Stress distribution on proximal ulna with implant

Abstract

Problems associate with total elbow replacement include infection, poor function,

pain, fracture, stiffness or instability of joints, loosening or wear of the artificial

parts and failure of the triceps tendon. The presence of the abnormal stress

could be the factor that resulted in aseptic loosening.

This project examined the stress distribution between the intact ulna and

implanted ulna. Three different forces, Axial Anteroposterior (AP) compression,

Anteroposterior compression with the magnitude of 1N applied and 1N-cm on the

torsion were applied. These reaction forces are the main responsible for the

loosening of the elbow prosthesis.

From the results obtained, it was found that the stress experienced by the

insertion of the implant has the most impact on the cortical bone as compared to

intact ulna, with an increase of nine-fold when the AP compression force is

applied, followed by the axial compression force which is 2.5 times as high as

compared to the intact model. This could be an indication that leading to the

component loosening. However, the stress is not altered when the torsion is not

applied.