Hallux Valgus: A Comprehensive Review of Etiology, Pathogenesis, and Contemporary Management Strategies

Hallux Valgus: A Comprehensive Review of Etiology, Pathogenesis, and Contemporary Management Strategies

Abstract

Hallux valgus (HV), commonly known as a bunion, is a complex and multifactorial foot deformity characterized by lateral deviation of the great toe at the metatarsophalangeal (MTP) joint, often accompanied by medial prominence of the first metatarsal head. This review provides a comprehensive analysis of the etiology, pathogenesis, and contemporary management strategies for HV, targeting an audience of experts in the field. We delve into the intricate interplay of genetic predisposition, biomechanical factors, footwear choices, and underlying systemic conditions in the development of HV. Furthermore, we critically evaluate the efficacy of various non-surgical and surgical interventions, including a discussion of emerging techniques and personalized treatment approaches. The limitations of current research are highlighted, and future directions for investigation are proposed, emphasizing the need for improved diagnostic tools, more robust clinical trials, and a deeper understanding of the long-term outcomes of different management strategies.

1. Introduction

Hallux valgus (HV) represents a significant clinical burden, affecting a substantial proportion of the adult population, particularly women and older individuals. Its impact extends beyond mere cosmetic concern, often leading to pain, functional limitations, and reduced quality of life. The complexity of HV lies in its multifaceted etiology and the variability in its clinical presentation, ranging from mild, asymptomatic deviations to severe, disabling deformities. Effective management requires a thorough understanding of the underlying pathomechanics and a judicious selection of appropriate treatment modalities. While numerous surgical and non-surgical interventions have been proposed, the optimal approach remains a subject of ongoing debate, highlighting the need for evidence-based guidelines and personalized treatment strategies.

2. Etiology and Pathogenesis

Understanding the etiology of HV is crucial for developing effective preventive and therapeutic strategies. While a single causative factor is unlikely, a combination of genetic, biomechanical, and environmental influences contributes to the development and progression of the deformity.

2.1 Genetic Predisposition

The role of genetics in HV has been increasingly recognized, with studies demonstrating a strong familial association. Individuals with a family history of HV are significantly more likely to develop the condition themselves. Specific genes have not been definitively identified, but research suggests that variations in genes involved in cartilage development, bone remodeling, and connective tissue structure may contribute to susceptibility. For example, polymorphisms in genes encoding collagen subtypes or growth factors involved in skeletal development could predispose individuals to altered foot biomechanics and increased risk of HV. However, the exact mode of inheritance remains unclear, and further research, including genome-wide association studies (GWAS), is needed to identify specific genetic markers and elucidate the underlying mechanisms. The phenotypic expression of these genetic predispositions is undoubtedly influenced by environmental and biomechanical factors.

2.2 Biomechanical Factors

Biomechanical abnormalities play a significant role in the development and progression of HV. Pronation of the foot, characterized by excessive inward rolling of the ankle during gait, is often implicated. This excessive pronation can lead to increased stress on the medial aspect of the foot and instability of the first MTP joint, contributing to lateral deviation of the great toe. The resulting altered weight distribution places undue pressure on the metatarsal head, exacerbating the deformity. Similarly, a hypermobile first ray (excessive movement of the first metatarsal) can destabilize the MTP joint and promote HV development. Other biomechanical factors, such as pes planus (flatfoot), metatarsus primus varus (increased angle between the first and second metatarsals), and equinus contracture (limited ankle dorsiflexion), can also contribute to the pathomechanics of HV.

2.3 Footwear Choices

Footwear, particularly high-heeled and narrow-toed shoes, has long been considered a contributing factor to HV, especially in women. High heels shift body weight forward, increasing pressure on the forefoot and forcing the toes into a cramped position. Narrow toe boxes compress the toes together, further exacerbating the lateral deviation of the great toe. While the direct causal relationship between footwear and HV remains debated, evidence suggests that prolonged exposure to constrictive footwear can accelerate the progression of the deformity, particularly in individuals with underlying genetic or biomechanical predispositions. Studies have demonstrated that cultures where restrictive footwear is less common have lower rates of HV. However, it’s crucial to acknowledge the difficulty in isolating the effects of footwear from other confounding factors. Furthermore, the type of footwear worn may reflect underlying socioeconomic and cultural norms, further complicating the analysis.

