Age and sex differences in tibia morphology in healthy adult Caucasians

The anterior offset of the standard entry point for tibial intramedullary nails: A transparent 3D-CT image based analysis

Background

This study examines the relationship between the anterior offset of the tibial intramedullary nail (TIN) entry point and the tibial shaft axis to enhance the fit and alignment of TINs, using transparent 3D-CT in an accurate lateral view to minimize rotational artifacts.

Methods

Data were collected from 100 adult patients undergoing tibial CT scans. Measurements included the anterior offset from the tibial axis to the entry point, tibial tubercle offset, tibial plateau length, posterior slope, tibial length, isthmus diameter, and the isthmus-to-tibial length ratio.

Results

Key findings reveal a median anterior offset of 9.8 mm from the tibial axis to the entry point, with 7 % of cases having an offset of less than 5 mm-potentially insufficient for standard TINs. The tibial tubercle offset was 16.7 mm, and the distance between the entry point and tubercle was 24.5 mm. The median tibial plateau length was 44.8 mm, and the posterior slope was 7.7°. The tibial length measured 330.4 mm, with a median isthmus diameter of 10.4 mm and an isthmus-to-tibial length ratio of 39.7 %. Correlations were found between entry point offset and tibial plateau length, tubercle offset, and age. The entry point was positioned 1.2 mm (median) anteroposteriorly and 6.5 mm mediolaterally from the anterior edge of the tibia.

Conclusion

The median anterior offset from the tibial axis to the starting point was approximately 10 mm, with 7 % of cases having an offset of less than 5 mm, which is too small for most TINs available. Surgeons should be cautious about cases with a small anterior offset to minimize risks during intramedullary nail insertion.

Improving the identification of bone-specific physical activity using wrist-worn accelerometry: A cross-sectional study in 11-12-year-old Australian children

Physical activity (PA) during childhood and adolescence is important for the accrual of maximal peak bone mass. The precise dose that benefits bone remains unclear as methods commonly used to analyze PA data are unsuitable for measuring bone-relevant PA. Using improved accelerometry methods, this study identified the amount and intensity of PA most strongly associated with bone outcomes in 11-12-year-olds. Participants (n = 770; 382 boys) underwent tibial peripheral quantitative computed tomography to assess trabecular and cortical density, endosteal and periosteal circumference and polar stress-strain index. Seven-day wrist-worn raw acceleration data averaged over 1-s epochs was used to estimate time accumulated above incremental PA intensities (50 milli-gravitational unit (mg) increments from 200 to 3000 mg). Associations between time spent above each 50 mg increment and bone outcomes were assessed using multiple linear regression, adjusted for age, sex, height, weight, maturity, socioeconomic position, muscle cross-sectional area and PA below the intensity of interest. There was a gradual increase in mean R2 change across all bone-related outcomes as the intensity increased in 50 mg increments from >200 to >700 mg. All outcomes became significant at >700 mg (R2 change = 0.6%-1.3% and p = 0.001-0.02). Any further increases in intensity led to a reduction in mean R2 change and associations became non-significant for all outcomes >1500 mg. Using more appropriate accelerometry methods (1-s epochs; no a priori application of traditional cut-points) enabled us to identify that ∼10 min/day of PA >700 mg (equivalent to running ∼10 km/h) was positively associated with pQCT-derived measures of bone density, geometry and strength in 11-12-year-olds.

Off-the-Shelf Tibial Cone Sizes May Not Accommodate All Patients' Bone Morphology and May Lead to Cortical Breaches in Revision Total Knee Arthroplasty: A 3D Modeling Study

Background

In revision total knee arthroplasty, tibial cones have demonstrated improved longevity and reduced incidence of aseptic loosening. Several currently available "off-the-shelf" (OTS) cone systems may not have sizes to accommodate all patient bone morphologies.

Methods

Computed tomographies from one hundred primary total knee arthroplasty patients and dimensions of 4 OTS cones were obtained. Press-fit stems were positioned in 3D tibia models to fit the diaphyseal trajectory. Cones were positioned around the stem at 1, 6, and 13 mm resections measured from the trough of the medial tibial plateau, simulating proximal tibial cuts and bone loss. Tibias were examined for cortical breaching following modeled cone preparation.

