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Table 2 Patient and surgical factors relating to the primary hip replacement procedure in all hips subsequently revised for ARMD

From: Adverse reactions to metal debris occur with all types of hip replacement not just metal-on-metal hips: a retrospective observational study of 3340 revisions for adverse reactions to metal debris from the National Joint Registry for England, Wales, Northern Ireland and the Isle of Man

Co-variate

All ARMD revisions (n = 3340) (100%)

ARMD revisions in MoM hips (n = 3091) (92.5%)

ARMD revisions in non-MoM hips (n = 249) (7.5%)

p-value

Odds ratio (95% CI)

Gender

 Female vs. male

1,967 (58.89)

1,810 (58.56)

157 (63.05)

0.165

0.87 (0.66–1.14)

Age (in years)a

 Mean (SD)

58.8 (10.0)

58.4 (9.8)

63.8 (11.0)

<0.0001

 

  < 50

557 (16.68)

534 (17.28)

23 (9.24)

<0.001

Ref

 50–59

1,113 (33.32)

1,061 (34.33)

52 (20.88)

1.12 (0.67–1.87)

 60–69

1,227 (36.74)

1,134 (36.69)

93 (37.35)

1.81 (1.11–2.93)

  ≥ 70

443 (13.26)

362 (11.71)

81 (32.53)

4.72 (2.86–7.78)

BMI (in kg/m2)b

 Mean (SD)

28.3 (4.8)

28.3 (4.9)

28.3 (4.4)

0.978

-

Primary hip design

 THR

2,359 (70.63)

2110 (68.3)

249 (100)

NA

-

 HR

981 (29.37)

981 (31.7)

0 (0)

  

Bearing surface

 MoM

3,091 (92.54)

3091 (100)

0 (0)

NA

-

 MoP

125 (3.74)

0 (0)

125 (50.20)

 CoC

75 (2.25)

0 (0)

75 (30.12)

 CoP

29 (0.87)

0 (0)

29 (11.65)

 CoM

16 (0.48)

0 (0)

16 (6.43)

 MoC

4 (0.12)

0 (0)

4 (1.61)

Femoral head size (mm)

 Mean (SD)

43.0 (6.4)

43.9 (5.7)

32.1 (4.0)

<0.0001

-

 Range

22.25–60

28–60

22.25–44

 Median

44

46

32

 Inter-quartile range

36–48

38–48

28–36

  ≤ 28

143 (4.28)

44 (1.42)

99 (39.76)

<0.001

 32

55 (1.65)

0 (0)

55 (22.09)

 36–42

1,197 (35.84)

1,103 (35.68)

94 (37.75)

 44–48

1,373 (41.11)

1,372 (44.39)

1 (0.40)

 50–52

449 (13.44)

449 (14.53)

0 (0)

  ≥ 54

123 (3.68)

123 (3.98)

0 (0)

Cup fixationb

 Uncemented

3,285 (98.73)

3,078 (99.96)

207 (83.46)

<0.001

-

 Cemented

42 (1.26)

1 (0.04)

41 (16.53)

Stem fixation (THR only)b

 Uncemented

2,090 (91.15)

1,922 (93.85)

168 (68.57)

<0.001

-

 Cemented

203 (8.85)

126 (6.15)

77 (31.43)

ASA grade

 1

1,228 (36.77)

1,169 (37.82)

59 (23.69)

<0.001

Ref

 2

1,948 (58.32)

1,776 (57.46)

172 (69.08)

1.61 (1.18–2.20)

 3 or above

164 (4.91)

14 (4.72)

18 (7.23)

1.68 (0.95–2.97)

Indication for surgery

 Primary OA vs. other

3,139 (93.98)

2,906 (94.01)

233 (93.57)

0.779

0.73 (0.42–1.26)

Surgeon grade

 Consultant vs. other

2,909 (87.10)

2,699 (87.32)

210 (84.34)

0.177

-

Complex primary

174 (5.21)

161 (5.21)

13 (5.22)

0.993

-

Surgical approachb

 Posterior vs. other

2,241 (69.04)

2,109 (70.23)

132 (54.32)

<0.001

-

VTE - chemical

 LMWH (+/-other)

1,673 (50.09)

1,524 (49.30)

149 (59.84)

<0.001

-

 Aspirin only

419 (12.54)

401 (12.97)

18 (7.23)

 Other

197 (5.90)

150 (4.85)

47 (18.88)

 None

1,051 (31.47)

1,016 (32.87)

35 (14.06)

VTE - mechanical

 Any vs. none

2,919 (87.40)

2,690 (87.03)

229 (91.97)

0.024

-

Adverse surgical eventsc

42 (1.83)

35 (1.68)

7 (3.30)

0.102

-

  1. ARMD Adverse reactions to metal debris, ASA American Society of Anesthesiologists, BMI Body mass index, CoC Ceramic-on-ceramic, CoM Ceramic-on-metal, CoP Ceramic-on-polyethylene, CI Confidence interval, HR Hip resurfacing, LMWH Low molecular weight heparin, MoC Metal-on-ceramic, MoM Metal-on-metal, MoP Metal-on-polyethylene, NA Not applicable, OA Osteoarthritis, Ref Reference group, SD Standard deviation, THR Total hip replacement, VTE Venous thrombo-embolism
  2. Values in brackets are percentages unless otherwise indicated. Statistically significant differences between the two groups (p < 0.05) have been highlighted in bold text
  3. aAffect of age at primary surgery on outcome was non-linear so variable was grouped
  4. bMissing data for stated number of hips: BMI (n = 2246); surgical approach (n = 94); cup fixation (n = 13); THR stem fixation (n = 66)
  5. cIntra-operative adverse events included: calcar crack; pelvic and/or femoral shaft penetration; trochanteric and/or femoral shaft fracture; other
  6. -Co-variate was not included in multivariable logistic regression model as either it was a surgical factor that is part of the causal pathway, or there was significant missing data
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BMC Musculoskeletal Disorders

ISSN: 1471-2474

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