Quantitative and comparative stress analysis in human femur under two different static situations by three‐dimensional photoelasticity

Abstract

Using the three-dimensional photoelastic method a quantitative analysis was carried out on the tension trends in the proximal third of a normal human femur in a stationary weight-bearing situation on two legs. The results obtained show that in this loading situation the maximum stress values (both for tension and compression) are in the area just below the subtrochanteric zone; while going up along the borders of the diaphysis, the tension trends do not vary appreciably. Moreover, the state of the stresses is not constant but varies slightly along the thickness of the bone. The neutral axis is considerably displaced towards the tensile area. A comparison between the stress tension trends in two different static loading situations (one-leg and two-leg support) was carried out. It was found that the maximum tensile stress value in the one-leg position was about 24 times greater than that in the two-leg position and the maximum compression stress value was about 14 times greater than in the two-leg situation.

Biomechanical stress maps of an artificial femur obtained using a new infrared thermography technique validated by strain gages

“…Prior methods for assessing partial or full stress profiles of an intact femur include digital image correlation, infrared thermography, photoelasticity, FEA, micro-FEA, and strain gages [39,[48][49][50][51][52][53][54][55]. Divergence of results from the present study are due to differences in computer modelling assumptions, mechanical test setup, femur material properties, femur geometry, etc.…”

“…This method requires multiple steps like applying a speckle coating to the specimen and using several cameras, but it can give full field strain distributions during dynamic loading. An older method like photoelasticity has been used on proximal human femurs to obtain three-dimensional strain fields, but is limited to quasi-static loading [55]. Future investigators may wish to directly compare multiple approaches like IR thermography, digital image correlation, photoelasticity, strain gages, etc., in a biomechanical application to determine their relative accuracy, precision, and resolution.…”

Experimental Methods for Studying the Contact Mechanics of Joints

“…Also, static compressive knee loads (30 and 80 kg) and flexion angles (0° and 30°) generated contact stress distributions similar to linear and nonlinear analytical models. Another study did 3D experiments mimicking a hip joint [ 73 ]. The investigators made a synthetic femur using epoxy resin, applied static compressive hip joint load in an oven at an elevated temperature, allowed the specimen to cool so its stress state would be maintained (i.e., “stress freezing”), and then physically cut the specimen into slices to image the stress pattern at several planes.…”

Management of Subtrochanteric Fracture Femur- by ProximalFemoralNailing

“…[8] In the subtrochanteric area, tensile and compressive stresses are larger than body weight. [9] Closed proximal femoral nailing allows for rotation and axial translation control while retaining the hematoma and periosteal envelope, which aids healing. This was a prospective study of proximal subtrochanteric femur fractures treated with proximal femur nailing at our tertiary care centre.…”