheres. The radius of the medial fitting sphere R M was 20.69 ± 2.19 mm which was significantly smaller than the radius of the lateral fitting sphere R L of 21.32 ± 1.88 mm. After grouping all data by the average radius of fitting spheres, the result showed that different sizes of the upper part of the talus presented significantly different parameters except the orientation of the lateral cutting plane, indicating that the orientation of the lateral cutting plane may keep consistent for all upper part of the talus and have no relationship with the size. The linear regression analyses demonstrated a weak correlation ( R 2 < 0.5) between the majority of parameters and the average radius of the fitting spheres. Therefore, different sizes of the upper part of the talus presented unique morphological features, and the design of different sizes of talar components for TAR should consider the size-specific characteristics of the talus. The parameters measured in this study provided a further understanding of the talus and can guide the design of different sizes of the talar components of the TAR implant., Competing Interests: The authors received no financial support for the research, authorship, and/or publication of this article., (Copyright © 2022 Jian Yu et al.)

Neanderthal foot bone proportions and morphology are mostly indistinguishable from those of Homo sapiens, with the exception of several distinct Neanderthal features in the talus. The biomechanical implications of these distinct talar features remain contentious, fueling debate around the adaptive meaning of this distinctiveness. With the aim of clarifying this controversy, we test phylogenetic and behavioral factors as possible contributors, comparing tali of 10 Neanderthals and 81 H. sapiens (Upper Paleolithic and Holocene hunter-gatherers, agriculturalists, and postindustrial group) along with the Clark Howell talus (Omo, Ethiopia). Variation in external talar structures was assessed through geometric morphometric methods, while bone volume fraction and degree of anisotropy were quantified in a subsample (n = 45). Finally, covariation between point clouds of site-specific trabecular variables and surface landmark coordinates was assessed. Our results show that although Neanderthal talar external and internal morphologies were distinct from those of H. sapiens groups, shape did not significantly covary with either bone volume fraction or degree of anisotropy, suggesting limited covariation between external and internal talar structures. Neanderthal external talar morphology reflects ancestral retentions, along with various adaptations to high levels of mobility correlated to their presumably unshod hunter-gatherer lifestyle. This pairs with their high site-specific trabecular bone volume fraction and anisotropy, suggesting intense and consistently oriented locomotor loading, respectively. Relative to H.sapiens, Neanderthals exhibit differences in the talocrural joint that are potentially attributable to cultural and locomotor behavior dissimilarity, a talonavicular joint that mixes ancestral and functional traits, and a derived subtalar joint that suggests a predisposition for a pronated foot during stance phase. Overall, Neanderthal talar variation is attributable to mobility strategy and phylogenesis, while H. sapiens talar variation results from the same factors plus footwear. Our results suggest that greater Neanderthal body mass and/or higher mechanical stress uniquely led to their habitually pronated foot posture., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Purpose: Vascularized pedicled bone-grafting from the cuboid to the talus provides low donor site morbidity and satisfactory outcomes in patients with early-stage talar avascular necrosis. We investigated the anatomy of the rotational vascularized pedicled bone graft from the cuboid., Methods: 15 embalmed cadaver specimens were perfused with red latex via the popliteal artery. The lateral malleolus was dissected. The course of the lateral tarsal artery and the vascular territory in the cuboid supplied by the lateral tarsal artery were observed. Vessel diameters were measured., Results: The course of the lateral tarsal artery to the cuboid was consistent, and a vascularized pedicle of the lateral tarsal artery was present in all specimens. Mean diameter of the lateral tarsal artery was 1.40 ± 0.12 mm (range 1.67-1.25). Mean length of the vascularized pedicle was 67.15 ± 3.18 mm (range 62.43-74.36). The pedicle bone graft was long enough to reach the bony border of both the lateral and medial malleolus., Conclusion: A vascularized pedicled cuboid bone graft based on the lateral tarsal artery has clinical utility for early-stage talar avascular necrosis., (© 2021. The Author(s), under exclusive licence to Springer-Verlag France SAS, part of Springer Nature.)

Sex estimation is essential for forensic scientists to identify human skeletal remains. However, the most sexually dimorphic elements like pelvis or skull are not always assessable. Osteometric analyses have proven useful in sex estimation, but also to be population specific. The main purpose of this study was to test the validity of contemporary Greek and Spanish discriminant functions for the talus and the patella, respectively, on a Swiss skeletal sample and to quantify the utility of the measurements as a novel approach in osteometric sex assessment. Four talus and three patella measurements on dry bone were obtained from 234 individuals of the modern cemetery SIMON Identified Skeletal Collection. The previously derived discriminant functions were applied, accuracies determined, the utility of the different measurements was assessed and new multivariable equations constructed. Accuracies varied between 67% and 86% for talus and 63% and 84% for patella, similar to those reported by the original studies. Multivariable equations should be preferred over equations based on single measurements and combining the most significant measurements rather than using several variables obtained the best possible accuracy. The new discriminant functions did not provide a substantial improvement to the original ones. The overall utility of talus and patella is limited, allowing sex estimation with sufficient certainty only in a small proportion of individuals. Discriminant functions developed in contemporary Greek or Spanish populations are in principle applicable also to Swiss contemporary populations. We recommend that at present existent studies of this type should be validated and tested rather than developing new formulas., (Copyright © 2021 The Author(s). Published by Elsevier B.V. All rights reserved.)

Purpose: The aim of the study was to examine the ligaments of the os trigonum., Methods: The ankle joint magnetic resonance imaging (MRI) of 104 patients with the os trigonum (experimental group) and 104 patients without the os trigonum (control group) were re-reviewed. The connections of the os trigonum and posterior talofibular ligament (PTFL), the fibulotalocalcaneal ligament (FTCL), the paratenon of the Achilles tendon, the posterior talocalcaneal ligament (PTCL), the osteofibrous tunnel of the flexor hallucis longus (OF-FHL) and the flexor retinaculum (FR) were studied., Results: The os trigonum is connected to structures. The posterior part of the PTFL inserted on the os trigonum in 85.6% of patients, whereas in all patients in the control group, the posterior part of the PTFL inserted on the posterior talar process (p < 0.05). The connection of the PTCL was seen in 94.2% of patients in the experimental group, while it was seen in 90.4% of patients in the control group (p > 0.05). The connection to the FTCL in the experimental group was 89.4%, while in the control group, it was 91.3% (p > 0.05). The communication with the paratenon was seen more often in the control group compared to that in the experimental group (31.7% vs. 63.8%, p < 0.001). The FTCL was prolonged medially into the FR in 85.6% of patients in the experimental group and in 87.5% of patients in the control group (p > 0.05). The flexor hallucis longus (FHL) run at the level of articulation between the os trigonum 63.5% and the posterior process of the talus 25% and less often on the os trigonum 11.5%., Conclusion: The os trigonum is connected with all posterior ankle structures and more connections than previously reported., (© 2021. The Author(s).)

