Educational draft · awaiting clinical reviewThe full textbook explains uncertainty but does not replace live national or local guidance, specialist advice, or current prescribing information.
Claw toes and callosity
Musculoskeletal medicine and orthopaedics · UK scope · Sources checked 27 Aug 2026 · Clinical review pending
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Callus can conceal ulcer, infection or critical pressure
A haemorrhagic callus, underlying ulcer, drainage, spreading erythema, fever, black tissue, cool foot or rest pain may signal diabetic-foot infection, deep pressure injury or critical ischaemia rather than uncomplicated corn or toe deformity.
Action: Remove shoes and inspect both feet, assess perfusion and protective sensation, offload the threatened area, avoid self-applied acids or cutting, and arrange immediate acute diabetic-foot, surgical or vascular care for sepsis, deep infection, gangrene, critical ischaemia or rapidly progressive tissue loss.
Overview
Classify flexible and fixed lesser-toe deformity, treat callus as evidence of pressure rather than a skin diagnosis alone, identify neuropathy and ischaemia, and combine footwear, podiatry, orthoses and surgery without creating ulcer risk.
Ask which toe surface hurts and in which shoe. A dorsal corn, tip callus, interdigital soft corn and plantar metatarsal callus each identify a different pressure direction. Establish duration, progression, reducibility, ulcer or drainage, diabetes, neuropathy, vascular disease, rheumatoid disease, cavus, childhood or family neurological features and previous surgery. Ask about falls, weakness and footwear size; patients often buy the same nominal size despite increasing toe length or deformity.
Examine standing, walking and seated. Classify hammer, claw, mallet and crossover posture and note hallux valgus, arch, hindfoot and metatarsal callus. Gently correct each joint and repeat with the metatarsophalangeal joint and ankle positioned differently to identify tendon-driven flexibility. Test plantar-plate stability, long flexor and extensor pull, intrinsic strength and ankle dorsiflexion. Inspect between toes and beneath callus, then document monofilament sensation, temperature, refill and pulses.
Practice
Two practice questions
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Question 1 of 2
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Musculoskeletal medicine and orthopaedicsOriginal SBA
Claw-toe definition
A patient has hyperextension at the lesser-toe metatarsophalangeal joints with flexion of both proximal and distal interphalangeal joints. Which deformity is described?
Sources and review status4 sources · checked 27 Aug 2026 · clinical review pending+
Sources
Sources and review status
National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 27 Aug 2026; clinical approval remains outstanding.
Typical flexible deformity and pressure callus are clinical diagnoses. Weight-bearing AP, oblique and lateral foot radiographs show metatarsophalangeal subluxation, interphalangeal arthritis, metatarsal length, hallux conflict and cavus when surgery or a fixed pattern is considered. Ultrasound or MRI is reserved for plantar-plate tear, mass or unresolved soft-tissue pain. Neurological examination, glucose or HbA1c and vascular tests follow specific findings rather than being omitted because the complaint looks mechanical.
Footwear is active treatment. Measure both feet standing and provide adequate length, width and depth with a soft upper and low heel. A silicone sleeve, crest pad, toe spacer or metatarsal dome should unload the exact prominence without creating a new pressure point. Flexible toes may benefit from taping or splinting and intrinsic, toe-flexor-extensor control and calf work. Devices should be checked inside the shoe and against skin after walking.
Callus should be reduced by a trained podiatrist when painful, thick, haemorrhagic or in a high-risk foot, while the pressure source is changed. Debridement alone gives temporary relief because keratin returns if load persists. Moisturiser can improve dry fissured plantar skin but should not macerate interdigital spaces. Patients with intact circulation and sensation may use simple non-medicated padding; blades and acidic corn remedies are unsafe in neuropathy, diabetes, ischaemia or fragile skin.
An ulcer changes the pathway. Measure depth and surrounding inflammation after cleansing and trained debridement, offload the exact site and assess infection and perfusion. A diabetic foot with ulcer, spreading infection, gangrene, critical ischaemia or possible Charcot disease needs NICE-defined rapid multidisciplinary referral. Antibiotics treat clinical infection, not pressure or colonisation. A normal ankle pressure can mislead in calcified diabetic vessels, so Doppler waveform and toe measures may be required.
Surgery is considered when appropriate shoes, padding, podiatry and flexible correction do not control pain or ulcer risk. A flexible deformity may use flexor-to-extensor transfer; a fixed proximal interphalangeal joint commonly needs resection or fusion. Metatarsophalangeal instability may require plantar-plate repair, tendon balance or metatarsal osteotomy, and hallux conflict may need simultaneous correction. Isolated corn excision without correcting pressure predictably recurs.
