Patients with diabetes are well known to the foot and ankle surgeon. A significant amount of time and effort has been dedicated to efforts to determine the pathomechanics of diabetes in relation to surgery. Even though there is more research to do, the data we have supports that patients with diabetes have a much higher risk of complications, including surgical site infection, in comparison to nondiabetics.

Patients with diabetes whose blood glucose levels regularly average above 200 mg/dl have a higher risk of surgical site infection [2]. In one study looking at cardiac surgery patients, they were able to control other comorbid conditions and concluded that blood glucose levels above 200 mg/dl had a significant risk of infection compared to patients with blood glucose levels below [2]. It is well known that poorly controlled diabetes leads to decreased phagocytosis and bactericidal activity of neutrophils. It has been shown that the threshold of proper neutrophil function is a blood glucose of less than 200 mg/dl [3].

There has been little research looking at surgical site infection in patients who have undergone foot and ankle surgery. One retrospective study looking at 1000 patients showed 2.8% of nondiabetic patients undergoing foot and ankle surgery developed infection compared to 13.2% in patients with diabetes [4]. Also in that study, the author concluded neuropathy as a factor in patients with diabetes developing an infection [4]. This finding is consistent with other research. Patients who do not have neuropathy likely do not have any more risk of infection than a nondiabetic patient [5].

It is our opinion that these patients also have other factors that are difficult to stratify. Oftentimes these patients are noncompliant with taking their medications, thus leading them down a path that includes neuropathy and other comorbid conditions associated with diabetes. If these patients are not compliant with managing their diabetes, one may question their ability to be compliant with instructions after surgery.

Renal disease is a condition that is often times associated with other comorbidities, such as diabetes, malnutrition, congestive heart failure, anemia, and coronary artery disease. These patients are inherently at risk of complications because they do not properly excrete toxins within the body, often times leading to an impaired immune response. Patients with renal disease are at significant risk of developing renal osteodystrophy, especially in those who are on dialysis. Renal osteodystrophy, also known as chronic kidney disease-mineral and bone disorder (CKD-MBD), causes malabsorption of calcium and phosphorous which leads to thinning of the bone and an increased risk of fracture [6]. It is known that patients with renal disease often times develop calcification of their arteries [7]. Because of this, the risk of wound healing complications significantly rises and makes it challenging for the foot and ankle or orthopedic surgeon to be able to properly manage these musculoskeletal problems in these patients [7]. Other potential causes of increased mortality and morbidity are elevated plasma homocysteine, enhanced coagulability, excess arterial calcification, and endothelial dysfunction [8].

Review of the literature demonstrates no available research looking at foot and ankle surgery and patients with chronic kidney disease. There is research looking at total knee and hip arthroplasty and chronic renal disease. All of these studies are consistent with an increased risk of morbidity/mortality [9]. In a study looking at more than 500 patients with chronic renal disease undergoing elective total joint procedures, there was found to be a significant increase in morbidity after surgery [10].

Current recommendations state that patients who are undergoing elective surgery and have chronic renal disease should receive hemodialysis the day before in order to minimize the adverse effects of fluid and electrolyte abnormalities [11]. The surgeon should weigh the risk of surgery when evaluating these patients.

One in five Americans are clinically obese [12]. Obesity is defined as a person with a BMI greater than or equal to 30. It has been reported that obesity will continue to significantly rise over the next 15 years [12]. Most surgeons would conclude that obese patients have a higher risk of complications. This idea, however, is not very well supported in the literature. It is thought that because obese patients have larger amounts of adipose tissue, there is a risk of loss of adherence of the skin to the underlying subcutaneous tissue and this could lead to an increased risk of wound dehiscence and risk of infection [13]. Most obese patients have other comorbid conditions such as diabetes, congestive heart failure, and coronary artery disease. It is because of these additional comorbid conditions that obese patients may have a higher risk of surgical complications.

