Orthopaedic Surgery - Hammer Toes

Basics

A hammer toe is a lesser-toe deformity characterized primarily by flexion at the proximal interphalangeal (PIP) joint.

The distal interphalangeal (DIP) joint is usually extended, while the metatarsophalangeal (MTP) joint may remain neutral or become mildly extended.

The deformity may be flexible or rigid.

Epidemiology

Hammer toes are common and may be present in up to approximately 20% of patients presenting with foot disorders.

They occur more frequently in females than males.

Prevention

Because constrictive footwear is a major contributing factor, prevention focuses on wearing shoes with a wide, deep toe box that allows adequate room for the lesser toes.

Shoes that compress the forefoot or force the toes into a flexed position should be avoided.

Etiology

The most common cause is poorly fitting footwear, particularly shoes with a narrow or shallow toe box.

Other associated causes include:

Neuromuscular disease, diabetes mellitus, inflammatory arthropathy, and previous compartment syndrome.

Pathophysiology

Hammer toe develops from an imbalance between the intrinsic and extrinsic muscles and tendons controlling the lesser toes.

Abnormal forces progressively alter PIP and MTP alignment.

Initially, the deformity may remain flexible, but chronic imbalance can lead to capsular contracture and a fixed rigid deformity.

Associated Conditions

Hammer toes frequently coexist with other forefoot abnormalities.

Hallux Valgus

A bunion or hallux valgus deformity may crowd the lesser toes and contribute to development or progression of hammer toe.

MTP Hyperextension

When substantial MTP dorsiflexion accompanies the deformity, the clinical pattern may overlap with a claw toe.

Diagnosis

Diagnosis is primarily clinical.

The examination should define the location of deformity, degree of flexibility, associated MTP instability, and the source of pain.

Signs and Symptoms

Dorsal PIP Prominence

A prominent PIP joint is usually visible over the dorsum of the affected toe.

This prominence may rub against footwear.

Erythema

Repeated shoe pressure may produce localized redness over the prominent joint.

Callus Formation

A painful dorsal callus or corn may develop because of chronic pressure between the PIP prominence and the shoe.

History

Patients commonly report pain over the dorsal PIP prominence, particularly when wearing closed shoes.

Symptoms often improve with wider footwear or removal of the shoe.

Metatarsalgia

Some patients also develop pain beneath the metatarsal heads because altered toe mechanics transfer pressure to the plantar forefoot.

Physical Examination

Flexibility

The examiner should determine whether the deformity is flexible or rigid.

A flexible hammer toe can be passively corrected toward normal alignment, whereas a rigid deformity cannot.

MTP Joint

The MTP joint should be examined for dorsal subluxation, instability, or fixed hyperextension.

MTP instability may influence both treatment and prognosis.

Hallux Valgus

The foot should be inspected for an associated bunion deformity because hallux valgus can worsen crowding of the lesser toes.

Skin

The dorsal PIP joint and plantar forefoot should be examined for calluses, corns, ulceration, erythema, and pressure-related skin breakdown.

This is particularly important in patients with diabetes or neuropathy.

Imaging

Plain radiographs may confirm the PIP flexion deformity and demonstrate associated abnormalities such as MTP subluxation, hallux valgus, or degenerative change.

Weight-bearing views are generally most useful when overall forefoot alignment is being assessed.

Differential Diagnosis

Claw Toe

A claw toe usually demonstrates MTP hyperextension with flexion of both the PIP and DIP joints.

The MTP abnormality is typically more pronounced than in an isolated hammer toe.

Mallet Toe

A mallet toe consists primarily of flexion at the DIP joint.

The PIP joint is usually relatively neutral.

Treatment

General Principles

Treatment is directed toward symptoms rather than appearance alone.

Initial management is usually nonoperative and aims to reduce pressure on the prominent toe, accommodate the deformity, and improve comfort.

Footwear Modification

Shoes with a wide and high toe box should be used to minimize pressure over the dorsal PIP joint.

Avoidance of tight or pointed shoes is an important part of treatment.

Flexible Hammer Toe

A flexible deformity may improve symptomatically with a Budin splint or similar toe-straightening device.

The splint helps hold the toe in a more extended position and decreases dorsal pressure.

Rigid Hammer Toe

When the deformity is rigid, correction with a splint is less effective.

Treatment focuses on reducing local pressure.

Padding

Doughnut-shaped pads, silicone gel sleeves, and other protective devices may decrease friction and pressure over the dorsal prominence.

Geriatric Considerations

Hammer toes are particularly common in older women.

Many elderly patients also have medical conditions that increase operative risk or impair wound healing.

Diabetes and Vascular Disease

In patients with diabetes mellitus, peripheral neuropathy, or peripheral vascular disease, nonoperative treatment should be maximized whenever possible.

Skin integrity must be monitored closely because pressure points can progress to ulceration.

Surgery

Surgery is considered when persistent pain, shoe intolerance, ulceration, or progressive deformity continues despite appropriate nonoperative treatment.

The procedure depends largely on whether the toe remains flexible or has become rigid.

Flexible Hammer Toe Surgery

A flexor-to-extensor tendon transfer may be used for selected flexible deformities.

The procedure redirects flexor force to help extend the PIP joint and rebalance the toe.

Rigid Hammer Toe Surgery

Rigid deformities usually require a bony procedure.

Resection Arthroplasty

One of the most commonly performed operations is resection arthroplasty of the distal portion of the proximal phalanx.

The toe may then be temporarily stabilized with a pin while the soft tissues heal in corrected alignment.

Intramedullary Implants

Intramedullary fixation devices have increasingly been used as alternatives to external pins.

Potential advantages include avoidance of an exposed pin and improved patient convenience, although implant-related complications can still occur.

PIP Arthrodesis

Fusion of the PIP joint is another common option for painful rigid hammer toe.

It can be used both for primary correction and for revision of recurrent deformity.

Referral

Patients whose symptoms persist despite shoe modification, padding, or splinting may benefit from surgical consultation.

Diabetes

Patients with diabetes, neuropathy, or threatened skin breakdown should be assessed early because progressive pressure may lead to neuropathic ulceration or infection.

Prognosis

Hammer toe deformities commonly progress gradually over time.

Flexible deformities may become rigid as soft tissues contract.

Pain, callus formation, and difficulty wearing shoes may increase as the deformity worsens.

Complications

Potential postoperative complications include:

Stiffness, wound infection, persistent pain, incomplete correction, implant irritation, and recurrence of deformity.

Patient Monitoring

Follow-up should assess pain, shoe tolerance, skin condition, callus formation, flexibility of the toe, MTP stability, and progression of deformity.

Patients with diabetes or neuropathy require particularly careful surveillance for pressure-related skin breakdown and ulceration.