What are the preferred irrigation solutions for spinal surgery? Do they differ for clean and contaminated procedures? Are there "best practices" available?

Comment by InpharmD Researcher

A moderate body of literature supports intraoperative wound irrigation for surgical site infection (SSI) prevention in spinal surgery, although evidence comparing solutions and establishing optimal protocols remains limited. Expert consensus recommendations support considering aqueous povidone-iodine irrigation before wound closure in clean spinal procedures, while evidence remains insufficient to recommend for or against normal saline, chlorhexidine, or antibiotic-containing solutions for SSI prevention in these procedures. For de novo non-specific spinal procedures, available expert consensus recommendations primarily address de novo spinal infections and support extensive irrigation with normal saline or an antiseptic solution, without specifying a preferred agent or standardized protocol. Supporting evidence from randomized controlled trials and meta-analyses suggests that diluted povidone-iodine may reduce SSI rates, with several trials evaluating 0.35% povidone-iodine applied for 3 minutes followed by normal saline irrigation. However, evidence remains insufficient to recommend a specific irrigation solution or technique for contaminated or infected spinal procedures, and findings from clean procedures may not be directly applicable to these settings.

A literature search was conducted using PubMed/MEDLINE, Google Scholar, and relevant clinical guidelines and expert consensus statements. Search terms included “spinal surgery,” “spine surgery,” “intraoperative wound irrigation,” “surgical site infection,” “normal saline,” “povidone-iodine,” “Betadine,” “chlorhexidine,” “antibiotic irrigation,” “gentamicin,” “clean surgery,” “contaminated wounds,” “infected spinal surgery,” and “irrigation best practices.”

Background

The 2024 European Association of Neurosurgical Societies (EANS) consensus recommendations on the diagnosis and management of de novo non-specific spinal infections were developed through a Delphi process involving 26 experts. Regarding surgical irrigation, the consensus recommends extensive irrigation of the entire surgical field with normal saline or an antiseptic solution during surgical management of spinal infections, with 93% expert agreement. However, the consensus does not specify a preferred antiseptic agent, irrigation concentration, volume, or frequency. Of note, the recommendations specifically address de novo non-specific spinal infections and do not include perioperative or postoperative spinal infections. [1]

The 2020 Consensus on Wound Care of Surgical Site Infections (SSIs) in Spine Surgery was developed during the 2018 Second International Consensus Meeting on Musculoskeletal Infection, where 15 spine specialists reviewed available literature and discussed recommendations using a Delphi method. Moderate-quality evidence from two randomized controlled trials and two observational studies supported the use of aqueous povidone-iodine irrigation before wound closure to reduce SSIs in clean spinal surgery. The two randomized controlled trials demonstrated significantly lower SSI rates with 0.35% povidone-iodine compared with normal saline irrigation (0% vs 4.8%, p= 0.029 and 0% vs 3.4%, p= 0.0072). The panel recommends considering aqueous povidone-iodine irrigation before closure but found insufficient evidence to recommend for or against normal saline, chlorhexidine, or antibiotic-containing irrigation solutions for SSI prevention in clean spinal surgery. Additionally, evidence was insufficient to establish the optimal irrigation volume, type, or frequency in clean procedures. For infected spinal surgery, the consensus found insufficient evidence to recommend a specific irrigation solution, volume, type, or frequency. The irrigation recommendations received 73% agreement among delegates. [2]

A 2021 review examines evidence-based strategies for preventing SSIs, including preoperative preparation, perioperative antibiotic prophylaxis, skin antisepsis, and measures to reduce intraoperative and postoperative infection risk. The review describes four surgical wound classifications, clean, clean-contaminated, contaminated, and dirty/infected, and notes that infection risk is presumed to increase with greater contamination, although the authors acknowledge debate about how well wound classification predicts SSI. The review focuses primarily on elective clean and clean-contaminated procedures rather than contaminated or infected cases. Among the prevention strategies discussed, the authors identify perioperative intravenous antibiotic prophylaxis, chlorhexidine-based skin antisepsis, maintenance of normal body temperature throughout the perioperative period, and smoking cessation before elective surgery as measures supported by evidence. They also discuss preoperative bathing, hair removal, surgical attire, and adhesive or iodine-impregnated surgical drapes, noting that the evidence for these interventions is variable and does not consistently demonstrate reduced SSI risk. The authors recommend administering prophylactic antibiotics before incision, generally within 1 hour, with selection and redosing based on the procedure and patient-specific factors; they also note evidence that prophylactic antibiotics do not need to be continued after wound closure solely to prevent SSI. However, the review does not specifically address spinal surgery irrigation, compare normal saline with antiseptic- or antibiotic-containing irrigation solutions, or establish different irrigation recommendations for clean versus contaminated procedures. [3]