Explain swelling, wire or implant care, stiffness, infection, recurrence, floating toe, transfer pain and delayed return to ordinary shoes. Diabetes and neuropathy increase wound and recurrence risk; vascular insufficiency may preclude elective surgery until assessed. Smoking and poor glycaemic control need optimisation. Anticoagulation requires a coordinated perioperative plan. Pregnancy generally favours footwear and padding, avoiding salicylic products and systemic NSAIDs according to gestation.
Key points
Classify the deformity precisely: hammer toe mainly flexes at the proximal interphalangeal joint, mallet toe at the distal joint, and claw toe combines metatarsophalangeal hyperextension with both interphalangeal joints flexed.
Test flexibility with the ankle and metatarsophalangeal joint positioned to relax tendons; a reducible deformity can respond to footwear, padding, splinting and exercise better than a fixed joint.
Callus and corns are pressure maps: dorsal corns indicate shoe contact, tip lesions indicate end pressure, interdigital soft corns indicate crowding and plantar callus indicates metatarsal loading.
First-line assessment includes standing alignment, joint stability, footwear, skin inspection, monofilament protective sensation, pulses and capillary refill in both feet.
First-line management is a wide and deep toe box, sufficient shoe length, low heel, pressure-specific padding, podiatry debridement and correction of the underlying load where possible.
Do not advise self-cutting or salicylic-acid corn plasters in diabetes, neuropathy, ischaemia or fragile skin; a professional should inspect beneath haemorrhagic callus.
Use weight-bearing radiographs for fixed, progressive or surgical deformity; perform neurological, diabetes and vascular testing when examination suggests systemic drivers.
Aetiology
01
Toe-box compression
Narrow or shallow shoes increase dorsal and tip pressure and can maintain flexible hammering, although established deformity commonly has additional mechanical or neurological drivers.
02
Intrinsic-extrinsic imbalance
Weak intrinsic muscles and relatively stronger long flexors and extensors hyperextend the metatarsophalangeal joint and flex interphalangeal joints into clawing.
03
Neurological and cavus disease
Diabetes, Charcot-Marie-Tooth disease, spinal or peripheral nerve injury and cavus alignment alter muscle balance, sensation and plantar pressure.
04
Inflammatory and structural disease
Rheumatoid arthritis, plantar-plate failure, hallux valgus and previous trauma destabilise lesser metatarsophalangeal joints and drive crossover or fixed deformity.
Pathophysiology
1
Hammer, claw and mallet patterns
Hammer toe flexes mainly at the proximal interphalangeal joint, claw toe combines metatarsophalangeal hyperextension with both interphalangeal joints flexed, and mallet toe flexes distally.
2
Progression from flexible to fixed
Initially reducible imbalance shortens capsule, tendon and skin over time, creating rigid joints that no longer straighten with manual correction.
3
Focal keratin response
Repeated pressure and shear accelerate keratin production, forming diffuse callus or a conical corn over a prominence or between crowded toes.
4
Pressure beneath callus
Thick keratin increases focal plantar pressure and can hide haemorrhage and ulceration, particularly when neuropathy removes protective pain.
5
Metatarsophalangeal instability
Plantar-plate attenuation permits dorsal toe subluxation and transfers weight to the metatarsal head, causing plantar callosity and crossover deformity.
Clinical features and red flags
Hammer-toe pattern
The proximal interphalangeal joint flexes while the distal joint and metatarsophalangeal posture vary according to stage and tendon balance.
Claw-toe pattern
Metatarsophalangeal hyperextension combines with flexion at both interphalangeal joints, often with cavus or neurological disease.
Mallet-toe pattern
Isolated distal interphalangeal flexion produces painful tip pressure and a corn near the nail or toe pulp.
Haemorrhagic callus
Dark blood within keratin in a neuropathic foot signals repetitive tissue injury and may overlie ulceration requiring trained assessment.
Neurovascular risk
Sensory loss, absent pulses, coolness, rest pain or tissue loss changes ordinary corn care into limb-protection and vascular assessment.
Red flags requiring action
Dark haemorrhage beneath callus, fluctuance or a skin break can conceal a neuropathic ulcer and requires prompt debridement and depth assessment by a trained foot service.
Spreading redness, warmth, purulence, lymphangitis, fever or systemic compromise requires urgent infection grading, antibiotics and source-control assessment.
Rest pain, coolness, pallor, delayed refill, tissue loss or absent pulses requires vascular review before debridement, padding or elective correction.
