What causes bunions?

Causes of Bunions

Bunions are primarily caused by foot deformities, which include abnormal foot structure and biomechanics that lead to increased plantar pressures and progressive deformity at the metatarsophalangeal joint. 1, 2

Primary Causes

• Foot deformities are a major cause of bunions, characterized by progressive deformity at the metatarsophalangeal joint, resulting in a painful dorsomedial prominence 2
• Abnormal biomechanics contribute to bunion formation, particularly when there is excessive subtalar joint pronation that affects foot alignment 3
• Congenital factors play a significant role, as many bunions develop due to inherited foot structure that predisposes individuals to this condition 2

Risk Factors

• Female gender is a significant risk factor, with bunions affecting approximately 35% of women over the age of 65 4
• Footwear choices, particularly narrow-toed shoes that compress the forefoot, can exacerbate bunion development and progression 5
• Aging increases the risk of bunion formation, with higher prevalence among older populations 2

Pathophysiology

• Joint incongruity develops as the bunion progresses, with subluxation of the sesamoid bones and decompensation of the metatarsophalangeal joint 6
• Increased plantar pressures result from the foot deformity, contributing to pain and further progression of the bunion 1
• Compensatory mechanisms initially may maintain joint congruity, but as the deformity progresses, the joint becomes incongruous and more symptomatic 6

Clinical Implications

• Pain and functional limitations result from bunions, potentially causing difficulties with shoe wear and contributing to falls in elderly patients 2
• Secondary complications may develop, including callus formation, corns, and skin breakdown at pressure points 5
• Mobility restrictions can occur due to bunion-related pain, leading to decreased physical activity which negatively impacts overall health 4

Prevention and Management Considerations

• Accommodative footwear with wide, soft-toed shoes is crucial for preventing progression and managing symptoms 5
• Muscle strengthening exercises may help reduce bunion-related pain and improve mobility by addressing potential muscle weakness that contributes to the condition 4
• Custom orthoses should be considered for patients with increased plantar pressures to redistribute pressure and potentially slow progression 1
• Daily foot inspection is important, especially for high-risk patients such as those with diabetes, as bunions increase the risk for ulceration 1

Special Considerations for High-Risk Populations

• Diabetic patients with bunions require special attention as they have increased risk for ulceration and potential amputation due to the combination of foot deformity and neuropathy 1
• Athletes may develop bunions that require specific management approaches, particularly if the deformity progresses rapidly 6
• Elderly patients with bunions face increased fall risk and may require more comprehensive interventions to maintain mobility and independence 2