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. 2018 Jul 31;19:274. doi: 10.1186/s12891-018-2166-8

Table 1.

Demographic data on patients in the unilateral and staged bilateral TKA groups

Variable Unilateral TKA group
(n = 53)
Bilateral TKA group
(n = 100)
P value
Age (years) 71.3(range, 55–84; SD, 6.3) 71.5 (range, 53–84; SD, 6.4) 0.891
Proportion of female patients 45 (84.9)* 85 (85)* 0.988
BMI (kg/m2) 26.9 (range, 20.9–44.8; SD, 4.1) 27.2 (range, 18.6–36; SD, 3.7) 0.684
Proportion undergoing general anesthesia 45 (84.9)* 95 (95)* 0.063
Operation time (min) 95.4 (range, 66–175; SD, 19) 91.2 (range, 43–140; SD, 16.2) 0.159
Length of hospital stay (days) 13.9 (range, 8–23; SD 2.7) 20.7 (range, 11–32; SD 3.9) < 0.001
Number of comorbiditiesa 1.4 (range, 0–5; SD, 1.0) 1.3 (range, 0–4; SD, 1.1) 0.331

Data are presented as means or numbers of patients. Ranges, standard deviations, and proportions* are shown in parentheses. Abbreviations = TKA Total knee arthroplasty, BMI Body mass index, SD standard deviation

aComorbidities include previous venous thromboembolism, varicose vein and previous operation on the leg, which are the major risk factors for deep vein thrombosis