An atlas of anatomical variants of the human calcaneus.

The usefulness of anatomical variation is determined by the knowledge of why nonmetric traits appear. Clear descriptions of the traits are a necessary task, due to the risk of confusing anatomical variants and evidence of trauma. Numerous interpretations of the appearance of calcaneal anatomical variants add to the need of an anatomical atlas of calcaneal nonmetric traits. We have analyzed a total of 886 calcanei; 559 belong to different modern and pre-Hispanic samples, and 327 bones were studied from a reference collection from Athens. In this study, we present the anatomical variations that exist on the calcaneus bone, some of which have rarely been mentioned in previous research. The standardization of methods proposed may be useful to experts working in human anatomy, physical anthropology as well as comparative morphology, due to usefulness of this information during surgery, and bioanthropology to observe and study the lifestyle of past populations.

Effect of sequential burr passes on osteotomy magnitude and calcaneal morphology in minimally invasive Zadek osteotomy.

PURPOSE: This study aimed to evaluate the impact of each burr pass on degree of correction, gap size and calcaneal morphology in MIS Zadek osteotomy. METHODS: MIS Zadek osteotomy was performed on ten cadaveric specimens using a 3.1 mm Shannon burr. After each burr pass, the osteotomy gap was manually closed, and the subsequent burr passes were carried out with the foot held in dorsiflexion, which was repeated five times. Lateral X-rays were taken before and after each burr pass. Two independent reviewers measured the dorsal calcaneal length after each burr passage, as well as changes in several calcaneal parameters including X/Y ratio, Fowler Philip angle, and Böhler angle. RESULTS: The average decrease in dorsal calcaneal cortical length with each burr pass was as follows: 2.6 ± 0.9 mm at the 1st pass, 2.4 ± 1 mm at the 2nd pass, 2 ± 1 mm at the 3rd pass, 1.6 ± 1 mm at the 4th pass, and 1.4 ± 0.7 mm at the 5th pass. The Fowler Philip and Böhler angles consistently decreased while the X/Y ratio consistently increased following each consecutive burr pass. Interobserver reliability analysis demonstrated good agreement for all parameters. CONCLUSION: The results revealed the trends of length and anatomical changes in the calcaneus with each burr pass. On average, a dorsal wedge resection of 10 mm was achieved after 5 burr passes. This data can aid surgeons in determining the optimal number of burr passes required for a particular amount of resection, ensuring the attainment of the desired patient-specific surgical outcome.

An anatomical approach to the tarsal tunnel syndrome: what can ankle's medial side anatomy reveal to us?

BACKGROUND: The heel is a complex anatomical region and is very often the source of pain complaints. The medial heel contains a number of structures, capable of compressing the main nerves of the region and knowing its anatomical topography is mandatory. The purpose of this work is to evaluate if tibial nerve (TN) and its main branches relate to the main anatomical landmarks of the ankle's medial side and if so, do they have a regular path after emerging from TN. METHODS: The distal part of the legs, ankles and feet of 12 Thiel embalmed cadavers were dissected. The pattern of the branches of the TN was registered and the measurements were performed according to the Dellon-McKinnon malleolar-calcaneal line (DML) and the Heimkes Triangle (HT). RESULTS: The TN divided proximal to DML in 87.5%, on top of the DML in 12,5% and distal in none of the feet. The Baxter's nerve (BN) originated proximally in 50%, on top of the DML in 12,5% and distally in 37.5% of the cases. There was a strong and significant correlation between the length of DML and the distance from the center of the medial malleolus (MM) to the lateral plantar nerve (LPN), medial plantar (MPN) nerve, BN and Medial Calcaneal Nerve (MCN) (ρ: 0.910, 0.866, 0.970 and 0.762 respectively, p <  0.001). CONCLUSIONS: In our sample the TN divides distal to DML in none of the cases. We also report a strong association between ankle size and the distribution of the MPN, LPN, BN and MCN. We hypothesize that location of these branches on the medial side of the ankle could be more predictable if we take into consideration the distance between the MM and the medial process of the calcaneal tuberosity.

