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

 Age (years)

65.6 (51–77, SD 5.31)

68.7 (56–79, SD 6.46)

 Gender

26 M, 69 F

22 M, 58 F

 ASA grade

1: 5, 5.26%,

1: 3, 3.75%

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%)

 FS

50.2 (5–80, SD 13.19,

47.3 (5–90, SD 16.00,

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,

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,

95% CI 23.5–26.3)

95% CI 23.5–26.9)

 LOS (days)

6.64 (3–12, SD 2.14,

12.35^a (7–65, SD 6.67,

95% CI 6.21–7.07)

95% CI 10.9–13.8)

6.07^b (2–43)

 OTT^c (mins) for 2 knees

152.8^c (68–478, SD 31.34,

180.3^c (111–417^c, SD 48.46,

95% CI 147.1–159.2)

95% CI 170–191)

 PhyS

14.56^d (3–26, SD 4.78,

17.90^d (11–37, SD 4.68,

95% CI 13.5–15.6)

95% CI 17.0–18.8)

 OccS

3.56^d (2–8, SD 1.97,

7.34^d (2–24, SD 2.40,

95% CI 3.16–3.96)

95% CI 6.81–7.87)

 PreHb (g/dL)

13.50 (9.8–16.6, SD 1.10,

13.00 (9.1–15.7, SD 1.31,

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,

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,

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)

 TV (units) for 2 knees

0.18 (0–6, SD 0.45,

0.09 (0–4, SD 0.76,

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)

 MedCR

3.68% (7 of 190 knees)

5.63% (9 of 160 knees)

10.5% (10 of 95 operations)

6.20% (10 of 160 operations)

RR

3.16% (3 of 95 operation)

4.38% (7 of 160 operations)

 30-days UPR

2.11% (2 of 95 operations)

6.92% (11 of 160 operations)

 90-days UPR

4.21% (4 of 95 operations)

9.43% (15 of 160 operations)