What Causes Bunions?
Bunions develop from progressive bony deformity at the metatarsophalangeal joint, creating a painful dorsomedial prominence, and are particularly common in older women. 1
Primary Etiologic Factors
The fundamental cause of bunion formation involves progressive structural deformity of the first metatarsophalangeal joint, leading to characteristic bony prominence. 1 While the provided evidence focuses heavily on bunions as a complication in diabetic foot care rather than primary etiology, the key causative mechanisms include:
Mechanical and Structural Factors
- Footwear pressure and friction contribute significantly to bunion development and symptom progression, particularly from shoes with inadequate toe box space 2
- Bony deformities at the metatarsophalangeal joint progress over time, with the joint becoming incongruous as sesamoids sublux in decompensated bunions 3
- Increased plantar pressures from prominent metatarsal heads accelerate deformity progression 4
Contributing Risk Factors
- Genetic predisposition plays a role, with bunions affecting approximately 35% of women over age 65 5
- Weak foot muscles may contribute to both bunion-related pain and progressive movement problems 5
- Rapid progression occurs when the joint becomes incongruous and sesamoids sublux laterally 3
Clinical Significance in High-Risk Populations
In diabetic patients specifically, bunions represent a critical foot deformity that substantially increases ulceration risk through elevated plantar foot pressures. 4 The combination of peripheral neuropathy, minor trauma, and foot deformity (including bunions) was present in over 63% of diabetic patients with ulcerations. 4
Key Clinical Pitfall
Do not dismiss bunions as merely cosmetic issues - they represent progressive structural deformities that increase fall risk in elderly patients and ulceration risk in those with neuropathy. 1, 4 Cosmesis alone is never an indication for surgical management. 1