3D characterization of the triple-bundle Achilles tendon from in vivo high-field MRI.

The Achilles tendon consists of three subtendons that transmit force from the triceps surae muscles to the calcaneus. Individual differences have been identified in Achilles subtendon morphology and twist in cadavers, which may have implications for triceps surae mechanics and function. High-field magnetic resonance imaging (MRI) can be used to identify boundaries within multi-bundle tissues, which could then enable studies of subtendon structure-function relationships in humans. The objective of this study was to use high-field MRI (7T) to image and reconstruct Achilles subtendons arising from the triceps surae muscles. We imaged the dominant lower leg of a cohort of healthy human subjects (n = 10) using a tuned musculoskeletal sequence (double echo steady state sequence, 0.4 mm isotropic voxels). We then characterized the cross-sectional area and orientation of each subtendon between the MTJ and calcaneal insertion. Image collection and segmentation was repeated to assess repeatability. Subtendon morphometry varied across subjects, with average subtendon areas of 23.5 ± 8.9 mm2 for the medial gastrocnemius, 25.4 ± 8.9 mm2 for the lateral gastrocnemius, and 13.7 ± 5.9 mm2 for the soleus subtendons. Repeatable subject-specific variations in size and position of each subtendon were identified over two visits, expanding on prior knowledge that high variability exists in Achilles subtendon morphology across subjects.

Sustentaculum tali in Chinese population: anatomy and clinical significance.

BACKGROUND: Previous studies lacked adequate quantitative data on sustentaculum tali (ST), especially in Chinese population. The aims of this study are to explore the quantitative morphology of ST in dried bone specimens, and to discuss its implications related to ST screw fixation, talar articular facet variation, as well as subtalar coalitions. METHODS: A total of 965 dried intact calcanei from Chinese adult donors were evaluated. All linear parameters were measured by two observers with a digital sliding vernier caliper. RESULTS: Most parts of ST body can accommodate a commonly-used 4-mm-diameter screw, but the minimum height of anterior ST is only 4.02 mm. The shapes of the STs are slightly affected by left-right, subtalar facet, but the subtalar coalition may potentially increase the sizes of STs. The incidence of tarsal coalition is 14.09%. Among the osseous connection, there are 58.8% of type A articular surface and 76.5% of middle and posterior talar facet (MTF and PTF) involvement. ROC curve shows that subtalar coalition will be detected when ST length is greater than 16.815 mm. CONCLUSIONS: Theoretically, all the STs can accommodate 4 mm diameter screw, but a 3.5 mm diameter screw is recommended to be placed in the middle or posterior of the small ST for safety. The shapes of the STs are greatly influenced by the subtalar coalition, while they are less affected by left-right, subtalar facet. The osseous connection is common in type A articular surface and always involved in the MTF and PTF. The cut-off value of the length of STs was confirmed as 16.815 mm for predicting subtalar coalition.

Anatomic Description of the Calcaneocuboid Joint: Implications for Staple Fixation.

Understanding the anatomy of the calcaneocuboid (CCJ) remains essential when selecting staple fixation to optimize osseous purchase during rearfoot procedures. This anatomic study quantitatively describes the CCJ in relation to staple fixation sites. The calcaneus and cuboid from 10 cadavers were dissected. Widths at 5 mm and 10 mm increments away from the joint were measured in dorsal, midline, and plantar thirds of each bone. The widths between each position's 5 mm and 10 mm increments were compared using the Student's t test. The widths among the positions at both distances were compared using an ANOVA then post hoc testing. Statistical significance was set at p ≤ 0.05. The middle (23 ± 3 mm) and plantar third (18 ± 3 mm) of the calcaneus at the 10 mm interval was greater than the 5 mm interval (p = .04). At 5 mm distal to the CCJ, the dorsal third of the cuboid maintained a statistically significant greater width than the plantar third (p = .02). The 5 mm (p = .001) and 10 mm (p = .005) dorsal calcaneus widths as well as the 5 mm (p = .003) and 10 mm (p = .007) middle calcaneus widths were significantly greater than the plantar widths. This investigation supports the use of 20 mm staple 10 mm away from the CCJ in dorsal and midline orientations. Care should be taken when placing a plantar staple within 10 mm proximal to the CCJ as the legs may extend beyond the medial cortex compared to dorsal and midline placements.

