Inflammatory response in 85 patients with loosened hip prostheses: A prospective study comparing inflammatory markers in patients with aseptic and septic prosthetic loosening

Figures & data

Table 1.  Culture results in the infection group

Patient label	Infection clinically diagnosed at inclusion	No. of positive cultures / no. of samples	Etiology	Distribution of species when mixed culture
L329	+	0/10	negative^a
L330	–	4/10	Propionibacterium
L331	+	9/10	Anaerobic gram-positive cocci	8/10
			CoNS^b	2/10
L332	–	4/10	CoNS
L333	+	0/10	negative^c
L334	+	9/10	CoNS
L335	+	6/9	CoNS
L336	+	5/10	CoNS
L337	+	5/10	Enterococci	5/10
			CoNS	2/10
L338	+	1/10	(CoNS)^d
L339	+	4/10	β-hemolytic streptococci group B
L350	+	6/10	S. aureus	6/10
			CoNS	1/10
L351	+	9/10	Propionibacterium	8/10
			CoNS	1/10
L352	+	9/10	CoNS
L353	+	5/10	CoNS
L354	+	5/10	β-hemolytic streptococci group B	4/10
			CoNS	3/10
			Diphtheroid rods	1/10
L355	+	5/10	Propionibacterium
N318	+	0/10	negative^e
N340	+	5/10	CoNS
N341	+	5/10	Enterococci
N342	+	4/10	CoNS
N343	+	5/10	Propionibacterium
N344	+	4/10	S. aureus
N345	+	7/10	S. aureus	6/10
			CoNS	2/10
N310	+	1/10	(Propionibacterium)^f

^aPatient was clinically diagnosed with infection, and had X-ray-confirmed osteitis abscesses before revision surgery and lifelong antibiotic treatment after the revision surgery.

^bCoNS: Coagulase-negative staphylococci.

^cPatient with clinically diagnosed infection and a fistula.

^dPatient with clinically diagnosed infection and a fistula, and the synovial fluid aspirated for culture before revision surgery was cloudy and showed growth of CoNS.

^ePatient was clinically diagnosed with infection, and synovial fluid aspirated for culture before revision surgery was cloudy and showed growth of Propionibacterium.

^fPatient was clinically diagnosed with infection, and synovial fluid aspirated for culture before revision surgery showed growth of CoNS.

Table 2.  Bacterial etiology in infected patients

	No. of patients	Bacterial species
		single	mixed
CoNS^a	14	8	6
Propionibacterium	4	3	1
S. aureus	3	1	2
Enterococci	2	1	1
β-hemolytic streptococci group B	2	1	1
Anaerobic gram-positive cocci	1	0	1

^a Coagulase-negative staphylococci.

Table 3.  Cell infiltration in periprosthetic tissue in the revision and infection groups. Values are median (range) of cells/HPF

	PMNs	Plasma ells	B-cells	T-helper cells	T-cytotoxic cells	Macrophages
Revision group (n = 26)	0 (0−3)	0 (0)	0 (0−4)	1 (0−8)	12 (1−61)	72 (32–100)
Inflected group (n = 21)	25 (0−100)	0 (0−90)	3 (0−89)	9 (0−60)	21 (1−130)	80 (5−180)
P-value	< 0.001	< 0.001	< 0.001	< 0.001	0.02	0.91

PMN: polymorphonuclear cells; HPF: high-power field.

Table 4.  Data on arbitrary fibrosis and foreign body reactions in the revision and infection groups

	Grade^a	No. of patients with fibrosis	No. of patients with foreign body reactions
Revision group	0	0	5
	1	9	4
	2	14	12
	3	3	5
Total		26	26
Infected group	0	0	11
	1	9	9
	2	6	0
	3	6	1
Total		21	21

^a 0: none; 1: mild; 2: moderate; 3: substantial.

Table 5.  Preoperative C-reactive protein (CRP; mg/L) and erythrocyte sedimentation rate (ESR; mm/h) for the different groups

	CRP	ESR
Control group (n)	46	45
median (range)	≤10 (≤10−77)	14 (2−58)
Revision group (n)	56	55
median (range)	≤10 (≤ 10−87)	14 (2−80)
Infection group (n)	22	22
median (range)	24 (≤10−100)	36 (5−120)
P-value^a	< 0.001	< 0.001

^a Difference between revision and infection groups

Table 6.  White blood cell (WBC) count and lactate levels in synovial fluid

	WBC count (10^9/L)	Lactic acid (mmol/L)
Control group (n)	32	37
median (range)	0.3 (0−11)	4.0 (0.7−11)
Revision group (n)	49	45
median (range)	0.2 (0−93)	5.4 (0.4−9.1)
Infection group (n)	7	17
median (range)	23 (0.4−55)	5.8 (3.1−13)
P-value^a	< 0.001	0.4

^a Difference between revision and infection groups

Figure 1. Proinflammatory cytokine levels in synovial fluid (pg/mL), shown for individual patients in the control, revision, and infection groups. For each group, the number of patients is indicated and the median is marked with a horizontal bar. A. Median levels of TNF-α: control group, 12 pg/mL; revision group, 45 pg/mL; infection group, 113 pg/mL. The difference between the revision group and the infected group was statistically significant (p = 0.001). B. Median levels of IL-1β: control group, 22 pg/mL; revision group, 14 pg/mL; infection group, 63 pg/mL. The difference between the revision group and the infected group was statistically significant (p < 0.001). C. Median levels of IL-6: control group, 1450 pg/mL; revision group, 1490 pg/mL; infection group, 10,140 pg/mL. Note log scale. The difference between the revision group and the infected group was statistically significant (p = 0.003).

Table 7.  Statistical summary of the results of pre- and perioperative tests used to diagnose hip prosthesis infection

	Value chosen for cut-off	Sensitivity (%)	Specificity (%)	PPV (%)	NPV (%)
CRP (mg/L)	> 10	82	71	53	91
ESR (mm/h)	> 30	64	87	67	86
WBCs in SF (10^9/L)	> 1.7	86	92	60	98
PMNs in tissue (cells/HPF)	≥ 5	81	100	100	87
Plasma cells (cells/HPF)	≥ 1	48	100	100	70
B-cells (cells/HPF)	≥ 1	86	96	95	89
T-helper cells (cells/HPF)	≥ 5	71	92	88	80
T-cytotox cells (cells/HPF)	≥ 20	52	92	85	71
TNF-alfa in SF (pg/mL)	≥ 60	76	72	50	89
IL-1B in SF (pg/mL)	≥ 60	59	83	56	85
IL-6 in SF (pg/mL)	≥ 10,000	69	93	75	91

SF: synovial fluid; HPF: high-power field; PPV: positive predictive value; NPV: negative predictive value.