Diabetic/Neuropathic Foot Ulcer - Surgical Case Presentation

CHIEF COMPLAINT

HISTORY OF PRESENT ILLNESS

• Plantar callus buildup noted for years at the same site
• Peripheral sensory loss bilaterally - he cannot feel light touch past the mid-foot ("glove-and-stocking")
• Wears standard off-the-shelf athletic shoes

• No prior foot ulcers or amputations
• No claudication or rest pain
• No fevers, chills, or systemic sepsis

PAST MEDICAL / SURGICAL HISTORY

PHYSICAL EXAMINATION

Focused Lower Extremity Exam (Right Foot)

• Femoral pulse 2+, popliteal 2+
• Dorsalis pedis: diminished (1+)
• Posterior tibial: diminished (1+)
• Capillary refill: 3 seconds
• Skin: thin, shiny, hairless below mid-calf bilaterally

• Vibration sense absent to mid-foot bilaterally (128 Hz tuning fork)
• Monofilament (10-g Semmes-Weinstein): absent response at all plantar sites
• Proprioception: impaired at the hallux

• Location: plantar, beneath 2nd MTP head
• Dimensions: 2.5 cm × 1.8 cm, depth ~1.2 cm
• Margins: hyperkeratotic/callused rim, edges not undermined
• Base: pale pink granulation with central yellowish slough (~30% slough coverage)
• Exudate: moderate, serous-purulent
• Periwound: erythema extending 2 cm from wound margin, induration, warmth
• Probe-to-bone test: POSITIVE
• No fluctuance, no crepitus, no skin bullae

• Hammertoe deformity at 2nd digit
• Rigid equinus deformity (Silfverskiold test: positive - gastrocnemius-soleus contracture contributing to elevated forefoot pressure)
• No Charcot joint deformity on this presentation

CLASSIFICATION

Wagner Classification (Table 91.1 - Campbell's Operative Orthopaedics 15e)

SINBAD Score (IWGDF-endorsed)

WORKUP

Laboratory

Imaging

• Cortical irregularity and periosteal reaction at the 2nd metatarsal head
• Sub-metatarsal head soft tissue gas NOT present (no necrotizing fasciitis on plain film)

• T1: low signal in 2nd metatarsal head marrow (normal marrow replaced)
• T2/STIR: high signal in metatarsal head and adjacent soft tissue edema
• Gadolinium: enhancement of soft tissue tract and intramedullary marrow
• Impression: Osteomyelitis of 2nd metatarsal head with contiguous soft tissue infection; no discrete abscess; no deep space (plantar compartment) involvement

MRI is the most specific imaging modality for diabetic foot osteomyelitis. A positive probe-to-bone test carries ~89% positive predictive value for osteomyelitis. - Harrison's Principles of Internal Medicine 22E

Vascular Assessment

• ABI (right): 0.78 (borderline, PAD not excluded)
• Toe-brachial index: 0.52 (important in diabetic patients as tibial vessels may be falsely non-compressible on ABI)
• Duplex ultrasound: Triphasic flow in popliteal, biphasic in anterior tibial and peroneal arteries; posterior tibial diminished flow
• Vascular surgery consultation requested given borderline perfusion

DIAGNOSIS

1. Peripheral sensorimotor neuropathy → loss of protective sensation, intrinsic muscle wasting, hammertoe → elevated plantar pressure at 2nd MTP head
2. Autonomic neuropathy → anhidrosis → fissured, callused skin
3. Rigid equinus deformity (gastrocnemius tightness) → chronic forefoot overloading
4. Poorly controlled hyperglycemia → impaired neutrophil function, reduced wound angiogenesis, reduced collagen synthesis

MANAGEMENT

Immediate (Emergency Department / Admission)

1. Admit to surgery service - Wagner Grade III ulcer with osteomyelitis is a surgical emergency
2. IV antibiotics (empiric, broad-spectrum, pending tissue cultures):
   • Vancomycin 25 mg/kg IV q8-12h (MRSA coverage + CKD dose adjustment)
   • Piperacillin-tazobactam 3.375 g IV q6h (gram-negative and anaerobic coverage)
   • Note: In CKD Stage 3, dose-adjust all renally cleared agents
3. Strict non-weight bearing - bed rest, limb elevation
4. Glycemic control: Insulin infusion protocol, target BG 140-180 mg/dL inpatient; Endocrinology consult
5. Wound cultures: Obtain deep tissue intraoperatively (surface swabs are unreliable - colonization vs. true infection)
6. NPO after midnight for OR