Several systematic reviews and meta-analyses have evaluated intraoperative wound irrigation for preventing SSIs in spinal surgery. A 2025 meta-analysis of six randomized controlled trials (RCTs) involving 1,804 patients found that povidone-iodine (PI) irrigation reduced overall SSIs compared with control irrigation, primarily normal saline or saline with gentamicin (0.77% vs. 6.09%; relative risk [RR] 0.16; 95% confidence interval [CI] 0.08 to 0.34). A separate meta-analysis published in 2024, including 14 studies (six randomized trials and eight retrospective cohort studies), also found lower overall, superficial, and deep SSI rates with PI irrigation. Across these studies, PI concentrations ranged from 0.1% to 3.5%; commonly reported protocols involved applying diluted PI for 2-3 minutes before rinsing with normal saline. However, the optimal concentration, volume, and duration remain uncertain, and the 2025 analysis found no statistically significant differences between the protocol subgroups evaluated. Overall, the available literature supports diluted PI as a potential adjunct to SSI prevention in spinal surgery, but does not establish a standardized optimal protocol or demonstrate that irrigation solutions should differ between clean and contaminated procedures. [4], [5]

A 2022 meta-analysis evaluated 18 studies, including 3 randomized RCTs, 13 retrospective cohort studies, and 2 prospective cohort studies, examining intraoperative irrigation techniques for SSI prevention in spinal surgery. The meta-analysis focused on povidone-iodine (PVP-I) irrigation to reduce heterogeneity and maintain evidence quality. Across the PVP-I studies, 54 SSIs (1.8%) occurred among 2,944 patients receiving PVP-I irrigation compared with 159 SSIs (4.6%) among 3,408 controls, corresponding to an absolute risk reduction of 2.8% and a pooled risk ratio of 0.32 (95% CI 0.20–0.53, p<0.00001). PVP-I concentrations varied across studies, with two RCTs evaluating 0.35% PVP-I applied for 3 minutes followed by irrigation with 2 L of normal saline, both demonstrating significantly lower SSI rates compared with saline irrigation alone. Subgroup analysis restricted to RCTs and prospective cohort studies also supported the findings. Evidence for other irrigation solutions was more limited. One study associated saline irrigation volumes greater than 2,000 mL/hour with reduced SSIs (odds ratio [OR] 0.08, 95% CI 0.01–0.61), while evidence for chlorhexidine, hydrogen peroxide, and antibiotic-containing irrigation solutions remained insufficient or inconsistent. The authors concluded that PVP-I had the strongest supporting evidence for SSI prevention in spinal surgery, with Level II evidence, although the optimal irrigation solution and technique remained unclear. Findings were limited by heterogeneity, predominantly retrospective data, publication bias, and variations in irrigation protocols and concurrent prophylactic interventions. [6]

A 2022 network meta-analysis evaluated 10 studies involving 5,164 spinal surgery procedures in patients aged ≤22 years to compare six perioperative infection prophylaxis strategies, including Betadine irrigation, saline irrigation, intrawound vancomycin powder, Betadine irrigation plus intrawound vancomycin powder, combination therapy with Betadine, vancomycin, gentamicin, and cefuroxime, and no intervention. Betadine irrigation concentrations ranged from 0.3% to 0.35%. One included study directly compared 0.35% Betadine irrigation with normal saline irrigation, with both solutions applied for 3 minutes, and reported SSIs in 1 of 77 patients (1.3%) and 2 of 76 patients (2.6%), respectively. Another study evaluated 0.3% Betadine irrigation alone and in combination with intrawound vancomycin powder. Across all studies, 202 postoperative infections were reported, including 193 SSIs, 19 deep infections, and 9 non-SSI infections. Compared with no intervention, Betadine irrigation plus intrawound vancomycin powder (odds ratio [OR] 0.22, 95% CI 0.09–0.54), combination therapy (OR 0.24, 95% CI 0.07–0.75), and topical vancomycin (OR 3.26, 95% CI 1.96–5.44) significantly reduced SSIs. Betadine irrigation plus intrawound vancomycin powder received the highest ranking for preventing SSIs, deep infections, and total infections. However, no statistically significant differences were identified between the active prophylactic strategies. The authors noted limitations related to heterogeneity in surgical indications, techniques, prophylactic regimens, and outcome reporting. [7]

