Residency · Residency · Orthopedic Surgery
Hallux Valgus: Evaluation and Surgical Correction
Introduction
Hallux valgus (bunion) is the most common forefoot deformity, characterized by lateral deviation of the great toe and medial deviation of the first metatarsal. It affects approximately 23% of adults and up to 36% of older adults, with a strong female predominance. While many patients are managed successfully with nonoperative measures, surgical correction is frequently required for those with persistent pain and functional limitation.
Anatomy and Pathomechanics
The deformity involves a complex interplay of bony malalignment, soft tissue imbalance, and joint incongruity. First metatarsal primus varus describes medial deviation of the first metatarsal at the metatarsocuneiform (MTC) joint, accompanied by progressive lateral deviation of the proximal phalanx at the MTP joint. The medial eminence (the prominent medial aspect of the first metatarsal head) constitutes the "bunion."
As the deformity progresses, the abductor hallucis migrates plantarward and loses its corrective force. The adductor hallucis and lateral capsule contract, pulling the toe laterally. The sesamoids sublux laterally relative to the metatarsal head (or the metatarsal head displaces medially off the sesamoids). The extensor hallucis longus bowstrings laterally, worsening the deformity, and the medial capsule attenuates.
Risk Factors
Risk factors include female sex (9:1 female-to-male ratio for symptomatic disease), footwear (narrow pointed toe box and high heels contribute to progression but are not the sole cause), genetics (strong hereditary component with pes planus and first ray hypermobility running in families), hypermobility of the first tarsometatarsal joint, inflammatory arthritis (rheumatoid arthritis), and neuromuscular disorders (cerebral palsy, Charcot-Marie-Tooth).
Clinical Evaluation
History
Patients report medial bump pain from shoe pressure, difficulty fitting into shoes, pain under the lesser metatarsals (transfer metatarsalgia) from first ray insufficiency, and progressive deformity with the great toe crossing over or under the second toe.
Physical Examination
The hallux valgus angle is assessed clinically along with the deformity's flexibility (passively correctable vs. rigid). First ray mobility is evaluated, with excessive dorsal mobility suggesting first MTC joint hypermobility. Sesamoid position is assessed by palpation. The lesser toes are examined for crossover deformity, hammer toes, or claw toes. MTP joint range of motion is checked, with dorsiflexion of at least 50-60 degrees required for normal gait. Hindfoot alignment is evaluated, as associated pes planus may contribute.
Radiographic Assessment
Weight-bearing AP and lateral foot radiographs are mandatory. Key measurements on the AP view include the hallux valgus angle (HVA) (angle between the first metatarsal and proximal phalanx axes, normal less than 15 degrees), the intermetatarsal angle (IMA) (angle between the first and second metatarsal axes, normal less than 9 degrees), the distal metatarsal articular angle (DMAA) evaluating lateral tilting of the articular surface, and sesamoid position (graded 1-7 on the Hardy-Clapham scale, with subluxation beyond position 4 being significant). MTP joint congruity is assessed: a congruent joint has parallel articular surfaces while an incongruent joint has a laterally subluxed proximal phalanx. The first MTC joint is evaluated for arthritis, and overall foot alignment is assessed on the lateral view.
Nonoperative Management
Nonoperative measures include footwear modification (wide toe box, low heels, soft uppers), toe spacers and bunion pads to reduce pressure on the medial eminence, custom orthotics to control pronation and support the medial longitudinal arch, and activity modification with anti-inflammatory medications for acute symptoms. These measures do not correct the deformity but can effectively manage symptoms in many patients.
Surgical Decision-Making
Indications for Surgery
Surgery is indicated for persistent pain despite adequate nonoperative management, progressive deformity causing functional impairment, secondary lesser toe deformities (crossover second toe), and difficulty with shoe wear significantly impacting quality of life. Surgery should never be performed for cosmetic reasons alone.