There are few studies evaluating obesity and foot and ankle surgery. Most studies have looked at obesity and ankle fractures. Many have concluded that obese patients have a higher risk of a more severe fracture [14, 15]. One study compared patients with a BMI less than 30 and a BMI above or equal to 30 and determined that obese patients do not have a higher risk of infection or development of nonunions [15]. Therefore, the current literature does not necessarily support obesity alone as a risk factor for increased surgical complications.

Patients with protein and vitamin deficiencies are known to have increased risk of surgical complications [16]. It is believed that 50% of hospital patients are malnourished [16, 17]. Key laboratory markers include serum albumin, total lymphocyte count, and transferrin. Transferrin assists in decreasing inflammation as well as in impeding bacterial survival [18]. It has been shown that a transferrin of <226 mg/dL increases the rate of wound complications [19]. Lymphocytes are key to the body’s humoral and cell-mediated immunity. A decrease in total lymphocyte count below 1500/mm³ (1.5…109/L) increases the rate of infection [19]. Protein deficiency interferes with wound healing and humoral and cell-mediated immunity, thus lowering the host resistance and increasing risk of surgical site infection [20]. Serum albumin is one of the key markers used in assessment of nutritional status. Serum albumin of <3.5 g/dL indicates a nutritional deficiency and an increased risk of complications [16, 19]. Albumin, even though a good nutritional marker, also has limitations. It has a long half-life; therefore, it can take time to see the effects of any changes in diet [21]. Prealbumin is a better marker in identifying acute changes in protein because it reaches its peak at 2 days [21]. When evaluating the malnourished patient, a combination of all these markers should be utilized, and a proper consultation with a dietitian should be considered.

It is well know that osteoporosis leads to an increased incidence of fractures [22]. It is not well known if osteoporosis increases the risk of surgical complications [22]. Osteoporosis leads to thinning of the cortex and weakening of the bone. After surgical fixation of fractures or in patients undergoing elective orthopedic procedures such as osteotomies and arthrodesis, there is concern that there may be failure of fixation due to the compromised bone. There have been many biomechanical studies showing evidence that screw and plate fixation has an increased incidence of failure in compromised bone [22]. It has been more difficult to stratify this in real-world studies. The likely reasoning behind this is due to the significant amount of variables. These variables include poor testing or definition of osteoporosis, surgical technique (i.e., type of hardware), postoperative management, age, and additional comorbidities [22]. Thus, currently, there is no excellent literature that shows osteoporosis leads to complications, but one should be highly suspicious that it may be one of many factors that cause them.

Many patients undergoing surgery may be treated for multiple chronic conditions such as cardiovascular disease, hypertension, congestive heart failure, and chronic obstructive pulmonary disease. Most will have multiple comorbid conditions including diabetes and obesity. Patients with these conditions will oftentimes need preoperative workup such as basic lab work, CBC with differential, BMP, and INR. Additional studies such as chest X-ray, EKG, and stress test may need to be ordered, and the patient may need a referral to a specialist for surgical clearance. Most hospitals and surgery centers have set guidelines for preadmission testing that guide the evaluation of the patient and aid in determination of the appropriate tests and referrals.

Little research has been published looking at chronic conditions and their association with complications in regard to foot and ankle surgery. One study, looking at general orthopedics and the rate of mortality in inpatients, showed a 0.92% mortality [23]. Seventy-seven percent of all deaths occurred in patients more than 70 years old, and 50% of all deaths occurred in patients undergoing surgical management of hip fractures [23]. Medical risk factors associated with death included chronic renal failure, congestive heart failure, metastasis of the bone, atrial fibrillation, chronic obstructive pulmonary disease, and osteomyelitis [23]. Risk factors of diabetes, coronary artery disease, peripheral vascular disease, septic arthritis, and rheumatoid arthritis did not achieve significance [23]. In our opinion, even though there is little research in regard to chronic conditions and foot and ankle surgery, it is still important to be aware of your patient’s medical conditions and risk of problems. When appropriate, consult with other medical professionals so that these patients receive optimal medical management and the risk of surgical complications can be minimized.