Introduction: The shape of the talus determines the positional and kinematic features of the subtalar, talonavicular, and talocrural joints during walking. Thus, detailed knowledge of the pattern of sexual dimorphism of the human talus may be useful for revealing the pathogenetic mechanism of foot and knee disorders, which are more prevalent in females. The aim of this study was to characterize and visualize the three-dimensional shape variations of the talus in relation to sex and age using geometric morphometrics., Materials and Methods: Computed tomography images of 56 feet without talar injuries or disorders were used in this study. Thirty-seven anatomical landmarks were identified on a bone model of the talus to calculate principal components (PCs) of shape variations among specimens. PC scores were compared between sexes, and their correlations with age were also investigated., Results: The female talus had a longer neck and narrower head width than the male talus. The superior trochlea was tilted more laterally in the frontal plane in females. Furthermore, the female talar head was more twisted and was more elongated in the dorsoplantar direction., Conclusions: Morphological features of the talus in females could alter the subtalar and talonavicular joint kinematics during walking and could be a structural factor in the pathogenetic mechanism underlying foot and knee disorders. This study contributes to the comprehensive understanding of shape variations in the human talus., (© 2020 Wiley Periodicals, Inc.)

The high prevalence of foot pathologies in women and the elderly could be associated with gender and age difference in the morphology of the foot, particularly the morphology of the keystone of the foot, the talus. The present study investigated the orientation and curvature of the three articular surfaces of the talus in relation to sex and age based on computer tomography (CT), to identify possible morphological factors of the higher prevalence of foot disorders in women and elderly. Fifty-six participants were included in this study. The orientations of the talocrural, subtalar, and talonavicular joints were quantified three-dimensionally by calculating normal and principal axes of the articular surfaces defined by planar approximation. The curvature radii of the articular surfaces were quantified by cylindrical and spherical approximations. The talonavicular surface was significantly more twisted in the frontal plane and less adducted in the transverse plane in females than in males. With aging, the subtalar articular surface was significantly facing more posteriorly. Moreover, it was found that the curvature radii of the trochlea and navicular articular surfaces significantly increased with aging, indicating a flattening of these surfaces. The identified changes in the talar morphology with aging could potentially lead to a higher prevalence of foot disorders in the elderly.

The adoption of bipedalism is a key benchmark in human evolution that has impacted talar morphology. Here, we investigate talar morphological variability in extinct and extant hominins using a 3D geometric morphometric approach. The evolutionary timing and appearance of modern human-like features and their contributions to bipedal locomotion were evaluated on the talus as a whole, each articular facet separately, and multiple combinations of facets. Distinctive suites of features are consistently present in all fossil hominins, despite the presence of substantial interspecific variation, suggesting a potential connection of these suites to bipedal gait. A modern human-like condition evolved in navicular and lateral malleolar facets early in the hominin lineage compared with other facets, which demonstrate more complex morphological variation within Homininae. Interestingly, navicular facet morphology of Australopithecus afarensis is derived in the direction of Homo, whereas more recent hominin species such as Australopithecus africanus and Australopithecus sediba retain more primitive states in this facet. Combining the navicular facet with the trochlea and the posterior calcaneal facet as a functional suite, however, distinguishes Australopithecus from Homo in that the medial longitudinal arch had not fully developed in the former. Our results suggest that a more everted foot and stiffer medial midtarsal region are adaptations that coincide with the emergence of bipedalism, whereas a high medial longitudinal arch emerges later in time, within Homo. This study provides novel insights into the emergence of talar morphological traits linked to bipedalism and its transition from a facultative to an obligate condition., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Background: The prevalence of foot pathologies, such as flatfoot deformity and hallux valgus, is higher in women and increases with age. It has been reported that these types of foot disorders may also be linked to excessive mobility of the subtalar joint to the eversion direction during weight bearing. Given that the mobility of the joint is determined by its articular morphology, sex- and age-related variations in the subtalar articular surface morphology are possible. The purpose of this study was to investigate the orientation and the curvature radii of the talar articular facets of the calcaneus in relation to age and sex using three-dimensional computer tomography., Methods: Fifty-six feet without subtalar injuries or disorders were included in this study. The orientations of the talar articular surfaces of the calcaneus were quantified in the sagittal and coronal planes. The curvature radii of the articular surfaces of the calcaneus were also assessed based on the approximations of the sphere surfaces., Results: The talar articular surface was oriented more anteriorly and medially in the females than in the males. The curvature radius of the calcaneal posterior facet in the females exhibited a positive correlation with age, indicative of increased articular surface flattening., Conclusions: The morphological features of the female calcaneus could induce excessive eversion and could lead to a higher prevalence of foot disorders, including flatfoot and hallux valgus, in elderly females. This study contributes to an understanding of the sexual dimorphism of the articular surfaces of the calcaneus and provides insight into the mechanisms that underline various foot disorders., (Copyright © 2020 Elsevier GmbH. All rights reserved.)

