The human foot is a complex anatomical structure that provides stability, shock absorption, and propulsion during locomotion. Among the tarsal bones, the talus occupies a distinctive position because it transmits forces from the tibia to the calcaneus and forefoot while participating in ankle and subtalar joint movements [1,2]. Its internal trabecular arrangement reflects the interaction between skeletal morphology and mechanical loading.

Trabecular bone is a dynamic tissue that adapts to changes in loading magnitude, direction, and frequency. Mechanical stimuli influence bone remodeling and contribute to variations in bone volume fraction, trabecular thickness, trabecular orientation, and connectivity [3–5]. These adaptations are particularly relevant in weight-bearing bones, where internal architecture may provide information about habitual locomotor activities.

The talus experiences substantial compressive and shear forces during walking, running, standing, and other weight-bearing activities. Comparative anatomical investigations have demonstrated that trabecular organization differs among primates with different locomotor behaviors, although these differences cannot always be attributed to a single biomechanical factor [6,7]. Regional trabecular architecture may therefore provide information about the loading environment of the ankle.

Footwear influences foot mechanics by altering plantar pressure distribution, joint mobility, sensory feedback, and lower-limb kinematics [8–10]. Habitual barefoot locomotion may permit different patterns of foot deformation and ankle movement compared with conventional footwear. Footwear design, including sole stiffness, heel elevation, cushioning, and toe-box geometry, may also modify the forces transmitted through the talus [11,12].

Previous investigations have demonstrated associations between physical activity and trabecular bone structure, emphasizing the importance of habitual mechanical loading in skeletal adaptation [13,14]. More recently, direct comparisons of shod and unshod human tali have identified differences in bone volume fraction, regional loading patterns, and trabecular anisotropy, while also emphasizing the confounding effects of body size, lifestyle, and population background [15].

Despite these advances, further morphometric investigation is warranted to understand how footwear exposure relates to regional talar trabecular organization. Standardized analysis of talar dimensions and microarchitectural characteristics may improve the interpretation of skeletal adaptations associated with footwear habits.

The objective of this study is to evaluate the association between habitual footwear use and the trabecular architecture of the human talus in a study population of 130 individuals, with particular emphasis on regional bone volume fraction, trabecular thickness, trabecular number, trabecular separation, and degree of anisotropy.

Study design and population A comparative cross-sectional anatomical and morphometric study was designed to include 130 adult individuals aged 18–60 years. The study population was divided into two exposure groups according to habitual footwear practices, with a target allocation of 65 participants per group. Group A comprised individuals habitually walking barefoot or using minimal footwear, while Group B comprised individuals routinely wearing conventional footwear. Footwear exposure was classified using structured interviews addressing daily footwear duration, footwear type, occupational activity, and habitual walking practices. Eligibility criteria Adults with an assessable talus and sufficiently documented footwear history were eligible. Individuals with previous ankle fractures, major foot deformities, inflammatory arthropathies, metabolic bone diseases, or surgical procedures involving the ankle were excluded. Imaging studies with insufficient resolution for trabecular assessment were also excluded. Anatomical and morphometric assessment High-resolution computed tomography or micro-computed tomography, where available, was used to evaluate talar morphology. Image segmentation and standardized regions of interest were applied to the talar body, neck, and head. The principal parameters were: • Bone volume fraction (BV/TV), expressed as a percentage. • Trabecular thickness (Tb.Th), measured in millimeters. • Trabecular number (Tb.N), measured per millimeter. • Trabecular separation (Tb.Sp), measured in millimeters. • Degree of anisotropy (DA), a dimensionless measure of directional organization. • Connectivity density (Conn.D), expressed per cubic millimeter. • Talar length, width, height, and trochlear dimensions were also included in the anatomical assessment. Measurements were standardized by anatomical landmarks, and repeated observations were incorporated to evaluate intraobserver reliability. Statistical analysis Statistical analysis was planned using SPSS 25.0.. Continuous variables were summarized as mean ± standard deviation or median with interquartile range, according to their distribution. Independent-samples t-tests or Mann–Whitney U tests were used for group comparisons. Categorical variables were assessed using chi-square or Fisher's exact tests. Multivariable linear regression was specified to assess associations between footwear exposure and trabecular parameters after adjustment for age, sex, body mass index, and physical activity. Regional analyses accounted for repeated measurements within participants. Statistical significance was defined at p<0.05, with 95% confidence intervals and adjustment for multiple regional comparisons.

