What are the potential causes of left great toe and foot pain in an adult patient with possible underlying conditions such as diabetic neuropathy, gout, or infections?

Causes of Left Great Toe and Foot Pain

Left great toe and foot pain in adults requires immediate consideration of diabetic foot infection, gout, peripheral neuropathy, and trauma-related injuries, with diabetic foot complications representing the most limb-threatening and life-threatening emergency requiring urgent evaluation.

Critical Life-Threatening Causes to Exclude First

Diabetic Foot Infection with Sepsis

• If the patient has diabetes and presents with systemic signs (fever, hypotension, confusion, tachycardia), this represents a medical emergency requiring immediate hospitalization, fluid resuscitation, and broad-spectrum antibiotics 1
• Severe diabetic foot infections can progress rapidly to systemic sepsis, acute kidney injury, and multi-organ failure 1
• The International Working Group on the Diabetic Foot defines severe infection by systemic toxicity including fever, chills, hypotension, confusion, and new azotemia 1

Charcot Neuro-Osteoarthropathy (CNO)

• In diabetic patients, CNO must be excluded immediately as it presents with unilateral foot redness, warmth, and swelling, potentially with minimal pain due to neuropathy 2
• Immediate immobilization is mandatory while awaiting imaging, as delay can result in permanent foot deformity 2
• Plain radiographs should be obtained immediately to look for bone destruction or midfoot collapse 2

Common Causes by Clinical Presentation

Diabetic Foot Complications

Diabetic Peripheral Neuropathy (Painful DPN)

• Affects up to 50% of patients with diabetes and presents with distal, symmetrical pain with nocturnal exacerbation 3, 4
• Patients describe burning, shooting, stabbing, or electric shock-like sensations 3
• Diagnosis is clinical, relying on patient description of pain symptoms distal and symmetrical, supported by blunted sensation on examination 3
• The pain may be present even in the absence of signs in acute painful DPN 3

Diabetic Foot Ulceration and Infection

• Ill-fitting shoes and walking barefoot with insensitive feet are the most frequent causes of ulceration 3
• Neuropathic ulcers frequently occur on the plantar surface of the foot or in areas overlying bony deformity 3
• Infection is diagnosed by the presence of at least two signs or symptoms of inflammation: redness, warmth, induration, pain/tenderness, or purulent secretions 3, 2
• These inflammatory signs may be blunted by neuropathy or ischemia, and systemic findings are often absent 3

Diabetic Foot Osteomyelitis (DFO)

• Assess for osteomyelitis especially if there is a longstanding or deep wound, a wound overlying bone, or if it is possible to touch bone with a sterile metal probe (probe-to-bone test) 3
• Plain radiographs suffice for screening in most cases, though they have relatively low sensitivity and specificity 3
• MRI is the recommended diagnostic imaging test for DFO when needed 3

Gout

• Gout can present as an unusual cause of great toe and midfoot pain in diabetic patients with peripheral neuropathy, where pain may be masked or "silent" 5
• The classic presentation involves acute onset of severe pain, redness, warmth, and swelling of the first metatarsophalangeal joint 6
• In diabetic patients with neuropathy, gout may present with only mild pain despite severe tophaceous involvement and bony erosions 5
• Deep tissue sampling may be necessary to confirm diagnosis before definitive treatment, especially when osteomyelitis is in the differential 5

Peripheral Arterial Disease (PAD)

• PAD is present in up to 40% of diabetic foot infections and must be evaluated 1
• Evaluate all patients by taking a symptom-directed history and palpating foot pulses 3
• An ankle brachial index (ABI) 0.9–1.3 and triphasic pedal pulse waveform largely excludes PAD, as does a toe brachial index ≥0.75 3
• Ischemic ulcers are more common on the tips of the toes or lateral borders of the foot 3

Mechanical and Structural Causes

• Great-toe sprains (turf toe) can range from mild to severe with associated fractures 6
• Hallux rigidus (painful flexion deformity) is often seen in patients who stress the joint repetitively 6
• Hallux valgus (bunion) may be caused by heredity, improper footwear, injury, or hyperpronation 6
• Sesamoiditis is aggravated by weight-bearing activities, climbing stairs, or wearing high-heeled shoes 6
• Stress fractures and osteochondral defects are other causes of toe pain 6

Essential Diagnostic Approach

Immediate Clinical Assessment

• Assess for systemic signs of sepsis: fever, hypotension, tachycardia, confusion, or metabolic instability 3, 1
• Evaluate blood glucose level immediately, as severe hyperglycemia with or without diabetic ketoacidosis must be addressed promptly 3
• Test for protective sensation using monofilament testing—loss of sensation significantly increases risk of diabetic complications 2

Physical Examination Priorities

• Palpate dorsalis pedis and posterior tibial pulses bilaterally to assess vascular status 2
• Perform probe-to-bone test for any open wound—when properly conducted, it can help diagnose or exclude osteomyelitis 3
• Meticulously examine shoes and footwear behavior in all patients 3
• Look for pre-ulcerative signs including abundant callus, blisters, ingrown or thickened nails, and fungal infections 3

Imaging Protocol

• Obtain plain radiographs with three standard views (dorsoplantar, lateral, medial oblique) as initial evaluation 3
• Use radio-opaque marker to indicate ulcer location for accurate assessment 3
• Plain radiographs detect foreign bodies, gas in soft tissues, and screen for osteomyelitis, though sensitivity is limited 3, 7
• MRI is the most sensitive tool for soft tissues, bones, and joints when advanced imaging is needed 3, 7

Laboratory Evaluation

• Send appropriately obtained specimens for culture before starting empirical antibiotic therapy in all cases of infection, except mild and previously untreated cases 7
• Tissue specimens obtained by biopsy, ulcer curettage, or aspiration are preferable to wound swab specimens 7
• Bone biopsy provides the most definitive diagnosis of osteomyelitis through combined bone culture and histology 3

Critical Pitfalls to Avoid

• Do not rely on pain as a diagnostic indicator in diabetic patients with neuropathy—severe pathology including gout and osteomyelitis can present with minimal or absent pain 5
• Do not assume normal plain radiographs exclude osteomyelitis—repeat in 2-3 weeks or obtain MRI if clinical suspicion remains high 3
• Do not overlook the possibility of CNO in diabetic patients with unilateral foot inflammation—failure to immobilize can lead to permanent deformity 2
• Asymmetrical symptoms and/or signs in diabetic neuropathy should prompt careful assessment for other etiologies, as painful DPN is invariably symmetrical 3
• Do not perform debridement in non-infected ulcers with signs of severe ischemia 3