Background: Little is known about differences in the size and morphology of the right and left human tali. The present study demonstrates differences between right and left talar morphometric geometric profiles as fluctuating asymmetry in matched pairs of cadaveric specimens., Methods: In total, 24 tali were collected in this study. All eligible tali were systematically measured with a Vernier caliper and three-dimensional laser scanner, which provided data for further analysis regarding the talar morphometric geometric profiles. Data were calculated to demonstrate differences between the right and left talar profiles using a matched-pair method, including the general size of the talus., Results: The average talar length was 53.5 mm, the average talar dome height was 31.2 mm, and the average talar body width was 41.3 mm. The average anterior trochlear width, middle trochlear width, posterior trochlear width, and trochlear length were 31.8, 31.2, 28.3, and 30.7 mm, respectively. Eleven matched pairs of intact tali were eligible for the matched-pair study. Paired t-tests showed significant differences in the talar dome height (P = 0.019), middle trochlear width (P = 0.027), and posterior trochlear width (P = 0.016) between the right and left tali. However, there were no significant differences in the surface area or volume between the right and left tali., Conclusion: Significant differences in the morphometric profile were found between the right and left matched pairs of tali. This basic information indicates that the profile of the contralateral talus may not be used as a single reference to reconstruct or duplicate the talus of interest in certain conditions such as talar prosthesis implantation or customized total ankle replacement., Competing Interests: Dr. Angthong reports grants from Thammasat University (grant number: ทป2/43/ 2561, year 2018), personal fees from Phoenix Surgical Equipment (Thailand) Co., Ltd, personal fees from Amgen, personal fees from THAI ADK ENGINEERING COMPANY LIMITED, during the conduct of the study; In addition, Dr. Angthong has a patent Manufacture protocol for the artificial total talus (Thailand patent number: 14879) issued. This does not alter our adherence to PLOS ONE policies on sharing data and materials.

The homology and evolution of the archosaur ankle is a controversial topic that has been deeply studied using evidence from both extinct and extant taxa. In early stem archosaurs, the astragalus and calcaneum form the ancestral proximal tarsus and a single ossification composes the centrale series. In more recent stem archosaurs, the centrale is incorporated to the proximal row of tarsals laterally contacting the astragalus. This bone is subsequently lost as an independent ossification before the last common ancestor of birds and crocodilians, but the evolutionary fate of this element remains mostly unexplored. Here, we integrate embryological and palaeontological data with morphogeometric analyses to test the hypothesis of loss of the centrale or, alternatively, its incorporation into the archosaurian astragalus. Our results support the latter hypothesis, indicating that the astragalus developed ancestrally from two ossification centres in stem archosaurs and that the supposed tibiale of bird embryos represents a centrale. This conclusion agrees with previous embryological studies that concluded that the tibiale never develops in diapsids.

Objectives: The primate talus is known to have a shape that varies according to differences in locomotion and substrate use. While the modern human talus is morphologically specialized for bipedal walking, relatively little is known on how its morphology varies in relation to cultural and environmental differences across time. Here we compare tali of modern human populations with different subsistence economies and lifestyles to explore how cultural practices and environmental factors influence external talar shape., Materials and Methods: The sample consists of digital models of 142 tali from 11 archaeological and post-industrial modern human groups. Talar morphology was investigated through 3D (semi)landmark based geometric morphometric methods., Results: Our results show distinct differences between highly mobile hunter-gatherers and more sedentary groups belonging to a mixed post-agricultural/industrial background. Hunter-gatherers exhibit a more "flexible" talar shape, everted posture, and a more robust and medially oriented talar neck/head, which we interpret as reflecting long-distance walking strictly performed barefoot, or wearing minimalistic footwear, along uneven ground. The talus of the post-industrial population exhibits a "stable" profile, neutral posture, and a less robust and orthogonally oriented talar neck/head, which we interpret as a consequence of sedentary lifestyle and use of stiff footwear., Discussion: We suggest that talar morphological variation is related to the adoption of constraining footwear in post-industrial society, which reduces ankle range of motion. This contrasts with hunter-gatherers, where talar shape shows a more flexible profile, likely resulting from a lack of footwear while traversing uneven terrain. We conclude that modern human tali vary with differences in locomotor and cultural behavior., (© 2019 Wiley Periodicals, Inc.)

Sex determination is a pivotal step in forensic and bioarchaeological fields. Generally, scholars focus on metric or qualitative morphological features, but in the last few years several contributions have applied geometric-morphometric (GM) techniques to overcome limitations of traditional approaches. In this study, we explore sexual dimorphism in modern human tali from three early 20th century populations (Sassari and Bologna, Italy; New York, USA) at intra- and interspecific population levels using geometric morphometric (GM) methods. Statistical analyses were performed using shape, form, and size variables. Our results do not show significant differences in shape between males and females, either considering the pooled sample or the individual populations. Differences in talar morphology due to sexual dimorphism are mainly related to allometry, i.e. size-related changes of morphological traits. Discriminant function analysis using form space Principal Components and centroid size correctly classify between 87.7% and 97.2% of the individuals. The result is similar using the pooled sample or the individual population, except for a diminished outcome for the New York group (from 73.9% to 78.2%). Finally, a talus from the Bologna sample (not included in the previous analysis) with known sex was selected to run a virtual resection, followed by two digital reconstructions based on the mean shape of both the pooled sample and the Bologna sample, respectively. The reconstructed talus was correctly classified with a Ppost between 99.9% and 100%, demonstrating that GM is a valuable tool to cope with fragmentary tali, which is a common occurrence in forensic and bioarchaeological contexts., Competing Interests: The authors have declared that no competing interests exist.

Objectives: Finite element analysis has gained popularity in anthropological research to connect morphological form to measurable function but requires that loads are applied at appropriate anatomical locations. This is challenging for the ankle because the joint surfaces are not easily determined given their deep anatomical location. While the location of the talonavicular and subtalar joints can be directly determined via medical imaging, regression equations are a common, less invasive method to estimate joint locations from surface anatomy. We propose a regression-based method to locate the in vivo positions of the talonavicular and subtalar joints employing three-dimensional (3D) surface markers, such as those used routinely in gait studies., Methods: Navicular height was measured on weight-bearing radiographs (WBR) and simulated weight-bearing computed tomography (SWCT) scans to ensure SWCT correctly simulated foot weight-bearing configuration. The location of external foot markers and internal locations of the talonavicular and posterior subtalar joint were measured on each SWCT. Stepwise regression analysis was used to select the external markers that best predicted the three internal locations., Results: Navicular heights measured on WBR and SWCT scans were not statistically different (p = .44), indicating that SWCTs recreate the weight-bearing position of the foot. The navicular tubercle and medial and lateral malleoli were the best predictors of subtalar and talonavicular joint locations. These palpable anatomical locations explained more variation in internal joint location (r 2  > .79; SEE < 3.0 mm) than other landmarks., Discussion: This study demonstrates that external palpable landmarks can predict the location of the talonavicular and subtalar joints., (© 2019 Wiley Periodicals, Inc.)