Surgical Plan - Operating Room

1. Positioning: Supine, ankle roll under ipsilateral hip for slight internal rotation access; tourniquet applied (300 mmHg) but inflation deferred until bleeding assessment
2. Incision: Elliptical excision of ulcer margins; plantar longitudinal or racquet incision to gain access to metatarsal head
3. Exploration: Assess all deep tissue planes - plantar fascia, flexor tendons, metatarsal head, MTP joint
4. Sharp debridement: Remove ALL non-viable tissue including: callus rim, slough, necrotic tendon, infected synovium, periosteum
5. Bone resection: Metatarsal head resection using oscillating saw or rongeur - resection margins sent for culture and histopathology (confirm osteomyelitis; rule out Charcot)
6. Frozen section / permanent histology: Bone margins for residual infection
7. Irrigation: 3 liters pulsatile saline lavage
8. Wound closure: Primarily open (or partially closed over a drain) - allows for re-look debridement in 48-72 hours; do NOT close a contaminated wound primarily
9. Apply NPWT (Negative Pressure Wound Therapy): VAC dressing to provide moist environment, reduce edema, stimulate granulation

Grade III plantar ulceration at the forefoot. Dorsal erythema reflects contiguous deep infection. (Campbell's Operative Orthopaedics 15e)

Postoperative Management

• NPWT dressing changes every 2-3 days
• Re-look debridement in 48-72 hours if clinical improvement insufficient
• Moist wound healing principles: avoid hydrogen peroxide and betadine, which damage viable tissue; use saline irrigation
• "Avoid harsh chemicals such as hydrogen peroxide and betadine because these can damage the viable tissue in the ulcer and further delay healing." - Campbell's Operative Orthopaedics 15e

• Narrow antibiotic coverage once deep tissue culture results finalize (typically 48-72 hours)
• Duration for osteomyelitis: 4-6 weeks total (IV to PO transition based on bioavailability)
• If MRSA confirmed: IV vancomycin or oral linezolid/TMP-SMX (based on local antibiogram)

• Total contact cast (TCC) - gold standard for plantar ulcer offloading; removes mechanical trauma that retards healing
• Non-removable knee-high walkers as alternative
• Strict non-weight bearing during early post-debridement phase

• HbA1c target <7.5% long-term; acknowledge this is not achievable acutely
• Inpatient: insulin infusion protocol
• Transition to structured outpatient regimen with endocrinology

• If wound shows <50% area reduction at 4 weeks: reassess for PAD and consider vascular intervention
• Revascularization (endovascular or bypass) if significant ischemia identified

Adjunct / Advanced Wound Therapies (if no improvement at 4 weeks)

SURGICAL DECISION-MAKING FRAMEWORK

Reconstructive Ladder (for Wound Coverage)

1. Secondary healing (granulation + contraction) - preferred initial strategy in contaminated wounds
2. Delayed primary closure (after 48-72h re-look)
3. Split-thickness skin graft (STSG) - once clean, granulating wound bed established
4. Local flap reconstruction - for exposed tendon/bone after debridement
5. Free flap - rarely required; only if large structural defect and adequate perfusion

Limb-Salvage vs. Amputation Decision

COMPLICATIONS TO ANTICIPATE

PROGNOSIS

• Diabetic foot ulcers carry a 44% 5-year mortality - comparable to many cancers
• 3-year recurrence rate with CLTI is analogous to cancer recurrence patterns (Armstrong et al., IWJ 2025)
• Patient education reduces lower extremity amputation risk by 50-85%
• A multidisciplinary team (orthopaedics, vascular surgery, infectious disease, endocrinology, podiatry, orthotics, wound nursing) has been shown to be cost-effective and reduces amputation rates significantly

MULTIDISCIPLINARY TEAM INVOLVEMENT

TEACHING POINTS FOR ATTENDINGS

1. Probe-to-bone test is highly predictive of osteomyelitis (~89% PPV) - a positive result in this setting mandates MRI and surgical planning
2. Surface swabs are unreliable - always send deep tissue cultures from the operating room; surface colonization does not equal infection
3. Diabetic foot ulcers are surgical emergencies - delayed intervention leads to proximal infection extension and higher amputation levels
4. Wagner Grade III = OR, not clinic - cannot treat presumed osteomyelitis with antibiotics alone in the presence of devitalized tissue
5. Off-loading is as important as surgery - failure to off-load is the most common cause of non-healing despite technically adequate debridement
6. Rigid equinus is an underrecognized contributor - Achilles tendon lengthening or gastrocnemius recession (Strayer procedure) significantly reduces recurrent forefoot ulceration
7. The reconstructive ladder is always context-dependent - in a diabetic foot, simpler is often better; free flaps carry high failure rates in ischemic/infected fields
8. Multidisciplinary care is not optional - it reduces amputation rates and is cost-effective, particularly in patients over 70 years

KEY REFERENCES