Table 1.1.
Classification schemes used for chronic limb ischemia and ulceration
| Classification system | Ischemic rest pain | Ulcer | Gangrene | Ischemia | Infection | Key features and comments |
|---|---|---|---|---|---|---|
|
| ||||||
| Ischemia and PAD classifications | ||||||
| Fontaine (1954) | Yes (class III/IV) | Class IV/IV; ulcer and gangrene grouped together | Class IV/IV; ulcer and gangrene grouped together | Cutoff values for CLI based on European consensus document: Ischemic rest pain >2 weeks with AP <50 mm Hg or TP <30 mm Hg Ulcer and gangrene: AP <50 mm Hg, TP <30 mm Hg, absent pedal pulses in patient with diabetes |
No | Pure ischemia model No clear definitions of spectrum of hemodynamics; minimal description of wounds; infection omitted |
| Rutherford (1997) | Yes (category 4/6) | Category 5: minor tissue loss, nonhealing ulcer, focal gangrene with diffuse pedal ischemia | Category 6: major tissue loss extending above TM level, functional foot no longer salvageable (although, in practice, often refers to extensive gangrene, potentially salvageable foot with significant efforts) | Yes; cutoffs for CLI Category 4: resting AP <40 mm Hg; flat or barely pulsatile ankle or forefoot PVR; TP <30 mm Hg Category 5/6: AP <60 mm Hg; flat or barely pulsatile ankle or forefoot PVR; TP <40 mm Hg |
No | Pure ischemia model PAD classification system includes milder forms of PAD (categories 1–3). Categories 4–6 based on cutoff values for CLI; no spectrum of ischemia, does not acknowledge potential need for revascularization, with CLI cutoff depending on wound extent/infection; not intended for patients with diabetes; wound classes not sufficiently detailed; omits infection as a trigger |
| Second European Consensus (1991) | Yes; pain >2 weeks requiring analgesia; AP ≤50 mm Hg or TP ≤30 mm Hg | Yes, if AP ≤50 mm Hg or TP ≤30 mm Hg | Yes, if AP ≤50 mm Hg or TP ≤30 mm Hg | One hemodynamic cutoff for ulcer and gangrene, with or without diabetes | No | Ischemia threshold too low, especially for patients with diabetes; wounds not graded; infection not considered |
| TASC I (2000) | Yes, if ischemia criteria met | Yes, if ischemia criteria met | Yes, if ischemia criteria met | One hemodynamic cutoff, with no differentiation of diabetics from nondiabetics | No | Focused primarily on arteriographic anatomy without detailed stratification of the limb itself (wounds and infection not graded) |
| TASC II (2007) | Yes, if AP <50 mm Hg or TP <30 mm Hg | Yes, if ischemia criteria met of AP <70 mm Hg or TP <50 mm Hg | Yes, if ischemia criteria met of AP <70 mm Hg or TP <50 mm Hg | Yes, but noted “there is not complete consensus regarding the vascular haemodynamic parameters required to make the diagnosis of CLI” | No | Focused primarily on arteriographic anatomy without detailed stratification of the limb itself (wounds and infection not graded); issues with hemodynamic criteria noted |
| DFU classifications | ||||||
| Meggitt-Wagner (1976, 1981) | No | Grade 0: pre- or post-ulcerative lesion Grade 1: partial/full-thickness ulcer Grade 2: probing to tendon or capsule Grade 3: deep ulcer with osteitis Grade 4: partial foot gangrene Grade 5: whole foot gangrene |
Ulcer and gangrene grouped together; gangrene due to infection not differentiated from gangrene due to ischemia; also includes osteomyelitis | No | No for soft tissue component; included only as osteomyelitis | Orthopedic classification intended for diabetic feet No hemodynamics; gangrene from infection not differentiated from that due to ischemia; osteomyelitis included; soft tissue infection not separated from bone infection |
| University of Texas (1998) | No | Yes: grade 0-III ulcers Grade 0: pre- or post-ulcerative completely epithelialized lesion Grade I: superficial, not involving tendon, capsule, or bone Grade II: penetrating to tendon/capsule Grade III: penetrating to bone or joint |
No | Yes: binary ± based on ABI <0.8 | Yes ± wounds, with frank purulence or >2 of the following (warmth, erythema, lymphangitis, edema, lymphadenopathy, pain, loss of function) considered infected | Primarily intended for DFUs; includes validated ulcer categories; PAD and infection included, but only as ± variable with no grades/spectrum |