Purpose: Despite the increased use of ankle dorsiflexion without distraction, no reports have specifically addressed the arthroscopic anatomy of the ankle in this position. The purpose of this study was to describe the normal arthroscopic anatomy of the ankle joint, when using the ankle dorsiflexion and the dynamic distraction technique, and to propose an arthroscopic examination system for the anterior ankle compartment., Methods: Ankle arthroscopy was performed in 20 fresh frozen specimens. Arthroscopic examination was performed with the arthroscope introduced through the anteromedial portal. The anterior compartment was examined in ankle dorsiflexion without distraction. The compartment was examined in four steps: (1) lateral area including the lateral gutter; (2) the central area of the anterior tibial rim; (3) the medial area including the medial gutter; (4) the talar neck. Next, distraction was applied to visualise the anterior compartment again and to examine the central and posterior ankle compartments., Results: Anatomic intra-articular structures were visualised in all specimens. Four intra-articular fat pads, one anteromedial, two syndesmotic and another posteromedial, were constantly observed. A description of the normal arthroscopic anatomy of the ankle using the ankle dorsiflexion and the dynamic distraction technique is detailed for the anterior, central and posterior compartments., Conclusion: The ankle arthroscopic procedure without distraction allows constant visualisation of the ATFL's superior fascicle on the floor of the lateral gutter, the ATiFL's distal fascicle laterally and the most anterior margin of the deltoid ligament in the medial gutter (anterior tibiotalar ligament). However, ankle distraction is required to observe the central and posterior compartments, but it does not provide optimal visualisation of the anterior ankle compartment structures., Level of Evidence: V.

Purpose: The anterior tibiofibular ligament (ATiFL) and its distal fascicle have been the subject of numerous studies, mainly due to the involvement of this ligament in anterolateral soft-tissue impingement of the ankle. There is currently no firm evidence related to the incidence of the distal fascicle or the frequency with which it is in contact with the talus, or whether this is a constant anatomic finding. In addition, the terminology used to refer to this structure is not accurate and varies widely in previous studies. The purpose of this study was to perform an anatomic study on a large number of specimens to clarify the anatomy of the anterior tibiofibular ligament, and specifically its distal fascicle, and its possible role in anterior ankle impingement syndrome., Methods: During a 7-year period (2010-2016), cadaveric ankle specimens dissected at our Anatomy Department were included in this study, accounting for a total of 154 ankles. The incidence of the distal fascicle and its contact with the talus were documented., Results: One hundred and seventeen ankles were included [78 men, 39 women, with a median age of 79.3 years (range 51-100 years)]. The ATiFL was found to have a distal fascicle in 100% of ankles, contacting the anterolateral part of the talus in all cases. The contact was increased in plantarflexion and reduced in dorsiflexion and finally disappeared completely in maximum dorsiflexion., Conclusions: The ATiFL has a constant distal fascicle that is in contact with the talus in the neutral position and in plantar flexion. Contact disappears in maximum dorsiflexion.

Traumatic injury and idiopathic avascular necrosis of the talus bone can result in osteochondral lesions of the talus leading to pain, motion loss, and disability. Treatment with osteochondral allografting currently requires the donor talus to be size matched to the recipient talus to ensure precise fits. Eliminating or reducing the need for size matching would lessen costs and the delay between diagnosis and treatment. 3D models of 12 tali of varying sizes were used to analyze curvatures and profiles of select areas on the talar dome. The allograft procedure was mimicked to compare the results between using 20mm and 30mm osteochondral allografts with, and without, donor size matching. The observed curvatures and profiles on the talar dome were found to be consistent between tali of different sizes. Size matching was not required to have acceptable levels of deviation between donor and recipient tali when using 20mm length segments. Deviations without size matching were found to be very similar to the deviations with size matching with only 14.8% of the fits without size matching having larger deviations (although less than 1.5mm) than those with size matching. Using the 30mm segments, there was a significant difference between the small female tali and the largest male tali. Thus, donor size matching is not necessary when treating large osteochondral lesions of the talus with an osteochondral allograft taken from the central 20mm of the donor talar dome, and only sex matching may be necessary for 30mm grafts., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Previous investigations of the primate talo-crural joint (TCJ; specifically on the talus and distal tibia) have demonstrated that substrate preference significantly influences morphology, but this association is not necessarily found in subadults. This has been interpreted as the result of a plastic, behaviorally induced response of bone due to substrate use. In this investigation, we use geometric morphometric and phylogenetic comparative methods to investigate ontogenetic phenotypic plasticity in the catarrhine TCJ. Osteological specimens from four African hominoid and four cercopithecid species, divided into subadult and adult developmental stages based on molar eruption, formed the study group. We tested for phylogenetic signal in the shape of both the talar and tibial articular surfaces, at both developmental stages. We then used phylomorphospaces to examine the evolution of shape differences at each developmental stage for each element, and to determine if substrate usage is associated with shape in this phylogenetic context. A significant phylogenetic signal was found for both articular surfaces in subadults, but not adults. In phylomorphospace, both talar and tibial articular morphologies show an association with substrate preference in adults, but not in subadults. Our results provide confirmation of the significant effect of habitual substrate usage and the consequences of bone remodeling during ontogeny on the shape and presentation of the TCJ. These results also suggest caution when using adult talo-tibial shapes to evaluate phylogenetic relationships as TCJ morphology can be considered as a palimpsest, with substrate usage overwriting phylogenetic information in adult specimens. Anat Rec, 302:1977-1984, 2019. © 2019 American Association for Anatomy., (© 2019 American Association for Anatomy.)

Background: Access to the talar dome for the treatment of osteochondral lesions (OCLs) can be achieved via several different approaches to the ankle joint. The recent description of an anatomical nine-grid scheme of the talus has proven useful to localise OCLs but no studies have demonstrated which approaches are indicated to access each of these zones. The aim of this study is to demonstrate the access afforded to each zone by each approach., Methods: Four standard soft tissue ankle approaches were performed simultaneously in ten fresh-frozen cadavers (anterolateral - AL, anteromedial - AM, posterolateral - PL, posteromedial - PM). The area of the talus, which was accessible with an instrument perpendicular to the surface was documented for each of the approaches. Using ImageJ software the surface area exposed with each approach was calculated. The talar dome was then divided using a nine-grid scheme and exposure to each zone was documented., Results: The AL, AM, PL and PM approaches allow for exposure of 24%, 25%, 5%, 7% of the talar dome respectively. The AL gives access to zones 3 (completely) and 2, 5, 6 (partially); the AM to zones 1 (completely) and 2, 4, 5 (partially); the PL to zones 9 and 8 (partially); and the PM to zones 7 and 8 (partially)., Conclusions: A large area of the talar dome cannot be easily accessed with the use of standard soft tissue approaches (39%). Minimal or no access is achieved for grid zones 4-6 and 8. In those instances careful preoperative planning is necessary and extended exposure can be achieved with the use of osteotomies, section of the ATFL or through modified approaches., (Copyright © 2018 European Foot and Ankle Society. Published by Elsevier Ltd. All rights reserved.)