A comparison of effectiveness of sex estimation from the calcaneus and talus in a Thai population / Comparación de la efectividad de la estimación del sexo a partir del calcáneo y el talus en una población tailandesa

SUMMARY: Sex estimation is an important aspect of skeletal identification. In addition, previous studies have found that the sex estimation of each race is different. Thus, it is necessary to develop discriminant function equations for the estimation of sex for the Thai population. This study aims to investigate the relationship between width, length and height of the calcaneus and talus with regards to sex and compare the effectiveness of sex estimation between the calcaneus alone, the talus alone, and between both the calcaneus and talus. A total of 200 individuals (100 males and 100 females) were used in this study; ages ranged from 19 to 94 years. Thirteen variables of calcaneus and ten variables of talus were measured. The authors created discriminant function equations for the estimation of sex and tested the efficiency of the equations obtained by using a test group of 40 individuals (20 males and 20 females). By analyzing the mean values of the variables in the calcaneus and the talus, it was shown that males were significantly different from females (p0.05). A stepwise method was used to create 6 equations for sex estimation. The equations were categorized from between the calcaneus alone, the talus alone, and between both the calcaneus and the talus, providing a sex estimation accuracy of between 88.5 and 93.0 %. Using the test group, it was shown that discriminant function equations from the calcaneus alone, the talus alone, and the calcaneus and the talus together, can estimate sex at a high level of accuracy. Sex estimation accuracy was greater than 85 % in all equations. Therefore, the discriminant function equations from the calcaneus alone, the talus alone, and between both the calcaneus and the talus, from this study can be applied to the Thai population.

La estimación del sexo es un aspecto importante de la identificación esquelética. Estudios previos han encontrado que la estimación del sexo de cada raza es diferente. Por lo tanto, es necesario desarrollar ecuaciones de funciones discriminantes para la estimación del sexo de la población tailandesa. Este estudio tuvo como objetivo investigar la relación entre el ancho, el largo y la altura de los huesos calcáneo y talus con respecto al sexo y comparar la efectividad de la estimación del sexo entre el calcáneo solo, el talus solo y entre el calcáneo y el talus. Se utilizaron un total de 200 huesos de individuos adultos (100 hombres y 100 mujeres), cuyas edades oscilaron entre 19 y 94 años. Se midieron trece variables del calcáneo y diez variables del talus. Los autores crearon ecuaciones de funciones discriminantes para la estimación del sexo y probaron la eficiencia de ellas usando un grupo de prueba de huesos de 40 individuos (20 hombres y 20 mujeres). Al analizar los valores medios de las variables en el calcáneo y el talus, se demostró que los huesos de los hombres eran significativamente diferentes al de las mujeres (p0.05). Se utilizó un método paso a paso para crear 6 ecuaciones para la estimación del sexo. Las ecuaciones se clasificaron entre el calcáneo solo, el talus solo y entre el calcáneo y el talus, lo que proporcionó una precisión de estimación del sexo de entre 88,5 y 93,0 %. Usando el grupo de prueba, se demostró que las ecuaciones de funciones discriminantes del calcáneo solo, el talus solo y el calcáneo y el talus juntos pueden estimar el sexo con un alto nivel de precisión. La precisión de la estimación del sexo fue superior al 85 % en todas las ecuaciones. Por lo tanto, las ecuaciones de la función discriminante del calcáneo solo, el talus solo y entre el calcáneo y el talus de este estudio se pueden aplicar a la población tailandesa.

