Multicriteria Decision Analysis in Improving Quality of Design in Femoral Component of Knee Prostheses: Influence of Interface Geometry and Material

Table 10

Ranking of top materials and designs scenarios with regard to all technical criteria obtained from QFD.

Objectives		Max	Min	Min	Max	Min	Max	Max	Max	Relative closeness to the ideal solution	Ranking
Relative weights		0.13	0.10	0.13	0.08	0.10	0.16	0.17	0.13
Design options		A	B	C	D	E	F	G	H
Co-Cr alloy	Original	1.86	1.69	21.93	421.4	7.04	339.5	1	1	0.4531	6
	Design 3	1.570	2.189	20.13	423.78	6.68	377.1	1	1	0.4554	5
	Design 11	0.845	0.958	61.94	439.95	6.47	381	1	1	0.4142	8
	Design 15	0.892	1.148	63.25	439.89	6.61	381.7	1	1	0.4064	9
	Design 5	2.962	2.682	35.46	422.95	7.49	376.1	1	1	0.4367	7
FGM	Design 6	4.466	1.866	40.36	24.83	3.03	18.2	3	3	0.5868	1
	Design 7	1.741	1.249	18.03	34.29	2.95	17.3	3	3	0.5809	2
	Design 3	1.707	2.208	17.93	34.91	2.79	18.9	3	3	0.5584	3
	Design 1	3.100	2.655	30.61	28.84	3.13	17.6	3	3	0.5537	4

A: minimum of stress mean in different regions explained in Figure 9 (MPa).
B: maximum of stress STDV in different regions (MPa).
C: maximum contact slip at femoral component/bone interface (μm).
D: safety index of peg (difference between yield of material and maximum peg stress which is 450 and 49 MPa for Co-Cr alloy and FGM resp.).
E: weight index (area of cross section density (g/cm)).
F: safety index of main body (difference between yield of material and maximum stress at corner points of inner contour in which yields of 450 and 32 MPa for Co-Cr alloy and FGM were considered, resp.).
G: biocompatibility of material.
H: hardness of interface material with PE insert.