Background: Thorough understanding of the morphometry of the ankle joint is crucial to optimize conservative and operative therapy of ankle joint disorders. Despite recent improvements, basic anatomic and biomechanical correlations of the ankle joint including the orientation of the ankle joint axis and joint morphology as its key biomechanical features are not sufficiently recorded to date. The aim of this study was the evaluation of the ankle morphometry to gain information about the ankle joint axis., Material and Methods: In this study 98 high-resolution CT-scans of complete Caucasian cadaver legs were analysed. Using the software Mimics and 3-Matic (Materialize) 22 anatomic parameters of the talocrural joint were assessed, including the length, width and surface area of the tibial and talar articular areas. Additionally, the radii of the articular areas, the medial distal tibial angle and the height of the talar dome were determined., Results: The radius of the central trochlea tali was 44.6±4.1mm (mean±SD). The central trochlea tali arc length was 40.8±3.0mm and its width was 27.4±2.5mm. Additionally we determined 47.0±4.4mm for the tibial sagittal radius, 27.6±3.0mm for the tibial arc length and 27.4±2.5mm for the central tibial width., Conclusion: The present study describes the three-dimensional morphometry of Caucasian ankle joints in detail. This dimensional analysis of the ankle joint will inform the development and placements of implants and prostheses., (Copyright © 2018 European Foot and Ankle Society. Published by Elsevier Ltd. All rights reserved.)

Bone shapes, particularly those defining the subtalar joint (STJ), have not received much attention yet as a risk factor for developing chronic ankle instability (CAI) after sustaining a lateral ankle sprain (LAS). This study aimed to compare three-dimensional (3D) shape variations in the STJ bones within individuals with CAI and healthy controls. 3D statistical shape models (SSMs) of the STJ bones were built to describe the bone shape variations observed within a population consisting of 26 individuals with unilateral CAI and 26 healthy controls. Using the SSMs and analysis of covariance test, age- and gender-adjusted shape variations in the bones were compared within individuals with CAI and healthy controls. The mean age of the CAI patients (14 males and 12 females) and healthy controls (12 males and 14 females) was 29 (standard deviation [SD] = 11) and 36 years (SD = 11), respectively. Tali and calcanei did not significantly vary between ipsilateral CAI and their contralateral ankle. Two shape modes, one for the talus (p = 0.015, variations in the curvature of the talar lateral process and the inclination angle of the talar neck relative to the body) and one for the calcaneus (p = 0.003, variations in the medial and lateral tuberosities, and the contour of the anterior articular surface), described significant shape differences between the CAI patients and healthy controls. The CAI patients generally had flatter talar joint surfaces and a flattened calcaneal ground-contact surface. These findings suggest that specific bone shapes may increase the risk of developing CAI after sustaining a LAS. © 2019 The Authors. Journal of Orthopaedic Research ® Published by Wiley Periodicals, Inc. on behalf of Orthopaedic Research Society. J Orthop Res 37:1892-1902, 2019., (© 2019 The Authors. Journal of Orthopaedic Research® Published by Wiley Periodicals, Inc. on behalf of Orthopaedic Research Society.)

Objectives: In this study, we reexamined the body mass estimate for the Homo erectus specimen KNM-ER 5428 based on talus dimensions. Previous estimates of >90 kg for this fossil are large in comparison to body mass estimates for other H. erectus specimens., Materials and Methods: The study sample consisted of tali and femora of 132 modern cadaver males from a documented body mass skeletal collection. We recorded the talus trochlear mediolateral (TTML) breadth and femoral head diameter (FHD) for each modern human specimen, and obtained KNM-ER 5428's TTML values from the literature. We developed regression formulae based on TTML using the body mass estimated from FHD for the entire human sample and for known body masses from a normal-BMI subsample, and then used these formulae to calculate body mass for KNM-ER 5428. In addition, we examined the range of body masses for individuals with TTML measurements comparable to KNM-ER 5428., Results: The body masses of normal-BMI individuals with a TTML ≥32.3 mm (the smaller of the two fossil measurements from the literature) ranged between 60.3 and 86.2 kg and averaged 72.3 kg. The body masses of normal-BMI individuals with a TTML ≥33.7 mm (the larger measurement) ranged between 63.5 and 86.2 kg with a mean of 73.6 kg. The correlations between TTML and body mass are moderate. Revised body mass point estimates for KNM-ER 5428 ranged between 69.2 and 81.6 kg based on TTML, and average 70.5 and 76.0 kg., Discussion: Results suggest previously published body mass estimates of KNM-ER 5428's are too large. Its body mass was likely between 70 and 76 kg rather than >90 kg., (© 2019 Wiley Periodicals, Inc.)

Background: Radiographic imaging of the foot is commonly performed when medical evaluation is indicated. Angular measurements between bones may be assessed as part of the examination for trauma and foot biomechanics. However, angular relationships between surfaces of the physical bone as they compare with the bone's radiographic image has had limited investigation., Methods: For this study, 54 human feet from amputated limbs were imaged in standard radiographic views and skeletonized. Selected angular measurements were taken on each skeletonized talus and calcaneus and were compared with those taken from radiographic images using paired Student t tests and linear regression analysis., Results: Transverse plane measurements of the talus were not significantly different ( P ≥ .05), associating strongly ( r 2 = 0.67-0.75; all P < .001). Most transverse and sagittal plane measurements of the calcaneus were not significantly different ( P ≥ .05), with transverse plane measurements more strongly associated ( r 2 = 0.70-0.77; all P < .001) than sagittal plane measurements ( r 2 = 0.35-0.78; all P < .001)., Conclusions: Selected angular measurements of the talus and calcaneus taken from radiographic images can be compared quantitatively with the physical bone, demonstrating that angular measurements from radiographic images provide useful information concerning both of these bones. This knowledge can be applied to the understanding of the morphology of the calcaneus and talus as it relates to human foot biomechanics and should also be of use in the interpretation of the human fossil pedal record.

