Bunions

A bunion, known clinically as hallux valgus, is a progressive structural deformity of the joint at the base of the big toe. It develops when the big toe deviates toward the lesser toes, and the head of the first metatarsal bone shifts outward, creating the characteristic bony prominence on the inner edge of the foot. Bunions are one of the most common forefoot conditions worldwide, affecting up to 36% of adults over 65 and a significant number of younger adults -- particularly women.

In Singapore, the combination of genetic predisposition, common use of ill-fitting footwear (including narrow dress shoes and high heels), and a high proportion of flat-footed individuals makes bunions a frequently encountered condition. Despite being visible and often painful, many patients live with bunions for years before seeking specialist assessment -- partly due to the mistaken belief that surgery is the only option, or that bunion surgery means a long and difficult recovery.

Neither assumption is correct. Effective non-surgical management exists for mild and moderate bunions, and modern surgical techniques produce reliable correction with straightforward recovery.

Anatomy: What Happens in a Bunion

The first metatarsophalangeal (MTP) joint -- the joint where the big toe meets the foot -- is the largest joint in the forefoot and carries significant mechanical load with every step. It is stabilised by a combination of bony geometry, joint capsule, ligaments, and the intrinsic muscles of the foot.

Bunion development begins with a lateral drift of the big toe (hallux valgus -- the toe moving toward the little toe side) and a medial drift of the first metatarsal head (moving toward the midline of the body). As the deformity progresses, the joint capsule stretches on the inner side and becomes contracted on the outer side; the tendons that should pull the toe straight begin to pull it at an angle; and the sesamoid bones -- two small bones under the MTP joint that bear weight and protect the flexor tendon -- migrate laterally from their normal position.

The bony prominence on the inner aspect of the foot is not extra bone growth -- it is the head of the first metatarsal that has migrated out of alignment, combined with thickening of the overlying bursa (a fluid-filled sac that develops in response to friction). Over time, the joint cartilage can wear, causing a degree of osteoarthritis within the MTP joint.

Types of Bunions

While all bunions share the same underlying mechanism of hallux valgus deformity, several clinically distinct presentations are recognised.

Hallux valgus (classical bunion): The most common type. Deformity at the first MTP joint with medial prominence and lateral toe drift. Progressive and influenced by genetics, footwear, and foot mechanics.
Juvenile or adolescent bunion: Occurring in children and teenagers with open growth plates. Often has a strong hereditary component and may progress quickly during growth phases. Surgical management in children requires careful planning to avoid damage to the growth plates.
Congenital bunion: Present from birth. Associated with specific foot structural abnormalities.
Tailor's bunion (bunionette): A bony prominence at the base of the fifth (little) toe, caused by lateral bowing of the fifth metatarsal. The mechanism mirrors a classic bunion but on the opposite side of the forefoot. Often caused by narrow shoes that push the fifth metatarsal out.
Hallux valgus with associated deformities: In more severe or long-standing cases, the bunion causes secondary problems: hammer toe or crossover deformity of the second toe, metatarsalgia (pain under the ball of the foot), plantar calluses, and first MTP joint arthritis.

Symptoms associated with Bunions

Bunion symptoms range from none at all (particularly in mild deformities) to significant pain and functional limitation in more severe cases. The symptoms typically evolve gradually over years.

Local symptoms at the bunion

Bony prominence: The visible bump on the inner aspect of the foot at the base of the big toe
Pain and tenderness at the MTP joint: From joint inflammation, bursitis, or early arthritis
Skin changes: Redness, callus formation, or skin thickening over the bunion from footwear friction
Bursitis: Swelling of the fluid-filled sac overlying the bunion, particularly when shoe pressure is applied

Functional symptoms

Difficulty wearing shoes: The most consistently reported functional limitation. Many patients avoid closed shoes entirely or wear footwear two sizes too large to accommodate the deformity
Pain on walking: Typically worse with prolonged standing, uphill walking, or after exercise
Reduced range of motion: Stiffness at the MTP joint, particularly with push-off during walking
Numbness or tingling: From compression of the digital nerve on the inner side of the big toe by shoe pressure

