Importance of polyethylene thickness in total shoulder arthroplasty: a finite element analysis.
BACKGROUND
Articular surfaces reconstruction is essential in total shoulder arthroplasty. Because of the limited glenoid bone support, thin glenoid component could improve anatomical reconstruction, but adverse mechanical effects might appear.


METHODS
With a numerical musculoskeletal shoulder model, we analysed and compared three values of thickness of a typical all-polyethylene glenoid component: 2, 4 (reference) and 6mm. A loaded movement of abduction in the scapular plane was simulated. We evaluated the humeral head translation, the muscle moment arms, the joint force, the articular contact pattern, and the polyethylene and cement stress. Findings Decreasing polyethylene thickness from 6 to 2mm slightly increased humeral head translation and muscle moment arms. This induced a small decreased of the joint reaction force, but important increase of stress within the polyethylene and the cement mantel. Interpretation The reference thickness of 4mm seems a good compromise to avoid stress concentration and joint stuffing.
Laboratory of Biomechanical Orthopedics, Ecole Polytechnique Fédérale de Lausanne, Station 19, 1015 Lausanne, Switzerland. alexandre.terrier@epfl.ch
Alexandre
A
Terrier
Vittoria
V
Brighenti
Dominique P
DP
Pioletti
Alain
A
Farron
D001672:Biocompatible Materials / Q000737:chemistry*; D019544:Equipment Failure Analysis; D020342:Finite Element Analysis; D006801:Humans; D007595:Joint Prosthesis; D009119:Muscle Contraction; D018482:Muscle, Skeletal / Q000503:physiopathology*; D020959:Polyethylene / Q000737:chemistry*; D011474:Prosthesis Design; D016059:Range of Motion, Articular; D012785:Shoulder Joint / Q000503:physiopathology*
D001672:Biocompatible Materials; D020959:Polyethylene