5.1 Wound Classification & Staging
Key Takeaways
- Pressure injuries are staged 1-4 by depth of visible tissue loss; Unstageable wounds are obscured by slough or eschar and Deep Tissue Injury (DTI) presents as intact maroon or purple discoloration.
- The Wagner classification grades diabetic foot ulcers 0 through 5, where Grade 0 is intact at-risk skin and Grade 5 is gangrene of the whole foot requiring amputation referral.
- Arterial ulcers sit on distal toes with punched-out edges, pale wound beds, severe pain, diminished pulses, and an Ankle-Brachial Index (ABI) below 0.9.
- Venous ulcers appear in the medial gaiter area with irregular borders, heavy drainage, hemosiderin staining, and pulses that are usually present.
- A Braden Scale score of 18 or lower flags the patient as at risk for pressure injury and should trigger turning schedules and surface upgrades within the plan of care.
Why Wound Staging Matters For The PTA
The Physical Therapist (PT) performs the initial wound evaluation, sets the wound diagnosis, and writes the plan of care. The Physical Therapist Assistant (PTA) then implements positioning, off-loading, dressing changes, and exercise inside that plan and reports any change in wound status back to the supervising PT. On the National Physical Therapy Examination for Physical Therapist Assistants (NPTE-PTA), Integumentary items hover in the 3-8 question range, and most of them turn on the candidate recognizing a stage, grade, or ulcer pattern from a short scenario.
Pressure Injury Stages
The National Pressure Injury Advisory Panel (NPIAP) staging system describes how deep the visible tissue damage goes. A stage never decreases when the wound heals — a healing Stage 4 becomes a healing Stage 4, not a Stage 2.
| Stage | Skin Integrity | Depth | PTA Picture |
|---|---|---|---|
| Stage 1 | Intact | Non-blanchable erythema | Warm, painful red area over a bony prominence that does not blanch when pressed |
| Stage 2 | Broken | Partial-thickness dermal loss | Shallow open wound or intact serum-filled blister; pink-red base, no slough |
| Stage 3 | Broken | Full-thickness skin loss | Subcutaneous fat visible; possible slough, undermining, or tunneling; no exposed muscle or bone |
| Stage 4 | Broken | Full-thickness with exposed structure | Visible muscle, tendon, ligament, cartilage, or bone; often slough or eschar at edges |
| Unstageable | Broken | Depth obscured | Slough or eschar covers enough of the base that true depth cannot be determined |
| Deep Tissue Injury (DTI) | Intact or blistered | Suspected deep damage | Persistent maroon, purple, or blood-filled blister over a bony prominence |
Wagner Classification For Diabetic Foot Ulcers
When a stem mentions a person with diabetes and a plantar or toe lesion, expect Wagner.
- Grade 0 — Intact skin on a high-risk foot (callus, deformity, prior ulcer)
- Grade 1 — Superficial ulcer, no subcutaneous involvement
- Grade 2 — Deeper ulcer into tendon, capsule, or bone but no abscess or osteomyelitis
- Grade 3 — Deep ulcer with abscess, osteomyelitis, or joint sepsis
- Grade 4 — Localized gangrene (forefoot or heel)
- Grade 5 — Gangrene of the whole foot; surgical referral, PTA defers further local interventions
Differentiating Lower-Extremity Ulcers
Most NPTE-PTA wound items hinge on telling three lower-extremity ulcers apart.
| Feature | Arterial | Venous | Neuropathic (Diabetic) |
|---|---|---|---|
| Typical location | Distal toes, lateral malleolus, dorsum of foot | Medial gaiter region above the medial malleolus | Plantar surface under metatarsal heads or great toe |
| Wound bed | Pale, dry, punched-out | Ruddy red, irregular, wet | Pale or pink, often with surrounding callus |
| Pain | Severe, worse with elevation, relieved by dangling | Mild ache, relieved by elevation | Often painless due to neuropathy |
| Pulses | Diminished or absent | Usually present | Variable; check carefully |
| Ankle-Brachial Index (ABI) | Below 0.9 indicates arterial disease | Usually normal | May be falsely elevated above 1.3 from calcified vessels |
| Edema | Minimal | Significant, pitting | Usually localized |
A quick scope reminder: the PTA does not interpret a new ABI to set the diagnosis, but the PTA should know that an ABI below 0.5 contraindicates compression, and any reading the supervising PT did not anticipate must be reported before progressing the intervention.
Braden Scale Risk Triage
The Braden Scale scores six factors — sensory perception, moisture, activity, mobility, nutrition, and friction/shear — for a total of 6 to 23. A score of 18 or lower indicates the patient is at risk for pressure injury and should be on a turning schedule with appropriate support surfaces. PTAs use this score to justify position changes, off-loading, and patient/caregiver education embedded in the plan of care.
A PTA is treating a patient with a previously documented Stage 2 sacral pressure injury. During today's session, the PTA notes that the wound bed is now covered by 80% adherent yellow slough, and depth cannot be visualized. What is the most appropriate next action?
Which set of findings is most consistent with an arterial lower-extremity ulcer rather than a venous ulcer?