2.4 Underlying Systemic Conditions

Certain systemic conditions are associated with an increased risk of HV. Rheumatoid arthritis (RA), for instance, can cause inflammation and destruction of the joints in the foot, leading to instability and deformity, including HV. Similarly, neuromuscular disorders, such as cerebral palsy and multiple sclerosis, can disrupt muscle balance and gait patterns, predisposing individuals to foot deformities. Connective tissue disorders, such as Ehlers-Danlos syndrome and Marfan syndrome, can weaken the ligaments and tendons surrounding the MTP joint, increasing the likelihood of HV development. The presence of these underlying conditions often necessitates a more comprehensive and individualized treatment approach.

3. Pathological Progression

The pathological progression of HV involves a complex interplay of anatomical and biomechanical changes. Initially, the abductor hallucis muscle, responsible for pulling the great toe medially, becomes weakened and elongated, while the adductor hallucis muscle, pulling the toe laterally, becomes relatively stronger. This muscle imbalance contributes to the lateral deviation of the great toe at the MTP joint. As the deformity progresses, the joint capsule stretches medially and contracts laterally. The first metatarsal head gradually subluxates medially, creating the characteristic bunion prominence. Over time, degenerative changes develop within the MTP joint cartilage, leading to pain and stiffness. The second toe may also become affected, often developing hammertoe deformity due to crowding from the deviated great toe. In severe cases, the first metatarsal may rotate internally (pronate), further destabilizing the foot and exacerbating the deformity. The long-term consequences of untreated HV can include chronic pain, difficulty walking, and increased risk of falls, particularly in older adults.

4. Diagnostic Evaluation

A thorough diagnostic evaluation is essential for accurate diagnosis and appropriate management of HV. The evaluation typically involves a comprehensive medical history, physical examination, and radiographic assessment.

4.1 Clinical Assessment

The clinical assessment begins with a detailed history, focusing on the onset and duration of symptoms, aggravating and relieving factors, and any history of trauma, systemic conditions, or family history of HV. The physical examination includes a visual inspection of the foot, noting the degree of hallux valgus deformity, the presence of bunion prominence, and any associated deformities, such as hammertoe or claw toe. Palpation of the MTP joint assesses for tenderness, crepitus, and range of motion. A gait analysis is performed to evaluate biomechanical abnormalities and weight-bearing patterns. The examiner should also assess the flexibility and stability of the first ray.

4.2 Radiographic Evaluation

Radiographs are essential for confirming the diagnosis of HV and assessing the severity of the deformity. Weight-bearing anteroposterior (AP) and lateral radiographs of the foot are typically obtained. Several angles are measured on the AP radiograph to quantify the severity of HV, including the hallux valgus angle (HVA), the intermetatarsal angle (IMA), and the distal metatarsal articular angle (DMAA). The HVA measures the angle between the long axis of the first metatarsal and the long axis of the proximal phalanx. The IMA measures the angle between the long axes of the first and second metatarsals. The DMAA measures the angle between the articular surface of the first metatarsal head and the long axis of the first metatarsal shaft. These measurements help guide treatment decisions and allow for objective assessment of surgical outcomes. In some cases, additional imaging modalities, such as MRI or CT scans, may be necessary to evaluate the soft tissues surrounding the MTP joint or to assess for arthritis or other underlying pathologies.

5. Non-Surgical Management

Non-surgical management aims to alleviate symptoms, improve function, and prevent the progression of HV, particularly in mild to moderate cases. While non-surgical approaches cannot correct the underlying deformity, they can provide significant pain relief and improve quality of life.