Three-dimensional morphological variations in the calcaneus and talus in relation to the hallux valgus angle.

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.

Investigation of the relationship between foot deformities and radiographic measurements of the talus and calcaneus / Investigación de la relación entre las deformidades del pie y las mediciones radiográficas del talo y del calcáneo

SUMMARY: The weight of the body is transmitted to the foot through the subtalar joint and talus. Considering the important location of the talus and calcaneus, the morphological structures of these bones may affect the biomechanics of the subtalar joint. At the same time, the morphological structure of these bones is important in some common foot deformities. We aimed to investigate whether the various measurements of the talus and calcaneus are associated with different foot deformities in this study. In this study, radiography images of 158 (72 male and 86 female) patients within the mean age of 44 years were retrospectively examined. Eleven different measurements of the talus and calcaneus were obtained from the lateral and antero-posterior radiographs of the patients. A total of 158 patient's routine clinic radiographs were retrospectively assessed, which have calcaneal spur (n=63), hallux valgus (n=32) and control group (n=63). We determined that the body height of the calcaneus, maximum width of the head of the talus, minimum anterior width of the calcaneus were significantly different between calcaneal spur group and control group. Maximum length fibular malleolar facet of the talus was significantly different between age groups. And we determined that the calcaneal index was significantly different between hallux valgus group and control groups. Also all measurements were significantly different between males and females. As a result, some measurements that significantly determine the morphology of the talus and calcaneus were found to be significant between deformity groups and control groups. We think that our study will contribute to the literature as it is the first study in which the measurements obtained from the radiographic images of the talus and calcaneus are associated with foot deformities.

El peso del cuerpo se transmite al pie a través de la articulación subtalar y el talo. Teniendo en cuenta la importante ubicación del talo y el calcáneo, las estructuras morfológicas de estos huesos pueden afectar la biomecánica de la articulación subtalar. Al mismo tiempo, la estructura morfológica de estos huesos es importante en algunas deformidades comunes del pie. Nuestro objetivo fue investigar si las diversas medidas del talo y el calcáneo están asociadas con diferentes deformidades del pie en este estudio. Se examinaron retrospectivamente imágenes radiográficas de 158 pacientes (72 hombres y 86 mujeres) con una edad promedio de 44 años. Se obtuvieron once medidas diferentes del talo y el calcáneo a partir de las radiografías lateral y anteroposterior de los pacientes. Se evaluaron retrospectivamente un total de 158 radiografías clínicas de rutina de los pacientes, los cuales tenían espolón de calcáneo (n=63), hallux valgus (n=32) y grupo control (n=63). Determinamos que la altura del cuerpo del calcáneo, el ancho máximo de la cabeza del talo, el ancho anterior mínimo del calcáneo fueron significativamente diferentes entre el grupo con espolón calcáneo y el grupo control. La longitud máxima de la faceta maleolar fíbular del talo era significativamente diferente entre los grupos de edad. También determinamos que el índice calcáneo fue significativamente diferente entre el grupo de hallux valgus y los grupos controles. Además, todas las medidas fueron significativamente diferentes entre hombres y mujeres. Como resultado, algunas medidas que determinan la morfología del talo y el calcáneo resultaron significativas entre los grupos de deformidad y los grupos controles. Estimamos que nuestro estudio contribuirá a la literatura debido a que es el primer reporte en el que las medidas obtenidas de las imágenes radiográficas del talo y el calcáneo se asocian con deformidades del pie.

A new early hominin calcaneus from Kromdraai (South Africa).

