Hallux Valgus (Bunion) Deformity: Understanding, Diagnosing, and Treating a Common Foot Condition
Hallux valgus, commonly referred to as a bunion, is a progressive foot deformity where the big toe drifts laterally (toward the second toe), while the first metatarsal bone deviates medially. This results in the classic “bump” on the side of the foot at the base of the big toe. Although it may look like a simple bony growth, hallux valgus is a complex, three-dimensional condition affecting bones, joints, ligaments, tendons, and muscles of the forefoot​.
What Causes Hallux Valgus?
The precise biomechanical cause of hallux valgus remains under investigation, but it is widely accepted that the condition stems from a combination of genetic and environmental factors. People with a family history of bunions are significantly more likely to develop them themselves, suggesting a hereditary component. Contributing factors also include:
- Female gender – women are far more commonly affected due to foot structure and footwear habits.
- Footwear – tight, narrow shoes and high heels place increased pressure on the forefoot.
- Aging – natural degeneration of soft tissue and joint structures contributes over time.
- Foot shape or biomechanics – flat feet (pes planus), hypermobility of the first ray, or tight calf muscles (equinus contracture) can all predispose to bunion formation​
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Recognizing the Symptoms
Patients with hallux valgus typically report:
- Pain on the inside of the foot, especially at the bunion site
- A visible bump over the joint
- Redness, swelling, or thickening of the overlying skin
- Trouble fitting into shoes
- Overlapping of the big toe and second toe in severe cases
- Secondary issues such as hammertoes or transfer metatarsalgia, where excess pressure shifts to the smaller toes
Importantly, the severity of pain does not always correlate with how prominent the bunion appears​
Clinical and Radiological Evaluation
Diagnosis begins with a physical examination. The foot is assessed while both seated and standing, with attention to skin condition, joint mobility, and pain location. Doctors evaluate for:
- First ray hypermobility
- Limited range of motion
- Alignment of the toes
- Concomitant deformities like hammertoes or flatfoot
Radiographs (X-rays) are critical. The key angles used for assessment include:
- Hallux Valgus Angle (HVA): angle between the first metatarsal and proximal phalanx of the big toe; normal <15°.
- Intermetatarsal Angle (IMA): angle between first and second metatarsals; normal <9°.
- Distal Metatarsal Articular Angle (DMAA): assesses joint congruency.
- Hallux Valgus Interphalangeus (HVI): used to decide if the toe itself is deformed, requiring a phalangeal osteotomy (e.g., Akin procedure)​
Emerging technologies such as weight-bearing CT scans allow for more precise 3D evaluation, especially helpful for identifying metatarsal rotation.
Non-Surgical Management
While non-operative care does not reverse the deformity, it can provide significant relief. Conservative options include:
- Shoe modifications – wide toe boxes and cushioned soles
- Toe spacers or bunion pads
- Custom orthotics – especially for patients with flat feet
- Physical therapy – including calf stretches
- Activity modifications
These methods are typically advised for patients with mild symptoms or those not ready for surgery​
Surgical Options
Surgery is indicated when pain persists despite conservative care. More than 100 procedures exist, but they are broadly categorized into:
1. Soft Tissue Procedures
- Modified McBride Procedure: Involves lateral release of tight structures and tightening of the medial capsule. Often done in combination with bone realignment procedures​
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2. Distal Metatarsal Osteotomies
- Chevron Osteotomy: For mild to moderate deformities; involves a V-shaped cut at the metatarsal head to realign the joint.
- Biplanar or Long Arm Chevron: Allows better correction of angular and rotational components.
3. Diaphyseal Osteotomy
- Scarf Osteotomy: A powerful mid-shaft cut that enables rotational and angular corrections. Technically demanding but effective​
4. Proximal Osteotomies
- Proximal Chevron, Crescentic, or Opening Wedge: Reserved for severe bunions. Some versions lengthen or shorten the metatarsal to restore balance.
5. Lapidus Procedure (First TMT Arthrodesis)
- Particularly effective for hypermobility or when deformity recurs. Involves fusing the base of the first metatarsal to the medial cuneiform. The triplanar version addresses all axes of deformity and can permit early weight-bearing​
6. First MTP Joint Fusion
- Used when arthritis is present or for failed prior surgeries. It reliably eliminates motion and pain while restoring alignment.
7. Minimally Invasive Surgery (MIS)
- Techniques such as SERI and MIS Chevron + Akin are gaining traction. Benefits include shorter incisions, less soft-tissue trauma, and faster recovery. However, more long-term studies are needed​
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Risks and Complications
Complications vary by procedure and include:
- Recurrence (8–78%)
- Avascular necrosis of the metatarsal head
- Transfer metatarsalgia
- Hardware-related pain
- Hallux varus (overcorrection)
Proper surgical planning and meticulous technique help minimize these risks​
Recovery and Postoperative Care
Postoperative protocols differ by procedure. Generally:
- Distal osteotomies: Full weight-bearing in a surgical shoe with bunion taping for 6 weeks.
- Lapidus or proximal osteotomies: Typically non-weight-bearing for 4–6 weeks, then gradual return.
- Radiographs are taken periodically to assess healing​
Conclusion
Hallux valgus is a multifaceted deformity that requires a comprehensive evaluation and individualized treatment plan. While non-surgical methods can manage symptoms, surgical correction remains the definitive approach for lasting relief and functional improvement. With recent advances in imaging, surgical technique, and fixation methods, outcomes continue to improve, offering patients renewed comfort and mobility.
Dr. Mo Athar