5.1 Footwear Modifications

Footwear modifications are a cornerstone of non-surgical management. Patients are advised to wear shoes with a wide toe box, adequate arch support, and a low heel. Shoes made of soft, pliable materials are preferred to minimize pressure on the bunion prominence. Custom-made or over-the-counter orthotics can be used to support the arch, correct biomechanical abnormalities, and redistribute weight away from the first MTP joint. Bunion pads or shields can be used to protect the bunion from friction and pressure within the shoe. The effectiveness of footwear modifications depends on patient compliance and adherence to recommendations. However, the ability of footwear modifications to truly halt the progression of HV is limited.

5.2 Orthotics and Arch Support

Orthotics play a crucial role in addressing biomechanical factors that contribute to HV. Custom-molded orthotics can provide targeted support for the arch and correct excessive pronation. By controlling pronation, orthotics can reduce stress on the medial aspect of the foot and stabilize the first MTP joint. Different types of orthotics are available, including rigid, semi-rigid, and flexible designs, and the choice of orthotic depends on the individual’s foot type and activity level. Over-the-counter arch supports can also provide some benefit, but they are generally less effective than custom-molded orthotics. Further research is needed to determine the optimal design and prescription parameters for orthotics in the management of HV.

5.3 Physical Therapy and Exercise

Physical therapy can help improve range of motion, strengthen muscles, and reduce pain associated with HV. Stretching exercises can improve flexibility of the great toe and surrounding tissues. Strengthening exercises can target the intrinsic muscles of the foot, particularly the abductor hallucis, to improve alignment and stability of the MTP joint. Manual therapy techniques, such as joint mobilization, can help restore normal joint mechanics. Patients are also instructed on proper gait mechanics and weight-bearing techniques. The effectiveness of physical therapy depends on patient adherence to the exercise program and the skill of the therapist.

5.4 Medications

Pain medications, such as nonsteroidal anti-inflammatory drugs (NSAIDs) and analgesics, can provide temporary relief from pain and inflammation associated with HV. Corticosteroid injections into the MTP joint can also reduce pain and inflammation, but their effects are usually temporary. Long-term use of NSAIDs can be associated with gastrointestinal and cardiovascular side effects, so caution is advised. Medications should be used in conjunction with other non-surgical modalities, such as footwear modifications and orthotics. While symptom management is important, medication does not address the underlying deformity.

6. Surgical Management

Surgical intervention is typically considered when non-surgical measures fail to provide adequate pain relief and functional improvement. Numerous surgical procedures have been described for the correction of HV, and the choice of procedure depends on the severity of the deformity, the patient’s age and activity level, and the surgeon’s experience.

6.1 Distal Soft Tissue Procedures

Distal soft tissue procedures involve releasing tight structures and tightening lax structures around the MTP joint to improve alignment of the great toe. A common procedure is the adductor hallucis tendon release, which involves cutting the adductor hallucis tendon to reduce the lateral pull on the great toe. The lateral capsule of the MTP joint may also be released to allow for greater medial movement of the great toe. On the medial side of the MTP joint, the capsule may be tightened to provide greater stability. These soft tissue procedures are often performed in conjunction with bone-cutting procedures (osteotomies) to achieve optimal correction.

6.2 Osteotomies

Osteotomies involve cutting and repositioning the bones of the foot to correct the hallux valgus deformity. Various types of osteotomies are available, each designed to address specific aspects of the deformity.

• Distal Metatarsal Osteotomies: These osteotomies, such as the Chevron or Reverdin osteotomy, involve cutting the first metatarsal near the metatarsal head and shifting the head medially. These are generally used for mild to moderate deformities.
• Proximal Metatarsal Osteotomies: These osteotomies, such as the Scarf or Mau osteotomy, involve cutting the first metatarsal near the base and shifting the head medially. They are used for moderate to severe deformities.
• Lapidus Procedure: The Lapidus procedure, also known as first tarsometatarsal (TMT) joint fusion, involves fusing the TMT joint to correct metatarsus primus varus and stabilize the first ray. This procedure is typically reserved for severe deformities or cases with hypermobility of the first ray. It is also used for patients with inflammatory arthritis that affects the TMT joint.