| S(AD) SAD system (1999) | No | Yes: 0–3 based on area and depth Grade 0: skin intact Grade 1: superficial, < 1 cm2 Grade 2: penetrates to tendon, periosteum, joint capsule, 1–3 cm2 Grade 3: lesions in bone or joint space, >3 cm2 |
No | Pulse palpation only, no objective hemodynamic testing | Yes; 1 = no infection, 2 = cellulitis, 3 = osteomyelitis | Intended for DFUs; also includes neuropathy; does not mention gangrene; no hemodynamic information, perfusion assessment based on pulse palpation only |
| PEDIS (2004) | No | Yes: grades 1–3 Grade 1: superficial full-thickness ulcer, not penetrating deeper than the dermis Grade 2: deep ulcer, penetrating below the dermis to subcutaneous structures involving fascia, muscle, or tendon Grade 3: all subsequent layers of the foot involved including bone and joint (exposed bone, probing to bone) |
No | Yes: 3 grades, CLI cutoff Grade 1: no PAD symptoms, ABI >0.9, TBI >0.6, TcPo2 >60 mm Hg Grade 2: PAD symptoms, ABI <0.9, AP >50 mm Hg, TP >30 mm Hg, TcPo2 30–60 mm Hg Grade 3: AP < 50 mm Hg, TP <30 mm Hg, TcPo2 <30 mm Hg |
Yes: grades 1–4 based on IDSA classification | Primarily intended for DFUs; ulcer grades validated; includes perfusion assessment, but with cutoff for CLI; gangrene not separately categorized; includes validated IDSA infection categories |
| Saint Elian (2010) | No | Yes: grades 1–3 based on depth Grade 1: superficial wound disrupting entire skin Grade 2: moderate or partial depth, down to fascia, tendon, or muscle but not bone or joints Grade 3: severe or total, wounds with bone or joint involvement Multiple categories including area, ulcer number, location, and topography |
No | Yes: grades 0–3 Grade 0: AP >80 mm Hg, ABI 0.9–1.2 Grade 1: AP 70–80 mm Hg, ABI 0.7–0.89, TP 55–80 mm Hg Grade 2: AP 55–69 mm Hg, ABI 0.5–0.69, TP 30–54 mm Hg Grade 3: AP <55 mm Hg, ABI <0.5, TP <30 mm Hg |
Yes: grades 0–3 Grade 0: none Grade 1: mild; erythema 0.5–2 cm, induration, tenderness, warmth, and purulence Grade 2: moderate; erythema >2 cm, abscess, muscle tendon, joint, or bone infection Grade 3: severe; systemic response (similar to IDSA) |
Detailed system intended only for DFUs; comprehensive ulcer classification system with hemodynamic categories for gradations of ischemia; gangrene not considered separately Infection system similar to IDSA |
| IDSA (2012) | No | No | No | No | Yes: uninfected, mild, moderate, and severe | Validated system for risk of amputation related to foot infection but not designed to address wound depth/complexity or degree of ischemia |
| Recommended CLTI classification | ||||||
| SVS WIfI threatened limb classification (2014) | Yes, if confirmed by hemodynamic criteria | Yes: grades 0–3 Grouped by depth, location, and size and magnitude of ablative/wound coverage procedure required to achieve healing |
Yes: grades 0–3 Grouped by extent, location, and size and magnitude of ablative or wound coverage procedure required to achieve healing |
Yes: ischemia grades 0–3 Hemodynamics with spectrum of perfusion abnormalities; no cutoff value for CLI Grade 0 unlikely to require revascularization |
Yes: IDSA system (grades 0–3); grades corelate with amputation risk | Includes PAD ± diabetes with a range of wounds, ischemia, and infection, scaled from 0–3 No single cutoff for CLI as CLTI is considered a spectrum of disease Need for revascularization depends on degree of ischemia, wound, and infection severity Ulcers/gangrene categorized by extent and complexity of anticipated ablative surgery/coverage |
ABI, Ankle-brachial index; AP, ankle pressure; CLI, critical limb ischemia; DFU, diabetic foot ulcer; CLTI, chronic limb-threatening ischemia; IDSA, Infectious Diseases Society of America; PAD, peripheral artery disease; PEDIS, perfusion, extent depth, infection, and sensation; PVR, pulse volume recording; SVS, Society for Vascular Surgery; TASC, TransAtlantic Inter-Society Consensus; TBI, toe-brachial index; TcPo2, transcutaneous oximetry; TM, transmetatarsal; TP, toe pressure; WIfI, Wound, Ischemia, foot Infection.