Surgical Site Infection After Polymethyl Methacrylate Pedicle Screw Augmentation in Osteoporotic Spinal Vertebrae: A Series of 537 Cases

Charles Louis Mengis-Palleck; Félix Tomé-Bermejo; Ángel Piñera-Parrilla; Javier Cervera-Irimia; Jesús Gallego-Bustos; Francisco Garzón-Márquez; María G. Rodríguez-Arguisjuela; Sylvia Sanz-Aguilera; Alejandro Peiro-Garcia; Luis Álvarez-Galovich

doi:10.14444/8474

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Table 1

Qualitative data for patients who developed an infection (n = 28).

Variable	n (%)
Gender
Men	8 (28.6)
Women	20 (71.4)
Revision surgery
Yes	9 (32.1)
No	19 (67.9)
Area
Thoracic spine	2 (7.1)
Lumbar spine	20 (71.4)
Thoracolumbar spine	6 (21.4)
No. of segments fused
2	10 (35.7)
3	11 (39.3)
4	5 (17.9)
5	2 (7.1)
Antibiotic prophylaxis
Cefazolin	17 (60.7)
Vancomycin	1 (3.6)
Cefazolin + aminoglycoside	7 (25.0)
Cefazolin + gentamicin + rifampicin	2 (7.1)
Unspecified	1 (3.6)
Obesity (by body mass index [kg/m²])
<30	12 (46.2)
30–35	12 (46.2)
>35	2 (7.7)
Smoking
Yes	1 (3.6)
No	27 (96.4)
Malnutrition
No	28 (100)
American Society of Anesthesiologists class
I	10 (35.7)
III–IV	18 (64.3)
History of infection
Yes	1 (3.6)
No	27 (96.4)
Time at which infection occurred
Early	28 (100)
Infection level
Deep	28 (100)
Bacteria
Gram-positive	11 (39.3)
Gram-negative	7 (25.0)
Mixed	10 (35.7)
Sonication
Performed	2 (7.4)
Not performed	25 (92.6)
Pathogen concordance
Yes	13 (46.4)
No	15 (53.6)
Surgical procedure performed
Debridement with instrument retention/replacement	27 (96.4)
Complete removal	1 (3.6)
No. of irrigations
1	3 (46.4)
2	2 (42.9)
3	1 (3.6)
4	1 (3.6)
6	1 (3.6)
Status at 2 year follow-up evaluation
Infection cured with debridement	23 (82.1)
Infection cured with hardware replacement	4 (14.8)
Treatment failure	1 (3.6)
Plastic surgery
Yes	4 (14.3)
No	24 (85.7)
Vacuum-assisted closure therapy
Yes	6 (21.4)
No	22 (78.6)

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Table 2

Quantitative data for patients who developed an infection (n = 28).

Variable	Mean ± SD or Median (Interquartile Range)	Minimum, Maximum
Age, y	75.1 ± 6.58	60.0, 85.0
Length of procedure, min	236 (82.0)	143, 760
Blood loss, g/dL	3.12 ± 1.11	1.40, 5.60
Charlson Comorbidity Index	4.46 ± 1.20	2.00, 7.00
Body mass index, kg/m²	29.9 ± 3.95	23.4, 37.7
Serum albumin levels, g/dL	4.21 ± 0.38	3.20, 4.80
Time elapsed between the initial operation and infection occurrence, d	14.0 (8.00)	7.00, 74.0
C-reactive protein level at admission, mg/dL	19.0 ± 13.3	0.80, 48.0
Duration of empirical antibiotic therapy, d	5.00 (2.50)	2.00, 15.0
Duration of targeted antibiotic therapy, d	70.0 (35.5)	27.0, 270
Total duration of antibiotic therapy, d	75.0 (38.5)	34.0, 284

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Table 3
Surgical diagnoses in the study population (N = 537).
Condition for Which Surgery Was Performed n No. (%) of Infections in Group
Deformity 157 9 (6)
Degenerative disease 376 18 (5)
Cancer 4 1 (25)

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Table 4

Qualitative variables by group.

Variable	Deformity, n (%)	Degenerative Disease, n (%)	P Value
Gender
Men	4 (44.4)	4 (22.2)
Women	5 (55.6)	14 (77.8)	0.375
Revision surgery
Yes	2 (22.2)	7 (38.9)
No	7 (77.8)	11 (61.1)	0.667
Area
Thoracic spine	1 (11.1)	1 (5.6)
Lumbar spine	3 (33.3)	16 (88.9)
Thoracolumbar spine	5 (55.6)	1 (5.6)	0.003
No. of segments fused
2	1 (11.1)	8 (44.4)
3	3 (33.3)	8 (44.4)
4	3 (33.3)	2 (11.1)
5	2 (22.2)	0 (0.0)	0.057
Antibiotic prophylaxis
Cefazolin	4 (44.4)	13 (72.2)
Vancomycin	1 (11.1)	0 (0.0)
Cefazolin + aminoglycoside	3 (33.3)	4 (22.2)
Cefazolin + gentamicin + rifampicin	0 (0.0)	1 (5.6)
Unspecified	1 (11.1)	0 (0.0)	0.207
Obesity (by body mass index [kg/m²])
<30	5 (55.6)	7 (43.8)
30–35	3 (33.3)	8 (50.0)
>35	1 (11.1)	1 (6.2)	0.840
Smoking
Yes	1 (11.1)	0 (0.0)
No	8 (88.9)	18 (100)	0.333
No malnutrition	8 (100)	18 (100)	0.050
American Society of Anesthesiologists class
II	1 (11.1)	9 (50.0)
III	8 (88.9)	9 (50.0)	0.091
History of infection
Yes	1 (11.1)	0 (0.0)
No	8 (88.9)	18 (100)	0.333
Early infection	8 (100)	18 (100)	0.050
Deep infection level	9 (100)	18 (100)	0.083
Bacteria
Gram-positive	3 (33.3)	7 (38.9)
Gram-negative	4 (44.4)	3 (16.7)
Polymicrobial	2 (22.2)	8 (44.4)	0.268
Measurement of C-reactive protein level
Performed	0 (0.0)	1 (5.9)
Not performed	7 (100)	16 (94.1)	1.000
Sonication
Performed	1 (12.5)	1 (5.6)
Not performed	7 (87.5)	17 (94.4)	0.529
Pathogen concordance
Yes	4 (44.4)	9 (50.0)
No	5 (55.6)	9 (50.0)	1.000
No. of irrigations
1	3 (33.3)	10 (55.6)
2	4 (44.4)	7 (38.9)
3	1 (11.1)	0 (0.0)
4	0 (0.0)	1 (5.6)
6	1 (11.1)	0 (0.0)	0.303
Plastic surgery
Yes	3 (33.3)	2 (11.1)
No	6 (66.7)	16 (88.9)	0.295
Vacuum-assisted closure therapy
Yes	4 (44.4)	2 (11.1)
No	5 (55.6)	16 (88.9)	0.136

