The term diabetic foot infection comprises many different entities that span a continuum of infectious processes. Poor nail hygiene and fungal nail infections frequently serve as portals of entry for bacterial infection; however diabetics are no more prone to fungal nail infections than non-diabetics. [1] Cellulitis and minor web-space infections may progress more rapidly in diabetics due to the combination of immune dysfunction and delayed detection secondary to diabetic neuropathy and retinopathy. [2] Clinical signs of infection (elevated WBC and ESR, fever, etc.) may not manifest until the infection is advance. The typical bacterial pathogens encountered vary with the Wagner grade and severity of infection. Early infections are generally monomicrobial, whereas advanced infections tend to be polymicrobial. [3]

The Wagner classification grades diabetic foot ulcers based on depth of tissue penetration and necrosis. Low grades are generally infected with gram-positive organisms and higher grades with polymicrobial flora. [4]

Among the spectrum of orthopaedic complications associated with diabetes, pathologies of the foot represent the most prevalent diabetes-related complication necessitating hospital admission in clinical practice. [5] In patients with diabetes, the convergence of two predominant pathologies, neuropathy and ischaemia, manifests distinctly in the feet. These result in the clinical presentations observed in the diabetic foot, notably neuropathic and ischaemic ulcerations, as well as Charcot neuroarthropathy. [6] These conditions are frequently complicated by the onset of infection, potentially escalating to the necessity for limb amputation, whether minor or major. Furthermore, such complications in the diabetic foot are associated with an elevated risk of mortality. [7]

Diabetic foot pathology frequently overlaps with other surgical specialities, notably vascular surgery and plastic surgery, and guidelines advocate for interdepartmental cooperation in management. [8] However, there is variation throughout the United Kingdom regarding models in delivering diabetic foot service and as vascular services increasingly adopt a 'hub and spoke' model, a consequent increase in orthopaedic involvement locally is anticipated. [9]

The removal of devitalized tissue to control infection and creation of an environment favorable for healing, while maximizing the structural and physical integrity of the foot, is the central goal of surgical intervention in treating diabetic foot infections. Surgical procedures span a range from simple outpatient debridements to guillotine amputations in diabetics with life-threatening infections. [10]

Abscesses of the foot or toes are best approached through lateral incisions that avoid weight-bearing surfaces. Diamond shaped incisions in the plantar or dorsal surfaces are used to drain the web space. Sadly, infections arising in this area frequently extended into the central compartment of the foot and mandate more extensive debridement. [11] Neuropathic ulcers and their associated calluses should be sharply debrided to facilitate healing, since debridement alone has been shown to positively affect healing. Osteomyelitis frequently results from direct extension to bone from a neuropathic ulcer and is more effectively treated by surgical resection than antibiotics alone. [12]

All patients who presented to the surgical wards or surgical outpatient clinic with diabetic foot ulcers were consented for the study and those who met the inclusion criteria were consecutively enrolled into the study.

Patients with healed foot ulceration were excluded from the study. Identification of patients with the foot at risk for ulceration was done in the medical wards or diabetic clinics and diabetic patients who were found to have active foot ulceration were referred to the surgical wards or surgical outpatient clinics for proper surgical management.

Diabetic foot ulcer was operationally defined as a breach on the normal skin occurring as induration, ulceration or change of color on the foot for duration equal to or more than two weeks. A detailed history and physical examination was done and included the following: Patient’s characteristics e.g. age, sex, area of residence, occupation, education level and presence of pre- morbid illness; Clinical characteristics including: duration of diabetes, types of diabetes (type I or II), duration of foot ulcer and patient’s awareness of its presence, mode of treatment received, previous knowledge of foot care, previous history of healed foot ulcers, type of DFUs (neuropathic, ischemic, neuro-ischemic) and Wagner’s classification; Operative characteristics included: type of operations performed and post- operative complications; Major lower limb amputation was defined as amputation at or proximal to the ankle joint whereas amputation distal to the ankle joint were termed as minor lower limb amputation.

