Comparison of polyethylene wear in anatomical and reversed shoulder prostheses.
Wear of polyethylene is associated with aseptic loosening of orthopaedic implants and has been observed in hip and knee prostheses and anatomical implants for the shoulder. The reversed shoulder prostheses have not been assessed as yet. We investigated the volumetric polyethylene wear of the reversed and anatomical Aequalis shoulder prostheses using a mathematical musculoskeletal model. Movement and joint stability were achieved by EMG-controlled activation of the muscles. A non-constant wear factor was considered. Simulated activities of daily living were estimated from in vivo recorded data. After one year of use, the volumetric wear was 8.4 mm(3) for the anatomical prosthesis, but 44.6 mm(3) for the reversed version. For the anatomical prosthesis the predictions for contact pressure and wear were consistent with biomechanical and clinical data. The abrasive wear of the polyethylene in reversed prostheses should not be underestimated, and further analysis, both experimental and clinical, is required.
Terrier
A
A
Ecole Polytechnique Fédérale de Lausanne, Station 15, 1015 Lausanne, Switzerland. alexander.terrier@epfl.ch
Merlini
F
F
Pioletti
D P
DP
Farron
A
A
D000203:Activities of Daily Living; D001696:Biomechanical Phenomena; D019544:Equipment Failure Analysis; D006801:Humans; D007595:Joint Prosthesis / Q000009:adverse effects; D008953:Models, Anatomic; D020959:Polyethylene / Q000009:adverse effects; D011474:Prosthesis Design; D012785:Shoulder Joint / Q000033:anatomy & histology / Q000503:physiopathology*
D020959:Polyethylene