Brief communication: Cineradiographic analysis of the chimpanzee (Pan troglodytes) talonavicular and calcaneocuboid joints

During terrestrial locomotion, chimpanzees exhibit dorsiflexion of the midfoot between midstance and toe‐off of stance phase, a phenomenon that has been called the “midtarsal break.” This motion is generally absent during human bipedalism, and in chimpanzees is associated with more mobile foot joints than in humans. However, the contribution of individual foot joints to overall foot mobility in chimpanzees is poorly understood, particularly on the medial side of the foot. The talonavicular (TN) and calcaneocuboid (CC) joints have both been suggested to contribute significantly to midfoot mobility and to the midtarsal break in chimpanzees. To evaluate the relative magnitude of motion that can occur at these joints, we tracked skeletal motion of the hindfoot and midfoot during passive plantarflexion and dorsiflexion manipulations using cineradiography. The sagittal plane range of motion was 38 ± 10° at the TN joint and 14 ± 8° at the CC joint. This finding indicates that the TN joint is more mobile than the CC joint during ankle plantarflexion–dorsiflexion. We suggest that the larger range of motion at the TN joint during dorsiflexion is associated with a rotation (inversion–eversion) across the transverse tarsal joint, which may occur in addition to sagittal plane motion. Am J Phys Anthropol 154:604–608, 2014. © 2014 Wiley Periodicals, Inc.     

Three-dimensional in vivo motion of adult hind foot bones

Knowledge of hind foot bone motion is important for understanding gait as well as various foot pathologies, but the three-dimensional (3D) motion of these bones remains incompletely understood. The purpose of this study was to quantify the motion of the talus, calcaneus, navicular, and cuboid in normal adult feet during open chain quasi-static uniplanar plantar flexion motion. Magnetic resonance images of the right feet of six normal young adult males were taken from which 3D virtual models were made of each hind foot bone. The 3D motion of these models was analyzed. Each hind foot bone rotated in the same plane about half as much as the foot (mean 0.54 degrees of bone rotation per degree of foot motion, range 0.40-0.73 degrees per degree of foot motion as measured relative to the fixed tibia). Talar motion was primarily uniaxial, but the calcaneus, navicular, and cuboid bones exhibited biplanar (sometimes triplanar) translation in addition to biaxial rotation. Net translational motions of these bones averaged 0.39 mm of bone translation per degree of foot motion (range 0.06-0.62 mm per degree of foot motion). These data reflect the functional anatomy of the foot, extend the findings of prior studies, provide a standard for comparison to patients with congenital or acquired foot deformities, and establish an objective reference for quantitatively assessing the efficacy of various hind foot therapies.     

Apparent density of the primate calcaneo‐cuboid joint and its association with locomotor mode,foot posture,and the “midtarsal break”

Primates use a range of locomotor modes during which they incorporate various foot postures. Humans are unique compared with other primates in that humans lack a mobile fore‐ and midfoot. Rigidity in the human foot is often attributed to increased propulsive and stability requirements during bipedalism. Conversely, fore‐ and midfoot mobility in nonhuman primates facilitates locomotion in arboreal settings. Here, we evaluated apparent density (AD) in the subchondral bone of human, ape, and monkey calcanei exhibiting different types of foot loading. We used computed tomography osteoabsorptiometry and maximum intensity projection (MIP) maps to visualize AD in subchondral bone at the cuboid articular surface of calcanei. MIPs represent 3D volumes (of subchondral bone) condensed into 2D images by extracting AD maxima from columns of voxels comprising the volumes. False‐color maps are assigned to MIPs by binning pixels in the 2D images according to brightness values. We compared quantities and distributions of AD pixels in the highest bin to test predictions relating AD patterns to habitual locomotor modes and foot posture categories of humans and several nonhuman primates. Nonhuman primates exhibit dorsally positioned high AD concentrations, where maximum compressive loading between the calcaneus and cuboid likely occurs during “midtarsal break” of support. Humans exhibit less widespread areas of high AD, which could reflect reduced fore‐ and midfoot mobility. Analysis of the internal morphology of the tarsus, such as subchondral bone AD, potentially offers new insights for evaluating primate foot function during locomotion. Am J Phys Anthropol, 2010. © 2009 Wiley‐Liss, Inc.     

