Table 4.
The prevalence of metal allergies and the type of material inserted during hip operation in patients who were patch-tested prior to the operation (n = 292) and in patients who were patch-tested after the operation (n = 64)
| Cases patch-tested | ||||
|---|---|---|---|---|
| before operation (n = 292) % (n) | after operation (n = 64) % (n) | OR (95% CI) a | p-value a | |
| Metal allergy b | 16 (47) | 6.3 (4) | 2.87 (1.00–8.30) | 0.4 |
| Nickel allergy | 11 (33) | 4.7 (3) | 2.59 (0.77–8.73) | 0.1 |
| Cobalt allergy | 6.5 (19) | 0 (0) | – | 0.03 |
| Chromium allergy | 3.1 (9) | 3.1 (2) | 0.98 (0.21–4.67) | 1.0 |
| Cause of revision | ||||
| Aseptic loosening | 7.5 (22) | 9.4 (6) | 0.79 (0.31–2.03) | 0.2 |
| Osteolysis | 0 | 1.5 (1) | – | |
| Deep infection | 1.0 (3) | 1.5 (1) | 0.65 (0.07–6.39) | |
| Fracture or luxation | 1.3 (4) | 0 | – | |
| Other | 0.3 (1) | 0 | – | |
| Femoral head material | ||||
| Metal | 81 (236) | 84 (54) | 0.78 (0.37–1.63) | 0.6 |
| Ceramics | 13 (38) | 13 (8) | 1.05 (0.46–2.37) | |
| Not exchanged (at revision) | 0 | 0 | – | |
| Other or missing | 6.2 (18) | 3.1 (2) | 2.04 (0.46-9.01) | |
| Acetabular liner material | ||||
| Polyethylene | 35 (103) | 13 (8) | 3.81 (1.75–8.31) | 0.001 |
| Metal | 1.7 (5) | 0 | – | |
| Ceramics | 1.0 (3) | 0 | – | |
| Other or missing | 62 (162) | 88 (56) | 0.18 (0.08–0.39) | |
a Comparison of cases and controls (Chi-squared test). Fisher's exact test was used when the expected frequency in one of the cells was lower than 5.
b Metal allergy was defined as a positive patch-test reaction to nickel, cobalt or chromium.
OR: odds ratio.
CI: confidence interval.