Background References: [1] Kramer A, Thavarajasingam SG, Neuhoff J, et al. Diagnosis and management of de novo non-specific spinal infections: European Association of Neurosurgical Societies (EANS) Spine Section Delphi consensus recommendations. Brain Spine. 2024;5:104178. Published 2024 Dec 31. doi:10.1016/j.bas.2024.104178
[2] Galetta MS, Kepler CK, Divi SN, et al. Consensus on Wound Care of SSI in Spine Surgery. Clin Spine Surg. 2020;33(5):E206-E212. doi:10.1097/BSD.0000000000000853
[3] Fuglestad MA, Tracey EL, Leinicke JA. Evidence-based Prevention of Surgical Site Infection. Surg Clin North Am. 2021;101(6):951-966. doi:10.1016/j.suc.2021.05.027
[4] Egu C, Muscogliati R, Nocun W, et al. RCT-based meta-analysis of povidone-iodine irrigation in spinal surgery: clarifying efficacy and safety. Eur Spine J. 2025;34(10):4670-4679. doi:10.1007/s00586-025-09243-8
[5] Mu X, Wei X, Li Z, Wei M, Wei J. Does intraoperative wound irrigation with diluted povidone-iodine prevent surgical site infection in spine surgery?. EFORT Open Rev. 2024;9(11):1087-1096. Published 2024 Nov 8. doi:10.1530/EOR-24-0091
[6] Torres KA, Konrade E, White J, et al. Irrigation techniques used in spine surgery for surgical site infection prophylaxis: a systematic review and meta-analysis. BMC Musculoskelet Disord. 2022;23(1):813. Published 2022 Aug 26. doi:10.1186/s12891-022-05763-2
[7] Shaffer A, Naik A, MacInnis B, et al. Perioperative prophylaxis for surgical site infections in pediatric spinal surgery: a systematic review and network meta-analysis. J Neurosurg Pediatr. 2022;31(1):43-51. Published 2022 Oct 28. doi:10.3171/2022.9.PEDS22316
Literature Review

A search of the published medical literature revealed 8 studies investigating the researchable question:

What are the preferred irrigation solutions for spinal surgery? Do they differ for clean and contaminated procedures? Are there "best practices" available?

Level of evidence

C - Multiple studies with limitations or conflicting results  Read more→


Please see Tables 1-8 for your response.

 

Does intraoperative antiseptic solution soaking reduce microbial contamination in spine surgery? A randomized controlled trial
Design

Single-center, single-blinded, randomized controlled trial

N= 105
Objective To evaluate the effectiveness of intraoperative antiseptic solution soaking with normal saline (NS), povidone-iodine (PVP-I), and chlorhexidine gluconate (CHG) in reducing bacterial contamination in lumbar instrumented fusion surgery
Study Groups

NS (n=35)

PVP-I (n=35)

CHG (n=35)
Inclusion Criteria Patients aged ≥18 years undergoing lumbar posterior decompression and instrumented fusion with pedicle screws and cages
Exclusion Criteria Patients with prior lumbar procedures, known allergies to antiseptics, previous spinal infections, trauma, or tumors
Methods Patients were randomized into three groups, each receiving a 3-minute soak with the assigned antiseptic solution before wound closure, followed by normal saline irrigation. Swab samples were collected pre- and postirrigation for bacterial culture and 16S rRNA PCR analysis. 
Duration January 2021 to March 2024
Outcome Measures

Primary: Reduction in bacterial contamination

Secondary: Incidence of postoperative SSIs and clinical complications over a 6-month follow-up period
Baseline Characteristics   Normal saline group (n=35) Povidone-iodine group (n=35) Chlorhexidine gluconate group (n=35) p-value
Age, y, mean ± SD 68.71±10.01 64.31±12.95 66.14±12.92 .3116
Sex, male/female, n 12/23 20/15 12/23 .0818
Fusion number, n 1.74±0.75 1.40±0.55 1.83±0.79 .029*
Surgical time, min, mean ± SD 209.06±69.49 185.49±47.5 204.63±45.24 .170
BMI, mean ± SD 25.13±4.20 25.50±3.42 26.37±3.87 .385
DM, n 11 7 9 .550
Smoking, n 6 4 2 .323
Immunosuppression medication use, n 1 2 0 .357
Blood loss, mL 378.00±374.45 302.57±157.95 329.43±180.70 .463
ASA 1 2 3 2 .432
ASA 2 16 19 21 .432
ASA 3 16 13 12 .432
ASA 4 1 0 0 .432
Results
Positive culture rates
Irrigation solution Superficial: Before, n (%) Superficial: After, n (%) p-value Deep: Before, n (%) Deep: After, n (%) p-value Implants: Before, n (%) Implants: After, n (%) p-value
Normal saline (n=35) 15 (42.8) 8 (22.8) 0.12 8 (22.8) 5 (14.2) 0.53 10 (28.5) 10 (28.5) 1.0
Povidone-iodine (n=35) 20 (57.1) 9 (25.7) 0.015* 17 (48.5) 11 (31) 0.22 15 (42.8) 10 (28.5) 0.32
Chlorhexidine gluconate (n=35) 17 (48.5) 1 (2.8) <0.0001* 8 (22.8) 2 (5.7) 0.08 9 (25.7) 1 (2.8) 0.02*
Adverse Events No reported antiseptic-related complications
Study Author Conclusions This study confirms that bacterial contamination remains high despite standard preoperative disinfection in lumbar fusion surgery. Among the tested antiseptic solutions, CHG demonstrated superior efficacy in reducing bacterial residues, particularly on implant surfaces. These findings support CHG as a promising antiseptic for intraoperative irrigation in spine surgery. Further multicenter studies are needed to validate its impact on reducing SSIs and improving long-term outcomes.
Critique The study's strengths include its randomized controlled design and consistent surgical technique by a single surgeon, which minimized variability. However, the relatively small sample size and single-center design may limit the generalizability of the findings. Despite significant bacterial reduction, the low number of clinical SSIs limits the ability to statistically assess the direct impact of irrigation fluids on infection prevention. Larger, multicenter trials are warranted to validate these findings and better establish the clinical implications of reduced intraoperative contamination.
Table 1 References:
[8] Liu YF, Hsu YC, Chen PL, et al. Does intraoperative antiseptic solution soaking reduce microbial contamination in spine surgery? A randomized controlled trial. Spine J. 2025;25(9):1857-1865. doi:10.1016/j.spinee.2025.05.002