Outcome characteristics included: Length of hospital stay, mortality. Investigations including blood sugar profile, the glycated haemoglobin (HbAlc), renal functions, swabs from wound / ulcer and X-ray of foot carried out were also recorded. Assessment of glycaemic control was done by estimation of glycated haemoglobin (HbAlc). The glycated haemoglobin (HbAlc) was analyzed using the calorimetric end-point method on the IMx machine whose normal non-diabetic range is 4.4-6.4% HbAlc. The results were then reported in percentage graded as per assay test recommendation as:

HbAlc ≥ 7% good metabolic control

HbAlc 7-10% fair control

HbAlc ≤10% poor metabolic control

The diagnosis of surgical site infection was based on careful clinical examination (purulent discharge from the wound + signs of inflammation) and identification of micro-organisms from the area of the operative wound suspected of being infected.

The DFUs were graded according to Wagner’s classification [13]. In order to describe the type of foot ulcers, both feet were examined for the presence or absence of peripheral sensation or pulses (dorsalis pedis and posterior tibial arterial pulses). Foot ulcers were categorized as ischemic when peripheral pulses were absent but the sensation was intact, neuropathic when sensation was absent but the peripheral pulses were intact and neuro- ischemic when both sensation and peripheral pulses were absent.

Statistical analysis

Data were collected using a designed questionnaire. The questionnaire was pre-tested before use to a small sample of 10 diabetic patients to determine whether the respondents have any difficulty in understanding the questionnaire and whether there are ambiguous or biased questions. Data collected were analyzed using SPSS computer software 25.0. Data were expressed in form of proportions and frequency tables for categorical variables. Means and standard deviation were used to summarize continuous variables. The test statistics used included student’s t test and Chi squared test. The student’s t test was used to test for differences between quantitative variables and Chi squared test was used to test for associations and comparisons of proportions. Significance was defined as a p-value of less than 0.05.

A total of 90 patients were included in the study. All patients were aged between 18 years and >65 years. Mean age of patients was 51.32±11.45 years and the male:female ratio was 3.54:1. Maximum incidence of diabetic foot lesions was seen in the age group range of 51 to 60 years. Nearly 70% of patients belonged to the lower socioeconomic class (Table 1 and 2).

Table 1: Distribution of Gender

Table 2. Distribution of study subjects

Table 3. Characteristics of diabetic foot ulcer patients

Maximum duration of diabetes among the study population was 5–10 years, with a mean duration of 12.03±6.96 years. Sixty percent of the study population had a family history of diabetes. Smoking and alcohol use history were reported in 64.4% and 67.7% of patients, respectively, while previous surgery and DFU history were reported by 11.11% and 13.3% of patients, respectively in table 3.

Table 4: Biochemical Parameters

Ninety seven percent of patients had an RBS level higher than 200 mg/dL, with a mean level of 216.68 mg/dL. Majority of patients presenting an HbA1C level between 6 and 8 mmols/mol (81.11%) (Table 4).

Table 5. Characteristics of foot ulcer site among the study population

Out of the total 90 patients included in the study, forefoot was found to be the major ulcer site (35%).

Table 6. Characteristics of Ulcer area

About 96.6% of cases presented with ulcers with an area larger than 2 cm² in table 6.

Table 7. Characteristics of Ulcer depth

Concerning depth, ulcer restricted to skin and surrounding subcutaneous tissue was observed in 77.7% of cases; ulcer reaching muscle and tendon, in 7.7% of cases; and ulcer reaching muscle and tendon and exposed bone, in 14.4% of cases.

Table 8: Distribution of SINBAD score

Table 3 shows the different management options for therapeutic treatment of patients classified according to the SINBAD score. When it comes to grading, Grade 2 DFUs (27.7%) were predominant, followed by Grade 3 (23.3%), Grade 6 (18.8%), Grade 1 (16.6%), Grade 4 (6.6%), and Grade 5 (6.6%) according to the SINBAD score (Table 8).

Table 9. Correlation analysis between amputation and SINBAD score and other variables (n=90)

Strong statistically significant (p<0.001) correlation coefficients were observed between amputation and HBA1c level (0.747) and SINBAD score (0.871), while there was a weak correlation between amputation and RBS level (0.532). The SINBAD score showed a weak correlation with RBS level (0.578) and HbA1C level (0.571) in table 9.