The Kromdraai site in South Africa has yielded numerous early hominin fossils since 1938. As a part of recent excavations within Unit P, a largely complete early hominin calcaneus (KW 6302) was discovered. Due to its role in locomotion, the calcaneus has the potential to reveal important form/function relationships. Here, we describe KW 6302 and analyze its preserved morphology relative to human and nonhuman ape calcanei, as well as calcanei attributed to Australopithecus afarensis, Australopithecus africanus, Australopithecus sediba, Homo naledi, and the Omo calcaneus (either Paranthropus or early Homo). KW 6302 calcaneal morphology is assessed using numerous quantitative metrics including linear measures, calcaneal robusticity index, relative lateral plantar process position, Achilles tendon length reconstruction, and a three-dimensional geometric morphometric sliding semilandmark analysis. KW 6302 exhibits an overall calcaneal morphology that is intermediate between humans and nonhuman apes, although closer to modern humans. KW 6302 possesses many traits that indicate it was likely well-adapted for terrestrial bipedal locomotion, including a relatively flat posterior talar facet and a large lateral plantar process that is similarly positioned to modern humans. It also retains traits that indicate that climbing may have remained a part of its locomotor repertoire, such as a relatively gracile tuber and a large peroneal trochlea. Specimens from Kromdraai have been attributed to either Paranthropus robustus or early Homo; however, there are no definitively attributed calcanei for either genus, making it difficult to taxonomically assign this specimen. KW 6302 and the Omo calcaneus, however, fall outside the range of expected variation for an extant genus, indicating that if the Omo calcaneus was Paranthropus, then KW 6302 would likely be attributed to early Homo (or vice versa).

A morphometric analysis of early Eocene Euprimate tarsals from Gujarat, India.

Early Eocene primate postcranial bones from the Vastan lignite mine of Gujarat, India, have proven useful for understanding the haplorhine and strepsirrhine divergence. Previous analyses of material assigned to Asiadapidae supported interpretations that these primates were generalized arboreal quadrupeds, while the omomyid Vastanomys was likely to have been more proficient leaper than asiadapids. More recent examinations of long bone cross-sectional properties and calcaneal elongation have complicated the behavioral interpretations of these fossils. This study examines whole talar and calcaneal morphology of the Vastan material to refine the locomotor reconstructions of these fossils. A comparative sample of extant primate species representing various locomotor behaviors was obtained by accessing surface models from MorphoSource.org. Surface models of fossil specimens attributed to Asiadapis cambayensis, Marcgodinotius indicus, and Vastanomys major were generated from micro-computed tomography scans. A morphological analysis was carried out using weighted spherical harmonics, a Fourier-based method that represents surfaces using coefficients associated with a common set of spherical harmonic functions. The coefficients describing each surface were then used as shape variables in a principal components analysis. Significant differences between locomotor groups were assessed using nonparametric tests. Results from extant comparative samples show that locomotor behavior can be predicted from both talar and calcaneal morphology when phylogenetic relationships are known. Consistent with previous analyses, our results indicate that Asiadapis cambayensis and Marcgodinotius indicus were likely arboreal quadrupeds with some leaping capabilities. Vastanomys major is reconstructed as an arboreal quadruped with greater leaping proficiency than its asiadapid counterparts based on its talar morphology.

Growth and development of trabecular structure in the calcaneus of Japanese macaques (Macaca fuscata) reflects locomotor behavior, life history, and neuromuscular development.