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Table 5

Quantitative variables.

Variable	Deformity^{^a}	Degenerative Disease^{^a}	P Value
Age (y)	73.9 ± 7.69	76.2 ± 5.83	0.642
Duration of procedure (min)	309 (210)	218 (60.2)	0.010
Blood loss (g/dL)	3.36 ± 1.18	3.01 ± 1.12	0.368
Charlson Comorbidity Index	4.89 ± 1.76	4.28 ± 0.83	0.298
Body mass index (kg/m²)	29.5 ± 4.54	29.9 ± 3.72	0.934
Serum albumin levels (g/dL)	4.06 ± 0.42	4.30 ± 0.35	0.119
Time (d) elapsed between the initial operation and infection occurrence	14.0 (8.00)	13.0 (5.00)	0.244
C-reactive protein level (mg/dL) at admission	18.0 ± 15.9	19.6 ± 12.2	0.560
Duration (d) of empirical antibiotic therapy	4.50 (1.50)	5.00 (2.75)	0.465
Duration (d) of targeted antibiotic therapy	90.0 (19.8)	63.5 (27.5)	0.039
Total duration (d) of antibiotic therapy	94.5 (21.5)	67.5 (27.0)	0.048
Duration (d) of intravenous treatment	30.0 (23.0)	21.5 (17.8)	0.537

↵a Data are expressed as mean ± SD. The exceptions are for data on duration expressed in minutes or days, which are expressed as medians (interquartile ranges).

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Table 6

Frequency and percentage of successful and unsuccessful curing of infections in the 2 largest treatment groups.

Outcome at 2 y After Surgery	Deformity, n (%)	Degenerative Disease, n (%)	Relative Risk (95% CI)	P Value
Infection cured with debridement	5 (55.6)	17 (94.4)	1.70 (0.94, 3.08)	0.030
Infection cured with hardware removal/replacement	3 (33.3)	1 (5.6)	0.15 (0.02, 0.98)	0.030
Treatment failure (antimicrobial suppression failed or death occurred)	1 (11.1)	0 (0)

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Table 7

Prevalence and characteristics of SSI among various studies. Noncemented spinal instrumentation.

Author/Year	Patients, n	SSI, n (%)	Mean Age, y	Infection Characteristics	Implants Removed, n(%)	Implants Retained and ATB Suppression, n (%)	Implants Retained and Cured, n (%) Days of Oral Antibiotics
Zhang et al, 202230	27,881	521 (1.8%), 191 needing revision surgery	55.3	Most common microbe: Staphylococcus aureus (43.4%)	7 Of the 191 revisions (3.6%)	15.2%	175 Of the 191 revisions (91.6%) Complications secondary to antibiotic treatment was 7.8%
Kuroiwa et al, 202231	1832	44 (2.4%)	50.7	Most common microbe: S aureus (47%)	20 (45.5%) SSI needed >2 debridement or instrumentation removed or SSI led to death	-	24 (54.5%)
Cáceres et al, 201932	799	32 (4%) 3 Lost in follow-up	54.9	Most common microbe: S aureus	1 (4%)	-	24 (96%) 8 wk
Khanna et al, 201833	-	67	61.9	Most common microbe: S epidermidis	19 (9%)	25 (37%)	17 (25%) 255 d (Range 7–689)
Manet et al, 201834	1694	46 (2.7%) 9 Lost in follow-up	55	Most common microbe: S aureus	2 (4%)	-	31 (84%) 6 mo (Range 3–9)
Tsubouchi et al, 201835	3967	55 (1.4%)	72 (60–77)	Estimated blood loss significantly associated with implant removal	21 (38%)	-	33 60%)
Cho et al, 201836	-	102	63 (50–70)	Most common microbe: methicillin-resistant S aureus	19 (18.6%)	35 (34.3%)	48 (47%) 52 d (Range 34–88)
Yin et al, 201837	4057	42 (1%)	68.9	Most common microbe: S epidermidis	1 (2.4%)		41 (97.6%)
Takizawa et al, 201738	665	21 (3.2%), 9 Methicillin-resistant S epidermidis	64.3	-	2 Of the 9 methicillin-resistant S epidermidis SSI (22.2%)		7 Of the 9 methicillin-resistant S epidermidis SSI (77.8%)
Wille et al, 201739	4290	129 (3%) 1 Lost in follow-up	57	Most common microbe: S aureus Polymicrobial infection associated with relapse	5 (3.8%)	17 (13.2%)	106 (82.2%)