Biology subjects

Welte, L.

Publications and source records attributed to Welte, L..

4 recordsLinked to original sources

bioRxiv2024

The influence of talus size and shape on in vivo talocrural hopping kinematics

Talus implants often come in standard sizes and shapes; however, humans vary in their bone size and shape. Consequently, patient-specific implants are becoming available. Understanding how shape changes alter function in a healthy cohort may help designers determine how much specificity is required in talocrural implants. Nine participants (5 females) hopped on one leg while biplanar video radiography and force plate data were collected. 3D bone models were created from computed tomography scans. Helical axes of motion were calculated for the talus relative to the tibia (rotation axes) and a cylinder was fit through the talar dome (morphological axis). Bland-Altman plots and spatial angles tested whether the rotation and morphological axes agree. A shape model of 36 (15 females) participants was established and a cylinder fit was morphed through the range of {+/-}3 standard deviations. The rotation and morphological axes largely agree regarding their orientation and location during hopping. The morphological axis consistently overestimates the orientation-component in anterior-posterior direction. Some shape components affect talar dome orientation and curvature independent of size. This suggests that besides size, the shape of the talar dome might affect the movement pattern during locomotion. Our findings are important to inform talocrural joint arthroplasty design.

bioengineering↗

bioRxiv2023

Reassessing the role of foot power in human gait

The foot acts as the primary interface to the ground during bipedal locomotion. It absorbs and returns energy over stance as the longitudinal arch deforms and recoils. The term arch recoil evokes the concept that the foots returned energy directly propels the centre of mass forward by lifting the talus. However, recent work has shown that arch recoil does not directly drive the body forward; instead, it lowers and posteriorly tilts the talus, putting it into a more favourable position for upright gait. Here, we aim to supply a kinetic explanation for this mechanism. We applied the unified deformable power approach to highly accurate talus kinematics from biplanar videoradiography and force plate measurements to measure the power absorbed/produced by the foot. We coupled these measurements with a simple mathematical model that allowed us to restrict rotation and linear actuation of the talus caused by the recoil of the arch to demonstrate that positive foot power primarily contributes to posteriorly tilting the talus. This suggests the role of positive foot power during propulsion is to keep the talocrural surface in a more favourable position for upright gait rather than directly propelling the centre of mass forwards. These findings highlight that arch mobility during push-off is critical for allowing the ankle to directly propel the body forward and upward during the propulsive phase of gait.

physiology↗

bioRxiv2023

It is all about the talus - In vivo tarsal joint complex kinematics during walking, running, and hopping

The interaction among joints of the midtarsal complex and subtalar joint is essential role for locomotor function; however, its complexity poses substantial challenges in quantifying their motions. We determine the mobility of these joints across locomotion tasks and investigate their alignment with individual talus morphology. Utilizing highly accurate biplanar videoradiography, three-dimensional bone kinematics were captured during walking, running, and hopping. We calculated the axis of rotation of each midtarsal and subtalar joint for the landing and push-off phases, respectively. A comparison was made between these rotation axes and the morphological subtalar axis. Measurement included total rotation about, the orientation of the rotation axes in the direction of the subtalar joint and its deviation via spatial angles for both phases. The rotation axes of all three bones relative to the talus closely align with the morphological subtalar axis. This suggests that the midtarsal and subtalar joints motions might be described by one commonly oriented axis. Despite having such axis, the location of axes and ranges of motion differed among the bones. Our results provide a novel perspective of healthy foot function across different sagittal plane-dominant locomotion tasks underscoring the importance of midtarsal and subtalar motion with respect to subject-specific talus morphology.

bioengineering↗

bioRxiv2022

Mobility of the human foot's medial arch enables upright bipedal locomotion

Developing the ability to habitually walk and run upright on two feet is one of the most significant transformations to have occurred in human evolution. Many musculoskeletal adaptations enabled bipedal locomotion, including dramatic structural changes to the foot and, in particular, the evolution of an elevated medial arch (H. Elftman and Manter, 1935). The foots arched structure has previously been assumed to play a central role in directly propelling the centre of mass forward and upward through leverage about the toes (Herbert Elftman and Manter, 1935) and a spring-like energy recoil (Hicks, 1955). Paradoxically, these roles seemingly require either arch rigidity (for the former) or mobility (for the latter). However, it is unclear whether or how the mobility and height of the medial arch support its propulsive lever function. Here we show, using high-speed biplanar x-ray, that regardless of intraspecific differences in medial arch height, arch recoil enables a longer contact time and favourable propulsive conditions for walking upright on an extended leg. This mechanism presumably helped drive the evolution of the longitudinal arch after our last common ancestor with chimpanzees, who lack this mobility during push-off. We discovered that the previously overlooked navicular-medial cuneiform joint is primarily responsible for this mobility in human arches, suggesting that future morphological investigations of this joint will provide new interpretations of the fossil record. Our work further suggests that enabling the mobility of the longitudinal arch in footwear and surgical interventions is critical for maintaining the ankles natural propulsive ability.

physiology↗