What causes a toe to curve over another toe, particularly in older adults?

Toe Curving Over Another Toe: Causes and Clinical Approach

A toe curving over another toe is most commonly caused by hammertoe deformity, which results from muscle-tendon imbalance across the interphalangeal and metatarsophalangeal joints, often precipitated by ill-fitting footwear, diabetic neuropathy, or biomechanical foot abnormalities. 1

Primary Pathophysiology

Hammertoe develops from an imbalance between intrinsic and extrinsic muscles controlling toe movement, leading to fixed flexion at the proximal interphalangeal joint with the toe bending downward and potentially overlapping adjacent toes. 1, 2 This deformity originates from disrupted muscle function that normally maintains toe alignment, causing progressive contracture over time. 3

Key Contributing Factors

• Inappropriate footwear is the single most important modifiable cause, particularly shoes that are too tight, have rough edges, or compress the toes together 4
• Diabetic peripheral neuropathy causes muscle imbalance and altered biomechanics that predispose to toe deformities including hammertoes 4
• Genetic predisposition and underlying neuromuscular disorders can create the anatomic conditions for deformity development 1
• Trauma or chronic pressure on the toes from repetitive loading patterns 1

Clinical Examination Priorities

When evaluating a curving toe, focus on these specific findings:

• Assess flexibility: Determine if the deformity is flexible (passively correctable without pain) or rigid (fixed contracture), as this dictates treatment approach 5, 2
• Examine for neuropathy: Test protective sensation with 10-g monofilament at plantar sites, check vibration with 128-Hz tuning fork, and assess ankle reflexes 4
• Inspect for complications: Look for corns, calluses, or skin breakdown over bony prominences where the curved toe contacts adjacent toes or shoe surfaces 4, 1
• Evaluate metatarsophalangeal joint: Check for dorsal contracture or subluxation that elevates the toe and contributes to overlapping 2
• Assess vascular status: Palpate pedal pulses, as peripheral arterial disease compounds risk for complications 4

Risk Stratification for Diabetic Patients

If diabetes is present or suspected, use the International Working Group on Diabetic Foot classification:

• IWGDF Risk 2 (Moderate): Loss of protective sensation OR peripheral arterial disease PLUS foot deformity like hammertoe—requires examination every 3-6 months 4
• IWGDF Risk 3 (High): History of foot ulcer or amputation—requires examination every 1-3 months 4

Treatment Algorithm

For Flexible Deformities (Early Stage)

Conservative management should be the initial approach for all flexible toe deformities:

• Footwear modification: Switch to shoes with wide toe-box, soft uppers, extra depth to accommodate the deformity, and ensure internal shoe length is 1-2 cm longer than the foot 4
• Padding and orthoses: Use accommodative padding over bony prominences and custom pressure-relieving orthoses if plantar calluses indicate increased pressure 4
• Stretching exercises: Perform targeted exercises to strengthen and stretch affected muscles 1, 2
• Kinesiology taping: Consider taping methods to correct flexible deformities, which can modify foot loading patterns 5

For Rigid Deformities (Advanced Stage)

Surgical intervention becomes necessary when conservative measures fail and the deformity causes persistent pain or functional limitation:

• Proximal interphalangeal joint arthrodesis is the gold standard surgical treatment, providing pain relief in up to 92% of patients with fusion rates of 83-98% 2, 6
• Soft-tissue procedures: Extensor tendon Z-lengthening, capsulectomy, and collateral ligament release address metatarsophalangeal joint contracture 2
• Metatarsal osteotomy: Consider if residual subluxation persists after soft-tissue balancing 2

Critical Management Pitfalls

• Never assume mechanical cause alone: Screen for diabetes with hemoglobin A1c even in younger adults, as diabetic neuropathy is the most common systemic cause of foot deformities 7
• Avoid barefoot walking: Patients with neuropathy and toe deformities must wear appropriate footwear indoors and outdoors to prevent ulceration 4
• Do not delay specialist referral: Refer to podiatric foot and ankle surgeon if conservative treatment fails after 6-8 weeks or if skin breakdown occurs 4
• Prevent corns/calluses self-treatment: Chemical agents or plasters should never be used; only trained foot care specialists should debride these lesions 4
• Monitor for Charcot foot: Any patient with neuropathy presenting with acute onset of red, hot, swollen foot requires urgent evaluation to exclude Charcot neuroarthropathy 4

Daily Foot Care Instructions

For patients with toe deformities, especially those with neuropathy:

• Inspect feet daily including between toes, using a mirror if needed for visualization 4
• Apply moisturizers to dry skin but never between the toes 4
• Cut toenails straight across to prevent ingrown nails 4
• Notify healthcare provider immediately if blisters, cuts, or increased warmth develop 4
• Never walk barefoot or in thin-soled slippers, even at home 4