Wagner Grade Classification for Diabetic Foot Wounds: Why It Matters for HBOT

If you’re a diabetic patient seeking HBOT coverage through Medicare, you’ll hear about Wagner grades quickly. Medicare requires a Wagner Grade III or higher before it will consider HBOT for diabetic lower-extremity wounds. Understanding what that means — and how wounds get graded — helps you have better conversations with your care team.

The Wagner Scale: 0 Through 5

The Wagner Wound Classification was developed by Meggitt in 1976 and later popularized by Wagner in 1981. It’s a six-grade system based on wound depth and the presence of infection or gangrene.

Grade 0: No open wound. The foot has risk factors — calluses, bony deformity, neuropathy — but the skin is intact. The focus at Grade 0 is prevention.

Grade I: A superficial wound. The skin is open, but the wound doesn’t extend into deeper tissue structures. No infection. No tendon, joint, or bone involvement.

Grade II: A deep wound reaching tendon, joint capsule, or bone without osteomyelitis. The wound has penetrated through the dermal layers into deeper structures. Still no confirmed bone infection at this stage.

Grade III: A deep wound with osteomyelitis (bone infection), abscess, or infected tendon. This is the Medicare threshold for HBOT. At this depth, standard wound care alone has poor outcomes. Bone infection dramatically reduces the wound’s ability to heal without additional intervention.

Grade IV: Forefoot gangrene. Part of the forefoot (toes, ball of the foot) shows tissue death, but gangrene is localized.

Grade V: Full-foot gangrene. Widespread tissue death across the foot. Typically requires major amputation.

Why Medicare Draws the Line at Grade III

The reasoning is evidence-based. Grade I and II wounds, while serious, often heal with standard wound care — proper offloading, debridement, dressings, and blood glucose control. Adding HBOT at those grades has not consistently shown benefit over standard care alone.

Grade III changes the equation. Osteomyelitis means bone infection. The bone is poorly vascularized to begin with in diabetic patients. High-pressure oxygen can penetrate compromised tissue in ways that topical and systemic treatments can’t. HBOT’s bactericidal effects (high oxygen is toxic to anaerobic bacteria) and its support of angiogenesis are most valuable when the wound is this deep.

Beyond the grade itself, Medicare also requires documentation that 30 days of standard wound care has failed to produce adequate healing before HBOT will be approved.

How Wounds Are Graded

Your wound care physician grades the wound through clinical exam. The key question is depth: how far down does the wound go?

One bedside test for bone involvement is probe-to-bone testing. A sterile probe is inserted into the wound. If the probe reaches hard, gritty bone at the base of the wound, the IWGDF (International Working Group on the Diabetic Foot) considers this strongly predictive of osteomyelitis. This simple test has high positive predictive value.

Imaging is also used. X-ray can show late-stage bone destruction. MRI is more sensitive and can detect early osteomyelitis before it’s visible on X-ray. If bone involvement is suspected clinically, your care team will order imaging.

You don’t grade your own wound. Your physician does. Don’t arrive at a hyperbaric consultation claiming a specific grade — let the wound care team evaluate and document it.

TcPO2 Testing and HBOT Candidacy

Beyond Wagner grade, many hyperbaric programs use transcutaneous oxygen measurement (TcPO2 or TCOM testing) to assess whether a patient is a good HBOT candidate.

TcPO2 measures the oxygen tension at the skin surface over the wound area. Normal values are above 40 mmHg. Values below 40 mmHg suggest tissue hypoxia — the wound bed isn’t getting enough oxygen, which is what HBOT addresses.

A TcPO2 test breathing room air shows baseline tissue oxygen. The test is often repeated while the patient breathes 100% oxygen or while in a mild hyperbaric environment. If TcPO2 rises significantly with oxygen breathing, that’s a positive predictive sign for HBOT response.

If TcPO2 doesn’t rise with oxygen challenge, that may indicate irreversible vascular damage. HBOT is unlikely to help in that situation, and your physician may not recommend it.

After HBOT Is Approved

HBOT is an adjunct to wound care. Not a replacement. Throughout your HBOT course, you’ll continue standard wound care: debridement, dressings, offloading (keeping pressure off the wound), and blood glucose management. HBOT improves the environment for healing. The wound still needs direct care.

Your wound should be reassessed during the HBOT course. If adequate healing progress isn’t occurring despite HBOT, your care team will reassess the plan. HBOT isn’t continued indefinitely without signs of response.

FAQ

Q: What Wagner grade is required for HBOT coverage? Medicare requires Grade III or higher, plus 30 days of failed standard wound care.

Q: What is Grade III? A deep wound with osteomyelitis, abscess, or infected tendon. Bone infection is the key distinction from Grade II.

Q: How is a wound graded? By a wound care physician through clinical exam, probe-to-bone testing, and imaging. Patients don’t self-grade.

Q: What is TcPO2 testing? A tissue oxygen test that measures how much oxygen is reaching the wound area. Low values confirm hypoxia that HBOT targets. Rising values during oxygen breathing predict a good HBOT response.

Related: Diabetic Wounds and HBOT | Insurance Coverage for HBOT | Medicare HBOT Conditions

Medical Disclaimer: This content is for informational purposes only and does not constitute medical advice. Wound grading and HBOT candidacy require evaluation by a licensed physician. Always consult your care team about your specific wound and treatment options. This site does not establish a doctor-patient relationship.