Results

Increased rate of breaching was observed as size and depth of the cone increased. In 2/49 (4.1%) male and 19/46 (41.3%) female tibias, cones could not be positioned without breaching. No breaches were found in 22/49 (45.0%) male and 5/46 (10.9%) female tibias. For every 1 centimeter increase in patient height, odds of breaching decreased by 12% (odds ratio: 0.88, confidence interval: 0.84, 0.92). For every size increase in cone width, odds of breaching increased by 34% (odds ratio: 1.34, confidence interval: 1.28, 1.47). Placing cones deeper also increased breaching compared to the 1 mm cut.

Conclusions

In revision total knee arthroplasty, smaller OTS or custom tibial cones may be needed to fit a patient's proximal tibial geometry. This is especially true in patients not accommodated by the OTS cone sizes we tested, which impacted shorter patients and/or those with substantial bone loss requiring more tibial resection and deeper cone placement. Use of smaller or custom tibial cones should be considered where indicated.

Influence of femoral bowing on stress distribution of the proximal femur: a three-dimensional finite element analysis

BACKGROUND

Whether femoral bowing or its direction has a mechanical effect on the proximal femur is unclear. This study aimed to define the changes in stress distribution in the proximal femur associated with femoral bowing using finite element analysis.

METHODS

We created four femoral models: original, entire lateral bowing, entire anterior bowing, and the middle of both (50% anterolateral bowing) from computed tomography data of women with standard bowing. Each model's stress distribution was compared by two-layering the stress distribution under loading conditions during walking. We also evaluated displacement vectors.

RESULTS

In all directions of femoral bowing, the stress increased in the femoral neck and the femoral trochanter in the 50% anterolateral bowing. The direction of deformation of the vector for the femoral head increased anteroinferiorly in the 50% anterolateral bowing.

CONCLUSIONS

This study showed that the stress distribution at the proximal femur shifted laterally. The high-stress area increased at the femoral neck or trochanter due to increasing femoral bowing. Femoral bowing also increases the anteroinferior vector in the femoral head. This study provides valuable insights into the mechanism of proximal femoral fractures in older adults.

In silicomodeling of tibial fatigue life in physically active males and females during different exercise protocols

Preventing bone stress injuries (BSI) requires a deep understanding of the condition's underlying causes and risk factors. Subject-specific computer modeling studies of gait mechanics, including the effect of changes in running speed, stride length, and landing patterns on tibial stress injury formation can provide essential insights into BSI prevention. This study aimed to computationally examine the effect of different exercise protocols on tibial fatigue life in male and female runners during prolonged walking and running at three different speeds. To achieve these aims, we combined subject-specific magnetic resonance imaging (MRI), gait data, finite element analysis, and a fatigue life prediction algorithm, including repair and adaptation's influence. The algorithm predicted a steep increase in the likelihood of developing a BSI within the first 40 days of activity. In five of the six subjects simulated, faster running speeds corresponded with higher tibial strains and higher probability of failure. Our simulations also showed that female subjects had a higher mean peak probability of failure in all four gait conditions than the male subjects studied. The approach used in this study could lay the groundwork for studies in larger populations and patient-specific clinical tools and decision support systems to reduce BSIs in athletes, military personnel, and other active individuals.

A statistical shape model of the tibia-fibula complex: sexual dimorphism and effects of age on reconstruction accuracy from anatomical landmarks

A statistical shape model was created for a young adult population and used to predict tibia and fibula geometries from bony landmarks. Reconstruction errors with respect to CT data were quantified and compared to isometric scaling. Shape differences existed between sexes. The statistical shape model estimated tibia-fibula geometries from landmarks with high accuracy (RMSE = 1.51-1.62 mm), improving upon isometric scaling (RMSE = 1.78 mm). Reconstruction errors increased when the model was applied to older adults (RMSE = 2.11-2.17 mm). Improvements in geometric accuracy with shape model reconstruction changed hamstring moment arms 25-35% (1.0-1.3 mm) in young adults.

