Table 3.
Studies evaluating acute postoperative knee pain as a risk factor for chronic pain after TKR
| Author and year | Number in analysis | Risk factor measurement | Outcome(s) | Univariable or multivariable analysis | Association | Results summary |
| Edwards et al, 200939 | 43 | Global pain VAS at 1 month and 3 months | Global pain VAS at 6 and 12 months | Multivariable generalised estimating equation model | Yes | Global pain at a previous time point was a predictor of global pain at a future time point (estimate=0.43, SE=0.08, t=5.8, p<0.001). |
| Night pain VAS at 1 month and 3 months | Night pain VAS at 6 and 12 months | Yes | Night pain at a previous time point was a predictor of night pain at a future time point (estimate=0.32, SE=0.08, t=3.8, p<0.001). | |||
| Crosbie et al, 201038 | 100 | WOMAC Pain Scale at 2 weeks | WOMAC Pain Scale at 6 months | Multivariable linear regression | No | Not significant, results not reported |
| VAS at 2 weeks | No | Not significant, results not reported | ||||
| WOMAC pain at 8 weeks | Yes | Beta coefficient=+0.25±0.07 | ||||
| VAS at 8 weeks | No | Not significant, results not reported | ||||
| Pinto et al, 201345 | 42 | NRS at 48 hours | NRS at 4–6 months | Hierarchical logistic regression | No | Exp(B)=0.998 (95% CI 0.623 to 1.601), p=0.995 |
| Phillips et al, 201444 | 80 | PainDETECT at 6 weeks | Pain VAS at 39–51 months | Univariable correlation | Yes | PainDETECT at 6 weeks correlated moderately with VAS pain scores (r=0.53). |
| Veal et al, 201551 | 23 | VDS for average pain at 10 days | VDS for average pain at 12 months | N/A—statistical analysis inappropriate as data provided by authors on a small subset of patients | N/A | 11 patients had none/mild pain at 10 days, none of these patients had severe/moderate pain at 12 months. 12 patients had moderate/severe pain at 10 days, 2 of these patients had moderate/severe at 12 months. |
| VDS for worst pain at 10 days | VDS for worse pain at 12 months | 2 patients had none/mild pain at 10 days, none of these patients had severe/moderate pain at 12 months. 21 patients had moderate/severe pain at 10 days, 8 of these patients had moderate/severe at 12 months. |
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| VDS for average pain at 6 week | VDS for average pain at 12 months | 17 patients had none/mild pain at 6 weeks, 1 of these patients had moderate/severe pain at 12 months. 6 patients had moderate/severe pain at 6 weeks, 1 of these patients had moderate/severe at 12 months. |
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| VDS for worst pain at 6 weeks | VDS for worse pain at 12 months | 9 patients had none/mild pain at 6 weeks, 1 of these patients had severe/moderate pain at 12 months. 14 patients had moderate/severe pain at 6 weeks, 7 of these patients had moderate/severe at 12 months. |
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| Grosu et al, 201641 | 68 | VDS on days 1, 2 and 3 (cumulative value of maximal pain intensity) | VDS at 6 months VDS at 12 months |
Univariable correlation | Yes Yes |
r=0.350, p=0.009 r=0.350, p=0.009 |
| VDS on day 8 | VDS at 6 months VDS at 12 months |
No No |
Not significant, results not reported Not significant, results not reported |
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| VDS on day 30 | VDS at 6 months VDS at 12 months |
Yes No |
r=0.310, p=0.013 Not significant, results not reported |
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| VDS at 3 months | VDS at 6 months VDS at 12 months |
No No |
Not significant, results not reported Not significant, results not reported |
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| Sayers et al, 201647 | 277 | VAS for pain on rest on days 1, 2 and 3 (combined) | WOMAC pain at 12 months | Multivariable structural equation modelling | Yes | Beta=0.222, SE=0.058, 95% CI 0.109 to 0.336, p=0.0001 When preoperative pain added: beta=0.09, 95% CI −0.09 to 0.27, p=0.332 |
| VAS for pain on movement on days 1, 2 and 3 (combined) | Yes | Beta=0.140, SE=0.044, 95% CI 0.054 to 0.226, p=0.0014 When preoperative pain added: beta=0.00, 95% CI −0.14 to 0.15, p=0.955 |
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| Thomazeau et al, 201649 | 104 | NRS on days 1–4 | NRS at 6 months | Multivariate logistic regression | Yes | Patients with high-intensity acute postoperative pain (defined through latent class growth analysis) were more likely to have pain at 6 months than patients with low-intensity acute postoperative pain (OR=4.23, 95% CI 1.39 to 12.88, p=0.011). |
N/A, not applicable; NRS, Numerical Rating Scale; TKR, total knee replacement; VAS, Visual Analogue Scale; VDS, Verbal Descriptor Scale; WOMAC, Western Ontario and McMaster Universities Osteoarthritis Index.