Mechanická analýza styku hlavičky a jamky totální endoprotézy kyčelního kloubu

Mechanical analysis of contact between ball head and acetabular fossa of total hip prothesis

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The paper belongs to biomechanics of a hip joint section. It is engaged in problems with industrial tolerances as one of the possible total hip prothesis insufficiency. Three computation models of the ball head and acetabular fossa were made, on which interference or clearance fit were simulated. Two computation models were 2D, from which one involve pelvis os and one was 3D. Real loading conditions of the hip joint during the slow walk of a human were simulated. Ascertained were values of contact presses and frictional moment needed to turn ball head in acetabular fossa. Finite element method (FEM) system ANSYS was used to computation. On 2D solution on model of the ball head and acetabular fossa was verified that industrial tolerances have big effect on values of contact pressure and its distribution and also on value of frictional moment, needed to turn the ball head in acetabular. It can be definitely said that from aspect of value and distribution of contact pressure and value of frictional moment the interference fit is very disadvantageous. Effect of industrial tolerances wasn’t verified in case of 2D model with pelvis os, when acetabular fossa was loaded in physiological position. Flexibility of acetabular fossa an pelvis os caused occurrence of the same contact area in every kind of fit. Therefore the results of all ascertained values were identical. In the meanwhile it is not possible to give any conclusions in case of 3D solution. In the present we have results just for one kind of fit (clearance fit). Analysis is in development.

The paper belongs to biomechanics of a hip joint section. It is engaged in problems with industrial tolerances as one of the possible total hip prothesis insufficiency. Three computation models of the ball head and acetabular fossa were made, on which interference or clearance fit were simulated. Two computation models were 2D, from which one involve pelvis os and one was 3D. Real loading conditions of the hip joint during the slow walk of a human were simulated. Ascertained were values of contact presses and frictional moment needed to turn ball head in acetabular fossa. Finite element method (FEM) system ANSYS was used to computation. On 2D solution on model of the ball head and acetabular fossa was verified that industrial tolerances have big effect on values of contact pressure and its distribution and also on value of frictional moment, needed to turn the ball head in acetabular. It can be definitely said that from aspect of value and distribution of contact pressure and value of frictional moment the interference fit is very disadvantageous. Effect of industrial tolerances wasn’t verified in case of 2D model with pelvis os, when acetabular fossa was loaded in physiological position. Flexibility of acetabular fossa an pelvis os caused occurrence of the same contact area in every kind of fit. Therefore the results of all ascertained values were identical. In the meanwhile it is not possible to give any conclusions in case of 3D solution. In the present we have results just for one kind of fit (clearance fit). Analysis is in development.

Mechanical analysis of contact between ball head and acetabular fossa of total hip prothesis Mechanická analýza styku hlavičky a jamky totální endoprotézy kyčelního kloubu

2004-09-08

Strojnícka Fakulta STU v Bratislave

Bratislava

80-227-2105-0

Strojné inžinierstvo 2004

62–

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