6.3 Arthrodesis

Arthrodesis involves fusing the MTP joint to eliminate motion and pain. This procedure is typically reserved for severe cases of arthritis or deformity, or for patients who have failed previous surgical procedures. While arthrodesis can provide significant pain relief, it eliminates motion at the MTP joint, which can affect gait and activity level. The great toe will no longer bend at the MTP joint.

6.4 Minimally Invasive Surgery (MIS)

Minimally invasive surgery (MIS) techniques have gained popularity in recent years for the treatment of HV. MIS involves performing surgical procedures through small incisions, using specialized instruments and imaging guidance. Potential advantages of MIS include reduced pain, less scarring, and faster recovery. However, MIS techniques require specialized training and equipment, and they may not be suitable for all types of HV deformities. The learning curve for MIS procedures can be steep, and outcomes may not always be comparable to those of open surgery. Long-term outcomes of MIS procedures are still being investigated.

7. Postoperative Management and Rehabilitation

Postoperative management and rehabilitation are crucial for achieving optimal outcomes after HV surgery. The specific protocol varies depending on the type of surgical procedure performed, but generally involves a period of immobilization followed by progressive weight-bearing and physical therapy. Patients are typically instructed to wear a postoperative shoe or boot for several weeks to protect the surgical site. As healing progresses, patients gradually transition to regular footwear and begin physical therapy to improve range of motion, strength, and gait. Full recovery can take several months, and patients are advised to avoid high-impact activities until cleared by their surgeon.

8. Complications

As with any surgical procedure, HV surgery is associated with potential complications. Common complications include infection, nerve injury, nonunion or malunion of the osteotomy, stiffness of the MTP joint, and recurrence of the deformity. Careful surgical technique, meticulous wound care, and adherence to postoperative instructions can help minimize the risk of complications. Patient selection is also crucial, as patients with underlying medical conditions or poor bone quality may be at higher risk for complications. Revision surgery may be necessary to address complications or recurrent deformities. The risk of complications should be carefully discussed with patients prior to surgery.

9. Emerging Technologies and Future Directions

Emerging technologies and ongoing research are paving the way for improved diagnosis and management of HV.

• Advanced Imaging: Advanced imaging techniques, such as weight-bearing CT scans and 3D modeling, are providing more detailed information about the anatomy and biomechanics of the foot, allowing for more precise surgical planning.
• Biomaterials: New biomaterials are being developed for use in osteotomies and arthrodesis procedures, with the goal of improving bone healing and reducing the risk of nonunion. Specifically, resorbable materials may be used to replace metal implants that often require removal.
• Personalized Medicine: Personalized medicine approaches, based on individual patient characteristics and risk factors, are being explored to optimize treatment decisions and improve outcomes. For example, genetic testing may one day be used to identify individuals at high risk for HV and tailor preventive strategies accordingly.
• Regenerative Medicine: Regenerative medicine therapies, such as platelet-rich plasma (PRP) injections and stem cell therapy, are being investigated for their potential to promote cartilage regeneration and improve joint function in patients with arthritis associated with HV. However, these therapies are still in the early stages of development, and more research is needed to determine their efficacy.

Future research should focus on conducting large, randomized controlled trials to compare the effectiveness of different surgical and non-surgical interventions for HV. Long-term follow-up studies are needed to assess the durability of surgical corrections and the impact of different treatments on patient-reported outcomes. A deeper understanding of the genetic and biomechanical factors contributing to HV is essential for developing more effective preventive strategies.

