Diabetic Foot Ulcer Classifications: The Wagner Scale and the UT System

Diabetic foot ulcers (DFUs) occur in approximately 15% of patients with diabetes, and as of 2019, 37.3 million people in the U.S. have been diagnosed with diabetes. Prevalence like this calls for a relevant classification system.

DFU classification systems allow wound care clinicians to adequately assess and classify the stage and grade of diabetic foot ulcers. In turn, these systems guide clinicians in selecting the most appropriate course of treatment based on the grade or stage of the ulcer. Currently, there are several diabetic wound classification systems that exist. But how do you choose which one to use? This decision generally involves a combination of the clinician’s and organizational policy.

Here, we offer two wound care specialists’ overviews of two systems for DFU classification: The Wagner Scale and the University of Texas (UT) Diabetic Wound Classification System.

“I use the Wagner Scale in my office,” said Pam Sabet, DPM, a podiatrist who specializes in wound care in the Department of Wound Care and Hyperbaric Medicine at UC San Diego Health in San Diego. “It’s widely accepted, simple to use, and easy to understand across the board.”

According to Sabet, one drawback to the Wagner Scale is that it doesn’t describe infected or ischemic wounds. Despite this, she documents extensively (in her clinical notes) any infected and/or ischemic wounds.

Mariam Botros, DPM, AACFAS, a podiatrist in the Podiatry, Wound Healing, and Hyperbaric Oxygen Center with MemorialCare at Long Beach Medical Center in Long Beach, California, uses the UT system in her daily practice.

Botros studied podiatry at the Western University of Health Sciences in Pomona, California, under Lawrence B. Harkless, DPM, one of the creators of the UT Diabetic Wound Classification System. She learned the UT system in podiatry school.

One purpose of using a specific system to accurately diagnose and stage DFUs is to guide medical treatment. “It’s important for clinicians to back up their thought process regarding what they found during the physical exam and determine the progression or regression of a wound or wounds,” said Botros.

Another function for accurate DFU diagnosis is to determine if other disciplines are needed for the patient. “Your diagnosis may result in one or more referrals to another specialist of the healthcare team,” she said. “One example? Sending a patient for further evaluation for a vascular consult and possible vascular studies.”

Accurate staging is also needed for insurance purposes, said Sabet, who is an associate clinical professor at the University of California San Diego School of Medicine’s Department of Orthopedic Surgery.

Overview of the Wagner Scale

Sabet pointed out that the Wagner Scale assesses ulcer depth and the presence of osteomyelitis or gangrene by using the following grades:

• Wagner Grade 0: Skin is intact with no open lesion or a pre-ulcerative lesion — may have a deformity or cellulitis
• Wagner Grade 1: Partial- or full-thickness ulcer (superficial ulcer)
• Wagner Grade 2: Deep ulcer extended to ligament, tendon, joint capsule, bone, or deep fascia without abscess or osteomyelitis (OM)
• Wagner Grade 3: Deep abscess, OM, or joint sepsis
• Wagner Grade 4: Partial-foot gangrene
• Wagner Grade 5: Whole-foot gangrene

Overview of the UT Diabetic Wound Classification System

The grades of the UT system include:

• Grade 0: Pre- or post-ulcerative site (epithelialized wound)
• Grade 1: Superficial wound, not involving tendon, capsule, or bone
• Grade 2: Wound is penetrating to tendon or capsule
• Grade 3: Wound is penetrating bone or joint

There are four stages within each wound grade:

• Stage A: Clean wounds (no infection, no ischemia)
• Stage B: Nonischemic, infected wounds
• Stage C: Ischemic, noninfected wounds
• Stage D: Ischemic and infected wounds (both present)

The UT grading system, however, is more descriptive than the Wagner Scale, said Sabet. “It assesses ulcer depth, combines grade and stage, assesses the presence of wound infection and clinical signs of lower-extremity ischemia, and shows a greater association with increased risk of amputation and prediction of ulcer healing when compared with the Wagner system, based on several studies.”

In addition, the UT system uses a matrix of grade on the horizontal axis and stage on the vertical axis, Sabet added.

How assessment of DFUs determines treatment

Various factors for each wound contribute to clinical decision-making when it comes to the selection of specific treatments, according to Sabet. That’s why it’s essential to understand how certain physical characteristics guide your choice in treatment methods.

10 wound characteristics you’ll want to consider include:

1. Wound size
2. Wound depth
3. Wound base appearance
4. Presence of sinus tracts
5. Probe to bone
6. Amount of granular versus fibrotic or dysvascular tissue
7. Drainage
8. Signs of infection
9. Evaluation of exposed structures such as tendon and bone
10. Vascular component

Sabet emphasized the importance of evaluating for vascular and arterial disease. “This is an [essential] component to treating diabetic foot ulcers.”

It’s also imperative to check for signs of infection. This can include clinical indicators such as erythema, edema, pain, tenderness, and warmth, added Sabet.

When clinical infection is suspected, cultures are taken from the wound. This can be useful in determining the appropriate antibiotic therapy. “Although the most frequent infections are due to aerobic Gram-positive cocci and aerobic Gram-negative organisms, anaerobic organisms are often isolated,” she said.

Clinically uninfected ulcers should not be cultured, as the recovered organisms will contain only colonizing flora. “Empirical antibiotic therapy should be started and revised, if necessary, once culture results are obtained,” she added.

Wounds that are staged as a Wagner Grade 3 or higher that have failed conventional wound care for 30 days can be referred for hyperbaric medicine consultation, Sabet said. However, if infection is present in the bone, IV antibiotics, surgical debridement, or amputation might be necessary.

Regarding patient outcomes, Botros stated the greater the stage, the higher the risk of bone involvement. “The higher the stage, combined with the presence of infection and/or ischemia, the higher the risk of amputation,” Sabet added.

The goal with any wound is to heal quickly and effectively. But with diabetic foot ulcers, this can be a challenge. Whether you use the Wagner Scale or the UT grading system, classification systems like these can help guide you in choosing the most effective treatment method to give your patients the best outcomes.

Editor’s Note: This post was originally published in August 2021 and has been updated with new content.