Foot kinematics during walking measured using bone and surface mounted markers

The aim was to compare kinematic data from an experimental foot model comprising four segments ((i) heel, (ii) navicular/cuboid (iii) medial forefoot, (iv) lateral forefoot), to the kinematics of the individual bones comprising each segment. The foot model was represented using two different marker attachment protocols: (a) markers attached directly to the skin; (b) markers attached to rigid plates mounted on the skin. Bone data were collected for the tibia, talus, calcaneus, navicular, cuboid, medial cuneiform and first and fifth metatarsals (n=6). Based on the mean differences between the three data sets during stance, the differences between any two of the three kinematic protocols (i.e. bone vs skin, bone vs plate, skin vs plate) were >3 degrees in only 35% of the data and >5 degrees in only 3.5% of the data. However, the maximum difference between any two of the three protocols during stance was >3 degrees in 100% of the data, >5 degrees in 73% of the data and >8 degrees in 23% of the data. Differences were greatest for motion of the combined navicular/cuboid relative to the calcaneus and the medial forefoot segment relative to the navicular/cuboid. The differences between the data from the skin and plate protocols were consistently smaller than differences between either protocol and the kinematic data for each bone comprising the segment. The pattern of differences between skin and plate protocols and the actual bone motion showed no systematic pattern. It is unlikely that one rigid body foot model and marker attachment approach is always preferable over another.     

In vitro study of foot kinematics using a dynamic walking cadaver model

There is a dearth of information on navicular, cuboid, cuneiform and metatarsal kinematics during walking and our objective was to study the kinematic contributions these bones might make to foot function. A dynamic cadaver model of walking was used to apply forces to cadaver feet and mobilise them in a manner similar to in vivo. Kinematic data were recorded from 13 cadaver feet. Given limitations to the simulation, the data describe what the cadaver feet were capable of in response to the forces applied, rather than exactly how they performed in vivo. The talonavicular joint was more mobile than the calcaneocuboid joint. The range of motion between cuneiforms and navicular was similar to that between talus and navicular. Metatarsals four and five were more mobile relative to the cuboid than metatarsals one, two and three relative to the cuneiforms. This work has confirmed the complexity of rear, mid and forefoot kinematics. The data demonstrate the potential for often-ignored foot joints to contribute significantly to the overall kinematic function of the foot. Previous emphasis on the ankle and sub talar joints as the principal articulating components of the foot has neglected more distal articulations. The results also demonstrate the extent to which the rigid segment assumptions of previous foot kinematics research have over simplified the foot.     

Skeletal kinematics of the midtarsal joint during walking: Midtarsal joint locking revisited

The kinematics of the human foot complex have been investigated to understand the weight bearing mechanism of the foot. This study aims to investigate midtarsal joint locking during walking by noninvasively measuring the movements of foot bones using a high-speed bi-planar fluoroscopic system. Eighteen healthy subjects volunteered for the study; the subjects underwent computed tomography imaging and bi-planar radiographs of the foot in order to measure the three-dimensional (3D) midtarsal joint kinematics using a 2D-to-3D registration method and anatomical coordinate system in each bone. The relative movements on bone surfaces were also calculated in the talonavicular and calcaneocuboid joints and quantified as surface relative velocity vectors on articular surfaces to understand the kinematic interactions in the midtarsal joint. The midtarsal joint performed a coupled motion in the early stance to pronate the foot to extreme pose in the range of motion during walking and maintained this pose during the mid-stance. In the terminal stance, the talonavicular joint performed plantar-flexion, inversion, and internal rotation while the calcaneocuboid joint performed mainly inversion. The midtarsal joint moved towards an extreme supinated pose, rather than a minimum motion in the terminal stance. The study provides a new perspective to understand the kinematics and kinetics of the movement of foot bones and so-called midtarsal joint locking, during walking. The midtarsal joint continuously moved towards extreme poses together with the activation of muscle forces, which would support the foot for more effective force transfer during push-off in the terminal stance.     

