Stress risers between two ipsilateral intramedullary stems: a finite-element and biomechanical analysis.
Periprosthetic fracture after total joint replacement predominantly occurs at the stem tip. In this study, the effects of gap size, stem stability and cortical thickness between two press-fit, ipsilateral intramedullary stems on the tensile stresses created in the femur were investigated using finite-element models. The findings were confirmed with strain-gauge tests using a composite Sawbone femur. Gap size did not affect the level of stress on the femur. Cortical thickness had an important effect on stress distribution: peak stresses increased as bone cortical thickness decreased. Irrespective of gap size, the tips of loose stems acted as stress risers particularly with thinner cortices; the tips of well-fixed stems, however, did not.
Iesaka
Kazuho
K
NYU-Hospital for Joint Diseases, Department of Orthopaedic Surgery, New York, NY 10003, USA.
Kummer
Frederick J
FJ
Di Cesare
Paul E
PE
D001696:Biomechanical Phenomena; D002858:Chromium Alloys; D004548:Elasticity; D019544:Equipment Failure Analysis; D005264:Femoral Fractures / Q000503:physiopathology*; D005269:Femur / Q000503:physiopathology / Q000601:surgery; D020342:Finite Element Analysis; D015775:Fractures, Stress / Q000503:physiopathology*; D006622:Hip Prosthesis; D006801:Humans; D008953:Models, Anatomic; D011183:Postoperative Complications / Q000503:physiopathology*; D011474:Prosthesis Design; D013718:Tensile Strength / Q000502:physiology
D002858:Chromium Alloys