Claw Toe

Claw toe is a deformity of one or more lesser toes with hyperextension at the metatarsophalangeal joint and flexion at both the proximal and distal interphalangeal joints. The toe tip digs into the sole of the shoe, and the metatarsal heads are pushed down.

• Causes: neurological and muscular imbalance (intrinsic muscle weakness with unopposed long flexors and extensors) is the main mechanism. Common causes are Charcot-Marie-Tooth disease, diabetic and alcoholic peripheral neuropathy, spinal cord lesions (tethered cord, spinal dysraphism), stroke and cerebral palsy, Friedreich ataxia, rheumatoid arthritis, pes cavus, compartment syndrome of the leg or foot, trauma and ill fitting footwear.
• A unilateral or rapidly progressive claw toe deformity calls for a neurological and spinal workup.
• It is more severe than hammertoe, usually affects several toes in both feet, and is often accompanied by a cavus foot.

• Hyperextended metatarsophalangeal joints with flexed interphalangeal joints, painful dorsal corns over the proximal interphalangeal joints, tip corns and ulcers, painful plantar callus under the metatarsal heads, pain in shoes, and instability or dislocation of the metatarsophalangeal joint in advanced disease.
• The deformity is flexible early (it corrects when the ankle is plantarflexed, or on a push up test) and rigid late.
• Associated findings: high arch, hindfoot varus, weakness of dorsiflexion, reduced sensation, absent ankle reflexes, and spinal skin markers.
• Differential diagnosis: hammertoe, mallet toe, plantar plate rupture with metatarsophalangeal dislocation, rheumatoid deformity and post-traumatic deformity.
• Red flags: progressive weakness, bladder or bowel symptoms, back pain, sensory loss, ulceration, infection and rapid progression.
• Complications: plantar ulceration, osteomyelitis, metatarsophalangeal dislocation, chronic pain, gait change and falls.

• Clinical examination with a full neurological assessment (power, sensation, reflexes, gait), foot posture, perfusion and a family history.
• Weight bearing X-rays of the foot and ankle show joint subluxation, cavus alignment and arthritis. MRI of the spine in unexplained, progressive or unilateral claw toes. Nerve conduction studies and electromyography for neuropathy. Genetic testing for hereditary neuropathy when suspected.
• Blood tests: HbA1c, vitamin B12, thyroid function, CRP, rheumatoid markers, and alcohol and drug history.
• Probe ulcers to bone, and image for osteomyelitis.

• Treat the cause: glucose control and alcohol cessation, B12 replacement (hydroxocobalamin 1 mg IM on alternate days for 2 weeks then every 2 to 3 months if deficient), neurosurgical treatment of spinal lesions, and disease modifying drugs for rheumatoid arthritis.
• Conservative treatment for flexible deformity:
  • Deep, wide toe box shoes (extra depth), with soft uppers and a low heel.
  • Toe crest pads and sleeves, metatarsal pads or bars, custom orthoses to offload the heads, and silicone toe props.
  • Toe taping and stretching, and strengthening of the intrinsic muscles.
  • Callus and corn paring every 4 to 8 weeks by a podiatrist. Avoid acid plasters.
  • Paracetamol 1 g orally 6 hourly, short course NSAIDs, and for neuropathic pain gabapentin 300 mg at night increasing to 900 to 1800 mg daily, or duloxetine 30 to 60 mg daily.
• Surgery for pain, ulcer or progression after 3 to 6 months of failed care:
  • Flexible: flexor to extensor tendon transfer with extensor tendon lengthening and metatarsophalangeal capsule release.
  • Rigid: proximal interphalangeal joint resection arthroplasty or fusion, metatarsophalangeal release, and Weil shortening osteotomy for dislocation.
  • Great toe claw: transfer of the extensor hallucis longus to the neck of the first metatarsal with interphalangeal fusion.
  • In cavus feet, correct the foot deformity at the same time (first metatarsal osteotomy, plantar fascia release, calcaneal osteotomy).
  • Cefazolin 2 g IV prophylaxis. Pins stay 4 to 6 weeks, with a stiff soled shoe for 6 weeks.
• Infected ulcer or osteomyelitis: debridement and offloading, with amoxicillin clavulanate 875/125 mg orally 12 hourly for 7 to 14 days in mild soft tissue infection, or IV piperacillin tazobactam 4.5 g 6 to 8 hourly with vancomycin if severe, and 6 weeks for osteomyelitis without resection.
• Special groups:
  • Diabetes and neuropathy: therapeutic footwear, podiatry every 4 to 8 weeks, daily inspection, and early referral for any skin breakdown.
  • Children: refer to paediatric orthopaedics and neurology for evaluation of an underlying cause.
  • Pregnancy: supportive shoes and padding, paracetamol. Avoid NSAIDs after 20 weeks.
  • Renal impairment: reduce gabapentin dose.
• Follow up: review every 3 to 6 months. Refer to neurology for any neurological finding, and to orthopaedic foot surgery for ulceration, fixed deformity or progressive disease.