Table 3 Mean values and standard deviations (SD) of surface roughness values and hood scores of all implants investigated; N of all revision reasons. Comparison between the two implant designs using R² P-values < 0.05 were considered statistically significant

Tibial tray backside, %

0.39 +/−0.32

0.20 +/− 0.21

0.75 +/− 0.08

0.70

.000

0.59

.000

Dimensions

Mean, SD

Mean, SD

Mean, SD

R²

P

R²

P

Stem, mm

39.6 +/−4.6

41.2 +/−4.44

36.5 +/−3.4

0.24

.016

0.13

.093

Tray Lip, mm

0.57 +/− 0.03

0.57 +/− 0.03

0.56 +/− 0.04

0.02

.533

0.09

.199

Tray thickness, mm (including lip)

3.81 +/− 0.6

3.62 +/− 0.05

4.2 +/−1.00

0.21

.033

0.14

.090

Surface roughness (Ra)

Mean, SD

Mean, SD

Mean, SD

R²

P

R²

P

Tibial back lateral Ra

1.19 +/− 0.3

1.10 +/− 0.24

1.36 +/− 0.35

0.18

.047

0.19

.044

Tibial back medial Ra

1.21 +/− 0.32

1.12 +/− 0.28

1.39 +/− 0.34

0.16

.050

0.13

.098

Tibial stem Ra

1.02 +/− 0.34

0.89 +/− 0.19

1.26 +/− 0.44

0.27

.011

0.17

.055

Tibial back & stem Ra

1.14 +/− 0.3

1.04 +/− 0.20

1.34 +/− 0.37

0.23

.021

0.18

.046

Time to revision

5.92 +/−5.23

7.92 +/−5.5

2.2 +/− 0.94

0.29

0.009

n.a.

n.a.

Reason for revision

N (%)

N (%)

N (%)

R²

P

R²

P

Instability

17 (74)

9 (60)

8 (100)

0.19

.039

0.32

.006

Malalignment

3 (13)

2 (13)

1 (13)

0.00

.957

0.01

.607

Patellofemoral

4 (17)

1 (7)

3 (38)

0.15

.068

0.04

.360

Stiffness

4 (17)

3 (20)

1 (3)

0.00

.669

0.16

.070

Others (periprosthetic fracture, progression OA)

2 (10)

2 (13)

0 (0)

0.05

.301

0.01

.657