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Table 4 Implant type, design and validation strategies, and stress shielding measured of studies applying graded porosity designs

From: Additively manufactured controlled porous orthopedic joint replacement designs to reduce bone stress shielding: a systematic review

Study

Implant type

Porosity type

Main design strategy

Computational validation

Experimental validation

Main stress shielding measure

Max. stress shielding reduction

Overall quality score

[31]

Hip acetabular cup

Diamond, body- centered cubic, rhombic dodecahedron

3 porosity-graded layers from inside to bone–implant interface

Compression testing, DIC

Strains, deformation pattern

Not quantified

17

[84]

Hip femoral stem

Body‐centered cubic (BCC)

9 axially porosity-graded layers

Implanted model

Stress in bone

Gruen zone 7: + 50%

19

[47]

Hip femoral stem

Schwarz Primitive

9 axially porosity-graded layers

Implanted model

Stress in bone

Not quantified

16

[50]

Hip femoral stem

Auxetic

Positive to negative Poisson’s ratio from one side to another

Implanted model

Stress and strain in implant

Not quantified

20

[99]

Hip femoral stem

Square

2 axially porosity-graded layers

Implanted model

Stress in bone

Gruen zone 2: + 22% Gruen zone 3: + 18% Gruen zone 5: + 20% Gruen zone 6: + 36% Gruen zone 7: + 12%

20

[48]

Hip femoral stem

Porosity gradually decreased toward distal end

Implanted model

Stress in bone

Cortical: Steel: 29%, Titanium: + 21%, FGM: + 21%

Cancellous: Steel: + 14%, Titanium: + 10%, FGM: + 15%*1

15

[51]

Hip femoral stem

Auxetic, honeycomb

Positive to negative Poisson’s ratio from one side to another

Simplified implanted model

Strains in bone

Not quantified

15

[15]

Hip femoral stem

Octahedral

5 axially porosity-graded layers, 3 radially porosity-graded layers

Implanted model

Bending test, implanted model

Stress in bone

Gruen zone 7: + 368%

16

[49]

Hip femoral stem

Axially, radially and combined porosity-graded

Structural analysis

Stress shielding effect

SSE -31%

15

[52, 53]

Hip femoral stem

Variations of body-centered cubic (BCC)

Strut thickness based on interaction with cortical/trabecular bone, alternating pore size

Implanted model

Stress in implant

Not quantified

16

[46]

Hip femoral stem

Diamond

3 radially porosity-graded layers, 4 axially porosity-graded layers

Implanted model

Bone loss

Bone loss − 75%

20

[28]

Hip femoral stem

Cubic

3 radially porosity-graded layers

ISO 7206-4, implanted model

Stress in bone

Gruen zone 7: + 65%

17

[54]

Knee femoral component

Porosity decrease from uppermost to lowermost surface

Implanted model

Stress in bone (interface)

Stress + 41.5%

18

[55]

Metal block augmentation for knee tibial component

Cubic/grid

2 porosity sections based on topology optimization

Implanted model

Stress in bone

Stress + 18.60%

19

  1. *1The materials in this study were all porosity-graded, and FGM is referring to the combination of two materials (steel and titanium). The stress shielding measure chosen is the stress increase in the surrounding bone and reported separately for the cortical and cancellous area