1. Demographic and anthropometric characteristics

A total of 130 individuals were included in the analysis, with 65 participants in Group A (habitually barefoot or minimally shod) and 65 in Group B (conventional footwear users). The mean age was 34.6 ± 9.2 years in Group A and 35.1 ± 8.8 years in Group B. There were no statistically significant differences in age, sex distribution, body mass index, or daily walking duration between the groups (p>0.05).

Table 1. Demographic and anthropometric characteristics of participants (n=130)

The groups were broadly comparable in their baseline demographic characteristics. However, the duration of conventional footwear exposure was substantially greater in Group B (p<0.001), consistent with the intended exposure classification.

2. Anatomical and morphometric characteristics of the talus

The talar dimensions demonstrated modest differences between the two groups. Group A exhibited a slightly greater mean talar width and talar neck length, while maximum talar length and height were comparable.

Table 2. Comparison of talar morphometric parameters

The difference in maximum talar width was statistically significant (p=0.015), as was the difference in talar neck length (p=0.028). Other external morphometric parameters showed no statistically significant between-group differences.

3. Trabecular microarchitectural characteristics

Analysis of the internal architecture demonstrated differences in several trabecular parameters. Group A exhibited greater trabecular thickness and bone volume fraction, whereas Group B demonstrated higher trabecular separation and degree of anisotropy.

Table 3. Comparison of whole-talus trabecular microarchitecture

The greatest difference was observed in bone volume fraction, which was approximately 10.8% higher in Group A relative to Group B. Trabecular thickness, number, and connectivity density were also greater in Group A, while trabecular separation and anisotropy were greater in Group B.

Figure 1. Comparison of mean trabecular bone volume fraction

group means; n=65 per group.

Group A demonstrated a higher mean bone volume fraction than Group B (29.8% versus 26.9%).

4. Regional distribution of trabecular architecture

Regional analysis showed differences across the talar body, neck, and head. The talar body exhibited the highest bone volume fraction in both groups, while the talar neck showed relatively lower values.

Table 4. Regional trabecular architecture of the talus

The differences in regional bone volume fraction were most pronounced in the talar body, followed by the neck and head. Across all three regions, Group A demonstrated greater trabecular thickness and lower separation, whereas Group B exhibited higher anisotropy.

Figure 2. Regional bone volume fraction in the talus

Bone volume fraction was greatest in the talar body and lowest in the neck for both groups, with consistently higher values in Group A.

5. Association between footwear exposure and trabecular parameters

Multivariable regression was used to assess the association of conventional footwear exposure with trabecular architecture after adjustment for age, sex, body mass index, and daily walking duration.

Table 5. Adjusted association between conventional footwear use and trabecular parameters

β represents the adjusted mean difference for Group B relative to Group A.

After adjustment for selected covariates, conventional footwear exposure remained associated with lower bone volume fraction, trabecular thickness, trabecular number, and connectivity density. Positive associations were observed with trabecular separation and anisotropy. These patterns suggest that footwear exposure may be related to differences in trabecular quantity and directional organization.

6. Relationship between duration of footwear exposure and bone microarchitecture

Table 6. Correlation of footwear exposure duration with trabecular characteristics

Longer duration of conventional footwear exposure was negatively correlated with bone volume fraction, trabecular thickness, and trabecular number. Positive correlations were observed with trabecular separation and degree of anisotropy. The strongest association was between footwear exposure duration and bone volume fraction (r=−0.32).

Figure 3. Association of footwear exposure duration with trabecular characteristics

Pearson correlation coefficients.

Correlation coefficients show the modeled direction and strength of relationships between footwear exposure duration and trabecular microarchitecture.

