Table III.
Univariable and multivariable Cox regression analysis to identify predictors of re-revision surgery following revision surgery performed for adverse reactions to metal debris (ARMD)
| Covariate | Univariable hazard ratio (95% CI) | p-value | Multivariable hazard ratio (95% CI) | p-value |
|---|---|---|---|---|
| Gender (female versus male) | 1.41 (0.59 to 3.37) | 0.443 | * | * |
| Age at revision (per yr) | 0.97 (0.94 to 1.00) | 0.072 | 0.97 (0.93 to 1.01) | 0.165 |
| BMI (per kg/m2) | 1.04 (0.93 to 1.17) | 0.464 | * | * |
| Time from primary to revision (per yr) | 0.96 (0.82 to 1.13) | 0.659 | * | * |
| ASA grade at revision | ||||
| 1 | 1.00 | Ref | * | * |
| 2 | 1.95 (0.58 to 6.54) | 0.280 | ||
| ⩾ 3 | 0.46 (0.05 to 4.44) | 0.504 | ||
| VTE – chemical | ||||
| None | 1.00 | Ref | 1.00 | Ref |
| LMWH (+/-other) | 0.47 (0.14 to 1.60) | 0.227 | 0.26 (0.07 to 1.02) | 0.053 |
| Aspirin only | 0.28 (0.03 to 2.70) | 0.271 | 0.35 (0.03 to 3.65) | 0.378 |
| Other | 0.31 (0.07 to 1.31) | 0.111 | 0.21 (0.04 to 1.05) | 0.057 |
| VTE – mechanical (any versus none) | † | † | * | * |
| Revision surgeon grade (consultant versus other) | 1.23 (0.17 to 9.06) | 0.842 | * | * |
| Surgical approach (posterior versus other) | 1.48 (0.59 to 3.70) | 0.407 | * | * |
| Revision indications | ||||
| ARMD (+/-pain) only | 1.00 | Ref | 1.00 | Ref |
| Additional indications | 1.76 (0.76 to 4.09) | 0.186 | 2.78 (1.03 to 7.49) | 0.043 |
| Revision procedure‡ | ||||
| All components revised | 1.00 | Ref | 1.00 | Ref |
| Selective component revision | 5.01 (1.18 to 21.3) | 0.029 | 5.76 (1.28 to 25.9) | 0.022 |
| Revision femoral head size (in mm) | ||||
| ⩽ 28 | 1.00 | Ref | * | * |
| 32 | 1.09 (0.35 to 3.44) | 0.882 | ||
| ⩾ 36 | 1.11 (0.39 to 3.20) | 0.845 | ||
| Revision bearing | ||||
| MoP | 1.00 | Ref | 1.00 | Ref |
| CoC | 2.84 (0.98 to 8.18) | 0.054 | 1.79 (0.54 to 5.89) | 0.339 |
| CoP | 2.96 (1.00 to 8.83) | 0.051 | 3.08 (1.01 to 9.36) | 0.047 |
| Revision cup fixation | ||||
| Uncemented | 1.00 | Ref | * | * |
| Cemented | 0.99 (0.21 to 4.60) | 0.993 | ||
| Revision stem fixation | ||||
| Uncemented | 1.00 | Ref | * | * |
| Cemented | 0.51 (0.09 to 2.80) | 0.440 | ||
| Bone graft (femoral) | † | † | * | * |
| Bone graft (acetabular) | 1.31 (0.49 to 3.50) | 0.590 | * | * |
covariate was not eligible for inclusion in the final multivariable model
unable to calculate value as no hips in this subgroup underwent re-revision surgery
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)
ASA, American Society of Anesthesiologists; BMI, body mass index; CI, confidence interval; CoC, ceramic-on-ceramic; CoP, ceramic-on-polyethylene; LMWH, low-molecular weight heparin; Ref, reference group; MoP, metal-on-polyethylene; VTE, venous thromboembolism
Statistically significant differences (p < 0.05) have been highlighted in bold text
Due to missing BMI data, the univariable analysis for BMI was based on a cohort of 113 hip revisions with ten hips undergoing re-revision surgery
Multivariable analysis was based on a cohort of 167 hip revisions with 21 hips undergoing re-revision surgery