Computational foot models have significant application in surgical decision making, injury and disease diagnosis and prevention, sports performance analysis and footwear engineering. However, due to the substantial time in model building and the heavy computational costs from the complexity of the models, daily clinical application of these foot models has yet to be achieved. Much of the previous research adopted a detailed-geometry approach in modeling bones that potentially contributed to the heavy computational costs. In this research, we developed a computational talus model based on CT section image data, image reconstruction and segmentation, contact surface identification, standard shape fitting, and finite element auto meshing algorithms. Modeling the bones as rigid is common, and modeling the contact surfaces only for the rigid body saves additional computational resources. Priority, therefore, in the shape fitting with optimization is given to the contact surfaces of the talus. Thirteen sets (9 males and 4 females) of CT section data were obtained. Image reconstruction, segmentation and bone labeling were conducted on each set of CT data to identify talus and its adjacent bones. Contact surfaces of the talus were then identified based on bone spatial relationships. Apart from the talar dome surface which was fitted by a 3rd-order polynomial, standard shapes such as ellipsoids and planes were used to fit the selected contact surfaces so that the geometrical parameters maintain physical significance. Based on these parameters, we automatically recreated and meshed the least-squares fitted shapes rapidly with limited elements. Last, mean major contact surfaces of the talus were obtained and fitted by standard shapes. Although the number of samples in this study was relatively small, our method provides sufficient and accurate geometric parameters of these contact surfaces to completely describe and reproduce the talus, on both a subject specific and average basis. The method for describing the talus here helps to parametrize computational models using planes and ellipsoids, improves surgical decision making and implants with a more precise and physically significant measures, and the description provides bone geometric parameters which can later be used to relate risk analysis for bone shape specific injury rates., (Copyright © 2019 IPEM. Published by Elsevier Ltd. All rights reserved.)

Adaptive scenarios of crown primate origins remain contentious due to uncertain order of acquisition and functional significance of the clade's diagnostic traits. A feature of the talus bone in the ankle, known as the posterior trochlear shelf (PTS), is well-regarded as a derived crown primate trait, but its adaptive significance has been obscured by poorly understood function. Here we propose a novel biomechanical function for the PTS and model the talus as a cam mechanism. By surveying a large sample of primates and their closest relatives, we demonstrate that the PTS is most strongly developed in extant taxa that habitually grasp vertical supports with strongly dorsiflexed feet. Tali of the earliest fossils likely to represent crown primates exhibit more strongly developed PTS cam mechanisms than extant primates. As a cam, the PTS may increase grasping efficiency in dorsiflexed foot postures by increasing the path length of the flexor fibularis tendon, and thus improve the muscle's ability to maintain flexed digits without increasing energetic demands. Comparisons are made to other passive digital flexion mechanisms suggested to exist in other vertebrates. These results provide robust anatomical evidence that the habitual vertical support use exerted a strong selective pressure during crown primate origins.

Given that most species of primates are predominantly arboreal, maintaining the ability to move among branches of varying sizes has presumably been a common selective force in primate evolution. However, empirical evaluations of the relationships between morphological variation and characteristics of substrate geometry, such as substrate diameter relative to an animal's body mass, have been limited by the lack of quantified substrate usage in the wild. Here we use recently published quantitative data to assess the relationships between relative substrate size and talar morphology in nine New World monkey species at the Tiputini Biodiversity Station, Ecuador. Within this sample, both fibular facet angle (the angle between the fibular facet and the trochlear rims) and body-mass-standardized area of the medial tibial facet decrease as average and maximum relative substrate size increases. Correlations between medial tibial facet area and relative substrate size are driven by the inclusion of callitrichids in this sample. Nevertheless, these findings strengthen the hypothesis that variation in fibular facet orientation and medial tibial facet area are functionally correlated with habitual degrees of pedal inversion. They also strengthen the notion that evolutionarily changing body mass could impact habitat geometry experienced by a lineage and thereby substantially impact major trends in primate morphological evolution. This study highlights the importance of empirical data on substrate use in living primates for inferring functional and evolutionary implications of morphological variation., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

In this study, the inferior fascicle of the anterior inferior tibiofibular ligament (AITFL) was classified to provide basic information to help elucidate the mechanism of ankle joint anterolateral impingement, and the morphological features of each type were compared for the purpose of clarification. This investigation examined 100 feet from 52 cadavers. The AITFL was classified into four types according to the presence or absence of the inferior fascicle and the positional relationship between the AITFL and the inferior fascicle of the AITFL. The morphological features of the AITFL that were measured included the fibre bundle length, fibre bundle width, fibre bundle angle, and the distance between the joint levels. A distinct, independent inferior fascicle of the AITFL was identified in 15 feet (15%). There were no significant differences in the morphological features based on differences in the AITFL classification. Therefore, these findings suggest that the presence or absence of the inferior fascicle and the difference in the positional relationship between the AITFL and the inferior fascicle of the AITFL are less likely to be involved in impingement during ankle dorsiflexion.

Anatomic knowledge of lateral ligaments around the lateral malleolus is important for repair or reconstruction of ankle instability. The detailed structure of the connective fibers between the anterior talofibular ligament (ATFL) and the calcaneofibular ligament (CFL) is unknown. To clarify the anatomic structure of ATFL and CFL and the connective fiber between the 2 ligaments, the lateral ligament was dissected in 60 ankles of formalin-fixed cadavers, and the distance was measured between bony landmarks and fibular attachment of ATFL and CFL using a digital caliper. All ankles had connective fibers between ATFL and CFL. The structure of connective fibers consisted of a thin fiber above the surface layer of ATFL and CFL; it comprised thin fibrils of the surface layer covering the lower part of ATFL and the front part of CFL. Both ATFL and CFL were independent fibers, and both attachments of the fibula were isolated. Single bands of ATFL were noted in 14 of 60 (23.3%) ankles, double bands that divided the superior and inferior bands were observed in 42 of 60 (70.0%) ankles, and multiple bands were observed in 4 of 60 (6.7%) ankles. A cord-like and a flat and fanning type of CFL was noted in 22 (36.7%) and 38 (63.3%) of the 60 ankles, respectively. Distances between ATFL/CFL and articular and inferior tips of the fibula were 4.3 ± 1.1 mm/7.6 ± 1.6 mm and 14.3 ± 1.9 mm/7.4 ± 1.7 mm, respectively (mean ± standard deviation). The results of this study suggest that knowledge of more anatomic structures of ATFL, CFL, and connective fiber will be beneficial for surgeons in the repair or reconstruction of the lateral ligament of the ankle., (Copyright © 2018 the American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.)

