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Table 1 Results of comparison between same-stage and two-stage total knee replacements (TKRs)

From: Cost, safety, and rehabilitation of same-stage, bilateral total knee replacements compared to two-stage total knee replacements

Parameters Same-stage, bilateral TKR (n = 95) Two-stage, bilateral TKR (n = 80) P
Demographics
 Age (years) 65.6 (51–77, SD 5.31) 68.7 (56–79, SD 6.46) 0.041
 Gender 26 M, 69 F 22 M, 58 F 0.894
 ASA grade 1: 5, 5.26%, 1: 3, 3.75% <  0.001
2: 90, 94.74% 2: 54, 67.97%,  
3: 0% 3: 24, 30.07%  
Implant choice Triathlon 124 (65.3%)
Attune 66 (34.7%)
Triathlon 112 (70.0%)
Attune 48 (30.0%)
0.505
Pre-operation function
 FS 50.2 (5–80, SD 13.19, 47.3 (5–90, SD 16.00, 0.706
95% CI 47.7–52.9) 95% CI 43.8–50.8)  
 KS 44.3 (18–79, SD 13.54, 44.5 (12–77, SD 12.82, 0.025
95% CI 41.6–47) 95% CI 41.7–47.3)  
 OKS 24.9 (8–54, SD 6.69, 25.2 (6–54, SD 7.62, 0.855
95% CI 23.5–26.3) 95% CI 23.5–26.9)  
Cost-effectiveness
 LOS (days) 6.64 (3–12, SD 2.14, 12.35a (7–65, SD 6.67, <  0.001
95% CI 6.21–7.07) 95% CI 10.9–13.8)  
  6.07b (2–43) <  0.001
 OTTc (mins) for 2 knees 152.8c (68–478, SD 31.34, 180.3c (111–417c, SD 48.46, <  0.001
95% CI 147.1–159.2) 95% CI 170–191)  
 PhyS 14.56d (3–26, SD 4.78, 17.90d (11–37, SD 4.68, <  0.001
95% CI 13.5–15.6) 95% CI 17.0–18.8)  
 OccS 3.56d (2–8, SD 1.97, 7.34d (2–24, SD 2.40, <  0.001
95% CI 3.16–3.96) 95% CI 6.81–7.87)  
Safety
 PreHb (g/dL) 13.50 (9.8–16.6, SD 1.10, 13.00 (9.1–15.7, SD 1.31, 0.002
95% CI 13.3–13.7) 95% CI 12.7–13.3)  
 HbD1 (g/dL) 10.47 (7.0–14.1, SD 1.28, 10.93 (7.4–14.1, SD 1.43, 0.003
95% CI 10.2–10.7) 95% CI 10.6–11.2)  
 HbDrop (g/dL) 3.03 (0.0–6.0, SD 1.21, 2.07 (− 0.1–6.2, SD 1.01, <  0.001
95% CI 2.79–3.27) 95% CI 1.85–2.29)  
 Transfusion percentage 8.42% (16 of 190 knees) 3.75% (6 of 160 knees) 0.078
 TV (units) for 2 knees 0.18 (0–6, SD 0.45, 0.09 (0–4, SD 0.76, 0.116
95% CI 0.090–0.27) 95% CI − 0.52–0.70)  
 SurgCR 7.37% (7 of 95 operations) 5.63% (9 of 160 operations) 0.511
 MedCR 3.68% (7 of 190 knees) 5.63% (9 of 160 knees) 0.386
10.5% (10 of 95 operations) 6.20% (10 of 160 operations) 0.155
RR 3.16% (3 of 95 operation) 4.38% (7 of 160 operations) 0.548
 30-days UPR 2.11% (2 of 95 operations) 6.92% (11 of 160 operations) 0.094
 90-days UPR 4.21% (4 of 95 operations) 9.43% (15 of 160 operations) 0.129
  1. Abbreviations: ALOS average length of stay, ASA American Society of Anesthesiologists, FS Knee Society Function Score, HbD1 haemoglobin level on first day post-operation, HbDrop haemoglobin level drop, KS Knee Society Knee Score, MedCR medical complication rate, OKS Oxford Knee Score, OccS occupational therapy sessions, OTT operation theatre time, PhyS physical therapy sessions, PreHb pre-operative haemoglobin, RR reoperation rate, SD standard deviation, SurgCR surgical complication rate, TV transfusion volume, UPR unplanned readmission, 95% CI 95% confidence interval
  2. Statistically significant P values are presented in bold
  3. apatient-specific total ALOS of 2 knees in an individual patient
  4. bknee-specific ALOS of one knee
  5. cpresented as the total operation time for both knees
  6. dpresented as the total number for both knees