In-vivo range of motion of the subtalar joint using computed tomography

Understanding in vivo subtalar joint kinematics is important for evaluation of subtalar joint instability, the design of a subtalar prosthesis and for analysing surgical procedures of the ankle and hindfoot. No accurate data are available on the normal range of subtalar joint motion. The purpose of this study was to introduce a method that enables the quantification of the extremes of the range of motion of the subtalar joint in a loaded state using multidetector computed tomography (CT) imaging. In 20 subjects, an external load was applied to a footplate and forced the otherwise unconstrained foot in eight extreme positions. These extreme positions were foot dorsiflexion, plantarflexion, eversion, inversion and four extreme positions in between the before mentioned positions. CT images were acquired in a neutral foot position and each extreme position separately. After bone segmentation and contour matching of the CT data sets, the helical axes were determined for the motion of the calcaneus relative to the talus between four pairs of opposite extreme foot positions. The helical axis was represented in a coordinate system based on the geometric principal axes of the subjects’ talus. The greatest relative motion between the calcaneus and the talus was calculated for foot motion from extreme eversion to extreme inversion (mean rotation about the helical axis of 37.3±5.9°, mean translation of 2.3±1.1 mm). A consistent pattern of range of subtalar joint motion was found for motion of the foot with a considerable eversion and inversion component.     

Analysis of the intra-individual differences of the joint surfaces of the calcaneus

Patients with calcaneus fractures experience considerable interferences with daily living activities. The quality of anatomical reconstruction is important because of its influence on functional outcome. The aim of this study was to develop an automatic algorithm based on computer tomographic (CT) images to quantify the integrity of calcaneal joint surfaces. Validation of this algorithm was done by assessing intra-individual variations of characteristic joint parameters. Bilateral hind foot CT data of 12 subjects were manually segmented, and 3D models from the calcaneus, talus and cuboid were generated. These models were implemented in a custom-made software to analyse the area, 3D orientations and bone distance of the joint surfaces of the calcaneus. Three joints were detected, and the calculated parameters were compared between right and left hind foot by the evaluation of the directional asymmetry (%DA). The results were statistically analysed with a paired t-test. The median of area (5–7 %DA) of the joint surfaces and the distance between two articulating surfaces (8–9 %DA) showed the greatest intra-individual differences. Median differences in 3D orientation were comparatively low (1–2 %DA). None of these differences was statistically significant. Inter-individual variations among subjects were several magnitudes larger than intra-individual differences. The presented computational tool provides 3D joint-specific parameters of the calcaneus, which enable to describe their respective joint integrity. The results show that only small intra-individual differences within the anatomy exist. Surgical treatment should take place with the aid of CT data from the contralateral side. Thus, a good restoration of the anatomy may be reached. The computational tool assesses the quality of reduction, and may be helpful to evaluate the outcome and quality of operative treatment based on the calculated joint-specific parameters of joint reconstructions in the hind foot.     

Mechanics of the ankle and subtalar joints revealed through a 3D quasi-static stress MRI technique

A technique to study the three-dimensional (3D) mechanical characteristics of the ankle and of the subtalar joints in vivo and in vitro is described. The technique uses an MR scanner compatible 3D positioning and loading linkage to load the hindfoot with precise loads while the foot is being scanned. 3D image processing algorithms are used to derive from the acquired MR images bone morphology, hindfoot architecture, and joint kinematics. The technique was employed to study these properties both in vitro and in vivo. The ankle and subtler joint motion and the changes in architecture produced in response to an inversion load and an anterior drawer load were evaluated. The technique was shown to provide reliable measures of bone morphology. The left-to-right variations in bone morphology were less than 5%. The left-to-right variations in unloaded hindfoot architecture parameters were less than 10%, and these properties were only slightly affected by inversion and anterior drawer loads. Inversion and anterior drawer loads produced motion both at the ankle and at the subtalar joint. In addition, high degree of coupling, primarily of internal rotation with inversion, was observed both at the ankle and at the subtalar joint. The in vitro motion produced in response to inversion and anterior drawer load was greater than the in vivo motion. Finally, external motion, measured directly across the ankle complex, produced in response to load was much greater than the bone movements measured through the 3D stress MRI technique indicating the significant effect of soft tissue and skin interference.     

