Abstracts Posters SICOT-SOF meeting Gothenburg 2010 _2_

Poster
Topic: Arthroplasty - Knee
Abstract number: 23213
DYNAMIC AND STATIC ANALYSES OF INTERFACIAL STABILITY FOR
PATELLOFEMORAL PROSTHESIS-BONE CONSTRUCT
Chu An LUO 1 , Chun Ming CHEN 1 , Shang Chih LIN 2
1 Department of Mechanical Engineering, National Central University, Taoyuan,
Zhongli (TAIWAN), 2 Institute of Biomedical Engineering, National Central University,
Taoyuan, Zhongli (TAIWAN)
Introduction: From the viewpoints of minimal bone removal, the patellofemoral
arthroplasty is a promising treatment for the patients with only isolated patellofemoral
osteoarthritis. For the commercial system, the prosthesis is simply mounted to the
resected femur by fixing pin(s) and/or bone cement. Hence, the interfacial stability is
one of the major concerns. The current study is aimed to investigating the dynamic
behavior and stress distribution of the patellofemoral prosthesis-bone construct.
Methods: The 3D knee model with the patellofemoral prosthesis was simulated from
flexion 0 to 155 degrees, and verified by femoral rollback, screw home and
patellofemoral contact forces. The interfacial contact sites and forces were input into
the finite element analyses. The fixing pins, bone cement and preserved bone were
parameterized to evaluate the construct stability. Results: Only pin fixation induces
the highly concentrated stress around the pricked bone holes. The bone cement
quite significantly improves the stability of patellofemoral prosthesis. For the
innovative surgery, the bone cavity milled for setup of prosthesis most effectively
stabilizes the prosthesis even without cement used. If cement used or bone cavity
milled, the pin design plays minor effect on the prosthesis-bone stability. Discussion:
For the current patellofemoral surgery, the prosthesis was embedded in the bone
resected by a saw and further fixed by pins and cement. However, the use of cement
might cause an inflammatory tissue response and complications. By contrast, the
structural support from the surrounding bone cavity constrains the prosthesis and
serves as the stabilizer for the prosthesis.
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