Sex differences in the effect of diet, obesity, and exercise on bone quality and fracture toughness

Bone fragility and obesity are both diseases that are multifactorial in etiology and pathology. The contributing role of high fat diet (HFD) versus energy overconsumption on bone health is controversial. Exercise is often prescribed for improving bone health, but it is unclear whether HFD or overconsumption influences skeletal adaptations to exercise. Female and male Wistar rats were fed HFD or low fat diet (LFD) for 10 weeks, starting at 8 weeks of age. Within HFD, rats were labeled Obesity-Resistant (OR) or Obesity-Prone (OP) based on weight and fat gain. Within each diet and phenotype group, rats were randomized to treadmill exercise or sedentary control (SED) for the final 4 weeks. Femurs were assessed for fracture toughness. Cortical lamellar and nonlamellar bone microscale material behavior and chemistry were assessed using nanoindentation and Raman spectroscopy. Female bones had higher fracture toughness and mineral: matrix ratio than male bones. Diet and energy overconsumption affected bone characteristics in a sex-dependent manner, where the divergence between OP and OR in response to HFD occurred more rapidly in males. Diet composition, in general, had a stronger effect on bone quality than overconsumption. HFD dramatically decreased bone size and lamellar mineral:matrix compared to LFD. Effects of short-term exercise training on microscale tissue properties were generally more robust with LFD. Exercise enhanced the contrast between lamellar and nonlamellar bone for nanoindentation modulus but decreased this contrast for plastic work. Our data demonstrate the complexities in the relationship between diet and obesity and highlight the importance of addressing both aspects when characterizing bone quality and fracture resistance.

Age-related site-specific modifications in diaphyseal structural properties of the human fibula: Furrows and cross-sectional geometry

OBJECTIVES

Fibular structure is related to locomotor behavior, which allows an exploration of mobility in past human populations with diaphyseal cross-sectional geometry (CSG). However, bone structure depends on age-related changes. Nonmechanical alterations can affect biomechanical investigations. In this study, we examined how the cortical area and the variables used as functional markers in the fibular diaphysis (i.e., CSG and furrows) change with aging. We predict classic and specific modifications, and we discuss functional interpretations based on bone structure.

MATERIALS AND METHODS

The sample consisted of 124 individuals of known age in whom the fibular furrow depths were measured with calipers. Microcomputed tomography (micro-CT) scanning of 38 individuals provided CSG (e.g., cortical area, shape index, and robusticity) and fibular furrow indices. CSG was studied at five cross sections taken along the diaphysis. Linear regression analyses and age group comparisons were conducted.

RESULTS

The cross-sectional shape summary by fibular furrows and shape index and the total area did not change with aging; in contrast, the cortical area and the robusticity (Z_p-std) decreased with age.

DISCUSSION

The decrease in robusticity (Z_p-std) with aging is due to the maintenance of total area, which is related to the specific mechanical environment of the fibula, and to the loss of cortical bone and not to the decrease in mechanical stress. This finding is consistent with the lower bone modeling capacity in aged individuals, which also explains the lack of significant changes in the diaphyseal shape. Thus, fibular structure in older individuals is due to a combination of early bone adaptations to stress and aging effects.

Proximal tibial morphology and risk of posterior tibial cortex impingement in patients with AA-sized Oxford unicompartmental knee arthroplasty tibial implants

BACKGROUND

In cases of Oxford unicompartmental knee arthroplasty (UKA), an increase in anteroposterior and medial-lateral length is usually disproportional when comparing AA and A-sized tibial components. Asynchronous increments may cause tibial keel impingement leading to complications.

METHODS

Radiographic measurements were performed in five patients with AA-sized tibial implants. The posterior cortex of proximal tibia had two angles recorded as ∠ M1 and ∠ M2. The minimum distance between the tibial component keel and outer margin of the posterior tibial cortex (mDKC) was measured, and the correlation between the preoperative posterior slope angle (PSA), ∠ M1, and mDKC was analyzed.

RESULTS

All patients showed an acceptable component positioning. Only one patient had an mDKC of < 4 mm that fulfilled the criteria for the posterior tibial cortex at risk. The patient had an increased PSA and ∠ M1 compared to other patients. A negative correlation was found between preoperative PSA and mDKC (r = - 0.935, p = 0.0193); and ∠ M1 and mDKC (r = - 0.969, p = 0.0032). However, no stem tip pain, periprosthetic fracture, or component loosening were observed.