Bone structure dynamically adapts to its mechanical environment throughout ontogeny by altering the structure of trabecular bone, the three-dimensional mesh-like structure found underneath joint surfaces. Trabecular structure, then, can provide a record of variation in loading directions and magnitude; and in ontogenetic samples, it can potentially be used to track developmental shifts in limb posture. We aim to broaden the analysis of trabecular bone ontogeny by incorporating interactions between ontogenetic variation in locomotor repertoire, neuromuscular maturation, and life history. We examine the associations between these variables and age-related variation in trabecular structure in the calcaneus of Japanese macaques (Macaca fuscata). We used high-resolution micro-computed tomography scanning to image the calcaneus in a cross-sectional sample of 34 juvenile M. fuscata aged between 0 and 7 years old at the Primate Research Institute, Japan. We calculated whole bone averages of standard trabecular properties and generated whole-bone morphometric maps of bone volume fraction and Young's modulus. Trabecular structure becomes increasingly heterogeneous in older individuals. Bone volume fraction (BV/total volume [TV]) decreases during the first month of life and increases afterward, coinciding with the onset of independent locomotion in M. fuscata. At birth, primary Young's modulus is oriented orthogonal to the ossification center, but after locomotor onset bone structure becomes stiffest in the direction of joint surfaces and muscle attachments. Age-related variation in bone volume fraction is best predicted by an interaction between the estimated percentage of adult brain size, body mass, and locomotor onset. To explain our findings, we propose a model where interactions between age-related increases in body weight and maturation of the neuromuscular system alter the loading environment of the calcaneus, to which the internal trabecular structure dynamically adapts. This model cannot be directly tested based on our cross-sectional data. However, confirmation of the model by longitudinal experiments and in multiple species would show that trabecular structure can be used both to infer behavior from fossil morphology and serve as a valuable proxy for neuromuscular maturation and life history events like locomotor onset and the achievement of an adult-like gait. This approach could significantly expand our knowledge of the biology and behavior of fossil species.

Comparing and combining sliding semilandmarks and weighted spherical harmonics for shape analysis.

Quantifying morphological variation is critical for conducting anatomical research. Three-dimensional geometric morphometric (3D GM) landmark analyses quantify shape using homologous Cartesian coordinates (landmarks). Setting up a high-density landmark set and placing it on all specimens, however, can be a time-consuming task. Weighted spherical harmonics (SPHARM) provides an alternative method for analyzing the shape of such objects. Here we compare sliding semilandmark and SPHARM analyses of the calcaneus of Gorilla gorilla gorilla (n = 20), Pan troglodytes troglodytes (n = 20), and Homo sapiens (n = 20) to determine whether the SPHARM and sliding semilandmark analyses capture comparable levels of shape variation. We also compare both the sliding semilandmark and SPHARM analyses to a novel combination of the two methods, here termed SPHARM-sliding. In SPHARM-sliding, the vertices of the surface models produced from the SPHARM analysis (that are the same in number and relative location) are used as the starting landmark positions for a sliding semilandmark analysis. Calcaneal shape variation quantified by all three analyses was summarized using separate principal components analyses. Results were compared using the root mean square (RMS) and maximum distance between surface models of species averages scaled (up) to centroid size created from each analysis. The average RMS was 0.23 mm between sliding semilandmark and SPHARM average surface models, 0.19 mm between SPHARM and SPHARM sliding average surface models, and 0.22 mm between sliding semilandmark and SPHARM sliding average surface models. Although results indicate that all three analyses are comparable methods for 3D shape analysis, there are advantages and disadvantages to each. While the SPHARM analysis is less time-intensive, it is unable to capture the same level of detail around the sharp edges of articular facets on average surface models as the sliding semilandmark analysis. The SPHARM analysis also does not allow for individual articular facets to be analyzed in isolation. SPHARM-sliding, however, captures the same level of detail as the sliding semilandmark analysis, and (as in the sliding semilandmark analysis) allows for the evaluation of individual portions of bone. SPHARM is a comparable method to a 3D GM analysis for small, irregularly shaped bones, such as the calcaneus, and SPHARM-sliding allows for an expedited set up process for a sliding semilandmark analysis.

Ecomorphology of the cervid calcaneus as a proxy for paleoenvironmental reconstruction.

This study presents new ecomorphological models for the cervid calcaneus that can be used to make predictions about the nature of ancient environments. Using geometric morphometrics to quantitatively assess the length of the articular surface supporting the malleolus, the length and orientation of the tuber calcanei, and the position of the articular facets, we aimed to establish correlations between morphological traits, locomotor behavior, and environmental parameters in extant cervids. The morphology of the calcaneus was found to primarily vary with locomotor strategy and habitat, along a continuum from habitats with an open vegetation structure to habitats with a closed vegetation structure. Confounding factors, including sexual dimorphism, allometry, and phylogeny were accounted for using Principal Component Analysis, regressions and phylogenetic comparative methods. The results of our analyses suggested that these factors did not substantially obscure habitat predictions. As such, the calcaneus provides a valuable proxy for paleoenvironmental reconstruction that is broadly applicable to Quaternary fossil assemblages with a sufficiently large sample of cervids.