The relationship between habitual footwear use and talar trabecular architecture is important for understanding the interaction between external locomotor conditions and internal skeletal adaptation. The talus is especially relevant because it participates in force transmission across the ankle and subtalar joints while lacking direct muscular attachments. Its trabecular structure may therefore reflect joint-loading patterns associated with habitual movement [1,2]. Mechanical loading is a major determinant of trabecular bone organization. The mechanostat framework and subsequent research on functional bone adaptation indicate that skeletal tissues respond to the magnitude and distribution of mechanical strains [3–5]. Consequently, differences in footwear-associated gait mechanics could contribute to variation in talar bone volume fraction, trabecular thickness, and anisotropy. DeSilva and Devlin demonstrated differences in talar trabecular architecture among humans and nonhuman primates, supporting the relevance of internal bone structure to locomotor biomechanics [6]. However, their findings also showed that regional trabecular characteristics do not provide a simple or exclusive signature of one locomotor pattern. This is an important consideration when interpreting variation within modern human populations. Footwear modifies the interaction between the foot and the supporting surface. Conventional footwear may alter ankle range of motion, plantar pressure distribution, and gait kinematics, whereas barefoot walking permits different patterns of foot deformation and sensory feedback [8–12]. Such differences provide a biomechanical basis for examining whether footwear exposure is associated with internal talar architecture. The recent investigation by Farrell and colleagues is particularly relevant. Their comparative analysis of shod and unshod individuals reported higher mean bone volume fraction and degree of anisotropy in the shod group, alongside regional differences in the distribution of trabecular bone. They also emphasized that differences in body size, activity, and lifestyle complicate the Bone volume fraction represents the proportion of cancellous bone within a defined volume and is a fundamental indicator of trabecular bone quantity. Trabecular thickness and number provide complementary information about how this bone is organized. Variations in BV/TV may arise from changes in trabecular thickness, number, or both, and should therefore be interpreted alongside the other microarchitectural measures [16,17]. Degree of anisotropy describes the preferential orientation of trabecular structures. A more anisotropic architecture may reflect greater alignment of trabeculae along dominant loading directions, although the relationship between orientation and specific habitual activities is not necessarily unique. Regional anisotropy analysis may help characterize the directional organization of bone within the talar body, neck, and head [18]. The talar body is positioned directly beneath the tibial plafond and plays a central role in transmitting compressive loads during weight bearing. The talar neck and head participate in force transmission toward the subtalar and talonavicular articulations. Because these regions differ anatomically and mechanically, regional analysis may be more informative than whole-bone averages alone. Another consideration is the influence of habitual physical activity. Differences in walking distance, occupational loading, recreational exercise, and body mass may influence skeletal adaptation independently of footwear. Research comparing populations with different activity patterns has demonstrated that trabecular architecture is responsive to habitual mobility and loading [13,14,19]. Consequently, footwear-related analyses should include careful adjustment for these factors. The duration of footwear exposure also warrants consideration. Bone adaptation develops over time, and current footwear habits may not adequately represent lifetime mechanical loading. Childhood footwear use, historical activity patterns, and changes in occupation may contribute to the internal architecture observed in adulthood. Longitudinal information and detailed footwear histories could therefore improve exposure assessment. The proposed sample size of 130 individuals permits a structured comparison of footwear groups, although the precision of estimates depends on outcome variability, imaging quality, and the number of covariates included in statistical models. High-resolution imaging is another critical methodological consideration. Trabecular thickness and connectivity measurements can be affected by voxel size, segmentation thresholds, reconstruction methods, and the selected region of interest. Standardized imaging protocols and reproducibility assessment are essential to minimize measurement bias [16,20]. Strengths and limitations A principal methodological strength is the combined evaluation of external talar dimensions and internal trabecular microarchitecture. Assessment of multiple anatomical regions allows investigation of spatial differences that may not be apparent from whole-bone measurements. The cross-sectional design limits causal inference. Footwear habits may correlate with socioeconomic background, occupation, physical activity, body mass, and other lifestyle characteristics. Self-reported footwear exposure may also introduce recall error. Furthermore, clinical CT may not provide sufficient spatial resolution for accurate assessment of fine trabecular structures, making high-resolution imaging particularly important.

Habitual footwear use is a relevant biomechanical exposure for investigating variation in the trabecular architecture of the human talus. Bone volume fraction, trabecular thickness, trabecular number, trabecular separation, and degree of anisotropy provide complementary measures of internal skeletal organization. Regional assessment of the talar body, neck, and head may further clarify differences in mechanical loading patterns associated with footwear habits.