In vitro assessment of a motion-based optimization method for locating the talocrural and subtalar joint axes

The locations of the joint axes of the ankle complex vary considerably between subjects, yet no noninvasive method with demonstrated accuracy exists for locating these axes. The moments of muscle and ground reaction forces about the joint axes are dependent on axis locations, making knowledge of these locations critical to accurate musculoskeletal modeling of the foot and ankle. The accuracy of a computational optimization method that fits a two-revolute model to measured motion was assessed using computer-generated data, a two-revolute mechanical linkage, and three lower-leg cadaver specimens. Motions were applied to cadaver specimens under axial load while bone-mounted markers attached to the tibia, talus, and calcaneus were tracked using a video-based motion analysis system. Estimates of the talocrural and subtalar axis locations were computed from motions of the calcaneus relative to the tibia using the optimization method. These axes were compared to mean helical axes computed directly from tibia, talus, and calcaneus motions. The optimization method performed well when the motions were computer-generated or measured in the mechanical linkage, with angular differences between optimization and mean helical axes ranging from 1 deg to 5 deg. In the cadaver specimens, however, these differences exceeded 20 deg. Optimization methods that locate the anatomical joint axes of the ankle complex by fitting two revolute joints to measured tibia-calcaneus motions may be limited because of problems arising from non-revolute behavior.     

Kinematics of primate midfoot flexibility

This study describes a unique assessment of primate intrinsic foot joint kinematics based upon bone pin rigid cluster tracking. It challenges the assumption that human evolution resulted in a reduction of midfoot flexibility, which has been identified in other primates as the “midtarsal break.” Rigid cluster pins were inserted into the foot bones of human, chimpanzee, baboon, and macaque cadavers. The positions of these bone pins were monitored during a plantarflexion‐dorsiflexion movement cycle. Analysis resolved flexion‐extension movement patterns and the associated orientation of rotational axes for the talonavicular, calcaneocuboid, and lateral cubometatarsal joints. Results show that midfoot flexibility occurs primarily at the talonavicular and cubometatarsal joints. The rotational magnitudes are roughly similar between humans and chimps. There is also a similarity among evaluated primates in the observed rotations of the lateral cubometatarsal joint, but there was much greater rotation observed for the talonavicular joint, which may serve to differentiate monkeys from the hominines. It appears that the capability for a midtarsal break is present within the human foot. A consideration of the joint axes shows that the medial and lateral joints have opposing orientations, which has been associated with a rigid locking mechanism in the human foot. However, the potential for this same mechanism also appears in the chimpanzee foot. These findings demonstrate a functional similarity within the midfoot of the hominines. Therefore, the kinematic capabilities and restrictions for the skeletal linkages of the human foot may not be as unique as has been previously suggested. Am J Phys Anthropol 155:610–620, 2014. © 2014 Wiley Periodicals, Inc.     

Foot bones from Omo: implications for hominid evolution

We reanalyze a hominid talus and calcaneus from Omo dating to 2.2 mya and 2.36 mya, respectively. Although both specimens occur at different localities and times, both tarsals articulate well together, suggesting a single taxon on the basis of size and function. We attribute these foot bones to early Homo on the basis of their morphology. The more modern-like tarsal morphology of these Omo foot bones makes them very similar to a talus from Koobi Fora (KNM-ER 813), a specimen attributed to Homo rudolfensis or Homo erectus. Although the Omo tarsals are a million years younger than the oldest known foot bones from Hadar, both localities demonstrate anatomical differences representing two distinct morphological patterns. Although all known hominid tarsals demonstrate clear bipedal features, the tarsal features noted below suggest that biomechanical changes did occur over time, and that certain features are associated with different hominid lineages (especially the robust australopithecines).     

A closed-loop cadaveric foot and ankle loading model

Investigations of human foot and ankle biomechanics rely chiefly on cadaver experiments. The application of proper force magnitudes to the cadaver foot and ankle is essential to obtain valid biomechanical data. Data for external ground reaction forces are readily available from human motion analysis. However, determining appropriate forces for extrinsic foot and ankle muscles is more problematic. A common approach is the estimation of forces from muscle physiological cross-sectional areas and electromyographic data. We have developed a novel approach for loading the Achilles and posterior tibialis tendons that does not prescribe predetermined muscle forces. For our loading model, these muscle forces are determined experimentally using independent plantarflexion and inversion angle feedback control. The independent (input) parameters -- calcaneus plantarflexion, calcaneus inversion, ground reaction forces, and peroneus forces -- are specified. The dependent (output) parameters -- Achilles force, posterior tibialis force, joint motion, and spring ligament strain -- are functions of the independent parameters and the kinematics of the foot and ankle. We have investigated the performance of our model for a single, clinically relevant event during the gait cycle. The instantaneous external forces and foot orientation determined from human subjects in a motion analysis laboratory were simulated in vitro using closed-loop feedback control. Compared to muscle force estimates based on physiological cross-sectional area data and EMG activity at 40% of the gait cycle, the posterior tibialis force and Achilles force required when using position feedback control were greater.     

