Table I.
Patient and surgical factors for all non-metal-on-metal hip arthroplasties revised for adverse reactions to metal debris (ARMD), and in hips not undergoing re-revision surgery compared with those undergoing re-revision surgery
| Covariate | All ARMD hip revisions (n = 185) (100%) | ARMD hip revisions not undergoing re-revision surgery (n = 160) (86.5%) | ARMD hip revisions undergoing re-revision surgery (n = 25) (13.5%) | p-value |
|---|---|---|---|---|
| Female | 119 (64.3) | 101 (63.1) | 18 (72.0) | 0.389 |
| Age at revision (yrs), mean (sd) | 66.4 (10.6) | 67.0 (10.8) | 62.8 (9.0) | 0.046 |
| BMI (kg/m2)*, mean (sd) | 28.2 (5.0) | 28.1 (4.9) | 29.3 (6.5) | 0.589 |
| Time from primary to revision (yrs), mean (sd) | 3.1 (2.6) | 3.2 (2.7) | 2.8 (2.0) | 0.363 |
| Yr revision performed | ||||
| 2008 to 2011 | 56 (30.3) | 45 (28.1) | 11 (44.0) | 0.108 |
| 2012 to 2014 | 129 (69.7) | 115 (71.9) | 14 (56.0) | |
| ASA grade at revision | ||||
| 1 | 33 (17.8) | 30 (18.8) | ‡ | 0.234 |
| 2 | 128 (69.2) | 107 (66.9) | 21 (84.0) | |
| 3 | 24 (13.0) | 23 (14.4) | ‡ | |
| VTE – chemical | ||||
| LMWH (+/-other) | 114 (61.6) | 98 (61.3) | 16 (64.0) | 0.270 |
| Aspirin only | 10 (5.4) | 9 (5.6) | ‡ | |
| Other | 52 (28.1) | 47 (29.4) | ‡ | |
| None | 9 (4.9) | 6 (3.8) | ‡ | |
| VTE – mechanical (any versus none) | 180 (97.3) | 155 (96.9) | 25 (100) | 1.00 |
| Revision surgeon grade (consultant versus other) | 176 (95.1) | 152 (95.0) | 24 (96.0) | 1.00 |
| Surgical approach (posterior versus other) | 127 (68.7) | 108 (67.5) | 19 (76.0) | 0.394 |
| Revision indications/intra-operative findings | ||||
| ARMD (+/-pain) only | 82 (44.3) | 74 (46.3) | 8 (32.0) | 0.182 |
| Additional indications | 103 (55.7) | 86 (53.8) | 17 (68.0) | |
| ARMD | 185 (100) | § | § | § |
| Pain | 41 (22.2) | § | § | § |
| Aseptic loosening (any) | 45 (24.3) | § | § | § |
| Acetabular | 27 (14.6) | |||
| Femoral | 23 (12.4) | |||
| Osteolysis (any) | 21 (11.4) | § | § | § |
| Acetabular | 13 (7.0) | |||
| Femoral | 13 (7.0) | |||
| Other abnormal findings | ‡ | § | § | § |
| Implant malalignment | 18 (9.7) | § | § | § |
| Acetabular liner wear | 23 (12.4) | § | § | § |
| Fracture | 9 (4.9) | § | § | § |
| Dislocation/subluxation | 17 (9.2) | § | § | § |
| Infection | ‡ | § | § | § |
| Incorrect implant size | ‡ | § | § | § |
| Liner dissociation | 8 (4.3) | § | § | § |
| Implant fracture | 9 (4.9) | § | § | § |
| Revision procedure | ||||
| Selective component† | 134 (72.4) | 111 (69.4) | 23 (92.0) | 0.017 |
| All component | 51 (27.6) | 49 (30.6) | ‡ | |
| Revision femoral head size (mm)* | ||||
| Mean (sd) | 33.1 (3.7) | 33.1 (3.6) | 33.1 (4.3) | 0.969 |
| Range | 22.25 to 40 | 22.25 to 40 | 22.25 to 40 | |
| ≤ 28 | 42 (23.5) | 37 (23.7) | ‡ | 0.975 |
| 32 | 52 (29.1) | 45 (28.9) | 7 (30.4) | |
| ≥ 36 | 85 (47.5) | 74 (47.4) | 11 (47.8) | |
| Revision bearing* (n, %) | ||||
| MoP | 87 (51.5) | 81 (54.7) | 6 (28.6) | 0.072 |
| CoC | 45 (26.6) | 37 (25.0) | 8 (38.1) | |
| CoP | 37 (21.9) | 30 (20.3) | 7 (33.3) | |
| Revision component fixation | ||||
| Uncemented | 90 (81.8) | 81 (81.8) | 9 (81.8) | 1.00 |
| Cemented | 20 (18.2) | 18 (18.2) | ‡ | |
| Revision stem fixation | ||||
| Uncemented | 43 (51.2) | 39 (50.0) | ‡ | 0.676 |
| Cemented | 41 (48.8) | 39 (50.0) | ‡ | |
| Bone graft (femoral) | 7 (3.8) | 7 (4.4) | 0 (0) | 0.596 |
| Bone graft (acetabular) | 27 (14.6) | 22 (13.8) | ‡ | 0.375 |
missing data for stated number of hips: BMI (n = 72); revision femoral head size (n = 6); revision bearing surface (n = 16)
selective component revision procedures included cases where at least one component from the primary arthroplasty procedure was retained at revision. This included either the femoral or acetabular component being retained at revision, or both the femoral and acetabular components being retained, with revision of the femoral head and liner (with or without the use of a taper adapter)
data suppressed due to small count within the cell. The actual number was between one and five
due to small numbers, statistical comparisons between hips re-revised and hips not re-revised have not been performed for the individual revision indications
ASA, American Society of Anesthesiologists; BMI, body mass index; CoC, ceramic-on-ceramic; CoP, ceramic-on-polyethylene; LMWH, low-molecular weight heparin; MoP, metal-on-polyethylene; VTE, venous thromboembolism
All values in the table are number, with the percentages in brackets, unless otherwise indicated
Statistically significant differences between the re-revised and non re-revised hips (p < 0.05) are highlighted in bold text