Table 4.

Cox regression analysis. Risk of revision due to deep infection for the low-risk patient^a in four different procedure duration groups

					Cox regressiond
					Unadjusted		Adjusted
Procedure duration	No of TKA	No of revisionsb	K-M 1y %c	K-M 4y %c	HR (95% CI)	p-value	HR (95% CI)	p-value
<75	3232	31	0.68	1.00	1		1
75-89	3718	30	0.57	0.84	0.8 (0.5 - 1.4)	0.5	0.8 (0.5 - 1.3)	0.4
90-109	5130	44	0.49	0.78	0.9 (0.6 – 1.4)	0.6	0.8 (0.5 – 1.3)	0.4
≥110	4177	52	0.72	1.10	1.2 (0.8 – 1.9)	0.3	1.1 (0.7 – 1.7)	0.6

^aThe low-risk TKA patient: TKA patient with primary osteoarthritis, ASA 1 or 2, without any previous surgery to the knee and no registered perioperative complications (n = 16,257)

^bNumber of revisions due to deep infection (n = 157)

^cKaplan-Meier estimated proportion of revisions due to deep infection at 1 and 4 years follow-up

^dUnadjusted and adjusted Hazard ratios (HR) estimated with the Cox proportional hazards model, adjusted for sex and age