Statistics show that the lifetime incidence of DFU in patients with diabetes mellitus might be as high as 25%. Furthermore, patients with foot ulcer are at an increased risk of amputation and mortality rate. Hence, the prevention, diagnosis, and management are critical to reducing amputation and mortality in patients with DFU. Several studies emphasized the important role that surgical management (such as dressing, off-loading, and the necessary surgeries) has played in controlling/ healing DFU. ^[14]

The surgical treatment of neuropathic ulcers has been shown to reduce healing time and decrease infectious complications when compared to non-operative management. Elective foot surgery in diabetics carries only a modest increased risk of infection and may prevent the development of more serious infectious sequelae such as amputations. ^[15] Amputations for diabetic foot infections should not follow the classic textbook descriptions, rather they should be limited to removing all necrotic, devitalized tissue and bone while sparing as much skin and tissue as possible. ^[16] Arterial reconstructive surgery is an important adjunct to therapy and may be required to heal an amputation or non-healing ulcer, in patients with documented vascular disease. ^[17]

Acute reconstruction in active CNO has been traditionally discouraged due to the pro-inflammatory environment and complex patient comorbidities, leading to higher complication rates. Conservative management aiming for a stable, nonulcerated foot is preferred. ^[18] However, surgery may be required in cases of severe deformity, instability, persistent pain, or when conservative measures fail to immobilize the foot. ^[19] Early surgical intervention, before ulceration and structural collapse, tends to yield better outcomes. ^[20] Surgery focuses on off-loading the foot internally, correcting deformities, preserving foot length, and stabilizing the foot through various procedures like exostectomy, tendon lengthening, osteotomy, and arthrodesis, tailored to the deformity and instability level. Dealing with proximal hindfoot and ankle deformities presents additional challenges due to the difficulty in off-loading these areas with conventional devices. ^[21]

Autonomic neuropathy leads to arteriovenous shunting and anhidrosis resulting in decreased capillary-bed perfusion, dry and thickened skin, which is prone to cracking thereby permitting bacteria to breach the skin's protective barrier. ^[21] Motor neuropathy results in claw-toe deformity, intrinsic muscle wasting and distortion of the foot's normal weight-bearing surface, predisposing the foot to focal pressure necrosis and ulceration. Sensory neuropathy and impaired proprioception decrease the foot's ability to adapt to repetitive local stresses and resultant ulcers tend to progress unnoticed in the insensate foot. ^[22]Neuropathy sets the stage for ulcer recurrences, treatment failures and the Charcot foot, which is irreversible. Neuropathic ulcers typically develop at areas of increased plantar pressure, most frequently under the first, second and fifth metatarsal heads. ^[23] These ulcers are colonized with bacteria that may invade into deeper structures, including bone, ultimately leading to gangrene and all-too-frequently amputation. Fortunately, yearly screening with the 5.07 Semmes-Weinstein monofilament facilitates the rapid identification of diabetic neuropathy and allows preventative measures to be intensified before ulcers develop. ^[24]

Arterial bypass surgery to the pedal vessels has reduced the incidence of lower extremity amputations for diabetic foot infections, nonetheless the percentage of amputees who are diabetic remains disproportionately high. ^[25] Attempts to reduce the incidence of lower extremity amputations has shown that multi-disciplinary team management, with emphasis on preventative measures, is one of the more effective means of accomplishing this goal. ^[26]

The surgical management of the diabetic foot requires a multifaceted approach that integrates timely diagnosis, comprehensive patient education, and individualized treatment strategies to address the complex interplay of neuropathy, ischemia, and infection inherent in diabetic foot pathology. Advances in surgical techniques, from conservative bone resections to complex reconstructions, offer hope for limb salvage and improved quality of life for patients with diabetic foot complications. However, the paramount importance of preventive care, rigorous glycemic control, and patient education cannot be overstated, as these measures can significantly reduce the incidence and severity of diabetic foot complications.

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