Clinical Relevance of Vertebral Fractures in Men

Aging and Bone Metabolism

Changes in bone architecture and metabolism with aging increase the likelihood of osteoporosis and fracture. Age-onset osteoporosis is multifactorial, with contributory extrinsic and intrinsic factors including certain medical problems, specific prescription drugs, estrogen loss, secondary hyperparathyroidism, microenvironmental and cellular alterations in bone tissue, and mechanical unloading or immobilization. At the histological level, there are changes in trabecular and cortical bone as well as marrow cellularity, lineage switching of mesenchymal stem cells to an adipogenic fate, inadequate transduction of signals during skeletal loading, and predisposition toward senescent cell accumulation with production of a senescence-associated secretory phenotype. Cumulatively, these changes result in bone remodeling abnormalities that over time cause net bone loss typically seen in older adults. Age-related osteoporosis is a geriatric syndrome due to the multiple etiologies that converge upon the skeleton to produce the ultimate phenotypic changes that manifest as bone fragility. Bone tissue is dynamic but with tendencies toward poor osteoblastic bone formation and relative osteoclastic bone resorption with aging. Interactions with other aging physiologic systems, such as muscle, may also confer detrimental effects on the aging skeleton. Conversely, individuals who maintain their BMD experience a lower risk of fractures, disability, and mortality, suggesting that this phenotype may be a marker of successful aging. © 2023 American Physiological Society. Compr Physiol 13:4355-4386, 2023.

Situational risk factors for fall-related vertebral fractures in older men and women

Situational factors might help explain why most vertebral fractures occur in older people without a previous osteoporosis diagnosis. After adjusting for predisposing risk factors, the activity before the fall, type of fall, and falling direction remained as strong determinants of fall-related vertebral fractures in older men and women.

INTRODUCTION

A matched case-control study was conducted to investigate the effects of situational factors, in addition to predisposing factors, on clinical vertebral fractures in older men and women in Taiwan.

METHODS

Cases were community-dwelling individuals aged ≥ 65 years who visited emergency departments (EDs) of two university-affiliated hospitals due to a fall and had a primary diagnosis of a vertebral fracture during a 1-year period in 2017. Five control patients per case, matched by the time of falling, gender, and age, who sought care in the same ED due to a fall resulting in a soft tissue injury were selected. A total of 64 men (age range: 65 ~ 99 years) and 194 women (age range: 65 ~ 100 years), diagnosed with a vertebral fracture, participated in the study.

RESULTS

Multivariable logistic models were conducted separately for men and women. Results suggested that the following factors were significantly associated with an increased risk of vertebral fractures in men: a low educational level (adjusted odds ratio [OR] = 1.95; 95% confidence interval (CI), 1.02 ~ 3.71), asthma (OR = 2.96; 95% CI, 1.35 ~ 6.92), depression (OR = 4.31; 95% CI, 1.03 ~ 17.5), toileting (OR = 2.30; 95% CI, 1.04 ~ 4.94), slipping (OR = 5.27; 95% CI, 1.80 ~ 15.4), stepping down (OR = 3.99; 95% CI, 1.40 ~ 11.4), sudden leg weakness (OR = 3.73; 95% CI, 1.13 ~ 12.4), and falling backwards (OR = 3.78; 95% CI, 1.83 ~ 7.80); and in women: a fracture history (OR = 2.00; 95% CI, 1.07 ~ 3.76), osteoporosis (OR = 1.94; 95% CI, 1.15 ~ 3.49), getting in/out of the bed/chair (OR = 1.90; 95% CI, 1.07 ~ 3.39), stepping down (OR = 2.10; 95% CI, 1.17 ~ 3.77), and falling backwards (OR = 4.00; 95% CI, 2.39 ~ 6.68) and sideways (OR = 2.61; 95% CI, 1.38 ~ 4.96).

CONCLUSIONS

The combination of predisposing and situational risk factors may display a more comprehensive risk profile for the occurrence of VFs, and thus, interventions that add both types of risk factors may result in greater risk reduction of VFs, although those specifically targeted at situational risk factors during falls are limited and their effectiveness and efficiency remained to be explored.