Patients with autoimmune diseases, particularly rheumatoid arthritis (RA), have been reported to have an increased incidence of postoperative complications, though the existing literature is inconsistent. These complications include surgical site infections (SSI), wound healing, delayed or nonunion of arthrodesis procedures, deep venous thrombosis (DVT), and RA disease flare. The potential for an increased risk of postoperative complications is multifactorial, due in part to the disease process and potentially accentuated by the medical treatment of the disease. The disease process in patients with rheumatoid and other forms of reactive arthritis results in changes in steroidogenesis , leading to low levels of cortisol and other adrenal hormones. The effect of this hormonal alteration is perpetuation of inflammation and other immunomodulating effects [24]. Alternative research suggests the possibility of inherited collagen variants that could predispose to osteoporosis and impaired wound healing [25]. Agents used in the treatment and modulation of the RA such as steroids, methotrexate, and tumor necrosis factor-alpha (TNF-alpha) inhibitory agents have immunosuppressive effects and have been thought to increase the risk of infections and healing complications in those patients under active treatment [26–28]. Additionally, patients with RA often present with polyarticular foot and ankle deformities that require multiple procedures in order to achieve an improved function and to allow the patient to maintain ambulation without significant pain. Approximately 90% of adults with chronic RA will have forefoot degeneration and/or deformity, 58–72% will have hindfoot involvement, and many will have ankle involvement [29].

It has been noted by many that patients with RA have a higher baseline risk for surgical complications [28, 30]. In a population-based, age- and sex-matched retrospective review of 609 RA and 609 non-RA subjects over a 39-year time frame from 1955 to 1994, Doran et al. [28] found that surgical patients with RA are at twice the risk of developing an infection , an infection compared to non-RA surgical patients. They found the sites of infection with the highest risk ratio were bone, joints, skin, and soft tissues. However, there are many case series showing minimal or modest surgical risks associated with RA and the drugs used to treat the disease.

Grennan et al. [25] performed a prospective randomized study of patients with RA undergoing elective orthopedic surgery to determine the incidence of postoperative infection and surgical complications within 1 year of surgery. Three hundred eighty-eight patients were divided into three cohorts: the first is consisting of 88 patients who were receiving methotrexate and continued this in the perioperative period, the second group of 72 patients had been receiving methotrexate but discontinued this 2 weeks prior to surgery until 2 weeks postoperative, and these were compared to the third group of 288 patients with RA who were not receiving methotrexate. The results showed that patients receiving methotrexate did not have an increased risk of infection or complications after elective orthopedic surgery. Other researchers have found similar results with no significant increase in complications with perioperative continuation of methotrexate in orthopedic surgery [30–33].

Another group of RA medications that are becoming more commonly seen are the biologic antitumor necrosis factor class of disease-modifying drugs. Several researchers have evaluated the incidence of postoperative complications in orthopedic surgery when anti-TNF-alpha agents were continued perioperatively. One foot and ankle-specific study [34] found that if looking at infection and healing complications independently, the TNF-alpha inhibition group did not have a significant increase compared to the group that was not receiving treatment. However, the TNF-alpha inhibition group did show a statistically higher overall complication rate (p = 0.33). Others [35–37] have found that continuation of anti-TNF-alpha agents did not result in a significant increase in postoperative infection rates overall. However, there is also work to support that hypothesis that continuation of anti-TNF-alpha agents does increase the incidence of postoperative infections in orthopedic surgery [38].

A systematic review and meta-analysis [39] of the literature on the perioperative management of RA treatment with respect to medication continuation or discontinuation that included 27 studies, with 5268 patients and 7933 surgeries, found that the most studied drug was methotrexate. Their recommendation was that methotrexate should be continued in the perioperative period in the absence of other risk factors that would increase the likelihood of complications (level of evidence 1c, grade D recommendation) and that biological DMARDs such as anti-TNF-alpha agents should be temporarily suspended or the surgery should be scheduled as far as possible from the last dose (level of evidence 2c, grade D recommendation).