CONCLUSIONS

The distance between the tibial keel and posterior tibial cortex was reduced in AA-sized patients with a large PSA and ∠M1; therefore, the risk of the tibial cortex injury should be considered.

Cortical and medullary morphology of the tibia

Bone resorption caused by stress shielding and insufficient bone-implant contact continues to be problematic for orthopedic endoprostheses that utilize osseointegration (OI) for skeletal fixation. Morphologic analyses have helped combat this issue by defining anatomic parameters to optimize endoprosthesis loading by maximizing bone-implant contact. These studies have not typically included diaphyseal medullary morphology, as this region is not pertinent to total joint replacement. To the contrary, percutaneous OI endoprostheses for prosthetic limb attachment are placed in the diaphysis of the long bone. This study examined the cortical and medullary morphology of 116 fresh-frozen human cadaveric tibia using computed tomography. Anatomic landmarks were selected and custom MATLAB scripts were used to analyze the cross-sectional cortical and medullary morphology normalized to biomechanical length (BML). BML measured the distance between the tibial plateau and the tibial plafond. Properties such as cortical thickness, medullary diameter, and circularity of the medullary canal were quantified. We tested the influence of sex and laterality on morphology, and examined variations along the length of the bone. Results showed that while both sex and laterality impacted the location of anatomic landmarks, only sex influenced cross-sectional morphology. Overall, morphology significantly affected shape along the length of the bone for all examined properties except medullary circularity. This analysis found that distal to 35% BML, the canal is conducive to a circular implant, with medullary diameter ranging from 13 to 32 mm between 20 and 80% BML. A large size range is necessary for sufficient implant contact in order to accommodate residual limb length after amputation.

Sex differences in bone density, geometry, and bone strength of competitive soccer players

OBJECTIVES

To examine sex differences in bone characteristics in competitive soccer players.

METHODS

43 soccer players (male, n=23; female, n=20), and 43 matched controls (males, n=23; females, n=20), completed the study. Areal BMD (aBMD) of the total body, lumbar spine, and dual femur and tibiae volumetric BMD (vBMD), bone geometry, and bone strength variables (pQCT) were measured. Bone-specific physical activity and training history were assessed.

RESULTS

Male soccer players had significantly greater (p≤0.05) total body and hip aBMD, hip strength indices and 4% and 38% tibia variables than females. Regression analyses determined that BFLBM, not sex, was the strongest predictor of bone variables. Female soccer players exhibited significantly greater percent differences from controls for tibiae variables than males (p≤0.05). Soccer players had greater aBMD and hip strength indices than controls (p≤0.040). Soccer-specific asymmetries were found for 38% total area (2.1%) and pSSI (3.8%), favoring the non-dominant leg (both p≤0.017).

CONCLUSION

Bone characteristics adjusted for body size were greater in male versus female soccer players. However, body composition variables were more important predictors of bone characteristics than sex. There were no sex differences in the magnitude of limb asymmetries, suggesting skeletal responsiveness to mechanical loading was similar in males and females.

pQCT bone geometry and strength: population epidemiology and concordance in Australian children aged 11-12 years and their parents

OBJECTIVES

To describe the epidemiology and concordance of bone health in a population-based sample of Australian parent-child dyads at child age 11-12 years.

DESIGN

Population-based cross-sectional study (the Child Health CheckPoint) nested between waves 6 and 7 of the Longitudinal Study of Australian Children (LSAC).

SETTING

Assessment centres in seven cities around Australia, February 2015-March 2016.

PARTICIPANTS

of all participating CheckPoint families (n=1874), bone data were available for 1222 dyads (1271 children, 50% girls; 1250 parents, 86% mothers).

OUTCOME MEASURES

Peripheral quantitative CT (pQCT) of the non-dominant leg scanned at the 4% (distal) and 66% (mid-calf) tibial sites. Stratec XCT 2000 software generated estimates of bone density, geometry and polar stress-strain index.Parent-child concordance were assessed using Pearson's correlation coefficients and multivariable linear regression models. Percentiles were determined using survey weights. Survey weights and methods accounted for LSAC's complex sampling, stratification and clustering within postcodes.