Investigations
01First-line standing and flexible-toe examinationFirst stepFirst line
Why
Classify deformity, pressure site, reducibility, metatarsophalangeal stability and footwear conflict.
Interpretation and limitations
Flexible tendon imbalance supports splint and exercise options; fixed or unstable joints require structural imaging and possible referral.
02First-line protective-sensation and vascular assessmentFirst line
Why
Identify neuropathy and arterial disease that convert callus into ulcer and treatment risk.
Interpretation and limitations
Use monofilament with skin, temperature, pulses and refill; abnormal findings require diabetic-foot or vascular pathways before self-treatment.
Correlate standing alignment with the precise callus and pain site; non-weight-bearing films can hide metatarsophalangeal instability.
04Doppler waveform and toe-pressure assessment
Why
Clarify perfusion when pulses are reduced, wounds fail or diabetes may make ankle pressure unreliable.
Differential diagnosis
01
Plantar wart
Interrupted skin lines, pinpoint capillary bleeding and pain with side-to-side compression suggest verruca rather than pressure-aligned callus.
02
Neuropathic ulcer
Callus with underlying cavity, haemorrhage, drainage or probeable depth in an insensate foot is tissue breakdown, not a benign corn.
03
Inflammatory forefoot
Several swollen joints, prolonged morning stiffness and progressive subluxation suggests rheumatoid arthritis or another inflammatory synovitis.
04
Morton neuroma
Burning web-space pain radiating into adjacent toes without fixed joint posture localises to the interdigital nerve.
05
Neuromuscular disorder
Cavus, distal wasting, foot drop, areflexia or family history indicates inherited or acquired neurological imbalance needing wider assessment.
Additional chapter-specific clues
Flexible versus fixed
Manual correction and posture change can straighten an early deformity; a rigid joint retains its angle and has fewer non-operative correction options.
Management
01First-lineMap deformity and pressureFirst stepFirst lineA corn, callus or lesser-toe deformity presents without active ulcer, infection or ischaemia.+
1Classify hammer, claw, mallet or crossover pattern, test reducibility and examine metatarsophalangeal stability.
2Inspect every pressure surface and footwear and assess monofilament sensation, pulses, refill and arch or hallux contribution.
3Provide adequate shoe length, width and depth and select a pad or spacer that unloads rather than transfers pressure.
4Arrange podiatry debridement for symptomatic thick callus and combine it with flexible-toe and calf-foot rehabilitation.
02High-risk footProtect skin and perfusionDiabetes, neuropathy, haemorrhagic callus, ulcer or reduced circulation is present.+
1Avoid blades, acidic corn products, constrictive pads and unverified shoes and inspect beneath callus through trained care.
Complications
01
Ulcer and infection
Dorsal, tip and plantar pressure can breach skin and progress to cellulitis, abscess, septic joint or osteomyelitis when neuropathy or ischaemia impairs warning and healing.
02
Fixed deformity
Capsular and tendon contracture reduces brace and shoe tolerance and makes correction more invasive than treatment during the flexible phase.
03
Transfer metatarsalgia
Metatarsophalangeal hyperextension exposes the metatarsal head to load, producing painful focal plantar callus and adjacent-ray overload.
04
Self-treatment injury
Blades and salicylic-acid corn products can cause cuts and chemical burns, especially in diabetes, neuropathy or peripheral arterial disease.
05
Postoperative stiffness or floating toe
Imperfect balancing can leave recurrence, non-purchase, transfer pain, infection, nerve symptoms or a toe that no longer contacts the ground.
Monitoring and follow-up
Record toe flexibility, metatarsophalangeal stability, callus site, shoe tolerance and walking or work limitation at each review.
Inspect skin after every pad, spacer, orthosis or shoe change and review sooner when protective sensation is reduced.
For diabetic feet, repeat NICE risk categorisation and ensure the correct podiatry or multidisciplinary follow-up interval.
Measure any ulcer and track depth, tissue, exudate, infection and offloading response rather than callus thickness alone.
Reassess pulses and vascular measures when tissue fails to heal, colour changes or rest pain appears.
After surgery, follow wound, alignment, wire or implant site, toe purchase, transfer callus and recurrence.
Special situations
Callus is a load record
Its location reveals repeated pressure and shear; removing keratin without changing that force produces predictable recurrence.
Blood beneath callus is an alarm
Haemorrhage indicates tissue damage and can be the only visible sign of an underlying ulcer in an insensate foot.
Toe posture changes with ankle position
Improvement when the ankle is plantar-flexed suggests long-flexor tension from calf or neurological mechanics rather than fixed joint contracture alone.
