Table 2 Demographics, metal ion levels and frequencies of histological findings distributed by implant type

Demographic variables

Age

Mean (SD)

60.5 years (8.4)

50.4 years (8.6)

<.001

Gender

Males Females

72 69

12 10

.9

Metal ion levels

Whole blood

Median Co level (range)

11.9 ppb (1.1 – 139.9)

7.35 ppb (1 – 73)

.03

Median Cr level (range)

3.4 ppb (0.7 – 61.6)

3.85 ppb (0.8 – 31)

.4

Joint fluid

Median Co level (range)

1291 ppb (36 – 19150)

271 ppb (40–5702)

<.001

Median Cr level (range)

903 ppb (24 – 39160)

390 ppb (4 ppb – 7698)

.004

Histological observations

Lymphocyte cuff thickness

Absent

50

10

.3

<0.25 mm

81

12

0.25 – 0.75 mm

10

-

Histiocyte sheet thickness

Absent

4

-

.4

<1 mm

108

18

1–2 mm

24

2

>2 mm

5

2

Surface necrosis

Grade I

7

9

<.001

Grade II

34

4

Grade III

38

7

Grade IV

62

2

Particle load

Grade 0

28

4

.6

Grade 1

25

5

Grade 2

37

3

Grade 3

36

6

Grade 4

15

4