Changes in spinal bone density, back muscle size, and visceral adipose tissue and their interaction following a multi-component exercise program in older men: secondary analysis of an 18-month randomized controlled trial

In middle-aged and older men, an 18-month multi-component exercise program improved spinal trabecular BMD, paraspinal, and psoas muscle cross-sectional area (CSA) but not visceral adipose tissue (VAT). However, changes in both muscle and VAT CSA were associated with changes in spinal BMD, independent of the exercise intervention.

INTRODUCTION

In older men, we previously reported that a multi-component exercise program improved lumbar spine (LS) trabecular volumetric BMD (Tb.vBMD) compared with no exercise. This study aimed to investigate the following: (1) the effect of the exercise program on paraspinal and psoas (back) muscle CSA and VAT, and 2) if any exercise-related changes in muscle CSA and/or VAT were associated with changes in spinal BMD.

METHODS

Men (n = 180) aged 50-79 years were randomized to an exercise or no-exercise group. Exercise involved high-intensity progressive resistance training (60-85% max) with weight-bearing impact exercise (3 days/week) for 18 months. Quantitative computed tomography was used to assess L1-L3 Tb.vBMD, paraspinal, and psoas muscle CSA and VAT.

RESULTS

Exercise resulted in a 2.6% ((95% CI, 1.1, 4.1), P < 0.01) net gain in back muscle CSA, but no effect on VAT (-1.6% (95% CI, -7.3, 4.2)) relative to no exercise. Robust regression indicated that percentage changes in Tb.vBMD were positively associated with changes (expressed as z-scores) in back muscle CSA in both the exercise (beta (β)-coefficient = 1.9, 95% CI 0.5, 3.2, P = 0.007) and no-exercise (β = 2.6, 95% CI, 1.1, 4.1, P = 0.001) group, and negatively with the changes in VAT (β = -2.0, 95% CI -3.3, -0.7, P = 0.003) in the exercise only group. There were no group differences in the slopes for the muscle-bone or VAT-bone relationships. Regression analysis (pooled data) revealed that back muscle CSA and VAT were independent predictors of the change in Tb.vBMD, explaining 14% of the variance.

CONCLUSION

A multi-component exercise program in middle-aged and older men improved spinal BMD and back muscle size but not visceral fat. However, changes in back muscle size and VAT were associated with the changes in spinal BMD, independent of exercise.

TRIAL REGISTRATION

ACTRN 12617001224314, 22/08/2017 retrospectively registered.

Prevalence of vertebral fracture and densitometric osteoporosis in Spanish adult men: The Camargo Cohort Study

The aim of this study was to assess the prevalence of densitometric osteoporosis and vertebral fractures in Spanish men aged ≥50 years, and to study how the relationship between them may change depending on how osteoporosis is diagnosed. A community-based population of 1003 men aged ≥50 years was studied. Bone mineral density (BMD) was measured by DXA at the lumbar spine, femoral neck and total hip. Vertebral fractures were assessed by lateral thoracic and lumbar spine radiographs. The prevalence of osteoporosis was estimated with both the World Health Organization (WHO) (T-score of <-2.5 at the femoral neck, calculated using the young white female normal reference database) and the National Osteoporosis Foundation (NOF) criteria (T-score of <-2.5 at the femoral neck, total hip or lumbar spine, calculated using the young white male normal reference database). The prevalence of osteoporosis using the WHO criterion was 1.1% and using the NOF criterion was 13%, while that of vertebral fractures was 21.3%. The area under the curve (AUC) for the relationship between BMD and vertebral fracture prevalence was 0.64. The odds ratio for osteoporosis using the WHO definition was 2.57 (p = 0.13), and 1.78 (p = 0.007) using the NOF definition. Vertebral fracture prevalence rose with age. The prevalence of osteoporosis increased only moderately in men aged >70 years with the WHO criterion, and showed no change using the NOF definition. The prevalence of osteoporosis in Spanish men using the WHO definition is too small to have any meaningful clinical use. Although the figure is higher using the NOF definition, it would seem that population-based studies of BMD in men are of questionable value.