Table 1. Demographics of the study population.
| Revisions | Second revisions | Third revisions | ||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Male | Female | All | Male | Female | All | Male | Female | All | ||||||||||
| Totals (N, %) | 15080 | (45·3) | 18212 | (54·7) | 33292 | (100·0) | 1919 | (53·7) | 1656 | (46·3) | 3575 | (100·0) | 339 | (59·1) | 235 | (40·9) | 574 | (100·0) |
| Mean age in years (sd) | 67·1 | (9·7) | 67·5 | (10·3) | 67·3 | (10·0) | 66·1 | (9·7) | 66·7 | (10·0) | 66·4 | (9·8) | 66·0 | (9·6) | 65·4 | (9·9) | 65·8 | (9·7) |
| Age group (N, %) | ||||||||||||||||||
| <55 | 2611 | (17·3) | 3456 | (19·0) | 6067 | (18·2) | 435 | (22·7) | 396 | (23·9) | 831 | (23·2) | 91 | (26·8) | 67 | (28·5) | 158 | (27·5) |
| 55-64 | 5380 | (35·7) | 5953 | (32·7) | 11333 | (34·0) | 730 | (38·0) | 583 | (35·2) | 1313 | (36·7) | 128 | (37·8) | 84 | (35·7) | 212 | (36·9) |
| 65-74 | 5108 | (33·9) | 5853 | (32·1) | 10961 | (32·9) | 596 | (31·1) | 495 | (29·9) | 1091 | (30·5) | 97 | (28·6) | 73 | (31·1) | 170 | (29·6) |
| 75+ | 1981 | (13·1) | 2950 | (16·2) | 4931 | (14·8) | 158 | (8·2) | 182 | (11·0) | 340 | (9·5) | 23 | (6·8) | 11 | (4·7) | 34 | (5·9) |
| ASA grade (N, %) | ||||||||||||||||||
| ASA grade 1 | 1457 | (9·7) | 1370 | (7·5) | 2827 | (8·5) | 160 | (8·3) | 90 | (5·4) | 250 | (7·0) | 24 | (7·1) | 12 | (5·1) | 36 | (6·3) |
| ASA grade 2 | 9982 | (66·2) | 12475 | (68·5) | 22457 | (67·5) | 1155 | (60·2) | 1032 | (62·3) | 2187 | (61·2) | 194 | (57·2) | 125 | (53·2) | 319 | (55·6) |
| ASA grade 3 | 3497 | (23·2) | 4218 | (23·2) | 7715 | (23·2) | 578 | (30·1) | 511 | (30·9) | 1089 | (30·5) | 119 | (35·1) | 93 | (39·6) | 212 | (36·9) |
| ASA grade 4 | 143 | (0·9) | 148 | (0·8) | 291 | (0·9) | 26 | (1·4) | 23 | (1·4) | 49 | (1·4) | 2 | (0·6) | 5 | (2·1) | 7 | (1·2) |
| ASA grade 5 | 1 | (0·0) | 1 | (0·0) | 2 | (0·0) | 0 | (0·0) | 0 | (0·0) | 0 | (0·0) | 0 | (0·0) | 0 | (0·0) | 0 | (0·0) |
| Previous knee in situ (N, %) | ||||||||||||||||||
| <1 year | 2785 | (18·5) | 2763 | (15·2) | 5548 | (16·7) | 610 | (31·8) | 514 | (31·0) | 1124 | (31·4) | 129 | (38·1) | 79 | (33·6) | 208 | (36·2) |
| 1-3 years | 5845 | (38·8) | 7134 | (39·2) | 12979 | (39·0) | 836 | (43·6) | 678 | (40·9) | 1514 | (42·3) | 146 | (43·1) | 104 | (44·3) | 250 | (43·6) |
| 3-5 years | 2653 | (17·6) | 3555 | (19·5) | 6208 | (18·6) | 262 | (13·7) | 287 | (17·3) | 549 | (15·4) | 41 | (12·1) | 41 | (17·4) | 82 | (14·3) |
| 5 years + | 3797 | (25·2) | 4760 | (26·1) | 8557 | (25·7) | 211 | (11·0) | 177 | (10·7) | 388 | (10·9) | 23 | (6·8) | 11 | (4·7) | 34 | (5·9) |
| Revision procedure (N, %) | ||||||||||||||||||
| Amputation | 5 | (0·0) | 8 | (0·0) | 13 | (0·0) | 5 | (0·3) | 7 | (0·4) | 12 | (0·3) | 0 | (0·0) | 0 | (0·0) | 0 | (0·0) |
| Conversion to Arthrodesis | 24 | (0·2) | 23 | (0·1) | 47 | (0·1) | 23 | (1·2) | 17 | (1·0) | 40 | (1·1) | 4 | (1·2) | 6 | (2·6) | 10 | (1·7) |
| DAIR | 93 | (0·6) | 64 | (0·4) | 157 | (0·5) | 19 | (1·0) | 14 | (0·8) | 33 | (0·9) | 6 | (1·8) | 4 | (1·7) | 10 | (1·7) |
| Single stage | 12122 | (80·4) | 15881 | (87·2) | 28003 | (84·1) | 1231 | (64·1) | 1163 | (70·2) | 2394 | (67·0) | 202 | (59·6) | 151 | (64·3) | 353 | (61·5) |
| Stage 1 of 2 | 2074 | (13·8) | 1641 | (9·0) | 3715 | (11·2) | 418 | (21·8) | 276 | (16·7) | 694 | (19·4) | 74 | (21·8) | 48 | (20·4) | 122 | (21·3) |
| Stage 2 of 2 | 762 | (5·1) | 595 | (3·3) | 1357 | (4·1) | 223 | (11·6) | 179 | (10·8) | 402 | (11·2) | 53 | (15·6) | 26 | (11·1) | 79 | (13·8) |
ASA = American Society of Anesthesiologists; Stage 1 of 2 is the first stage of a revision procedure usually carried out as 2 operations i.e. under two separate anaesthetics. Stage 2 of 2 is the second of these operations.