Prevention of Surgical Site Infection Following Open Spine Surgery: The Efficacy of Intraoperative Wound Irrigation with Normal Saline Containing Gentamicin Versus Dilute Povidone-Iodine
Design

Prospective comparative study

N= 80
Objective To compare the effectiveness of saline with gentamicin versus povidone-iodine as intraoperative wound irrigation solutions in preventing surgical site infection (SSI) in open spine surgery
Study Groups

Saline with gentamicin (n= 40)

Dilute povidone-iodine (n= 40)
Inclusion Criteria Patients aged 18 years and above who underwent open spinal surgery with class I wounds as defined by the American College of Surgeons (AMA) and no evidence of systemic focus of infection
Exclusion Criteria Patients suspected of harboring a central nervous system infection prior to the procedure, with dirty or contaminated surgical wounds, who had instrumented spine surgery, were immunocompromised, on long-term steroids, with an intraoperative dural breach and cerebrospinal fluid (CSF) leak, with an ASA score of III and above, or who died within 30 days after surgery from complications not related to SSI
Methods

Patients were randomized into two groups of 40. Group A received intraoperative wound irrigation with 1 L of normal saline containing 80 mg of gentamicin, while Group B received 1 L of 3.5% diluted povidone-iodine solution. In both groups, the wound was filled with the assigned solution to skin level without overflow, maintained for 3 minutes, and subsequently flushed with the remaining solution before wound closure.

All patients received ceftriaxone 1 g at anesthesia induction, with repeat dosing for procedures lasting longer than 3 hours or blood loss exceeding 1 L, followed by ceftriaxone 1 g every 12 hours for 48 hours postoperatively. Patients were followed for 30 days, with wound assessments on postoperative days 5, 14, and 30 to evaluate surgical site infections and wound dehiscence. Surgical site infections were diagnosed and classified according to Centers for Disease Control guidelines, and infection rates were compared using logistic regression analysis.
Duration 2018 to 2020
Outcome Measures

Occurrence of SSI, types of SSI (superficial and deep), mean postoperative duration of SSI occurrence, bacterial causative organisms
Baseline Characteristics   Saline with gentamicin (n= 40) Dilute povidone-iodine (n= 40)
Male 23 (57.5%) 22 (55.0%)
Mean age, years 55.53 57.38
Mean body mass index, kg/m2 28.01 27.28

Comorbidities

No comorbidity

Diabetics

Hypertensive

Diabetics/Hypertensive

 

15 (37.5%)

1 (2.5%)

20 (50.0%)

4 (10.0%)

 

17 (42.5%)

3 (7.5%)

14 (35.0%)

6 (15.0%)

ASA scores

I

II

 

9 (22.5%)

31 (77.5%)

 

16 (40.0%)

24 (60.0%)

Surgical approach

Anterior 

Posterior

 

1 (2.5%)

39 (97.5%)

 

2 (5.0%)

38 (95.0%)

Baseline patient characteristics, including age, sex, obesity, comorbidities, and laboratory parameters, were comparable between the normal saline containing gentamicin and dilute povidone-iodine groups. Surgical characteristics, including type of surgery, surgical indication, surgical site, surgical approach, number of spinal levels operated on, and surgery duration, were also comparable between groups, with no statistically significant differences in the variables assessed (p> 0.05).
Results   Saline with gentamicin (n= 40) Dilute povidone-iodine (n= 40) p-value
Overall SSI rate 7 (17.5%) 1 (2.5%) 0.025
Superficial SSI rate 5 (12.5%) 0 (0.0%) 0.025
Deep SSI rate 2 (5.0%) 1 (2.5%) 0.556

The mean time to SSI occurrence was 9.5 days postoperatively, with no significant difference between groups. In the lumbosacral region, SSI rates were significantly lower with povidone-iodine irrigation compared with saline containing gentamicin (0% vs 31.6%, p= 0.006), while no differences were observed in the cervical or thoracic regions. Of the 8 patients who developed SSIs, 7 had positive bacterial cultures.

