SLR - January 2015 - Sam Gervais

Neuropathy and Poorly Controlled Diabetes Increase the Rate of Surgical Site Infection after Foot and Ankle Surgery

Reference: Wukich DK, Crim BE, Frykberg RG, Rosario BL. Neuropathy and Poorly Controlled Diabetes Increase the Rate of Surgical Site Infection after Foot and Ankle Surgery. J Bone Joint Surg Am. 2014 May 21;96(10): 832-839.

Scientific Literature Review

Reviewed By: Sam Gervais, DPM
Residency Program: HealthPartners Institute for Education and Research, St. Paul, MN

Podiatric Relevance: Diabetes mellitus affects millions of Americans and the prevalence of the disease continues to increase. A significant percentage of the podiatric surgeon’s patient population is comprised of diabetics and special considerations must be given in regard to surgical management of these patients. Diabetic patients often present with comorbidities such as peripheral neuropathy, Charcot neuroarthropathy, peripheral arterial disease, and ulcerations that can complicate the clinical picture and lead to complications postoperatively. Studies have demonstrated that there is an increased incidence of infection after foot and ankle surgery in patients with complicated diabetes in comparison to patients with uncomplicated diabetes and patients without diabetes. This prospective study validated the results of prior studies. In addition, this study demonstrated that peripheral neuropathy and an HbA1c ≥8 percent were independently associated with surgical site infection.

Methods: Patients >18 years of age who underwent foot/ankle surgery with open incision from 2008 to 2011 were enrolled in this prospective study. Exclusion criteria included patients with infected wounds or prior amputations. Four patient groups were defined. Group 1 included nondiabetic patients without peripheral neuropathy (n=1536). Group 2 included nondiabetic patients with peripheral neuropathy (n=201). Group 3 included patients with diabetes but no complications (n=100). Group 4 included diabetic patients with at least one complication (n=223). Complications include neuropathy, peripheral artery disease, and/or renal disease. Peripheral neuropathy was defined as Michigan Neuropathy Screening Instrument score of ≥2.5. Patients with abnormal vascular physical exam findings underwent noninvasive arterial studies and PAD was defined according to published guidelines. The absence of renal disease was confirmed with serum creatinine levels <1.4 mg/dL. Patients with diabetes or peripheral neuropathy without a history of diabetes had HbA1c levels within one month of surgery. Nondiabetic patients without neuropathy who had a random glucose level of >126 mg/dL had a HbA1c level and fasting blood glucose level drawn morning of surgery. Glycemic control was evaluated using HbA1c and blood glucose values of 8.0 percent and 140 mg/dL, respectively. All surgeries were performed by a single surgeon. Standard appointments were scheduled for one, three, six, and twelve weeks postoperatively.

Results: 2060 patients were included in results of this study. Diabetic patients with complications had higher occurrence of Charcot neuroarthropathy as compared to nondiabetic patients with peripheral neuropathy (41.7 percent vs 10.9 percent, p<0.05). Patients with complicated or uncomplicated diabetes had significantly higher levels of serum glucose and HbA1c than patients without diabetes. Overall, there was a 3.1 percent infection rate. 4.6 percent of patients with diabetes developed a mild infection compared with 1.7 percent of patients without diabetes (p<0.05 percent). 3.4 percent of patients with diabetes developed a severe infection compared to 0.5 percent in patients without diabetes (p<0.05 percent). Patients with complicated diabetes had a 7.25-fold increased risk of surgical site infection compared with nondiabetic patients without neuropathy and a 3.72-fold increased risk of surgical site infection compared with diabetic patients without complications. Nondiabetic patients with peripheral neuropathy had a 4.72-fold increased risk of surgical site infection compared to nondiabetic patients without neuropathy. Diabetic patients with a fasting blood glucose level ≥140 mg/dL on the morning of surgery had a 3-fold increased risk of developing surgical site infection compared with patients whose serum blood glucose was ≤140 mg/dL. Diabetic patients with an HbA1c ≥8 percent were 2.5 times more likely to develop a surgical site infection that patients whose HbA1c was <8 percent.

Conclusion: This study confirms previous findings that complicated diabetes increases the risk of surgical site infection compared to patients without complicated diabetes and patients with nondiabetic neuropathy. This study also demonstrated that peripheral neuropathy, even in the absence of diabetes, increased the risk of surgical site infection. Additionally, the importance of long term glycemic management of diabetic patients is critical in decreasing the risk of surgical site infection. The authors have modified their practice by delaying elective surgery in diabetic patients until they achieve HbA1c levels below 8 percent. The podiatric surgeon must be aware of risk factors that increase the risk of postoperative infection and must attempt to optimize patients preoperatively

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