Ontogenetic Patterning of Human Subchondral Bone Microarchitecture in the Proximal Tibia

Trabecular Bone Ontogeny of the Human Distal Tibia

OBJECTIVES

There is an increasing understanding of how trabecular bone adapts to biomechanical changes during ontogeny. However, limited research exists regarding the distal tibia, which is important in weight-bearing locomotion as part of the ankle joint. This study aims to document the ontogenetic trabecular patterns of the distal tibia, in addition to changes in its structural heterogeneity.

MATERIALS AND METHODS

Thirty-eight distal tibiae, ranging in age from 28 intrauterine weeks to 8 postnatal years, from the Scheuer juvenile skeletal collection were examined. Trabecular bone was analyzed using a quantitative volume of interest approach and qualitative whole bone mapping following microcomputed tomography.

RESULTS

Fetal and perinatal tibia lack mature organization and are associated with high bone volume fraction. During the first year of life, there is a decrease in bone volume fraction and an indication of early re-organization of trabecular struts in the distal tibia. After one year of age, the distal tibia exhibits increased trabecular structural heterogeneity.

DISCUSSION

The trabecular architecture of the fetal and perinatal distal tibia lacks mature organization and instead reflects ossification patterns. At these stages, there is a rapid accumulation of bone mass associated with gestational overproduction, hypothesized to be in preparation for subsequent postnatal changes. During the first year of life there is a decrease in volume fraction, associated with constructive regression. It is postulated this is related to changing biomechanical forces associated with the bipedal gait, in addition to growth demands. After one year of age, the distal tibia exhibits structural heterogeneity with trabecular adaption to accommodate specific bipedal stresses.

The developing juvenile talus: Radiographic identification of distinct ontogenetic phases and structural trajectories

Trabecular bone architecture in the developing skeleton is a widely researched area of bone biomechanics; however, despite its significance in weight-bearing locomotion, the developing talus has received limited examination. This study investigates the talus with the purpose of identifying ontogenetic phases and developmental patterns that contribute to the growing understanding of the developing juvenile skeleton. Colour gradient mapping and radiographic absorptiometry were utilised to investigate 62 human tali from 38 individuals, ranging in age-at-death from 28 weeks intrauterine to 20 years of age. The perinatal talus exhibited a rudimentary pattern comparable to the structural organisation observed within the late adolescent talus. This early internal organisation is hypothesised to be related to the vascular pattern of the talus. After 2 years of age, the talus demonstrated refinement, where radiographic trajectories progressively developed into patterns consistent with adult trabecular organisation, which are linked to the forces associated with the bipedal gait, suggesting a strong influence of biomechanical forces on the development of the talus.

Relationship between mechanical and microstructural parameters of rat lumbar spine in different ages

Exploring the relationships between microstructure and mechanical properties of bones may provide effective suggestions for increasing bone strength and reducing osteoporotic fracture. In this research, the tissue-level mechanical parameters, microstructure parameters of cancellous bone, and apparent mechanical parameters of L6 vertebral body were calculated in female SD rats aged 1-, 3-, 5-, 7-, 9-, 11-, 13-, 15-, 16-, and 17-month-old. Data were processed with Kruskal-Wallis test, linear regression and Spearman's rank correlation analysis. Appropriately increasing the plate Tb.N could enhance mechanical properties of bone. Tb.Th and Tb.N were two key factors in determining the tissue-level mechanical properties of cancellous bone. The microstructure could significantly predict mechanical parameters. Our findings may help to further understand the mechanism of osteoporotic fractures.

Development of a Bionic Tube with High Bending-Stiffness Properties Based on Human Tibiofibular Shapes

The human tibiofibular complex has undergone a long evolutionary process, giving its structure a high bearing-capacity. The distinct tibiofibular shape can be used in engineering to acquire excellent mechanical properties. In this paper, four types of bionic tubes were designed by extracting the dimensions of different cross-sections of human tibia-fibula. They had the same outer profiles, but different inner shapes. The concept of specific stiffness was introduced to evaluate the mechanical properties of the four tubes. Finite-element simulations and physical bending-tests using a universal testing machine were conducted, to compare their mechanical properties. The simulations showed that the type 2 bionic tube, i.e., the one closest to the human counterpart, obtained the largest specific-stiffness (ε = 6.46 × 10⁴), followed by the type 4 (ε = 6.40 × 10⁴) and the type 1 (ε = 6.39 × 10⁴). The type 3 had the largest mass but the least stiffness (ε = 6.07 × 10⁴). The specific stiffness of the type 2 bionic tube increased by approximately 25.8%, compared with that of the type 3. The physical tests depicted similar findings. This demonstrates that the bionic tube inspired by the human tibiofibular shape has excellent effectiveness and bending properties, and could be used in the fields of healthcare engineering, such as robotics and prosthetics.

The developing juvenile distal tibia: Radiographic identification of distinct ontogenetic phases and structural trajectories

A novel combination of radiographic colour gradient mapping and radiographic absorptiometry was utilised to examine 96 human distal tibiae from 54 individuals ranging in age-at-death from the foetal to 23 years. The purpose of this was to identify previously undocumented changes in the internal organisation during the development of the distal tibia and determine whether these changes could be described as distinct phases. Previous studies have demonstrated a rudimentary structural organisation in other skeletal elements that mirror more mature patterns of bone organisation. Results showed that the perinatal tibia did not exhibit a rudimentary structural pattern similar to the architecture observed within the late adolescent tibia. This lack of early internal organisation is hypothesised to be related to the rudimentary ossification process that is being laid down around a pre-existing vascular template which will be subsequently modified by locomotive forces. Between birth and 2 years of age, the tibia exhibited a period of regression where radiodensity decreased in comparison to the perinatal tibia. This period of regression was postulated to be due to a combination of factors including changing locomotive forces, weaning and growth resulting in a stage of development which is extremely demanding on calcium liberation from the skeleton. After 2 years of age, the distal tibia demonstrated refinement where radiographic trajectories progressively developed into patterns consistent with adult trabecular organisation. These trajectories are linked to the forces associated with the bipedal gait, suggesting a strong influence of biomechanical forces on the development of the distal tibia.