Staphylococcus and Pseudomonas species each accounted for 42.86% of SSIs in the saline-gentamicin group, whereas Pseudomonas species accounted for 100% of SSIs in the povidone-iodine group. The overall distribution of bacterial isolates did not differ significantly between groups (p= 0.141), although a statistically significant difference was reported in the lumbosacral region (p= 0.008). No organ/space SSIs were reported, and no significant wound dehiscence was detected in the povidone-iodine group.
Adverse Events Not reported
Study Author Conclusions Intraoperative wound irrigation (IOWI) with 3.5% dilute povidone-iodine solution is more efficacious in preventing SSI and has wider microbial coverage compared to normal saline containing gentamicin solution as IOWI fluid in noninstrumented open spine surgery.
Critique The study was strengthened by proper randomization and homogeneity of patient and surgical procedure characteristics, suggesting minimal bias. However, limitations included potential confounding from unaccounted SSI risk factors, such as intraoperative blood loss, smoking, shock, and hypoxia, as well as the possibility of missed early signs of SSI due to difficulty identifying erythema in patients with darker skin tones.
Table 2 References:
[9] Inojie MO, Okwunodulu O, Ndubuisi CA, Campbell FC, Ohaegbulam SC. Prevention of Surgical Site Infection Following Open Spine Surgery: The Efficacy of Intraoperative Wound Irrigation with Normal Saline Containing Gentamicin Versus Dilute Povidone-Iodine. World Neurosurg. 2023;173:e1-e10. doi:10.1016/j.wneu.2022.12.134

Reducing surgical site infections after spine surgery: the optimal amount of normal saline for intra-wound irrigation
Design

Retrospective study

N= 444
Objective To investigate if insufficient intraoperative irrigation may be a risk factor for postoperative SSI and to determine the optimal amount of normal saline for irrigation to prevent postoperative SSI
Study Groups

Bulb syringe (B group, n=193)

Interpulse battery-powered irrigation device (P group, n=251)
Inclusion Criteria Patients aged more than 18 years; received TLIF surgery due to degenerative lumbar spinal diseases; failure of conservative treatment for more than 6 months; minimum follow-up of 1 year
Exclusion Criteria Received additional prophylactic intraoperative antibiotics, povidone-iodine wound irrigation, or local application of vancomycin power; infections within the past month; taking immunosuppressants within the last 6 months
Methods Patients were grouped based on the irrigation method: bulb syringe with 2,000 mL NS or interpulse battery-powered device with >6,000 mL NS. All patients received the same preoperative preparation and standard surgical steps. The main outcome measures included superficial wound infection, deep infection, and overall infection
Duration January 2015 through April 2020
Outcome Measures

Primary: Overall SSI rate

Secondary: Superficial wound infection, deep wound infection, irrigation amount per hour
Baseline Characteristics   Bulb syringe (B group) (2,000 mL); n= 193 Interpulse battery-powered irrigation device (P group) (6,000 mL); n= 251 p-value
Gender, Male: Female 80:113 91:160 .266
Age, mean (SD), year 66.74 (13.82) 66.64 (11.58) .937
DM, (%) with data 41 (21.24%) 61 (24.32%) .495
Smoking, (%) with data 22 (11.05%) 35 (13.94%) .428
Body mass index, mean (SD) 26.3 (4.40) 26.8 (4.62) .264
Results   Bulb syringe (B group) (2,000 mL) Interpulse battery-powered irrigation device (P group) (6,000 mL) p-value
Estimated blood loss, mean (SD), mL 518.09 (428.296) 678.33 (399.30) < .001
Surgical time, mean (SD), minute 213.81 (80.02) 258.90 (93.73) .021
Irrigation amount, mean (SD), mL/h 652 (312.7) 1558 (571.6) <.001
Overall infection 9 (4.66%) 4 (1.59%) .075
Superficial wound infection 7 (3.63%) 1 (0.40%) .023
Deep wound infection 2 (1.04%) 3 (1.20%) .875
Adverse Events Not specifically reported
Study Author Conclusions Diabetes and lower volume of intraoperative irrigation were risk factors for postoperative SSI following degenerative lumbar spine surgery. Intra-wound irrigation with more than 1,400 mL/h of NS is recommended to reduce SSI.
Critique The study provides valuable insights into the optimal irrigation volume to prevent SSI, but its retrospective nature introduces potential selection bias. The lack of comparison between different irrigation pressures and the absence of a prospective design limit the generalizability of the findings. Additionally, the study did not evaluate the frequency of irrigation during surgery, which could impact outcomes.
Table 3 References:
[10] Hsiung W, Yao YC, Lin HH, et al. Reducing surgical site infections after spine surgery: the optimal amount of normal saline for intra-wound irrigation. Spine J. 2023;23(11):1580-1585. doi:10.1016/j.spinee.2023.07.011

Bulb Syringe and Pulsed Irrigation: Which Is More Effective to Remove Bacteria in Spine Surgeries?
Design

Retrospective study

N= 138
Objective To investigate the difference of efficacy between bulb syringe irrigation and pulsed irrigation in spinal surgeries
Study Groups

