Bone microarchitecture of the distal fibula assessed by HR-pQCT

The relationship between primate distal fibula trabecular architecture and arboreality, phylogeny and size

The fibula, despite being traditionally overlooked compared to the femur and the tibia, has recently received attention in primate functional morphology due to its correlation with the degree of arboreality (DOA). Highlighting further fibular features that are associated with arboreal habits would be key to improving palaeobiological inferences in fossil specimens. Here we present the first investigation on the trabecular bone structure of the primate fibula, focusing on the distal epiphysis, across a vast array of species. We collected μCT data on the distal fibula for 21 species of primates, with representatives from most of the orders, and we employed a recently developed approach implemented in the R package 'indianaBones' to isolate the entire trabecular bone underlying an epiphysis or articular facet. After extracting both traditional trabecular parameters and novel topological indices, we tested for the posited relationship between trabecular bone and DOA. To disentangle this effect from others related to body size and phylogenetic relationship, we included a body mass proxy as covariate and employed phylogenetic comparative methods. We ran univariate/multivariate and exploratory/inferential statistical analyses. The trabecular structure of the fibular distal epiphysis in primates does not appear to be associated with the DOA. Instead, it is strongly affected by body mass and phylogenetic relationships. Although we identified some minor trends related to human bipedalism, our findings overall discourage, at this stage, the study of distal fibula trabecular bone to infer arboreal behaviors in extinct primates. We further found that body size distribution is strongly related to phylogeny, an issue preventing us from unravelling the influence of the two factors and that we believe can potentially affect future comparative analyses of primates. Overall, our results add to previous evidence of how trabecular traits show variable correlation with locomotor aspects, size and phylogenetic history across the primate skeleton, thus outlining a complex scenario in which a network of interconnected factors affects the morphological evolution of primates. This work may represent a starting point for future studies, for example, focusing on the effect of human bipedalism on distal fibula trabecular bone, or aiming to better understand the effects of body size and phylogenetic history on primate morphological evolution.

A review of micro-computed tomography and artificial intelligence in talus-based forensic anthropology for sex and age estimation

Biological profiling is a crucial tool in forensic science, allowing for evaluating biological information from bones found at crime scenes. This method includes assessments of sex, age, stature, and ancestry. Sex assessment is the first step in biological profiling, as it influences other assessments. Age estimation is a particularly challenging aspect. Combining sex and age assessment may improve accuracy in age estimation. Researchers often use the pelvis and skull bones for these assessments due to their prevalence at crime scenes and their higher accuracy in evaluation. However, the talus, a foot bone with robust density, resilience, and resistance to damage, is another bone frequently encountered at crime scenes and may be a valuable subject for study. Medical imaging technology, particularly micro-CT imaging, supports sex and age assessment. Micro-CT images can significantly enhance the accuracy of assessments. The high resolution of these images presents an exciting opportunity for exploration in conjunction with artificial intelligence (AI), which has revolutionized forensic science workflows. AI can potentially improve the efficiency and accuracy of sex and age assessment from bones. This article compiles research on past sex and age assessments and evaluations of the talus, including the application of micro-CT images to support these assessments. The aim is to provide a comprehensive knowledge base for studying sex and age assessment from the talus using micro-CT images in conjunction with AI.

Pronounced cortical porosity and sex-specific patterns of increased bone and osteocyte lacunar mineralization characterize the human distal fibula with aging

The high occurrence of distal fibula fractures among older women suggests a potential link to impaired bone health. Here we used a multiscale imaging approach to investigate the microarchitecture, mineralization, and biomechanics of the human distal fibula in relation to age and sex. Micro-computed tomography was performed to analyze the local volumetric bone mineral density and various microarchitectural parameters of the trabecular and the cortical compartment. Bone mineral density distribution and osteocyte lacunar parameters were quantified using quantitative backscattered electron imaging in periosteal, endocortical, and trabecular regions. Additionally, cortical hardness and Young's modulus were assessed by nanoindentation. While cortical porosity strongly increased with age independent of sex, trabecular microarchitecture remained stable. Notably, nearly half of the specimens showed non-bony hypermineralized tissue located at the periosteum, similar to that previously detected in the femoral neck, with no consistent association with advanced age. Independent of this finding, cortical and trabecular mineralization, i.e., mean calcium content, as well as endocortical tissue hardness increased with age in males but not females. Importantly, we also observed mineralized osteocyte lacunae that increased with age specifically in females. In conclusion, our results indicate that skeletal aging of the distal fibula is signified not only by pronounced cortical porosity but also by an increase in mineralized osteocyte lacunae in females. These findings may provide an explanation for the increased occurrence of ankle fractures in older women.

