CAD, CAE and CAM for a new anisotropic carbon fiber reinforced hip endoprosthesis stem technology, test procedures and qualifying preclinical results

An uncemented hip endoprosthesis shaft has been developed using a thick HT carbon fiber/polyetheretherketone (PEEK) laminate. Model processing steps for obtaining a 32 mm thick laminate regarding autoclave cycles were obtained using a polyamide 12 matrix and HT carbon fibres. These results were used to evaluate an optimal autoclave cycle for the PEEK-laminate. A standard design of a hip endoprosthesis shaft was defined in CATIA and NC data feeding a 5 axis machining center were generated. Shafts were machined and tested in a hip pulsator applying cyclic load with 2800 N peak load and 300 N basic load. Inclined implantation in sagittal and frontal planes in a PMMA bed (DIN 58840 modified) assured application of torsion to the stem. Stems were macroscopically undamaged. Destructive testing was additionally performed revealing a typical compression failure mode medially and a tensile failure mode laterally. A scaled-down version for implantatioll in sheep using an identical laminate is intended.