Group I (bulb syringe) (n= 79)

Group II (pulsed irrigation) (n= 59)
Inclusion Criteria Consecutive patients who underwent posterior lumbar interbody fusion for 6 months between June 1, 2010, and December 31, 2010
Exclusion Criteria Not specified
Methods Patients were divided into two groups based on the irrigation method used during surgery: bulb syringe (group I) and pulsatile irrigator with 17 psi (group II). Intraoperative irrigations were performed 3 times with normal saline. Culture specimens were obtained from the muscle layer and intervertebral space after the last irrigation. Antibiotics were administered 30 minutes before surgery and re-dosed every 4 hours or after 1500 mL blood loss.
Duration June 1, 2010, to December 31, 2010
Outcome Measures

Primary: Positive rate of bacterial culture from muscle layer and intervertebral space 
Baseline Characteristics   Group I (n= 79) Group II (n= 59)
Age (years) 60.8 (±13.2) 63.3 (±10.5)
Operation time (min) 172.0 (±47.7) 193.1 (±47.9)
Blood loss (mL) 1070.9 (±516.6) 1050.2 (±541.7)
Saline amount (mL) 4151.9 (±1199.2) 4576.3 (±1206.4)
Results   Group I Positive Group II Positive p-value
Muscle Layer 8/79 (10.1%) 1/59 (1.6%) 0.046
Intradiscal Space 6/79 (7.6%) 5/59 (8.5%) 0.546
Adverse Events There was no neurological injury by the pulsatile irrigation. No real surgical site infection developed regardless of microbiological results.
Study Author Conclusions Pulsed irrigation was more effective than bulb syringe irrigation to reduce bacterial contamination in the posterior muscle layers. In the intervertebral space, both methods were insufficient to eradicate contaminated bacteria. There was no neurological injury due to the pulsed irrigation.
Critique The study was limited by its non-randomized design and the endpoint was bacterial culture incidence rather than surgical site infection. The groups were not completely homogeneous, which may affect the results. The study suggests potential benefits of pulsed irrigation but does not provide a decisive conclusion on its impact on surgical site infections.
Table 4 References:
[11] Ahn DK, Lee S, Moon SH, Kim DG, Hong SW, Shin WS. Bulb Syringe and Pulsed Irrigation: Which Is More Effective to Remove Bacteria in Spine Surgeries?. Clin Spine Surg. 2016;29(1):34-37. doi:10.1097/BSD.0000000000000068

Prevention of post-operative infections in spine surgery by wound irrigation with a solution of povidone–iodine and hydrogen peroxide
Design Prospective and retrospective study N= 950 (460 in 2008 and 490 in 2009)
Objective To verify the effectiveness of intra-operative application of a PVP–I and H2O2 solution in reducing surgical site infection (SSI) in spine surgery
Study Groups

2008 group (n= 460)

2009 group (n= 490)
Inclusion Criteria Patients undergoing spine surgery with preserved dural integrity
Exclusion Criteria Cases with dural opening or laceration
Methods Irrigation of surgical wounds with a solution of 10 cc of PVP–I 10%, 5 cc of H2O, and 1 cc of H2O2 before wound closure, followed by copious irrigation with physiological sodium chloride solution. Standard aseptic procedures and antibiotic prophylaxis were applied
Duration 2008 to 2009
Outcome Measures Primary: Incidence of post-operative infections Secondary: Adverse reactions to the irrigation solution
Baseline Characteristics   2008 group (n= 460) 2009 group (n= 490)
Number of infections 7 0
Results   2008 group (n= 460) 2009 group (n= 490)
Post-operative infections 7 0
Adverse Events No adverse reactions were observed
Study Author Conclusions Wound irrigation with diluted PVP–I and H2O2 before closure is effective in reducing the incidence of surgical site infection after spinal surgery. This method is safe, simple, fast, and inexpensive.
Critique The study demonstrated a significant reduction in infection rates with the use of PVP–I and H2O2 irrigation. However, the retrospective component and lack of randomization may introduce bias. The study did not compare the solution with other antiseptic methods or include a control group without irrigation, which limits the ability to attribute the reduction in infections solely to the intervention.
Table 5 References:
[12] Ulivieri, S., Toninelli, S., Petrini, C. et al. Prevention of post-operative infections in spine surgery by wound irrigation with a solution of povidone-iodine and hydrogen peroxide. Arch Orthop Trauma Surg 131, 1203-1206 (2011). https://doi.org/10.1007/s00402-011-1262-0

Risk factors for surgical site infection following spine surgery: efficacy of intraoperative saline irrigation
Design

Retrospective cohort study

N= 223
Objective To identify risk factors for surgical site infection after spine surgery, noting the amount of saline used for intraoperative irrigation to minimize wound contamination
Study Groups

Noninfected (n= 209)