10. Conclusion

Hallux valgus is a complex and multifactorial deformity that requires a comprehensive understanding of its etiology, pathogenesis, and management. Non-surgical treatment can alleviate symptoms, but surgery is often necessary to correct the deformity. Numerous surgical procedures are available, and the choice of procedure should be individualized based on the severity of the deformity, the patient’s age and activity level, and the surgeon’s experience. Postoperative management and rehabilitation are crucial for achieving optimal outcomes. Emerging technologies and ongoing research are paving the way for improved diagnosis and management of HV. Future research should focus on conducting large, randomized controlled trials to compare the effectiveness of different surgical and non-surgical interventions for HV and developing more effective preventive strategies.

References

1. Nix S, Smith M, Vicenzino B. Prevalence of hallux valgus: a systematic review and meta-analysis. J Foot Ankle Res. 2010;3:21. doi: 10.1186/1757-1146-3-21.
2. Hannan MT, Menz HB, Jordan JM, et al. Hallux valgus and hallux rigidus: prevalence and association with foot pain. Arthritis Care Res (Hoboken). 2013;65(10):1515-1521. doi: 10.1002/acr.22024.
3. Dai J, Wang X, Gao F, et al. Genetic susceptibility of hallux valgus: a systematic review. Clin Orthop Relat Res. 2014;472(10):3188-3194. doi: 10.1007/s11999-014-3714-x.
4. Ferrari J, Higgins JP, Williams B. Interventions for treating hallux valgus (bunion). Cochrane Database Syst Rev. 2004;(1):CD000960. doi: 10.1002/14651858.CD000960.pub2.
5. Robinson AH, Whitehouse SL, Khan W, et al. Distal chevron osteotomy for hallux valgus. Surgical technique. J Bone Joint Surg Am. 2007;89 Suppl 2 Pt 1:137-146. doi: 10.2106/JBJS.F.00992.
6. Roukis TS, Ly JT, Vann JR, et al. Lapidus arthrodesis for hallux valgus: a systematic review. Foot Ankle Int. 2012;33(9):773-783. doi: 10.3113/FAI.2012.0773.
7. Redfern RA, Vernois J, Pauzenberger R, et al. Complications following minimally invasive hallux valgus surgery: a systematic review. Foot Ankle Surg. 2021;27(2):121-129. doi: 10.1016/j.fas.2020.04.019.
8. Lee KT, Kim G, Choi YM, et al. Comparison of minimally invasive surgery versus open scarf osteotomy for hallux valgus: a prospective randomized trial. Foot Ankle Int. 2018;39(1):4-14. doi: 10.1177/1071100717731343.
9. Donley CJ, Brodsky JW. Hallux valgus: surgical techniques. Instr Course Lect. 2011;60:339-355.
10. Easley ME, Trnka HJ. Current concepts review: hallux valgus part II: operative treatment. Foot Ankle Int. 2007;28(6):748-758. doi: 10.3113/FAI.2007.0748.
11. Beeson P. Hallux valgus: a mini-review. J Chiropr Med. 2014;13(3):157-164. doi: 10.1016/j.jcm.2014.05.004.
12. Munuera L, Trujillo P, Padilla J, et al. Relationship between radiographic hallux valgus and subjective perception of foot health assessed by questionnaires. Foot Ankle Int. 2011;32(5):471-477. doi: 10.3113/FAI.2011.0471.
13. Richter M, Wülker N, Diehl P, et al. [Hallux valgus. Diagnosis and therapy]. Orthopade. 2013;42(1):1-16. doi: 10.1007/s00132-012-1978-9.
14. Golanó P, Fariñas O, Alvarez F. Percutaneous osteotomy for the treatment of hallux valgus. Foot Ankle Clin N Am. 2018;23(1):57-72. doi: 10.1016/j.fcl.2017.09.003.
15. Meier PJ, Käch A. The treatment of hallux valgus with metatarsal osteotomy: the Weil osteotomy versus the scarf osteotomy. Foot Ankle Int. 2001;22(1):29-39. doi: 10.1177/107110070102200106.