Hammer Toe Deformity

The hammer toe deformity is one of the most common deformity of lesser toes of the foot. It’s used to describe an abnormal flexion posture of the proximal interphalangeal joint of one of the lesser four toes.

The distal joint usually stays supple, but it also may develop a flexion or an extension deformity.

The flexion deformity may be fixed (not passively correctable to the neutral position) or flexible (passively correctable).

It’s more common in women than in men, and the 2nd toe is more commonly involved.

See Also: Adult Hallux Valgus

Hammer Toe Causes

Causes of hammer toe deformity include:

1. Synovitis (the most common cause).
2. The long-term use of poorly fitting shoes
3. Foot trauma.
4. Untreated compartment syndrome in deep posterior compartment of the leg or foot that causes Complex regional pain syndrome (Sudeck atrophy).
5. It can be associated with cavus deformity, neuromuscular disease or inflammatory arthropathies.

See Also: Foot Anatomy

Differential Diagnosis

Lesser toe deformities include the following:

	Hammer Toe	Mallet Toe	Claw Toe
DIP	Extension	Flexion	Flexion
PIP	Flextion	Normal	Flexion
MTP	normal (slight extension)	Normal	Hyperextension

Clinical Evaluation

Three areas may be painful in this deformity:

1. The most common area is the dorsum of the proximal interphalangeal joint, where a hard corn caused by pressure from the toe box or vamp of the shoe develops.
2. When a flexion posture or end-bearing posture of the distal interphalangeal joint is present, a painful callus develops just plantar to the nail end. This is called an end corn.
3. Finally, a painful callus may develop beneath the metatarsal head if the proximal phalanx subluxates dorsally.

Radiology

The anterior-posterior, oblique, and lateral plain film radiographs are helpful in the evaluation of hammertoe deformities and should be taken with the patient being weight-bearing. It may be used to assess contractures, seeing into the medullary canal of the proximal phalanx is associated with hammertoe deformities, and this sign is called the “gun barrel.”

Imaging makes it further possible to evaluate the relative metatarsal lengths, identifying hallux valgus as well as metatarsus adductus by examining the overall forefoot alignment. This is particularly helpful during a pre-operative assessment. To determine the length of the hammertoe pre-operatively, a transverse line may be drawn on the radiograph from the tips of the distal phalanges of the adjacent digits on either side; a long toe would overlap this line.

Magnetic resonance imaging MRI series may be helpful in the event that there is a suspicion for a plantar plate rupture.

Treatment

Hammer toe treatment is dependent upon the flexibility of the deformity.

Flexible deformity

Nonoperative: protective padding, tall toe-box shoes, corrective hammer-toe splints are effective.

Operative: flexor tenotomy or flexor to extensor tendon transfer.

Fixed deformity

Nonoperative: accommodative shoes and protective padding can minimize callous formation. A corrective splint should NOT be used.

Operative: PIP arthroplasty (resection of distal neck and head of proximal phalanx) or PIP arthrodesis.

References & More

• Campbel’s Operative Orthopaedics 12th edition Book.
• Millers Review of Orthopaedics -7th Edition Book.
• Goransson M, Constant D. Hammertoe. [Updated 2022 May 30]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK559268/
• Malhotra K, Davda K, Singh D. The pathology and management of lesser toe deformities. EFORT Open Rev. 2017 Mar 13;1(11):409-419. doi: 10.1302/2058-5241.1.160017. PMID: 28461920; PMCID: PMC5367573.
• Coughlin MJ, Dorris J, Polk E. Operative repair of the fixed hammertoe deformity. Foot Ankle Int. 2000 Feb;21(2):94-104.