Abstract
Surgical site infections (SSIs) increase healthcare costs and can worsen outcomes after foot and ankle surgery, including prolonged hospitalization, readmissions, and risk of additional amputations. Although chlorhexidine gluconate (CHG) has been studied as an irrigant additive in elective procedures, its role in operative management of foot and ankle infections remains unclear. We performed a retrospective review of 67 consecutive surgical cases conducted by a single podiatrist for eradication of foot and ankle infection. Patients were assigned to cohorts based on intraoperative irrigation with either normal saline or CHG solution. Participants were followed for six months to evaluate postoperative erythema and drainage (infection), wound dehiscence, need for additional surgery, and microbiology and pathology results. Of the 67 patients, 41 received CHG irrigation and 26 received saline irrigation. Baseline clinical and demographic characteristics were similar between groups. Postoperative infection rates, defined by erythema and drainage, did not differ between cohorts. Rates of positive microbiology cultures and pathology findings were also comparable.
Postoperative weight-bearing status affected dehiscence rates; however, irrigation type was not associated with dehiscence. In this first study assessing CHG irrigation in surgical treatment of foot and ankle infection, CHG demonstrated outcomes equivalent to normal saline with respect to postoperative erythema/drainage, culture and pathology results, and wound dehiscence, suggesting additional comparative studies may not be necessary.
Background
One-third of people with diabetes will develop a diabetic foot ulcer (DFU) over their lifetime, of which 20% of these patients will undergo an amputation. The re-amputation rates for patients undergoing a minor amputation has been quoted at around 20% with increased risk factors for patients who have concomitant peripheral arterial disease (PAD), or positive cultures with Pseudomonas or Escherichia coli . Despite these risks, many patients and providers will still prefer to perform more distal amputations due to the impact on quality of life it may have on patients. This presents a crucial need to eradicate infection during the initial amputation surgeries.
Surgical irrigation solutions offer one solution to mitigate the incidence of postoperative surgical site infection. Between the 1960’s and 1980′s, a number of studies assessed various surgical irrigants. Historically, these irrigants were non-sterile, often “pulled off the shelf”, and some are still currently in use including: hydrogen peroxide, sodium hypochlorite, hypochlorous acid, gentamycin containing normal saline, and povidone iodine (PVI). However, a majority of studies have failed to demonstrate significantly reduced infection rates, compered to normal saline. ,,
Chlorhexidine is a cationic biguanide molecule most commonly used for surgical antisepsis in it’s water soluble form, Chlorhexidine Gluconate (CHG). Chlorhexidine Gluconate’s anti-microbial profile is broad, ranging from a number of gram-positive and gram negative bacteria (excluding bacterial spores), as well as fungi. At low concentrations, CHG is bacteriostatic, causing potassium ions to leak from the bacterial cell, inhibiting growth. At high concentrations, CHG is bactericidal, causing bacterial cytoplasm to lose its structure, leading to cell death.
There has been some evidence that low concentration chlorhexidine (0.05%) in sterile water reduces postoperative infection rates, postoperative dehiscence rates, and seroma formation when used for loop ileostomy closure and reconstructive foot and ankle surgery. ,
For patients undergoing amputations, there is a crucial need to eradicate all infection during the primary amputation in order to prevent complications such as postoperative infections, and further surgeries. The primary aim was to compare use of chlorhexidine irrigation (0.05%) to normal saline irrigation in regard to postoperative infection, as defined by postoperative erythema and drainage, as well the need for secondary surgeries, such as repeat amputations. We hypothesized that patients who underwent intraoperative irrigation with chlorhexidine irrigation (0.05%) will see no difference in these findings in comparison to patients who underwent intraoperative irrigation with normal saline during their primary amputation. Additionally, we hypothesize that there will be no significant difference in positive postoperative cultures or pathology results between these two irrigation methods.
Methods
A longitudinal chart review study of all patients undergoing an amputation secondary to a diabetic foot ulceration from June 1, 2022 through June 30, 2024 was conducted. Surgical intervention performed by one single podiatrist during this time were followed. Patients were excluded from the study if primary surgery was staged, or if primary amputation required multiple procedures. Additionally, amputations in which the incision site was not fully closed at the time of the primary amputation were excluded. Patients who did not follow up for the ninety-day period of follow up needed for this study were excluded from this study. All elective foot and ankle procedures that could not be categorized as amputations (i.e. bone biopsy, exostectomies) were excluded from this study. 67 patients were included for analysis in this study.
In both groups the intraoperative process was similar, except in terms of the irrigation system used. Amputation was performed at a level that was predetermined by the patient and physician. Following this, the patient was either irrigated with normal saline or chlorhexidine solution. Solution was not approved for use at facility until September 2023; all patients before this date were irrigated with normal saline irrigation, and all patients afterwards were irrigated with chlorhexidine solution. After irrigation and suction, intraoperative cultures including aerobic, anaerobic, fungal and acid-fast bacilli were obtained as well as proximal margin for pathology results. After obtaining both of these, the surgical site was irrigated once more, however this time with normal saline, and final closure was performed.