The use of mouse models as a tool to study ankle sprain requires a basic understanding of the similarities and differences between human and mouse ankle joint anatomy. However, few studies have been conducted that address the merits and drawbacks of these differences in the functioning of joints. Twenty hindfoot specimens were obtained from 10 male C57BL/6J mice and scanned using micro-CT. The foot and ankle skeletal structures were reconstructed in three dimensions. Morphological parameters were then measured using a plane projection method and normalized data were compared with those of human ankles. There was no significant difference in the malleolar width, maximal tibial thickness, tibial arc length, trochlea tali arc length or trochlea tali width of the mouse specimens compared with the human model. However, a groove was observed on the talar dome in the mouse specimens which was not observed in humans, the talar dome being more symmetric. The mouse ankle was to a large extent able to mimic the mechanism of a human ankle and so a mouse model could be appropriate for expanding our understanding of ankle biomechanics in general. However, the structural differences in the talar dome in the mouse and human should not be ignored. Although there are some differences in the mouse and human ankle that cannot be ignored, compared to other animals, the human ankle is more similar to that of the mouse.

Foot type has been associated with pain, injury, and altered gait mechanics. Morphological variations in foot bones due to foot type variation may impact surgical and therapeutic treatments. The purpose of this study was to utilize principal component analysis (PCA) to determine how morphology of the hind- and midfoot bones differs among foot types and sex. The calcaneus, talus, navicular, and cuboid were segmented using previously obtained computed tomography (CT) scans and converted to surface models. The CTs were sorted into four foot types-cavus, neutrally aligned, asymptomatic planus, and symptomatic planus. Morphometric shape analysis software (Geomorph) was used to perform a PCA to determine which components varied between foot types and between sexes. The calcaneus showed planus feet of both types to have calcanei that have decreased height and increased length compared to neutrally aligned feet. The talus demonstrated increased posterior mass for cavus feet compared to neutrally aligned feet. For the navicular, symptomatic planus had a more posteriorly positioned tuberosity and were wider than asymptomatic planus feet. The cuboid did not exhibit any differences between foot types. Sex differences, found only at the talus and navicular, were subtle. PCA is an objective technique that helped elucidate differences in bone morphology between foot types and sex without needing to determine the features of interest before comparing groups. Understanding these variations can help inform diagnosis of foot pathologies and surgical protocols as well as improve computer models of the foot. Published 2018. This article is a U.S. Government work and is in the public domain in the USA. J Orthop Res 9999:1-16, 2019., (Published 2018. This article is a U.S. Government work and is in the public domain in the USA.)

Accurate sorting of commingled human remains comprises a fundamental requirement for all further anthropological analyses. The lower limb bones are particularly important for reconstructing biological profiles. This study introduces a metric technique for sorting these elements using eight standard anthropological measurements and 222 adult individuals from Greece. The bones utilized were the os coxae, the femora, the tibiae and the tali. Simple regression analyses were used to develop functions for reassociating articulating bones, providing strong correlations (r = 0.74-0.95, p-value <0.05) and high coefficients of determination (r 2 =0.54-0.91). Blind tests demonstrated that combining metric and morphoscopic techniques provides an excellent sorting accuracy for the hip and knee joints (ten of ten individuals), allowing for a reliable reassociation between a sex and age indicator (os coxae) and a body size indicator (femur). Overall, these results indicate the high value of metric methods in sorting commingled human remains., (© 2018 American Academy of Forensic Sciences.)

Background:: Third generation total talar prostheses (TTPs) are viable options for talar avascular necrosis (AVN) in the absence of neighboring joint pathology. The use of modern three-dimensional (3D) printing allows the production of custom implants that exactly mimic the patient's anatomy. The aim of this study is to determine the accuracy of 3D printing in reproducing a synthetic talus and, in doing so, restoring more normal anatomical relationships. We hypothesize that this mode of replication will restore and maintain normal radiographic alignment of the ankle, subtalar, and forefoot joints in the setting of talar AVN., Methods:: A retrospective analysis was performed on all patients undergoing TTP implantation for the treatment of talar AVN between 2016 and 2017. Radiographic measurements were taken preoperatively and postoperatively to determine native talar dimensions, TTP implant dimensions, and the corresponding radiographic alignment about the forefoot, hindfoot, and ankle., Results:: A total of 14 patients were identified in our cohort. Talar arc length and width were not found to be significantly changed; however, talar height was significantly increased with use of TTP. Five alignment dimensions were measured, of which, only talar tilt angle was significantly changed. Instances of Meary's angle correction were observed in cavus and planus foot deformity., Conclusion:: As a proof of concept, 3D-printed TTP was successful in restoring talar height and talar tilt in the setting of AVN. Additionally, the procedure maintained normal alignment in nonpathological joints. TTPs, based on our cohort, are a viable option to restore more normal anatomical alignment., Levels of Evidence:: Level IV: Case series.

