What is the diagnosis and management for a patient with bilateral hardening of the feet, potentially associated with underlying conditions such as diabetes?

Bilateral Hardening of Feet: Diagnosis and Management

Immediate Diagnostic Considerations

Bilateral hardening of the feet in a diabetic patient most likely represents callus formation secondary to diabetic peripheral neuropathy with abnormal biomechanical loading, requiring immediate assessment for underlying neuropathy, foot deformities, and pre-ulcerative changes. 1

However, you must first exclude acute neurological emergencies before attributing this to routine diabetic neuropathy, as unilateral or atypical presentations require immediate neurological consultation and imaging to rule out stroke, spinal cord pathology, or mononeuropathy multiplex. 2

Clinical Assessment Algorithm

Step 1: Rule Out Acute Processes

• Assess for asymmetry or rapid progression - if present, obtain immediate brain and spinal cord imaging (MRI preferred) to exclude stroke, TIA, or spinal cord lesions 2
• Perform comprehensive neurological examination including cranial nerves, motor strength in all dermatomes, reflexes, and check for upper motor neuron signs (hyperreflexia, Babinski sign, spasticity) 2
• Palpate dorsalis pedis and posterior tibial pulses bilaterally - absence suggests peripheral arterial disease present in up to 50% of diabetic foot complications 1, 2

Step 2: Classify Foot Risk Category

Once acute processes are excluded, classify using the IWGDF Risk Classification System:

• Category 0: No peripheral neuropathy - screen annually 1
• Category 1: Peripheral neuropathy present - screen every 6 months 1
• Category 2: Peripheral neuropathy with foot deformities - screen every 3-6 months 1
• Category 3: Previous ulcer/amputation history - screen every 1-3 months 1

Step 3: Assess for Charcot Neuro-osteoarthropathy

If the foot shows warmth, erythema, or swelling alongside hardening:

• Obtain bilateral weight-bearing plain X-rays immediately (AP, medial oblique, and lateral projections) 1
• If X-rays are normal but clinical suspicion remains high, perform MRI to diagnose or exclude active Charcot neuro-osteoarthropathy 1
• Initiate immediate knee-high immobilization/offloading while awaiting imaging if active Charcot is suspected, as early immobilization minimizes deformity development 1

Management of Callus (Hardened Skin)

Immediate Treatment

Remove abundant callus immediately as it leads to further abnormal loading, subcutaneous hemorrhage, and eventual ulceration. 1 This should be performed by a trained foot care specialist and repeated until the pre-ulcerative sign resolves. 1

Footwear Assessment

• Meticulously examine the patient's shoes - ill-fitting shoes and walking barefoot are the most frequent causes of ulceration even in patients with purely ischemic ulcers 1
• For patients with neuropathy (Category 1+), prescribe therapeutic footwear: the shoe should be 1-2 cm longer than the foot, with internal width equal to the foot width at metatarsal phalangeal joints 1
• If foot deformities are present or there are signs of abnormal loading (hyperemia, callus), refer for special footwear including custom insoles and orthoses with demonstrated reduced plantar pressure 1

Patient Education (Critical)

Educate the patient to:

• Perform daily foot inspection including areas between toes (or designate someone to assist if visually impaired) 1
• Never walk barefoot, in socks without shoes, or in thin-soled slippers whether indoors or outdoors 1
• Notify healthcare provider immediately if foot temperature is markedly increased or if blisters, cuts, or ulcers develop 1
• Inspect inside all shoes before wearing them 1

Pathophysiology Context

The hardening (callus) develops because diabetic peripheral neuropathy causes insensitive and sometimes deformed feet with abnormal walking patterns. 1 Loss of sensation, foot deformities, and limited joint mobility result in abnormal biomechanical loading, producing high pressure in specific areas. 1 The body responds with thickened skin (callus), which paradoxically leads to further increase in abnormal loading, often with subcutaneous hemorrhage and eventual ulceration if the patient continues walking on the insensitive foot. 1

Critical Pitfalls to Avoid

• Do not attribute bilateral foot changes to routine diabetic neuropathy without first excluding acute neurological emergencies requiring time-sensitive interventions 2
• Do not delay callus removal - waiting allows progression to subcutaneous hemorrhage and ulceration 1
• Do not allow patients to select their own footwear if they have neuropathy (Category 1+) - they require professional fitting and often therapeutic footwear 1
• Do not treat clinically uninfected wounds with antimicrobial therapy 1

Topical Therapy Consideration

For hyperkeratotic lesions, salicylic acid 6% may be applied to affected areas at night after washing, with the medication washed off in the morning. 3 However, avoid prolonged use over large areas in patients with significant renal or hepatic impairment due to risk of salicylism, and do not apply occlusive dressings to prevent excessive systemic exposure. 3

Follow-up Strategy

• Schedule regular podiatry visits based on risk category (every 1-6 months depending on classification) 1
• Repeat callus debridement until pre-ulcerative signs resolve and do not recur 1
• Ensure multidisciplinary team involvement including endocrinology for glycemic control, vascular surgery if PAD is present, and orthopedics if surgical correction of deformities is needed 1