Table II.
Characteristics of primary and revision surgery. All p-values were calculated using chi-squared test.
| Characteristic | Hip | Knee | ||||
|---|---|---|---|---|---|---|
| Unplanned revision (n = 199) |
Planned revision (n = 106) |
p-value* | Unplanned revision (n = 161) |
Planned revision (n = 102) |
p-value* | |
| Diagnosis at primary surgery | ||||||
| OA | 135 (67.8) | 66 (62.3) | 0.395 | 116 (72.0) | 79 (77.5) | 0.406 |
| Arthritis | 14 (7.0) | 7 (6.6) | 1.000 | 14 (8.7) | 9 (8.8) | > 0.999 |
| Trauma | 16 (8.0) | 10 (9.4) | 0.842 | 11 (6.8) | 6 (5.9) | 0.962 |
| Congenital | 4 (2.0) | 3 (2.8) | 0.957 | 1 (0.6) | 0 (0.0) | > 0.999 |
| Other | 29 (14.6) | 15 (14.2) | 1.000 | 23 (14.3) | 11 (10.8) | 0.525 |
| Don’t know | 11 (5.5) | 10 (9.4) | 0.296 | 9 (5.6) | 3 (2.9) | 0.484 |
| Complications after first operation on hip/knee | 57 (28.9) | 46 (43.8) | 0.014 | 62 (38.5) | 47 (47.0) | 0.221 |
| Infection | 10 (5.0) | 16 (15.1) | 0.005 | 18 (11.2) | 12 (11.8) | > 0.999 |
| Dislocation | 29 (14.6) | 8 (7.5) | 0.108 | 5 (3.1) | 2 (2.0) | 0.866 |
| Other | 24 (12.1) | 25 (23.6) | 0.014 | 49 (30.4) | 39 (38.2) | 0.241 |
| Mean time to revision, yrs (SD) | 0.142 | 0.092 | ||||
| < 5 (reference) | 46 (23.12) | 36 (33.96) | 51 (31.68) | 46 (45.10) | ||
| 5 to 10 | 41 (20.60) | 14 (13.21) | 33 (20.50) | 21 (20.59) | ||
| > 10 | 89 (44.72) | 46 (43.40) | 58 (36.02) | 29 (28.43) | ||
| Not specified | 23 (11.56) | 10 (9.4) | 19 (11.80) | 6 (5.88) | ||
| Reason for revision | ||||||
| Infection | 15 (7.5) | 12 (11.3) | 0.370 | 32 (19.9) | 14 (13.7) | 0.266 |
| Aseptic loosening | 85 (42.7) | 50 (47.2) | 0.532 | 60 (37.3) | 32 (31.4) | 0.399 |
| Stiffness | 2 (1.0) | 3 (2.8) | 0.470 | 9 (5.6) | 5 (4.9) | > 0.999 |
| Pain | 69 (34.7) | 56 (52.8) | 0.003 | 85 (52.8) | 59 (57.8) | 0.500 |
| Wear | 14 (7.0) | 11 (10.4) | 0.427 | 16 (9.9) | 14 (13.7) | 0.458 |
| Osteolysis | 13 (6.5) | 13 (12.3) | 0.136 | 7 (4.3) | 3 (2.9) | 0.802 |
| Periprosthetic fracture | 33 (16.6) | 3 (2.8) | 0.001 | 9 (5.6) | 0 (0.0) | 0.037 |
| Implant failure | 9 (4.5) | 3 (2.8) | 0.678 | 12 (7.5) | 6 (5.9) | 0.810 |
| OA progression | 0 (0.0) | 0 (0.0) | - | 5 (3.1) | 6 (5.9) | 0.435 |
| Dislocation | 47 (23.6) | 10 (9.4) | 0.004 | 5 (3.1) | 0 (0.0) | 0.182 |
| Instability | 3 (1.5) | 3 (2.8) | 0.719 | 12 (7.5) | 8 (7.8) | > 0.999 |
| Other | 5 (2.5) | 1 (0.9) | 0.612 | 0 (0.0) | 0 (0.0) | |
*
Chi-squared test.
OA, osteoarthritis; SD, standard deviation.