Kinematics of primate midfoot flexibility

Abstract

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.

Chimpanzee ankle and foot joint kinematics: Arboreal versus terrestrial locomotion

“…However, this morphology has mainly been related to sagittal plane mobility, and we recently found that humans use a greater range of midfoot sagittal plane motion overall than chimpanzees during bipedal walking (Holowka et al, ). This finding runs counter to the notion that cuboid–metatarsal joint morphology is reflective of overall midfoot sagittal plane range of motion across taxa (see also Greiner and Ball, ), although DeSilva et al () found evidence for a relationship between this morphology and midtarsal break magnitude within humans. However, the results of this study suggest that midfoot inversion and abduction are particularly critical to arboreal locomotion, and thus, further work exploring the relationship between these motions and cuboid–metatarsal joint morphology is needed.…”

“…The cuboid–metatarsal joints are also likely sites of some component of the midfoot motion measured in this study. These joints present articular surfaces that are more dorso‐plantarly concavo–convex in chimpanzees than in humans, and have consequently been implicated mainly in sagittal plane motion (DeSilva, ; Greiner and Ball, ; Proctor, ). They could potentially contribute to the midfoot abduction and inversion motions that we measured in this study as well, but establishing the mobility of these joints outside of the sagittal plane requires further investigation.…”

“…The cuboid–metatarsal joints, which we did not investigate in that study, are another possible site of substantial midfoot sagittal plane motion. Greiner and Ball () quantified cuboid–metatarsal joint motion in four cadaveric chimpanzee specimens during passive manipulations and measured <9° peak dorsiflexion on average (Figure ; Greiner and Ball, ). When considering that we quantified midfoot motion spanning the medial and lateral sides of the foot, it is not surprising that the peak dorsiflexion angles that we measured in this study (13–13.5° on average) are between the peak passive ranges for the medial (18.5°) and lateral (<9°) sides of the foot that can be deduced by combining the results from Thompson et al () and Greiner and Ball ().…”

Midtarsal break variation in modern humans: Functional causes, skeletal correlates, and paleontological implications

“…As the midtarsal break has received more attention in recent years (D'Août et al, 2002; Vereecke et al, ; Lovejoy et al, ; Crompton et al, ; DeSilva, ; Nowak et al, ; Crompton et al, ; Bates et al, ; DeSilva and Gill, ; Greiner and Ball, ; Thompson et al, ), it has become clear that this once simple and dichotomous trait is more interesting and complex than previously thought. This study adds important new contributions to our understanding of the human midfoot and the evolutionary history of the midtarsal break.…”

Rethinking the evolution of the human foot: insights from experimental research

“…Further, largely based on this mechanism, they argue that the foot of the human-chimpanzee LCA functioned similarly to that in cercopithecines. However, this argument is undermined by evidence that gibbons and cercopithecines have highly compliant feet relative to humans and chimpanzees (DeSilva, 2010;Greiner and Ball, 2014;Vereecke and Aerts, 2008), and the lack of solid evidence that the peroneus longus can stiffen the midfoot in humans. Thus, the functional implications of the os peroneum are unclear.…”