Age-related dynamic deformation of the femoral shaft and associated osteoporotic factors: a retrospective study in Chinese adults

Abstract

Dynamic skeletal deformation with ageing showed important signs of degenerative and osteoporotic diseases. We found that both femoral bowing and cortical thickness were correlated with ageing in a Chinese population. Further, femoral cortical index, an osteoporotic indicator, was negatively correlated with femoral bowing angle. Hence, more attention should be paid to these femoral morphological changes to avoid fragility fractures and failed internal fixation.

Purpose: The purpose of this study was to determine whether morphological parameters of the femoral shaft are in age-related deformation and identify correlations between parameters of femoral cortical thickness and femoral shaft bowing.

Methods: One hundred twenty patients (mean 50 years, range 18~104 years) who had received standard long-standing anteroposterior and femoral lateral radiographs from October 2016 to October 2019 were included in this retrospective study. The sagittal femoral bowing angle (sFBA), sagittal femoral cortical index (sFCI), coronal femoral bowing angle (cFBA), and coronal femoral cortical index (cFCI) were measured by two orthopaedists separately. All the participants' demographic data, including age, sex, body laterality, height, and weight, were collected. The Student's t test, Mann-Whitney U test, two-way ANOVA, Pearson correlation, and multiple linear regression were used in the statistical analysis.

Results: The mean age of the male and female participants was 46.95 ± 15.25 and 52.22 ± 15.61 years, respectively. Two-way ANOVA revealed that females had a significantly lower sFCI than males at the right side (P < 0.05). There were no significant interactions between sex or body laterality and the sFBA, cFBA, sFCI, and cFCI groups (P > 0.05). Pearson correlation revealed that sFCI was strongly correlated with sFBA (r = - 0.535, P < 0.05) and cFBA (r = - 0.535, P < 0.05). Multiple linear regression analysis demonstrated that both age (β = 0.304 and 0.308 respectively) and sFCI (β = - 0.322 and - 0.414 respectively) were two independent predictors associated with sFBA and cFBA respectively.

Conclusions: The femoral shaft bowing of the Chinese population was positively correlated with ageing, whereas the sagittal femoral cortical thickness negatively correlated with ageing. A high FBA occurred in femoral shafts with a low sFCI, which revealed that femoral shaft bowing was associated with femoral cortical thickness. During femur-related surgery in older patients, more attention should be paid to these femoral morphological changes.

Keywords: Ageing; Dynamic deformation; Femoral bowing angle (FBA); Femoral cortical index (FCI); Osteoporosis; Radiograph.