RESULTS

Concordances were greater for the geometric pQCT parameters (periosteal circumference 0.38, 95% CI 0.33 to 0.43; endosteal circumference 0.42, 95% CI 0.37 to 0.47; total cross-sectional area 0.37, 95% CI 0.32 to 0.42) than density (cortical density 0.25, 95% CI 0.19 to 0.30). Mother-child and father-child values were similar. Relationships attenuated only slightly on adjustment for age, sex and body mass index. Percentiles and concordance are presented for the whole sample and by sex.

CONCLUSIONS

There is strong parent-child concordance in bone geometry and, to a lesser extent, density even before the period of peak adolescent bone deposition. This geometrical concordance suggests that future intergenerational bone studies could consider using pQCT rather than the more commonly used dual X-ray absorptiometry (DXA).

Type 1 diabetes onset at young age is associated with compromised bone quality

Women with type 1 diabetes (T1D) are at increased risk for fracture. We studied the association of T1D and young age at T1D onset (T1D onset before 20 years) on bone structural quality. 24 postmenopausal women with T1D (mean age 60.9 years, mean T1D duration 41.7 years) and 22 age, sex- and body mass index (BMI)-matched controls underwent dual X-ray absorptiometry (DXA) measured areal bone mineral density (aBMD) at the lumbar spine, hip and distal radius. Bone mass, geometry and estimated bone strength were assessed at distal and shaft of non-dominant radius and tibia using peripheral quantitative computed tomography (pQCT). Postmenopausal women with T1D had lower trabecular volumetric bone mineral density (vBMD) (LSM ± SEM; 166.1 ± 8.2 vs 195.9 ± 8.3 mg/cm3, p = 0.02) and compressive bone strength (24.6 ± 1.8 vs 30.1 ± 1.9 mg2/mm4, p = 0.04) at the distal radius compared to controls adjusting for age, BMI and radius length. At the distal radius, patients with young onset T1D had lower total vBMD (258.7 ± 19.7 vs 350.8 ± 26.1 mg/cm3, p = 0.02) and trabecular vBMD (141.4 ± 11.6 vs 213.6 ± 15.4 mg/cm3, p = 0.003) compared to adult onset T1D patients adjusting for age, BMI and the radius length. At the tibial shaft, young onset T1D patients had larger endosteal circumference (39.1 ± 1.2 vs 32.1 ± 1.6 mm, p = 0.005) with similar periosteal circumference (67.1 ± 0.9 vs 65.1 ± 1.2 mm, p = 0.2) resulting in reduced cortical thickness (4.4 ± 0.1 vs 5.2 ± 0.1 mm, p = 0.004) compared to adult onset T1D patients adjusting for age, BMI and the tibia length. There was no difference in the lumbar spine, femoral neck, total hip and distal radius DXA-measured aBMD between subjects with T1D and controls. T1D is associated with lower trabecular vBMD at the distal radius. T1D onset before age 20 is associated with cortical bone size deficits at the tibial shaft.

Bone health, activity and sedentariness at age 11-12 years: Cross-sectional Australian population-derived study

AIM

To examine cross-sectional associations of children's bone health (size, density, strength) with moderate-vigorous physical activity (MVPA) and sedentary behaviour by considering: (1) duration of activity, (2) fragmentation, and (3) duration/fragmentation combined.

METHODS

Design: Population-based cross-sectional study.

PARTICIPANTS

11-12 year-olds in the Longitudinal Study of Australian Children's Child Health CheckPoint. Exposures: MVPA and sedentary behaviour (7-day accelerometry), yielding (1) daily average durations (min/day) and (2) fragmentations (the parameter alpha, representing the relationship between activity bout frequency and bout length).

OUTCOMES

Tibial peripheral quantitative computed tomography (bone density, geometry, strength).

ANALYSIS

Multivariable regression models including activity durations and fragmentations separately and combined.

RESULTS

Of 1357 children attending the CheckPoint, 864 (64%) provided both bone and accelerometry data (mean age 11.4 years (standard deviation (SD) 0.5); 49% male). Mean daily MVPA and sedentary behaviour durations were 34.4 min/day (SD 28.3) and 667.9 min/day (SD 71.9) respectively for boys and girls combined. Each additional daily hour of MVPA was associated with small bone health benefits comprising greater periosteal and endosteal circumference (standardised effect sizes 0.25, 95% CI 0.10 to 0.40 and 0.21, 95% CI 0.03 to 0.39, respectively) and bone strength (0.26, 95% CI 0.14 to 0.38). Sedentary duration and fragmentation of either MVPA or sedentary behaviour showed little association with bone health.