Morphological differences in the calcaneus among extant great apes investigated by three-dimensional geometric morphometrics.

Investigating the morphological differences of the calcaneus in humans and great apes is crucial for reconstructing locomotor repertories of fossil hominins. However, morphological variations in the calcaneus of the great apes (chimpanzees, gorillas, and orangutans) have not been sufficiently studied. This study aims to clarify variations in calcaneal morphology among great apes based on three-dimensional geometric morphometrics. A total of 556 landmarks and semilandmarks were placed on the calcaneal surface to calculate the principal components of shape variations among specimens. Clear interspecific differences in calcaneal morphology were extracted, corresponding to the degree of arboreality of the three species. The most arboreal orangutans possessed comparatively more slender calcaneal tuberosity and deeper pivot region of the cuboid articular surface than chimpanzees and gorillas. However, the most terrestrial gorillas exhibited longer lever arm of the triceps surae muscle, larger peroneal trochlea, more concave plantar surface, more inverted calcaneal tuberosity, more everted cuboid articular surface, and more prominent plantar process than the orangutans and chimpanzees. These interspecific differences possibly reflect the functional adaptation of the calcaneus to locomotor behavior in great apes. Such information might be useful for inferring foot functions and reconstructing the locomotion of fossil hominoids and hominids.

Calcaneal Fractures-Which Approach for Which Fracture?

Treatment of calcaneal fractures has to be tailored to the individual pathoanatomy. If operative treatment is chosen, anatomic reconstruction of the calcaneal shape and joint surfaces is mandatory. For most of the displaced, intraarticular fractures, this can be achieved by less invasive reduction and fixation via a sinus tarsi approach, which may be extended along the "lateral utility" line for calcaneocuboid joint involvement or calcaneal fracture-dislocations. Purely percutaneous fixation is the treatment of choice for displaced extraarticular fractures and simple intraarticular fractures with adequate control of joint reduction. Specific approaches are used for rare calcaneal fracture variants.

Calcaneal shape variation in humans, nonhuman primates, and early hominins.

The foot has played a prominent role in evaluating early hominin locomotion. The calcaneus, in particular, plays an important role in weight-bearing. Although the calcanei of early hominins have been previously scrutinized, a three-dimensional analysis of the entire calcaneal shape has not been conducted. Here, we investigate the relationship between external calcaneal shape and locomotion in modern Homo sapiens (n = 130), Gorilla (n = 86), Pan (n = 112), Pongo (n = 31), Papio (n = 28), and hylobatids (Hylobates, Symphalangus; n = 32). We use these results to place the calcanei attributed to Australopithecus sediba, A. africanus, A. afarensis, H. naledi, and Homo habilis/Paranthropus boisei into a locomotor context. Calcanei were scanned using either surface scanning or micro-CT and their external shape analyzed using a three-dimensional geometric morphometric sliding semilandmark analysis. Blomberg's K statistic was used to estimate phylogenetic signal in the shape data. Shape variation was summarized using a principal components analysis. Procrustes distances between all taxa as well as distances between each fossil and the average of each taxon were calculated. Blomberg's K statistic was small (K = 0.1651), indicating weak phylogenetic effects, suggesting variation is driven by factors other than phylogeny (e.g., locomotion or body size). Modern humans have a large calcaneus relative to body size and display a uniquely convex cuboid facet, facilitating a rigid midfoot for bipedalism. More arboreal great apes display relatively deeper cuboid facet pivot regions for increased midfoot mobility. Australopithecus afarensis demonstrates the most human-like calcaneus, consistent with obligate bipedalism. Homo naledi is primarily modern human-like, but with some intermediate traits, suggesting a different form of bipedalism than modern humans. Australopithecus africanus, A. sediba, and H. habilis/P. boisei calcanei all possess unique combinations of human and nonhuman ape-like morphologies, suggesting a combination of bipedal and arboreal behaviors.

