Population-based, three-dimensional analysis of age- and sex-related femur shaft geometry differences.

This study deals with differences of femoral geometric focus on the bowing and width. Analysis using three-dimensional skeletonization showed increase of femoral bowing and femur width over life (more in women), and widening of the medullary canal only in women after 50 years old, not in men. INTRODUCTION: The changes in femur geometry that occur with aging and lead to fragility or insufficiency fracture remain unclear. The role of the lower limb geometry, including the femur and femoral bowing, has become a point of discussion, especially in atypical femur fracture. This study aimed to analyze femur shaft geometry using three-dimensional skeletonization. METHODS: We acquired computed tomography images of both femurs obtained. A total of 1400 age- and sex-stratified participants were enrolled and were divided into subgroups according to age (by decade) and sex. The computed tomography images were used to produce 3-dimensional samplings of anatomical elements of the human femur using reconstruction and parametrization from these datasets. The process of skeletonization was conducted to obtain compact representation of the femur. With the skeletonization, we were able to compare all parameters according to age and sex. RESULTS: The femur length was 424.4 ± 28.6 mm and was longer in men (P < 0.001). The minimum diameter of the medullary canal was 8.9 ± 2.0 mm. The radius of curvature (ROC) was 906.9 ± 193.3 mm. Men had a larger femur length, femur outer diameter, and the narrowest medullary diameter (P < 0.001, respectively). Women had significantly smaller ROC (P < 0.001). ROC decreased by 19.4% in men and 23.6% in women between the ages of 20 to 89 years. Femur width increased over life by 11.4% in men and 24.5% in women. Between the ages of 50 and 89 years, the medullary canal appears to have increased by 32.7% in women. CONCLUSION: This geometry analysis demonstrated that femoral bowing and femoral width increased related to aging, and that the medullary canal widened after the age of 50 years in women. This cross-sectional study revealed important age- and sex-related differences in femur shaft geometry that occur with aging.

New Computerized Method in Measuring the Sagittal Bowing of Femur from Plain Radiograph-A Validation Study.

BACKGROUND: Mismatch of intramedullary nails with the bowing of femur is a frequent clinical finding. Previous studies showed inconsistent results. METHODS: We present an algorithm of region growing territory method to get the radii of the anterior bowing of femur. We also tested it on ten radiographs. Plain radiographs of the lateral view of femur from five men and five women taken between January and August 2014 in Taipei Hospital were chosen randomly. The curvature of femur outline and medullary canal were measured for three times each. Radii of curvature of whole femur, proximal, middle and distal parts were calculated and analyzed. RESULTS: The coefficient of variation of the 240 measurements ranged from 0.007 to 0.295 and averaged 0.088. The average radii of curvature of the whole, proximal, middle, and distal femur were 1318 mm, 752 mm, 1379 mm, and 599 mm, respectively. At the distal part of the femur, the radius of curvature of the femur outline (452 mm) was smaller than the medullary canal (746 mm) (p < 0.05). Women's femur was straighter than men's when we compared the whole length (1435 mm vs. 1201 mm, p < 0.05). The radii we calculated were smaller than the current intramedullary nails. CONCLUSION: The results showed that the inter-observer and intra-observer differences are acceptable, support the impression that different bowing conditions existed for Asians as compared to Caucasians, and also indicate the mismatch of current instruments to the curvature of femur.