A corn can be soft
Interdigital moisture macerates keratin into a painful soft corn, usually where adjacent bony prominences compress each other.
Acid is dangerous without sensation
A patient who cannot feel chemical injury may continue salicylic-acid exposure until a deep burn or ulcer develops.
Surgery must rebalance load
Correcting a bent joint while ignoring plantar-plate failure, hallux crowding or metatarsal length can create floating toe and transfer pain.
Common pitfalls
01
Using hammer, claw and mallet interchangeably without documenting which joints are flexed and whether they correct.
02
Shaving callus repeatedly while leaving shoe contact, metatarsal overload and tendon imbalance unchanged.
03
Advising blades or corn plasters to a person with diabetes, neuropathy, poor circulation or fragile skin.
04
Failing to inspect beneath haemorrhagic callus for ulceration and infection.
05
Assuming a normal or high ankle pressure excludes arterial disease in a calcified diabetic circulation.
06
Operating on an isolated toe posture without addressing metatarsophalangeal instability, hallux conflict or neurological disease.
Refer painful fixed deformity, recurrent ulceration or failed shoe accommodation for procedure selection that corrects metatarsophalangeal instability and tendon imbalance, not the corn alone.
Rapidly progressive clawing, asymmetric weakness, cavus change or widespread sensory loss requires neurological investigation rather than shoe treatment alone.
A hot swollen neuropathic foot with changing shape requires immediate non-weight-bearing Charcot assessment.
Interpretation and limitations
Arterial calcification can yield falsely high ankle indices; toe pressure and waveform interpretation guide vascular referral.
05Targeted neurological and metabolic testing
Why
Investigate progressive, asymmetric or cavus-associated clawing and identify diabetes or systemic neuropathy.
Interpretation and limitations
Distal weakness, wasting, reflex loss or family history warrants neurology and possible electrodiagnosis or genetic assessment.
06Ultrasound or MRI for plantar-plate or mass question
Why
Define soft-tissue instability, neuroma or tumour when clinical examination remains uncertain.
Interpretation and limitations
Advanced imaging is not routine for a straightforward pressure corn or visible fixed toe deformity.
2Offload any ulcer, measure depth and assess clinical infection and arterial supply.
3Refer active diabetic-foot problems within the NICE timeframe, immediately for sepsis, gangrene, critical ischaemia or deep infection.
4Use Doppler waveforms, toe measures and vascular input when calcified arteries make ankle pressure unreliable.
03Stepwise correctionTreat the mechanical driverPain or recurrent pressure persists despite correctly fitted footwear, padding, podiatry and rehabilitation.+
1Obtain weight-bearing radiographs and identify flexibility, plantar-plate instability, metatarsal overload, hallux conflict and neurological balance.
2Refer for flexible tendon transfer or fixed-joint fusion or resection according to the actual deformity components.
3Correct metatarsophalangeal instability or metatarsal alignment when needed rather than excising a corn in isolation.
4Optimise skin, perfusion, diabetes, smoking, bone health and postoperative support before elective surgery.
04UrgentEscalate infection or tissue threatEscalationCallus opens, erythema spreads, pus, necrosis, rest pain or systemic illness develops.+
1Assess ABCDE, glucose, wound depth, perfusion and neurovascular status and remove pressure immediately.
2Obtain deep tissue or bone samples when clinically appropriate without delaying antibiotics in sepsis.
3Involve surgical, diabetic-foot and vascular services according to infection depth and limb perfusion.
4Do not rely on oral antibiotics or superficial swabs while abscess, osteomyelitis or critical ischaemia remains untreated.
Key medicines and prescribing safety2 treatments · regimens, roles and cautions+
Softens hyperkeratotic dry skin and reduces fissuring while footwear and pressure correction address the mechanical cause.
Urea foot cream for intact dry callused skin
Apply a urea-containing emollient, commonly 10% to 25%, thinly to intact dry plantar skin once or twice daily according to the product, avoiding toe webs, open ulcers and macerated or infected areas.
Do not substitute cream for trained debridement or offloading, stop if irritation occurs, and seek specialist advice before strong keratolytics in diabetes, neuropathy, poor circulation or broken skin.
Provides limited temporary relief while pressure is removed and callus or deformity receives definitive care.
Simple analgesia for pressure pain
Use paracetamol 500–1000 mg orally when required at least 4 hours apart, maximum 4 g in 24 hours, with a lower maximum for low weight, frailty, malnutrition or liver risk.
Check duplicate combination products and hepatic risk; analgesia must not permit continued loading of an ulcerated, ischaemic or infected pressure point.