Morphological variability of the plantaris tendon in the human fetus.

Muscular anatomy often differs between species and individuals. In particular, the plantaris muscle (PM) demonstrates great morphological variability in its course and its proximal and distal attachments. The aim of this study was to investigate the morphological variation of the PM tendon in human fetuses. Forty-six spontaneously aborted human fetuses (23 male, 23 female) aged 18-38 weeks of gestation were studied. Morphology of the attachment of the PM was assessed in both lower extremities (n = 92). The PM was present in 72 lower limbs (78.26%) and absent in 20 (21.74%). Eight types of PM distal attachment were identified. We propose an eight-fold classification of PM insertion in fetuses. Leg length, length of tendon, extension point (ExP) from the calcaneus, and ExP thickness differed significantly among types of PM insertion.

Evaluation of computed tomography images of calcaneus for estimation of sex.

Estimation of sex from bone remnants after medicolegal issues or mass disasters constitute a challenge. Our objective was to investigate if morphometric measurements performed on computed tomography (CT) images of the calcaneus can be useful for sex estimation. The measurements were performed on CT images of calcaneus bones of 489 patients (203 women, 286 men). The parameters under investigation were maximum length (MAXL), load arm length (LAL), minimum breadth (MINB), body height (BH), maximum height (MAXH), dorsal articular facet length (DAFL), dorsal articular facet breadth (DAFB), and cuboidal facet height (CFH). All parameters were remarkably increased in men compared to women (p < 0.001, for all). The highest performances for sex estimation were displayed by DAFL (92.8%) and BH (92.6%). The concomitant use of variables MAXL, BH, CFH, and DAFL revealed accuracy as high as 96% for gender discrimination. We suggest that morphometric measurements performed on CT images of the calcaneus can provide useful data for the estimation of sex.

Three-Dimensional Printing-Assisted Masquelet Technique in the Treatment of Calcaneal Defects.

OBJECTIVE: The aim of the present study was to summarize the clinical efficacy of three-dimensional (3D) printing technology combined with the Masquelet technique in the treatment of calcaneal defects. METHODS: From January 2018 to April 2019, 3D printing combined with induced masquelet technology was used to treat four patients with calcaneal defects, including two men and two women. The patients were aged 22-52 years old, with an average age of 36 years. There were two cases of traffic accident injuries, there was one case of a fall from height, and there was one case of crush injury. CT scans were used to reconstruct the bilateral calcaneus, mirror technology was used to construct the bone defect area, and Materialise 3-matic software was used to design the calcaneus shaper mold and 3D print the mold. During the operation, the mold was used to shape the bone cement and fill the bone defect. In the second stage, the bone cement was removed and autologous bone was implanted to repair the bone defect. All patients were followed up to observe the effect. RESULTS: All four patients were followed up for 14 months (range, 10-18 months). There were three cases of infectious bone defects: two cases of Escherichia coli and one case of Pseudomonas aeruginosa. The 3D printed mold was used to shape the bone cement. During the operation, it was found to have a high degree of matching with the defect area of calcaneus. There is no need to adjust it again, and the wound healed well after the first stage. In the second stage of surgery, it was found that the induced membrane formed was complete and of appropriate size; the bone cement was easily removed during the operation. The fracture healing time was 3-6 months, with an average of 4 months. At the last follow up, there was no pain and the patients walked with full weight bearing. The Maryland score was 94 points (range, 88-98 points); three cases were excellent and one case was good. The AOFAS score ranged from 86 to 98, with an average of 92.8 points; three cases were excellent and one case was good. CONCLUSION: Three-dimensional printing technology combined with induced membrane technology is an effective approach for treating calcaneal bone defects.