Related Experiment Video
Updated: Jul 22, 2026
08:04
Proximal Cadaveric Femur Preparation for Fracture Strength Testing and Quantitative CT-based Finite Element Analysis
Published on: March 11, 2017
A simple method of computing hip axis length using fan-beam densitometry and anthropometric measurements
J T Young1, K Carter, M S Marion
1Division of Geriatrics, UCLA School of Medicine, 10833 Le Conte Avenue, Los Angeles, CA 90095-1687, USA. jyoung@mednet.ucla.edu
Summary
Hip axis length (HAL) measured by fan-beam DXA can be accurately estimated using a model combining manual HAL measurements with anthropometric data. This overcomes magnification errors in newer DXA systems, providing reliable hip fracture prediction.
Area of Science:
- Orthopedics
- Radiology
- Gerontology
Background:
- Hip axis length (HAL) is a predictor of hip fracture, independent of bone mineral density and age.
- Pencil-beam dual X-ray absorptiometry (DXA) provides accurate HAL measurements.
- Fan-beam DXA systems introduce magnification errors, leading to inaccurate automatic HAL calculations.
Purpose of the Study:
- To develop a model for accurately calculating HAL from fan-beam DXA scans.
- To use anthropometric measures combined with fan-beam HAL to predict pencil-beam HAL.
- To provide a reliable method for HAL estimation using contemporary DXA technology.
Main Methods:
- Proximal femur scans were performed using both pencil-beam and fan-beam DXA in 21 women (ages 24-60).
- Anthropometric data including height, weight, hip circumference, and manual HAL measurements were recorded.
- A linear model was developed using fan-beam HAL and anthropometric data to predict pencil-beam HAL.
Main Results:
- A simple linear model incorporating manual fan-beam HAL, height, weight, BMI, and hip circumference accurately predicted pencil-beam HAL (R² ≥ 0.96).
- Anthropometric measurements, except for greater trochanter height, were reproducible.
- The developed model provided nonbiased and accurate HAL estimates compared to the pencil-beam method.
Conclusions:
- A validated model enables accurate HAL calculation from fan-beam DXA scans.
- This method overcomes fan-beam DXA magnification errors, offering a reliable alternative to pencil-beam DXA.
- Researchers and clinicians can utilize this model for improved hip fracture risk assessment.
Related Concept Videos
01:29Load along a Single Axis
In structural engineering, the analysis of beams subjected to varying loads is a critical aspect of understanding the behavior and performance of these structural elements. A common scenario involves a beam subjected to a combination of different load distributions.
Consider a beam of length L subjected to a varying load, which is a combination of parabolic and trapezoidal load distribution along the x-axis. In this case, it is essential to determine the resultant loads, their locations, and...
Consider a beam of length L subjected to a varying load, which is a combination of parabolic and trapezoidal load distribution along the x-axis. In this case, it is essential to determine the resultant loads, their locations, and...
01:27Method of Sections: Problem Solving I
Consider a symmetrical roof truss structure, composed of vertical, diagonal, and horizontal members. The length of each horizontal member is 4 m. The lengths of the vertical members FB and HD are 4 m, while the length of member GC is 6 m. The loads acting at joints F, G, and H are 2 kN, while those at joints A and E are 1 kN.
01:15Prismatic Beams: Problem Solving
In the design of a supported timber beam subjected to a distributed load, both the beam's physical dimensions and the timber's characteristics, such as its grade and species, are critical. These factors determine the allowable stress values, which are crucial for calculating the necessary beam depth to ensure structural integrity and safety.
The design begins with analyzing the beam as a free body to identify moments and force balances, thereby determining support reactions. Next, the designer...
The design begins with analyzing the beam as a free body to identify moments and force balances, thereby determining support reactions. Next, the designer...
01:16Shear on the Horizontal Face of a Beam Element
To understand shear on the flat side of a prismatic beam element, consider the vertical and horizontal shearing forces, and the normal forces, acting on the element. The element's upper (U) and lower (L) sections, which are divided by the beam's neutral axis, are examined. The equilibrium of these forces is determined by applying the equilibrium equation, which helps identify the horizontal shearing force. This force is directly related to the bending moments and the cross-section's first...
01:15Beams with Symmetric Loadings
The moment-area method is an analytical tool used in structural engineering to determine the slope and deflection of beams under various loads. Consider a cantilever with a concentrated load and moment at the free end. The first step is constructing a free-body diagram to calculate the reactions at the fixed end. Next, the bending moment diagram is plotted to visualize how the bending moment varies along the beam's length, focusing on points where the bending moment equals zero.
The M/EI...
The M/EI...
01:17Beams with Unsymmetric Loadings
Analyzing a supported beam under unsymmetrical loadings is essential in structural engineering to understand how beams respond to varied force distributions. This analysis involves calculating the deflection and identifying points where the slope of the beam is zero, which are crucial for ensuring structural stability and functionality.
The first moment-area theorem determines the slope at any point on the beam. This theorem indicates that the change in slope between two points on a beam...
The first moment-area theorem determines the slope at any point on the beam. This theorem indicates that the change in slope between two points on a beam...