Does a specific MR imaging protocol with a supine-lying subject replicate tarsal kinematics seen during upright standing?

Magnetic resonance (MR) imaging is becoming increasingly important in the study of foot biomechanics. Specific devices have been constructed to load and position the foot while the subject is lying supine in the scanner. The present study examines the efficacy of such a newly developed device in replicating tarsal kinematics seen during the more commonly studied standing loading conditions. The results showed that although knee flexion and the externally applied load were carefully controlled, subtalar and talo-navicular joint rotations while lying during MR imaging and when standing (measured opto-electrically with markers attached to intracortical pins) did not match, nor were they systematically shifted. Thus, the proposed MR protocol cannot replicate tarsal kinematics seen during upright standing. It is concluded that specific foot loading conditions have to be considered when tarsal kinematics are evaluated. Improved replication of tarsal kinematics in different postures should comprehensively consider muscle activity, a fixed hip position, and a well-defined point of load application.     

Technical note: Mapping of trabecular bone anisotropy and volume fraction in 3D using μCT images of the human calcaneus

Trabecular bone anisotropy, describing preferential trabecular co-alignment, is a proxy for its long-term loading history. Trabecular anisotropy varies locally, thus rendering averaged calculations across an entire bone inutile. Here we present a 3D trabecular anisotropy mapping method using vector fields where each vector reflects the extent of local co-alignment of the elementary units of surface. 3D anisotropy maps of hundreds of thousands of vectors were visualized by their magnitude and direction. Similarly, volume fraction was mapped as 3D scalar fields. We constructed anisotropy and volume fraction maps using micro-computed tomography of four presumably nonpathologic human calcanei and compared their anisotropy signature with pathologically loaded calcanei in club foot and calcaneonavicular ankylosis. In the nonpathologic calcaneus, a pattern of four anisotropy trajectories (bands) was consistently identified as dorsal, plantar, Achilles', and peroneal bands. Both pathologic specimens deviated from the nonpathologic maps. The calcaneus in the congenitally disused club foot showed very low local anisotropy values, no co-oriented bands, and low volume fraction. The ankylosed calcaneus showed lower anisotropy than the nonpathologic calcaneus, but not to the same extent as the club foot, and showed patchy high volume fraction. The directionality of co-oriented bands was barely discernable in the ankylosed calcaneus as compared to nonpathologic calcaneus. The anisotropy signature of the nonpathologic calcaneus is consistent with a kinetic loading pattern attributable to walking. The loss of this kinetic loading results in an absent/vanishing anisotropy signature. Such 3D mapping adds new dimensions to quantitative bioimaging of bone and the understanding of skeletal adaptation.     

The effect of falling height on muscle activity and foot motion during landings

The aims of this study were: (a) to examine the effect of falling height on the kinematics of the tibiotalar, talonavicular and calcaneocuboid joints and (b) to study the influence of falling height on the muscle activity of the leg during landings. Six female gymnasts (height: 1.63±0.04 m, weight: 58.21±3.46 kg) participated in this study. All six gymnasts carried out barefoot landings, falling from 1.0, 1.5 and 2.0 m height onto a mat. Three genlocked digital high speed video cameras (250 Hz) captured the motion of the left shank and foot. Surface electromyography (EMG) was used to measure muscle activity (1000 Hz) from five muscles (gastrocnemius medialis, tibialis anterior, peroneus longus, vastus lateralis and hamstrings) of the left leg. The kinematics of the tibiotalar, talonavicular and calcaneocuboid joints were studied. The lower-leg and the foot were modelled by means of a multi-body system, comprising seven rigid bodies. The falling height does not show any influence on the kinematics neither of the tibiotalar nor of the talonavicular joints during landing. The eversion at the calcaneocuboid joint increases with increasing falling height. When augmenting falling height, the myoelectric activity of the muscles of the lower limb increases as well during the pre-activation phase as during the landing itself. The muscles of the lower extremities are capable of stabilizing the tibiotalar and the talonavicular joints actively, restricting their maximal motion by means of a higher activation before and after touchdown. Maximal eversion at the calcaneocuboid joint increases about 52% when landing from 2.0 m.