Patients were followed for a minimum of ninety days after their primary amputation for post operative infections as defined by erythema that did not improve with leg elevation, and drainage. Surgical site dehiscence was noted if there was any separation of incision site as noted by primary surgeon’s notes post operatively. Secondary surgery was only noted if it was in relation to the primary surgery, and within the first ninety days of the primary surgery. Positive pathology results were defined as noting either acute or chronic osteomyelitis results. Positive cultures were defined as more than one microbe had growth on cultures after aerobic, anaerobic and fungal cultures were obtained intraoperatively.
Regression analysis was performed throughout this study comparing patients with normal saline irrigation versus patients with chlorhexidine irrigation. Statistical significance was set at 0.05.
Results
67 patients were included in this study. 41 patients underwent irrigation with CHG and 26 with normal saline. There was no difference in who was more likely to have CHG irrigation as opposed to NS irrigation in terms of gender or level of amputation ( Table 1 ).
Table 1
Demographics of patients enrolled in the study by type of irrigation product used intraoperatively.
|
CHG Irrigation
(n = 41) |
Normal Saline Irrigation
(n = 26) |
R-Value | p-value | |
|---|---|---|---|---|
| Age | 64.7 | 62.0 | ||
| Gender | ||||
|
Male
Female |
33 8 |
20 6 |
0.002 |
0.73 |
|
Type of intervention
Partial Digit Digital Partial Ray Transmetatarsal |
9 15 12 4 |
5 8 10 3 |
0.01 |
0.41 |
| Pathology Results | ||||
|
Negative for osteomyelitis
Positive for osteomyelitis |
25
16 |
12
14 |
0.006 | 0.24 |
| Culture Results | ||||
|
No growth
Growth |
8
33 |
6
20 |
0.002 | 0.73 |
| Post operative erythema | ||||
|
No
Yes |
36
5 |
20
6 |
0.02 | 0.25 |
| Post operative drainage | ||||
|
No
Yes |
26
15 |
17
9 |
0.0004 | 0.87 |
| Post operative dehiscence | ||||
|
No
Yes |
17
24 |
11
15 |
<0.005 | 0.95 |
| Need for secondary surgical intervention | ||||
|
No
Yes |
33
8 |
22
4 |
0.003 | 0.67 |
| Post Intervention Antbiotics | ||||
|
None
Oral IV |
11
20 10 |
9
15 2 |
0.002 | 0.29 |
Irrigation Method. The type of irrigation used, NS vs CHG, did not reduce post operative complications such as post operative erythema or post operative drainage. Patients who underwent CHG irrigation also saw similar rates of postoperative dehiscence rates, and need for secondary surgical interventions. In addition, there was no difference in rates of negative culture growth or negative pathology findings between the two groups.
Post operative erythema . Post operative erythemadeveloped in twelve patients in total, with six in each irrigation method used. Males were found to be more likely to develop post operative erythema in comparison to females. Comorbidities such as peripheral vascular disease, renal disease, cardiovascular disease, diabetes, and smoking history did not affect whether a patient was more likely to develop post operative erythema or not. Weightbearing status did not affect whether or not a patient would develop post operative erythema. Positive culture and pathology results were not associated with whether a patient would develop post operative erythema. ( Table 2 )
Table 2
Patient demographics of patients who developed post operative erythema by irrigation product used intraoperatively.
|
CHG Irrigation
N = 5 |
Normal Saline Irrigation
N = 6 |
R-value | p-value | |
|---|---|---|---|---|
| Age | 71.6 | 59.3 | ||
| Gender | ||||
|
Male
Female |
4
1 |
4
2 |
0.1 | 0.1 |
| Intervention Type | ||||
|
Partial Digit
Digit Partial Ray Transmetatarsal |
2
1 2 0 |
0
2 3 1 |
0.1 | 0.1 |
| Pathology Result | ||||
|
Negative
Positive |
4
2 |
3
3 |
0.01 | 0.8 |
| Culture Results | ||||
|
No growth
Positive Growth |
1
4 |
2
4 |
0.02 | 0.7 |
|
Post Intervention Antbiotics
None Oral IV |
1 2 2 |
3 2 1 |
0.1 |
0.3 |
| Weightbearing status | ||||
|
Non-WB
Partial WB WBAT |
2
0 3 |
5
0 1 |
0.2 | 0.2 |
| Diabetes | ||||
|
No
Yes |
1
4 |
0
6 |
0.1 | 0.3 |
|
Cardiac Comorbidities
No Yes |
1 4 |
0 6 |
0.04 |
0.09 |
|
Peripheral Vascular Disease
No Yes |
1 4 |
4 2 |
0.2 |
0.2 |
|
Renal Comorbidities
No Yes |
3 2 |
2 4 |
0.07 |
0.4 |
|
Smoking History
None Former Current |
3 2 0 |
4 1 1 |
0.005 |
0.8 |
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