Table 1.
Characteristics of patients undergoing primary total hip replacement and revision between 1995 and 2007
| DHAR a(n=70,698) % (n) | Cases b (n=356) % (n) | OR (95% CI) c | p-value c | |||
| Gender | ||||||
| Female | 58.8 | (41, 136) | 67 | (238) | 0.68 (0.55–0.85) | 0.001 |
| Age-groups | ||||||
| 10–49 | 5.8 | (4,145) | 1.1 | (4) | 5.45 (2.03–14.61) | 0.001 |
| 50–59 | 13 | (9,442) | 4.5 | (16) | 3.26 (1.97–5.38) | |
| 60–69 | 28 | (20,060) | 23 | (81) | 1.34 (1.04–1.71) | |
| 70–79 | 35 | (24,821) | 32 | (113) | 1.15 (0.92–1.44) | |
| >80 | 18 | (12,586) | 40 | (142) | 0.32 (0.26–0.40) | |
| Primary diagnosis | ||||||
| Primary osteoarthritis | 76 | (53,944) | 70 | (249) | 1.35 (1.08–1.70) | 0.05 |
| Sequelae of trauma | 14 | (10,183) | 19 | (68) | 0.71 (0.54–0.92) | |
| Avascular necrosis | 2.4 | (1,726) | 3.4 | (12) | 0.71 (0.40–1.27) | |
| Rheumatoid arthritis | 2.1 | (1,487) | 3.1 | (11) | 0.67 (0.37–1.22) | |
| Paediatric conditions | 3.4 | (2,385) | 2.5 | (9) | 1.34 (0.69–2.60) | |
| Other diagnoses | 1.9 | (1,329) | 2.0 | (7) | 0.95 (0.45–2.01) | |
| Cause of revision | ||||||
| Aseptic loosening | 7.4 | (5,284) | 7.9 | (28) | 0.94 (0.64–1.39) | 0.2 |
| Osteolysis | 0.2 | (133) | 0.3 | (1) | 0.67 (0.09–4.77) | |
| Deep infection | 1.3 | (908) | 1.1 | (4) | 1.14 (0.42–3.06) | |
| Fracture or luxation | 2.8 | (1,986) | 1.1 | (4) | 2.53 (0.94–6.79) | |
| Other | 1.3 | (925) | 0.6 | (2) | 2.33 (0.58–9.39) | |
| Femoral head material | ||||||
| Metal | 76 | (53,618) | 82 | (290) | 0.70 (0.54–0.91) | 0.2 |
| Ceramics | 16 | (11,292) | 13 | (46) | 1.27 (0.93–1.74) | |
| Not exchanged (at revision) | 0.004 | (29) | 0 | – | ||
| Other or missing | 8.6 | (6 115) | 5.6 | (20) | 1.58 (1.01–2.49) | |
| Acetabular liner material | ||||||
| Polyethylene | 40 | (28,425) | 31 | (111) | 1.47 (1.18–1.84) | 0.3 |
| Ceramics | 2.6 | (1,862) | 0.8 | (3) | 3.17 (1.02–9.87) | |
| Metal | 1.6 | (1,132) | 1.4 | (5) | 1.14 (0.47–2.75) | |
| Other or missing d | 56 | (39,635) | 67 | (237) | 0.63 (0.51–0.79) | |
| Articulations | ||||||
| Metal-on-polyethylene | 28 | (19,933) | 23 | (83) | 1.28 (1.00–1.64) | 0.5 |
| Ceramic-on-ceramic or | ||||||
| ceramic-on-polyethylene | 12 | (8,211) | 7.0 | (25) | 1.73 (1.15–2.60) | |
| Metal-on-metal | 1.1 | (748) | 1.1 | (4) | 0.94 (0.35–2.52) | |
| Missing b | 59 | (42,161) | 68 | (244) | 0.67 (0.54–0.84) |
a DHAR: Patients from the Danish Hip Arthroplasty Register (DHAR) 1996–2007.
b Cases, defined as dermatitis patients from the DHAR who were also examined for metal allergy at Gentofte
Hospital.
c Comparison of patients from the Danish Hip Arthroplasty Registry (DHAR) and patients from the DHAR
who were also examined for metal allergy (Chi-square test). Fisher's exact test was used when the expected
frequency in one of the cells was lower than 5.
d The proportion of missing data was high, as the variable was introduced in recent years.
OR: odds ratio.
CI: confidence interval.