Infected (n= 14)
Inclusion Criteria Patients who underwent spine surgery at Tokai University School of Medicine between January 2006 and December 2006, requiring surgical incision and drainage with positive intraoperative cultures
Exclusion Criteria Not explicitly stated
Methods Data were collected from patient charts, electronic records, and operative logs. Univariate and multivariate logistic regression analyses were conducted. Factors analyzed included patient characteristics, preoperative risk factors, and intraoperative factors such as type of procedure, estimated blood loss, duration of operation, and mean amount of saline used for irrigation per hour
Duration January 2006 to December 2006
Outcome Measures

Primary: Incidence of surgical site infection

Secondary: Association of risk factors such as diabetes, trauma, and amount of saline irrigation with surgical site infection
Baseline Characteristics   Noninfected (n= 209) Infected (n= 14)
Age, years (mean) 53 49
Male/Female 138/71 9/5
BMI, kg/m2 (mean) 23.1 23.9
Preoperative hospital stay, days (mean) 5.7 11.1
Results   Non-infected Infected OR (95% CI) p-value
Diabetes 29 4 4.88 (1.01–23.51) 0.048
Trauma 25 8 9.42 (1.59–55.73) 0.013
Mean amount of saline irrigated per hour >2000 ml 91 3 0.08 (0.01–0.61) 0.015
Incidence of surgical site infection: 6.3% (14 of 223 patients)
Adverse Events N/A
Study Author Conclusions Diabetes, trauma, and insufficient intraoperative irrigation of the surgical wound were independent and direct risk factors for surgical site infection following spine surgery. It is important to control perioperative serum glucose levels in patients with diabetes, avoid delays in surgery for trauma patients, and use sufficient saline irrigation to reduce intraoperative contamination
Critique The study provides valuable insights into risk factors for surgical site infections, highlighting the importance of intraoperative saline irrigation. However, the retrospective design may limit the ability to establish causation. The study's findings may not be generalizable to populations outside of Japan due to differences in obesity rates and healthcare practices. Additionally, the exclusion criteria were not explicitly stated, which may affect the study's internal validity.
Table 6 References:
[13] Watanabe M, Sakai D, Matsuyama D, Yamamoto Y, Sato M, Mochida J. Risk factors for surgical site infection following spine surgery: efficacy of intraoperative saline irrigation. J Neurosurg Spine. 2010;12(5):540-546. doi:10.3171/2009.11.SPINE09308

Outcomes of an Intraoperative Povidone-Iodine Irrigation Protocol in Spinal Surgery for Surgical Site Infection Prevention
Design

Retrospective observational study

N= 323
Objective To evaluate the efficacy of a new protocol for preventing postoperative surgical site infection (SSI) following spinal surgery
Study Groups

Study group (PVP-I irrigation) (n= 177)

Control group (saline irrigation) (n= 146)
Inclusion Criteria All cases of spinal surgery at the hospital between October 2011 and September 2016
Exclusion Criteria PVP-I allergy, prior surgical debridement for infection, and implant removal surgery
Methods Patients received normal saline irrigation after 90 seconds of 1% PVP-I pooling every 1.5 hours (study group) or only routine saline irrigation every 1.5 hours (control group). Cefazolin was administered preoperatively and postoperatively as prophylactic antibiotic treatment.
Duration October 2011 to September 2016
Outcome Measures

Primary: Rate of surgical site infection (SSI)

Secondary: Rate of deep SSI
Baseline Characteristics   Study Group (n= 177) Control Group (n= 146) p-value
Age (y) 67.3 (18–85) 67.1 (24–90) 0.94
Sex (female/male) 73/104 67/79 0.47
Immunocompromised states* 44 38 0.86
Location - Cervical 45 42  
Location - Thoracic 25 20 0.59
Location - Lumbar 107 84  
Instrumentation (-/+) 82/95 54/92 0.091
Operation time (min) 185.8 (24–523) 197.6 (9–638) 0.52
Amount of bleeding (g) 381 (0–2500) 326 (0–3228) 0.12
Results   Study Group (n = 177) Control Group (n = 146) p-value
SSI patients 3 5 0.32
Superficial SSI 3 1 0.41
Deep SSI 0 4 0.027
Adverse Events No adverse events occurred in the study group.
Study Author Conclusions The protocol of 90 seconds of 1% PVP-I pooling every 1.5 hours followed by saline irrigation is effective in reducing the incidence of postoperative deep SSI after spinal surgery without adverse clinical events.
Critique The study's retrospective design and nonrandomized patient allocation are limitations. Additionally, the appropriate irrigation frequency and PVP-I concentration remain unclear. Future prospective, randomized, controlled studies with larger populations and long-term follow-up are needed to validate these findings.
Table 7 References:
[14] Onishi Y, Masuda K, Tozawa K, Karita T. Outcomes of an Intraoperative Povidone-Iodine Irrigation Protocol in Spinal Surgery for Surgical Site Infection Prevention. Clin Spine Surg. 2019;32(10):E449-E452. doi:10.1097/BSD.0000000000000908

