What is the Most Common Cause of Hammertoe?
The most common cause of hammertoe is ill-fitting footwear, particularly shoes that are too tight or have high heels, which leads to chronic mechanical stress and muscular imbalance in the toes.
Primary Etiology
The fundamental mechanism underlying hammertoe development involves an imbalance between the muscles and tendons that control toe movement 1. This imbalance specifically affects the antagonistic action between the toe extensors and intrinsic flexors at the metatarsophalangeal joint 2.
The Footwear Connection
Ill-fitting footwear is the predominant extrinsic factor driving hammertoe formation 1, 3. The pathophysiology is well-established:
- High-heeled shoes maintain chronic dorsiflexion of the toes, stretching plantar structures beyond their physiological length even during the foot-flat interval of walking 2
- This prolonged stretching causes age-related inefficiency of the plantar structures (intrinsic flexors, plantar joint capsule, and plantar aponeurosis) 2
- Measurements from lateral weight-bearing radiographs demonstrate significantly increased dorsiflexion in older age groups (means of 33-39° versus 23-25° in younger groups), suggesting cumulative elongation from years of improper footwear 2
Contributing Factors
While footwear is primary, other factors contribute:
- Genetic predisposition - some individuals have inherent structural vulnerabilities 1
- Trauma to the foot or toes 1
- Neuromuscular disorders including diabetic neuropathy 1, 3
- Plantar plate attenuation and rupture 3
- Morton's toe (second toe longer than first) - associated with increased risk of hammertoe development 4
Clinical Progression
The deformity progresses through a specific sequence:
- Hyperextension of the proximal phalanx becomes the primary deformity 2
- In this hyperextended position, the long extensor loses its tenodesis effect 2
- Flexion deformity of the proximal interphalangeal joint results secondarily 2
- Marked flexion at the PIP joint with extension at the MTP joint becomes established 3
Clinical Pitfalls
Do not assume all hammertoes have the same cause - while footwear is most common, rare causes like soft-tissue chondroma can present identically and require different management 5. Always perform thorough clinical examination and consider imaging when the presentation is atypical or unresponsive to conservative measures.
The diabetes connection deserves special attention: hammertoes in diabetic patients represent a significant risk factor for ulceration and require aggressive preventive management with appropriate footwear 6, 7, 6.