title: Stress risers between two ipsilateral intramedullary stems: a finite-element and biomechanical analysis.
abstract: 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.
authors.affiliation: NYU-Hospital for Joint Diseases, Department of Orthopaedic Surgery, New York, NY 10003, USA.
authors.forename: Kazuho
authors.initials: K
authors.lastname: Iesaka
authors.forename: Frederick J
authors.initials: FJ
authors.lastname: Kummer
authors.forename: Paul E
authors.initials: PE
authors.lastname: Di Cesare
mesh_terms: 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
chemical_list: D002858:Chromium Alloys