Stress analysis of total hip arthroplasty with a fully hydroxyapatite-coated stem: comparing thermoelastic stress analysis and CT-based finite element analysis

Abstract

Purpose: The aim of this study was to evaluate the stress distribution in a synthetic femur that was implanted with a fully hydroxyapatite-coated stem using thermoelastic stress and finite element analyses, and to clarify the differences in the stress distributions between these two methods. Methods: Thermoelastic stress analysis is a stress-analysis technique that employs the thermoelastic effect. Sinusoidal vertical loads were applied to the head of the stem placed on the synthetic femur, and surface stress distribution images were acquired using an infrared stress measurement system. The finite element model for the synthetic femur and stem were set up similarly to the thermoelastic stress analysis experiment, and vertical load was applied to the head of the stem. Surface stress distribution and stress values obtained via these two methods were compared. Results: Thermoelastic stress analysis showed that compressive and tensile stresses were distributed from the proximal femur to the diaphysis, not only on the medial and lateral surfaces, but also on the anterior and posterior surfaces. However, finite element analysis showed that compressive stress was not distributed on the anterior and posterior surfaces of the femoral intertrochanter. The stress values of thermoelastic stress analysis tended to be higher in the proximal femur than that obtained via the finite element analysis. Conclusions: The surface stress distribution obtained by these two methods were different specifically in the proximal femur. Our results imply that thermoelastic stress analysis has a better potential than finite element analysis to show the surface stress distribution that reflects the stem design.

Influence of the type of stem and its fixation on revision and immediate postoperative mortality in elective total hip arthroplasty

“…The reduced rate of revision using collared stems has been reported in other studies without elaborating on the effect of sex or age. 18,19,27,28 Our findings emphasize the importance especially for female patients in all age cohorts, as the use of a collar was associated with a clear reduction in the rate of revision (Table II). Other studies have also shown good long-term results of certain uncemented designs of stem in the elderly, which is also reflected in the non-inferiority analysis of the Old cohort.…”

“…Collared stems provide increased primary stability and a reduced risk of subsidence and early periprosthetic fracture. 18,19 The indications for their use have been extended from younger to elderly patients. 20 The aim of this study was to investigate the influence of stem design and the method of fixation on the revision rate, and immediate postoperative mortality rate, focusing on the patients' age and sex, based on the data available in the EPRD.…”

Bone mineral density changes around the stem correlate with stress changes after total hip arthroplasty: A study using thermoelastic stress analysis

“…The stress distribution differs depending on the type of stem, and the contact condition of the stem influences stress distribution [ 13 , 29 ]. In addition, as this method can measure the stress at any point or area on the surface, it may be compared and validated using FEA and strain gauge methods [ 3 , 31 ].…”