Secondary symptoms from associated deformities

Second toe pain and crossover deformity -- as the big toe deviates, it pushes the second toe upward and medially, causing hammer toe deformity with dorsal and plantar calluses
Metatarsalgia -- pain under the ball of the foot as the big toe joint loses its ability to properly load, transferring excess pressure to the second and third metatarsal heads
Plantar calluses under the lesser metatarsal heads -- from abnormal forefoot loading
Altered gait -- subconscious avoidance of push-off through the big toe changes the walking pattern over time

Causes and Risk Factors

Structural and Biochemical Causes

Hereditary foot structure: The most significant cause. Approximately 70% of bunion patients have a positive family history. The inherited factors include first metatarsal length, ligament laxity, and the mechanics of the foot's arch.
Flat feet (pes planus): A collapsed medial arch changes the direction of forces through the first MTP joint, promoting lateral big toe drift
Loose limbs: Hypermobile joints allow greater deformation of the forefoot under load. Ligament laxity is common in women and increases during pregnancy due to relaxin hormone effects.
First metatarsal length -- a relatively long first metatarsal transfers more load to the first MTP joint during the propulsive phase of walking

Footwear and lifestyle factors

Narrow, pointed, or tight-toed shoes: Force the toes into a valgus position and accelerate deformity in those with an underlying structural predisposition. They do not cause bunions in structurally normal feet.
High heels: Shift weight onto the forefoot and increase pressure at the first MTP joint
Prolonged standing or walking occupations: Cumulative forefoot loading contributes to deformity progression

Medical Conditions

Rheumatoid arthritis: Inflammatory joint destruction loosens the ligamentous stabilisers of the MTP joint and commonly produces severe hallux valgus
Gout: Recurrent gout attacks in the first MTP joint can damage joint structure and contribute to deformity
Neuromuscular conditions: Spasticity or muscle weakness affecting foot mechanics can cause or worsen bunion deformity

Preventing Bunion Progression

While bunions caused by hereditary structural factors cannot be fully prevented, their progression can be significantly slowed:

Choose shoes with wide, round toe boxes that do not press the toes together: This is the single most impactful daily choice
Limit high-heel use: Keep heels below 5 cm for everyday use. If heels are worn occasionally, alternate with flat supportive shoes.
Wear supportive footwear with a firm heel counter and arch support: Not just sandals or slippers
Use custom orthotics if you have flat feet: They address one of the primary mechanical drivers of bunion progression
Maintain a healthy body weight: Reduced forefoot loading slows progression
Perform toe and foot strengthening exercises regularly -- strong intrinsic foot muscles better resist the deforming forces
Monitor your feet: If the bunion is visibly enlarging, or if second toe crossover begins to develop, seek assessment before the secondary deformity becomes established

How are Bunions Diagnosed?

Diagnosis is primarily clinical, based on history and physical examination. Imaging confirms the severity and guides treatment planning.

Clinical Examination:Visual assessment of the bunion deformity in standing (weight-bearing). Your doctor will perform palpation for tenderness at the joint, bursa, and adjacent structures. Assessment of big toe's range of motion and an examination for second toe crossover, hammer toe deformity, and metatarsalgia. It also involves assessment of your gait.
X-ray: X-rays of the foot are essential for assessing joint space preservation (arthritis), sesamoid position, and bone quality.
CT Scan: Three-dimensional bony assessment used in complex cases, revision surgery planning, and when first TMT joint arthritis or instability requires detailed assessment prior to a Lapidus procedure.
Ultrasound: Assesses the soft tissue component of the bunion -- bursa size, bursitis, and synovitis at the MTP joint. Used for ultrasound-guided corticosteroid injection when bursitis is causing acute pain.
MRI: Used when articular cartilage assessment is required, when sesamoid pathology is suspected, or when the diagnosis is uncertain. Not routinely needed for straightforward bunion assessment.
Gait Analysis: Formal gait analysis or in-shoe pressure measurement may be used in complex cases, in patients with associated neuromuscular conditions, or for designing custom orthotic devices to address abnormal forefoot loading patterns.