Influence of Polyethylene Thickness on Axis Pin in Linked Elbow Implant

Abstract

Elbow joint failure results in weakness, instability, pain and loss of motion. Total Elbow replacement is last way to relief pain and instability. One of available complications after total elbow replacement is bushing wear. Excessive bushing wear may cause instability, pain and inflammatory reply to implant loosening. New prosthetic designs is probably responsible for positive changes to decrease complications. The aim of the present study was to analyze effect of ulnar bushing thickness on transmitted stress to axis pin in linked elbow implant. Axis pin, humeral/ulnar components and polyethylene bushings were modeled. All materials were assumed linear, homogenous, elastic and isotropic. A 50 N force was applied in tip of ulnar component. Distal and proximal of humeral component were fixed. Results showed maximum stress at 94 MPa for axis pin contacting ulnar bushing with 10mm outer diameter while values were 111MPa and 138MPa for ulnar bushing with 9mm and 8mm outer diameters respectively. The present study demonstrates that changing bushing thickness affects stress of axis pin.