CONCLUSIONS

In early adolescence, MVPA duration showed associations with better bone health that, while modest, could be of population-level importance. MVPA fragmentation and sedentary behaviour duration and fragmentation seemed less important.

Comparison of Clinical Results and Injury Risk of Posterior Tibial Cortex Between Attune and Press Fit Condylar Sigma Knee Systems

BACKGROUND

We compared clinical and radiographic results after total knee arthroplasty (TKA) using Attune and Press Fit Condylar Sigma, and investigated whether use of the current prosthesis increased injury risk to the tibial cortex in Asian patients. We also assessed whether a preoperative posterior tibial slope angle (PSA) is associated with the injury when using the current prosthesis.

METHODS

The 300 TKAs with Attune (group A) were compared to the 300 TKAs with Press Fit Condylar Sigma (group B). Demographics were not different, except follow-up periods (24.8 vs 33.3 months, P < .001). The Western Ontario and McMaster Universities Index and range of motion were compared. A minimum distance between tibial component stem and posterior tibial cortex (mDSC) was compared. The correlation between preoperative PSA and mDSC was analyzed in group A.

RESULTS

The postoperative Western Ontario and McMaster Universities Index and range of motion of group A were better than those of group B (17.7 vs 18.8, P = .004; 131.4° vs 129.0°, P = .008). The mDSC was shorter in group A (6.3 vs 7.0 mm, P < .001), which made up a higher proportion of the high-risk group for posterior tibial cortical injury with an mDSC of <4 mm (20.0% vs 10.7%, P = .002). A negative correlation was found between the preoperative PSA and mDSC in group A (r = -0.205, P < .001).

CONCLUSION

The TKA using the current prosthesis provided more satisfactory results than the TKA using the previous prosthesis. However, the injury risk to the posterior tibial cortex increased in the knees with a large PSA when using the current prosthesis for Asian patients.

Differences of bone mineral mass, volumetric bone mineral density, geometrical and structural parameters and derived strength of the tibia between premenopausal and postmenopausal women of different age groups: a peripheral Quantitative Computed Tomography (pQCT) study

Menopause constitutes a significant cause of bone loss, and it is currently debated whether bone mass is preserved or begins to decline substantially before that time in women. We used pQCT of the tibia to estimate differences of bone mineral mass, bone geometry and derived strength between premenopausal and postmenopausal Caucasian women of different age-groups per decade of age (20-79y). For each individual, we assessed total, trabecular and cortical bone mineral content (BMC, mg) and volumetric bone mineral density (BMD, mg/cm3); total and cortical cross-sectional areas (CSA, mm2); periosteal circumference (PERI_C, mm); endosteal circumference (ENDO_C, mm); mean cortical thickness (CRT_THK, mm); and Stress-Strain Index (SSI) . Comparisons were made both between premenopausal (N=84) and postmenopausal (N=231) women as distinct groups, and among women of the different age-groups. Our results indicated that premenopausal women had significantly higher trabecular and cortical BMC and vBMD, with higher cortical CSA, CRT_THK and SSI than postmenopausal women. Moreover, significant differences of trabecular but not cortical BMC, vBMD or SSI were found between women of the younger (<48y) age-groups. PERI_C, ENDO_C displayed lower values in the 20-29y group and higher values in the 70-79y group, denoting significant differences of bone geometry with aging.

