IN-VITRO BIOMECHANICAL ASSESSMENT OF A NEWLY DESIGNED CEMENT LESS FEMORAL STEM

Abstract: The stability of an artificial cement less femoral stem depends on its fit within the femoral cavity. In this study, a cement less hip joint stem was designed based on the anthropometric data of 98 femurs of patients of Indian (Asia) origin. The design was manufactured on a standard CNC milling machine and was made of Ti6Al4V. In vitro stability studies were carried out using standard test protocol incorporating standard potting cement, a selective laser sintered (SLS) femur and a dry cadaveric femur. The micro-motion of the stem was measured using LVDTs attached at various locations along the designed implant. The entire setup was placed in an Instron test machine with an applied static axial load of 2500N. For the test in potting cement, the strains ranged between 320 and 1211 ?m over the measured sites. Strain on the lateral side was found to be less for the new design as compared with a conventional design, while on the medial side it was almost the same for both. The maximum micro motion for the stem-dry femur construct was found to be 1800 ?m whereas for the stem-SLS femur combine, it was found to be 380 ?m. The finite element models developed were found to closely match the behavior of the stem-potting cement construct and stem-SLS femur.

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