Age-, sex-, and subregion-specific properties of distal fibular microarchitecture and strength: An ex vivo HR-pQCT study

Despite its clinical relevance in the context of ankle fractures, little is known about the bone microarchitecture and strength of the distal fibula, especially regarding age-, sex-, and subregion-specific effects. To address this gap of knowledge, we obtained fibulae from 30 skeletally intact donors at autopsy (each 15 male and female), which were analyzed by high-resolution peripheral quantitative computed tomography including micro-finite element analysis. Scans were performed in a 7-cm volume of interest and evaluated in three subregions according to the Danis-Weber fracture classification. Group comparisons and linear regression analyses were applied to evaluate the effects of age, sex, and subregion. From distal to proximal, we observed an increase of cortical parameters and a decrease of trabecular parameters. Age was primarily associated with a cortical decrease in all subregions (Danis-Weber type A, B, and C) in women. While women showed a greater magnitude of decline, men also exhibited an age-associated decrease for some parameters, including cortical area and cortical thickness in the type C subregion. Stiffness and failure load were highest in the type C subregion in both women and men. A critical age-related decline in bone strength parameters in the type B subregion was observed in women, providing an explanation for the increased incidence of low-traumatic type B fractures in the elderly. Together, these findings extend the current understanding of distal fibular microarchitecture, likely explaining the epidemiologic features of distal fibula fractures and emphasizing the need for age-adapted treatment algorithms.

Compartment-specific effects of muscle strength on bone microarchitecture in women at high risk of osteoporosis

BACKGROUND

It is well known that skeletal integrity is influenced by the musculature. Poor muscle strength (i.e. sarcopenia) is considered a major predictor of fragility fractures. While this observation appears particularly relevant for older women with increased risk of osteoporosis, there has been no comprehensive investigation to determine the influence of muscle performance on compartment-specific bone microarchitecture in multiple body regions.

METHODS

We retrospectively analysed data from different muscle performance and bone microarchitecture assessments in 230 women (aged 21 to 87 years) at high risk of osteoporosis. Muscle performance tests included grip strength and chair rising test (CRT) combined with mechanography. Balance was determined by Romberg posturography. Areal bone mineral density (BMD) was measured by dual-energy X-ray absorptiometry (DXA) at the hip and lumbar spine. Compartment-specific volumetric BMD, microarchitecture, and geometry were assessed by second-generation high-resolution peripheral quantitative computed tomography (HR-pQCT) at multiple skeletal sites (distal radius, tibia, and fibula). Regression models were applied to test for interactions between muscle and bone parameters. Subgroups were defined to compare women with osteoporosis and osteosarcopenia regarding BMD and microarchitecture.

RESULTS

While osteoporosis was diagnosed in 115/230 (50.0%) women, sarcopenia was detected in 38/230 (16.5%). Positive associations of both grip strength and CRT maximum force with cortical geometric and microarchitectural parameters were detected at all measured sites, with the strongest effect applying to CRT maximum force and tibial parameters (e.g. tibial cortical area R2  = 0.36, P < 0.0001, and tibial cortical thickness R2  = 0.26, P < 0.0001). Balance parameters showed much weaker or no associations with HR-pQCT parameters. Major associations between muscle strength and trabecular parameters could not be confirmed. Age and body mass index were confirmed as negative and positive predictors for several microarchitectural parameters, respectively. An independent predictive value of grip strength on radial, tibial, and fibular (all P < 0.01) cortical area and of CRT maximum relative force on cortical thickness (all P < 0.05) was revealed. Women with osteosarcopenia showed significantly reduced cortical HR-pQCT parameters but no differences in DXA values compared with women with osteoporosis but no sarcopenia. Stratification by fracture and treatment status revealed that vertebral fractures and denosumab treatment altered the muscle-bone interaction.

CONCLUSIONS

A systemic interaction between muscle strength and bone microarchitecture was demonstrated, and this interaction appears to be primarily with the cortical bone compartment. The value of muscle assessments in fracture risk evaluation may be partly mediated by their effects on bone microarchitecture.

Superior Bone Microarchitecture in Anatomic Versus Nonanatomic Fibular Drill Tunnels for Reconstruction of the Posterolateral Corner of the Knee

Background:

Several fibula-based reconstruction techniques have been introduced to address ligamentous injuries of the posterolateral corner of the knee. These techniques involve a drill tunnel with auto- or allograft placement through the proximal fibula.

Purpose:

To determine the skeletal microarchitecture of the proximal fibula and its association with age and to compare the microarchitecture within the regions of different drill tunnel techniques for reconstruction of the posterolateral corner.

Study Design:

Descriptive laboratory study.

Methods:

A total of 30 human fibulae were analyzed in this cadaveric imaging study. High-resolution peripheral quantitative computed tomography measurements were performed in a 4.5 cm–long volume of interest at the proximal fibula. Three-dimensional microarchitectural data sets of cortical and trabecular compartments were evaluated using customized scripts. The quadrants representing the entry and exit drill tunnel positions corresponding to anatomic techniques (LaPrade/Arciero) and the Larson technique were analyzed. Linear regression models and group comparisons were applied.

Results:

Trabecular microarchitecture parameters declined significantly with age in women but not men. Analysis of subregions with respect to height revealed stable cortical and decreasing trabecular values from proximal to distal in both sexes. Along with a structural variability in axial slices, superior values were found for the densitometric and microarchitectural parameters corresponding to the fibular drill tunnels in the anatomic versus Larson technique (mean ± SD; bone volume to tissue volume at the entry position, 0.273 ± 0.079 vs 0.175 ± 0.063; P < .0001; cortical thickness at the entry position, 0.501 ± 0.138 vs 0.353 ± 0.081 mm; P < .0001).

Conclusion:

Age represented a relevant risk factor for impaired skeletal microarchitecture in the proximal fibula in women but not men. The region of drill tunnels according to anatomic techniques showed superior bone microarchitecture versus that according to the Larson technique.