Procedure Selection Based on Deformity Severity
| Severity | HVA | IMA | Procedure | Key Features |
|---|---|---|---|---|
| Mild | <30° | <13° | Distal chevron osteotomy | V-shaped cut at metatarsal head; 6-8 mm correction |
| Moderate | 30-40° | 13-16° | Proximal osteotomy (scarf, proximal chevron) | Greater correction; combined with distal soft tissue procedure |
| Severe | >40° | >16° | Lapidus (1st TMT arthrodesis) | Addresses hypermobility; most powerful IMA correction |
| Arthritic MTP | Any | Any | 1st MTP arthrodesis | Fused at 15-20° valgus, 10-15° dorsiflexion |
Mild Deformity (HVA < 30, IMA < 13)
The distal metatarsal osteotomy (chevron osteotomy) is the workhorse procedure. This V-shaped osteotomy at the metatarsal head allows lateral translation, combined with medial eminence resection and lateral soft tissue release (adductor hallucis, lateral capsule). It corrects up to 6-8 mm of lateral translation and can address DMAA abnormality with a biplanar modification.
Moderate Deformity (HVA 30-40, IMA 13-16)
Proximal metatarsal osteotomy (scarf, proximal chevron, or closing wedge osteotomy) provides greater correction than distal osteotomies. The scarf osteotomy is a Z-shaped diaphyseal osteotomy allowing translation, rotation, and shortening; it is versatile but technically demanding. These are always combined with a distal soft tissue procedure (modified McBride).
Severe Deformity (HVA > 40, IMA > 16)
The Lapidus procedure (first tarsometatarsal arthrodesis) addresses the deformity at its apex, particularly when first MTC joint hypermobility is present. It provides the most powerful correction of the IMA, eliminates hypermobility as a source of recurrence, and with modern fixation using locking plates, allows early weight-bearing.
Arthritic MTP Joint
First MTP arthrodesis is the gold standard for hallux valgus with degenerative changes at the MTP joint. The joint is fused in 15-20 degrees of valgus and 10-15 degrees of dorsiflexion relative to the first metatarsal. It provides reliable pain relief and eliminates recurrence. Patients must adapt to reduced toe motion but generally tolerate this well.
Postoperative Management
After distal osteotomies, patients bear weight in a stiff-soled shoe immediately with union at 6-8 weeks. Proximal osteotomies require protected weight-bearing for 6-8 weeks. The Lapidus procedure traditionally requires non-weight-bearing for 6-8 weeks, though modern protocols with locking plate fixation allow earlier weight-bearing. Progressive return to regular footwear occurs at 8-12 weeks with full activity at 3-6 months.
Complications
Recurrence is the most common long-term complication and may indicate undertreated hypermobility or inadequate correction. Hallux varus (overcorrection) results from excessive medial capsule plication, over-resection of the medial eminence, or excessive lateral release. Transfer metatarsalgia results from excessive shortening of the first metatarsal. Avascular necrosis of the metatarsal head is rare but risk is higher with combined medial and lateral soft tissue stripping. Nonunion is a particular concern with the Lapidus procedure (historically 5-10%, lower with modern fixation). Stiffness of the MTP joint may also occur.
Key Clinical Pearls
Always obtain weight-bearing radiographs; non-weight-bearing films underestimate the true deformity and lead to inadequate surgical planning. Match the procedure to the deformity: distal osteotomies for mild deformity, proximal osteotomies or scarf for moderate, and Lapidus for severe deformity or first ray hypermobility. The Lapidus procedure addresses the root cause of the deformity at the first tarsometatarsal joint and is the procedure of choice for severe hallux valgus with first ray hypermobility. Hallux varus from overcorrection is a difficult problem to manage; avoid excessive lateral release, particularly the fibular sesamoid ligament, in congruent joints.
References
- Coughlin MJ, Jones CP. Hallux valgus: demographics, etiology, and radiographic assessment. Foot Ankle Int. 2007;28(7):759-777.
- Robinson AHN, Limbers JP. Modern concepts in the treatment of hallux valgus. J Bone Joint Surg Br. 2005;87(8):1038-1045.
- Patel S, Ford LA, Etcheverry J, et al. Modified Lapidus arthrodesis: rate of nonunion in 227 cases. J Foot Ankle Surg. 2004;43(1):37-42.
- Easley ME, Trnka HJ. Current concepts review: hallux valgus part II: operative treatment. Foot Ankle Int. 2007;28(6):748-758.