Wound Contamination in Pediatric Spinal Surgery Using Betadine Versus Saline
Design

Multicenter, single-blind, pilot randomized controlled trial

N= 175
Objective To evaluate the feasibility of a complete randomized controlled trial to study the efficacy of surgical site irrigation with povidone-iodine (PVP-I) compared with sterile saline (SS) to reduce the bacterial contamination rate before closure in children undergoing posterior spine fusion (PSF)
Study Groups

PVP-I (n= 77)

SS (n= 76)
Inclusion Criteria 3 to 18 years old on day of surgery, spinal deformity, and undergoing elective PSF
Exclusion Criteria Renal failure, allergy to iodine or shellfish, previous spine fusion surgery, fusing fewer than 6 levels, anterior or anterior-posterior surgery, and preoperative antibiotic use
Methods Patients were randomized to PVP-I or SS irrigation. Before closure, a wound culture was collected, and the wound was soaked with 0.35% PVP-I or SS for 3 minutes, followed by irrigation with 2 L of saline. A second sample was collected postirrigation. All patients received IV antibiotics preoperatively and intraoperatively.
Duration Recruitment: July 2017 to May 2018 Follow-up: 90 days postoperative
Outcome Measures

Primary: Feasibility of a larger RCT

Secondary: Baseline tissue colonization rates, bacteriology before closure, population-specific differences in contamination
Baseline Characteristics   Povidone-Iodine (n = 77) Saline (n = 76)
Age at surgery (mean ± SD) 14.6 ± 2.39 14.8 ± 2.04
Sex (male) 15 (20%) 16 (21%)
ASA 1 23 (30%) 20 (26%)
ASA 2 34 (44%) 34 (45%)
ASA 3 19 (25%) 22 (29%)
ASA 4 1 (1%) 0
Risk group - Low risk (idiopathic) 59 (77%) 57 (75%)
Risk group - High risk (other etiologies) 18 (23%) 19 (25%)
Results             
Outcome Povidone-iodine (n=77) Sterile saline (n=76) Statistical comparison
Positive cultures before irrigation 14/77 (18%) 13/76 (17%) Not separately reported
Positive cultures after irrigation 12/77 (16%) 14/76 (18%) Not separately reported
Change in culture status from before to after irrigation Positive cultures decreased from 14 to 12 Positive cultures increased from 13 to 14 No difference between irrigation groups: p= 0.96; no difference between risk groups: p= 0.17
High-risk patients with positive cultures before irrigation 2/18 (11%) 3/19 (16%) Not reported
High-risk patients with initially positive cultures: results after irrigation Both remained positive with the same organism All 3 remained positive with the same organism Not reported
High-risk patients with initially negative cultures that became positive after irrigation 3/16 (19%) 1/16 (6%) Not reported
Low-risk patients with positive cultures before irrigation 12/59 (20%) 10/57 (18%) Not reported
Low-risk patients with initially positive cultures: results after irrigation 6 retained the same organism; 1 had a new organism; 5 became culture-negative 8 retained the same organism; 2 became culture-negative Not reported
Low-risk patients with initially negative cultures that became positive after irrigation 0/47 (0%) 2/47 (4%) Not reported
Persistence of the same organism versus detection of a new organism after irrigation Results shown above by risk group Results shown above by risk group No difference between irrigation groups: p= 0.87; no difference between risk groups: p= 0.81
Bacteriology All cultured bacteria were gram-positive All cultured bacteria were gram-positive Across both groups, Propionibacterium acnes occurred in 43/53 (81%) positive cultures
Postoperative infection within 30 days 1 patient, classified as high risk 2 patients, both classified as high risk Overall, 3/37 (8%) high-risk patients developed infection; no statistical comparison reported
Adverse Events Three HR subjects (1 PVP-I, 2 SS) experienced infection at 30 days postoperative. Diagnoses included cerebral palsy, posttraumatic paraplegia, and Rett syndrome.
Study Author Conclusions Positive cultures were similar across treatment and risk groups. The bacterial contamination of wounds before closure remains high regardless of irrigation type. A complete randomized controlled trial would be challenging to adequately power given the similarity of tissue positivity across groups.
Critique The study was well-designed as a pilot RCT to assess feasibility, but it was underpowered to detect significant differences between treatment arms. The similarity in contamination rates suggests that a larger RCT may not be feasible without a very large cohort. The study's single-blind design and the allowance for crossover in treatment arms could have impacted the results. Additionally, the use of different culture methods (swabs vs. tissue) across sites may have influenced the findings. Future studies should consider a more standardized protocol and focus on specific high-risk populations.
Table 8 References:
[15] Cohen LL, Schwend RM, Flynn JM, et al. Why Irrigate for the Same Contamination Rate: Wound Contamination in Pediatric Spinal Surgery Using Betadine Versus Saline. J Pediatr Orthop. 2020;40(10):e994-e998. doi:10.1097/BPO.0000000000001620