Skeletal maturity leads to a reduction in the strain magnitudes induced within the bone: a murine tibia study

Bone adapts to changes in the local mechanical environment (e.g. strains) through formation and resorption processes. However, the bone adaptation response is significantly reduced with increasing age. The mechanical strains induced within the bone by external loading are determined by bone morphology and tissue material properties. Although it is known that changes in bone mass, architecture and bone tissue quality occur with age, to what extent they contribute to the altered bone adaptation response remains to be determined. This study investigated alterations in strains induced in the tibia of different aged female C57Bl/6J mice (young, 10-week-old; adult, 26-week-old; and elderly, 78-week-old) subjected to in vivo compressive loading. Using a combined in vivo/in silico approach, the strains in the bones were assessed by both strain gauging and finite element modeling experiments. In cortical bone, strain magnitudes induced at the mid-diaphysis decreased by 20% from young to adult mice and by 15% from adult to elderly mice. In the cancellous bone (at the proximal metaphysis), induced strains were 70% higher in young compared with adult and elderly mice. Taking into account previous studies showing a reduced bone adaptation response to mechanical loading in adulthood, these results suggest that the diminished adaptive response is in part due to a reduction in the strains induced within the bone.

Sex classification using the three-dimensional tibia form or shape including population specificity approach

The aims of this study were to enable geometric morphometric sex classification using tibial proximal and distal sexual dimorphism and to evaluate the secular trend of tibial shape/form from the early 20th century to the present day. The study samples consisted of 61 adult tibias from an early 20th-century Czech population and 57 three-dimensional tibias from a 21st-century population. Discriminant function analysis with cross-validation was carried out to assess the accuracy of sex classification. Shape analysis revealed significant sex differences in both tibial extremities of the 21st-century sample and in the proximal tibia of the 20th-century population. Sex-based divergence varied between the analyzed samples, raising the issues of population specificity and diachronic change. Classification using tibial form was more successful than using tibial shape. The highest values of correct assignment (91.80% and 88.52%) were found using the form from the early 20th Czech population.

Exercise to improve pediatric bone and fat: a systematic review and meta-analysis

PURPOSE

This study aimed to determine the effects of school-based, bone-focused exercise interventions on bone, fat, and lean mass in children by systematically reviewing and meta-analyzing the literature.

METHODS

Potentially relevant articles were identified by searching electronic databases. Abstracts were included if they described the effects of an in-school exercise intervention for children 5-17 yr old compared with controls and presented baseline and follow-up results for bone, fat, and lean measures. Identified studies were systematically reviewed for methodological quality. Meta-analyses were performed for whole body, lumbar spine, and femoral neck bone mineral content (BMC), fat, and lean mass.

RESULTS

Sixteen eligible trials were identified including eight randomized controlled trials, three clinical controlled trials, and five nonrandomized, nonmatched studies. The quality analysis revealed two studies had low, nine had medium, and five had a high risk of bias. Meta-analyses revealed a small positive effect of bone-targeted exercise on whole body BMC (standardized mean difference [SMD] = 0.483, 95% CI = 0.132-0.833), femoral neck BMC (SMD = 0.292, 95% CI = -0.022 to 0.607), lumbar spine BMC (SMD = 0.384, 95% CI = 0.193-0.575), fat mass (SMD = -0.248, 95% CI = -0.406 to -0.089), and lean mass (SMD = 0.159, 95% CI = -0.076 to 0.394).

CONCLUSIONS

Beneficial effects of school-based, bone-targeted exercise were observed for bone and fat, but not for lean mass. Excluding trials with high risk of bias strengthened that effect. Considerable study heterogeneity may have obscured effects on lean mass. The effects observed for bone and fat support the pursuit of brief, jumping-focused interventions to reduce fat as well as enhance musculoskeletal tissue in school age children.

Age-related changes in trabecular and cortical bone microstructure

The elderly population has substantially increased worldwide. Aging is a complex process, and the effects of aging are myriad and insidious, leading to progressive deterioration of various organs, including the skeleton. Age-related bone loss and resultant osteoporosis in the elderly population increase the risk for fractures and morbidity. Osteoporosis is one of the most common conditions associated with aging, and age is an independent risk factor for osteoporotic fractures. With the development of noninvasive imaging techniques such as computed tomography (CT), micro-CT, and high resolution peripheral quantitative CT (HR-pQCT), imaging of the bone architecture provides important information about age-related changes in bone microstructure and estimates of bone strength. In the past two decades, studies of human specimens using imaging techniques have revealed decreased bone strength in older adults compared with younger adults. The present paper addresses recently studied age-related changes in trabecular and cortical bone microstructure based primarily on HR-pQCT and micro-CT. We specifically focus on the three-dimensional microstructure of the vertebrae, femoral neck, and distal radius, which are common osteoporotic fracture sites.