The bones forming the talocrural joint (TCJ) and subtalar joint (STJ) are often assumed to be bilaterally symmetric. Therefore, the contralateral limb (i.e. the fibula, tibia, calcaneus and talus) is used as a template or an intra-subject control in clinical and research practice. However, the validity of the symmetry assumption is controversial, because insufficient information is available on the shape variations and bilateral (a)symmetry of the fibula, tibia, calcaneus and talus. Using three-dimensional spatially dense sampled representations of bone shapes extracted from bilateral computed tomography scans of 66 individuals (55 male, mean age: 61 ± 10 years; 11 female, mean age: 53 ± 15 years), we analyzed whether: (i) similar shape patterns exist in the left and right bones of the same type; (ii) gender has an effect on bone shape variations; (iii) intra-subject shape variation is smaller than that of inter-subject for a given shape variance direction. For the first set of analyses, all left and right instances of the same type of bone were considered as two separate groups, and statistically compared with each other on multiple aspects including group location (central tendency), variance-covariance scale (dispersion) and orientation (covariance structure) using distance-based permutational tests. For the second and third sets of analyses, all left and right bones of the same type were pooled into one group, and shape variations in the TCJ and STJ bones were extracted using principal component analysis. The effects of gender on age-adjusted bone shape differences were assessed using an analysis of covariance. Moreover, intra-class correlation was employed to evaluate intra- and inter-subject bone shape variations. For each bone type, both sides had similar shape patterns (P permutational -values > 0.05). After Bonferroni adjustment, gender led to shape differences, which were mainly in the lateral and medial condyles of the tibia (P = 0.003), the length and height of the calcaneus (P < 0.001), the posterior and anterior talar articular surfaces of the calcaneus (P = 0.001), and in the posterior aspect of the talus (P = 0.001). Intra-subject shape variations in the tibial tuberosity together with the diameter of the tibia, and the curvature of the fibula shaft and the diameter of the fibula were as high as those of inter-subject. This result suggests that the shape symmetry assumption could be violated for some specific shape variations in the fibula and tibia., (© 2018 The Authors. Journal of Anatomy published by John Wiley & Sons Ltd on behalf of Anatomical Society.)

Purpose: The variations in the subtalar joint regarding its morphology and articulation of bones are common worldwide. This study aimed to analyze the morphometric variations in articulating facets of talus and calcaneum in South Indian population., Methods: For this study, the morphometric parameters of 92 dry tali and 49 dry calcanei of unknown gender were analyzed. The pattern of articulating facets was classified based on Boyan et al. as Type A (A1-A4), Type B (B1 and B2), and Type C., Results: Type B was found to be the most common pattern in the study population (talus-97.8%; calcaneus-80.2%). The morphometric parameters were expressed as mean ± 2 SD. The anteroposterior length of the left talus was more than right talus, while the transverse width of right and left talus is almost equal. The length of right sulcus tali appears to be more than left sulcus tali, whereas the width and depth of right and left sulcus tali was almost equal. The transverse width of the right calcaneus was greater than left calcaneus. Width and depth of right and left sulcus calcanei were almost equal, but the length of right sulcus calcanei was more than the left sulcus calcanei (p value - 0.036)., Conclusion: Analysis of the pattern of articulating facets of talus and calcaneum and establishing the common types and their morphometric parameters will be helpful as an important tool for reconstruction surgeries of hind-foot deformities and foot rehabilitation procedures.

Purpose: The purpose of this study is to clarify the morphological characteristics of the lateral talocalcaneal ligament (LTCL)., Methods: This study examined 100 legs from 54 Japanese cadavers. The LTCL was classified into three types: Type I, the LTCL branches from the calcaneofibular ligament (CFL); Type II, the LTCL is independent of the CFL and runs parallel to the calcaneus; and Type III, the LTCL is absent. The morphological features measured were fiber bundle length, fiber bundle width, and fiber bundle thickness., Results: The LTCL was classified as Type I in 18 feet (18%), Type II in 24 feet (24%), and Type III in 58 feet (58%). All LTCLs were associated with the anterior talofibular ligament at the talus. There was no significant difference in morphological characteristics by Type for each ligament., Conclusions: The LTCL was similar to the CFL in terms of fiber bundle width and fiber bundle thickness.

Purpose: The coupled behavior of talocrural joint motion is primarily determined by the morphological features of the talar trochlea and tibiofibular mortise. Features of the radius of curvature of the talocrural joint, however, remain unclear. The objectives of this study were to evaluate the radius of curvature at the mid, medial, and lateral regions of both the talar trochlea and the tibial plafond, and to estimate subject-specific kinematics of the talocrural joint., Methods: Computed tomography images of 44 subjects with healthy talocrural joints were assessed by creating three-dimensional bone models. The radii of curvature of the anterior and posterior regions at the mid, medial, and lateral regions of both the talar trochlea and the tibial plafond were calculated. Hypothetical dorsiflexion and plantarflexion axes of the talocrural joint were estimated from the shape of the talar trochlea. Orientations and distances of these axes were calculated., Results: At both the talar trochlea and the tibial plafond, the anteromedial and posteromedial radii exhibited the largest coefficients of variation. The anterior-to-posterior radius ratio (APRR) of the medial talar trochlea significantly correlated with the mid APRR, anterior medial-to-lateral radius ratio (MLRR), and posterior MLRR of the trochlea (r = 0.45, 0.52, - 0.60, respectively, and all P < 0.01)., Conclusions: The asymmetric shape of the medial talar trochlea seems to determine a fixed or changing axis of rotation at the talocrural joint. This subject-specific rotational axis of the talocrural joint should be considered in the management of patients with ankle injuries.

BACKGROUND With the complexity of calcaneal fracture (CF) increasing, its treatment has changed to include inserting the screw used to secure the facies articular posterior into the sustentaculum tail (ST). Some research progress has been made in this area, but there has been little in-depth research on the anatomical morphology of the sustentaculum tail, which is necessary for clinical surgery, and more information about Chinese anatomic characteristics and improved surgical techniques for CF are needed. MATERIAL AND METHODS This anatomical study, based on a three-dimensional (3D) computed tomographic (CT) reconstruction technique, included 287 dry calcaneus, consisting of 144 left and 143 right calcaneus. The images were reconstructed in 3D after CT scanning. Seven subjects were enrolled (L and R): (1) The vertical distance from inside the sustentaculum tail (IST) to inside the facies articularis talaris posterior; (2) The vertical distance from IST to the outside facies articularis talaris posterior; (3) The thickness of sulcus calcaneal nadir; (4) The distance from IST to processus medislis tuberis calcaneus; (5) The distance from IST to calcaneal posterosuperior tuber; (6) The angle of the prolate axial intersection between ST and calcaneus on the normal superior as ˂α; and (7) The angle of the prolate axial intersection between ST and calcaneus on the normal posterior as ˂β. All measurement results were analyzed by SPSS 22.0. RESULTS Based on morphological classification, the average length of AB, AC, AE, and AF on left ST were 16.956±1.391 mm, 37.803±2.525 mm, 43.244±3.617 mm, and 51.113±4.455 mm, respectively. Among the others, ˂β was 81.227±6.317 mm on the left and 74.581±9.008 mm on the right (P<0.05). CONCLUSIONS These results suggest better ways to treat the special characteristics and to reduce the risk of CF surgery.