Revision of infected knee arthroplasties in Denmark

Figures & data

Figure 1. Selection of the study population. DNPR: the Danish National Patient Registry; DKR: the Danish Knee Arthroplasty Registry. ^a Registered as 2 procedures in the DKR and both were excluded.

Figure 2. Results of the partial revisions.

Table 1. Surgical subgroups, demographics, and related outcomes

	Partial revision	2-stage revision
Procedures	105	215
Patients	100	205
Mean age (SD)	70 (9.8)	69 (10)
Female, n (%)	49 (47)	85 (40)
Mean BMI (SD)^a	30 (6.0)	29 (5.0)
First-time revision of a primary prosthesis, n (%)^b	73 (70)	117 (54)
Outcome parameters
Re-revision due to infection (%) (95% CI)	42 (40) (31–50)	52 (24) (19–30)
90-day mortality (%) (95% CI)	3 (3) (1–8)	10 (5) (3–8)
Median total LOS (range) ^c	18 (2–201)	24 (5–268)
Time course
Median time from previous procedure, days (range) ^d	34 (10–6,325)	349 (10–5,463)
Median time from first to second stage, days (range)	-	84 (9–597)
Median time to re-revision due to infection, days (range)	138 (11–1,306)	95 (5–1,004)

a Missing data in 36 cases.

b Missing data in 3 cases.

c For 2-stage procedures, accumulated LOS is given. The very short LOS in a few patients was due to early postoperative mortality.

d Missing data in 21 cases.

Table 2. Causes of mortality within 90 days postoperatively

Cause of death		Days postop.	Comment
Age	Surgical procedure^a
Infection (n = 7)
89	2	1	Sepsis, multiple organ failure
65	2	5	Sepsis, endocarditis, and stroke (cerebral embolism)
86	1	6	Sepsis, endocarditis, and multiple organ failure
80	2	16	Sepsis, treatment failure despite femoral amputation
86	2	46	Sepsis, treatment failure, Clostridium difficile infection, and renal failure
86	2	58	Sepsis, Clostridium difficile infection, and renal failure
75	2	75	Sepsis, Clostridium difficile infection; no further treatment at patient’s request
Cardiac (n = 3)
73	1	6	Unexpected cardiac arrest, failed resuscitation, no autopsy
83	2	15	Cardiac failure; no intensive care treatment at patient’s request
75	1	77	Acute myocardial infarction, confirmed by autopsy
Pulmonary (n = 2)
91	2	2	Aspiration pneumonia
77	2	40	Bilateral pneumonia, bacteremia
Gastrointestinal (n = 1)
91	2	23	Ileus; no treatment at patient’s request

a 1 means partial revision and 2 means 2-stage revision.

Figure 3. Results of the 2-stage procedures.

Table 3. Center volume and related outcomes

	High-volume centers ^a	Remaining centers	p-value
No. of centers	4	21
Total procedures (%)	155 (48)	165 (52)
Partial/2-stage revisions	50/105	55/110
Mean age (SD)	70 (9.8)	69 (10.4)	0.1 ^b
Mean BMI (SD)	29 (5.1)	29 (5.6)	0.4 ^b
First-time revision of
primary prosthesis (%)	84 (54)	106 (64)	0.06 ^c
Outcome parameters
Re-revision due to infection (%) (95% CI)	43 (28) (21–35)	51 (31) (24–38)	0.5 ^d
90-day mortality (%) (95% CI)	1 (0.6) (0.1–3.6)	12 (7.3) (4.2–12)	0.003 ^e
Time course
Median time from first to second stage, days (range) ^f	82 (9–343)	87 (42–597)	0.1 ^e

a > 30 procedures in 2 years

b t-test.

c Pearson chi-squared test.

d Fisher’s exact test.

e Mann-Whitney U-test.

f Only 2-stage procedures.