Hallux Valgus

Effective treatment of HV depends on a solid understanding of the anatomy involved (see the images below).

During the gait cycle, the hallux and the digits generally remain parallel to the long axis of the foot, regardless of the degree of forefoot abduction (or pronation) occurring (see the image below). This is because of the pull of the conjoined adductor tendon, EHL tendon, and flexor hallucis longus (FHL) tendon. The tendons gain greater mechanical advantage the further the joint is displaced, with tension created in the medial aspect of the joint and compression laterally.

Medial tension causes the medial collateral ligaments to pull on the dorsomedial aspect of the first MT head, causing bony proliferation. Lateral tension causes the sesamoid apparatus to fixate in a laterally dislocated position. Remodeling also occurs laterally in addition to medially, as evidenced by the increase of the proximal articular set angle (PASA) or structural remodeling of the cartilage. Therefore, without correction of the biomechanical factors, excessive pronation continues, with propagation of the deformity.

HV is known to have numerous etiologies, including biomechanical, traumatic, and metabolic factors. The most common etiology, yet the most difficult to understand, is biomechanical instability. Contributing factors, if present, may include the following:

• Gastrocnemius or gastrocnemius-soleus equinus
• Flexible or rigid pes planovalgus
• Rigid or flexible forefoot varus
• Dorsiflexed first ray
• Hypermobility
• Short first MT

Most often, pronation at the midtarsal and subtalar joints compensates for these factors throughout the gait cycle. However, excessive pronation produces too much midfoot mobility, which decreases stability and prevents resupination and creation of a rigid lever arm; these effects make propulsion difficult, with resultant jamming at the first metatarsophalangeal (MTP) joint. 

The hallux and the first MT (also commonly referred to as the first ray) are inherently unstable, secondary to their axial position. Biomechanical stabilizers exist in the form of ligamentous and capsular attachments; dynamic stabilizers include long tendon insertions from the peroneus longus and the instrinsic musculature.[1]  

Footwear-based attempts to stabilize this first ray further, however, can keep the hallux in an abducted position if HV is present, causing mechanical stretch and deviation of the medial soft tissue and aggravating symptoms. In addition, tight shoes can cause medial bump pain and nerve entrapment. 

During normal propulsion, approximately 65° of dorsiflexion is necessary at the first MTP joint, yet only 20-30° is available from hallux dorsiflexion. Therefore, the first MT must plantarflex at the sesamoid complex to gain the additional 40° of motion needed. Failure to attain the full 65° because of jamming of the joint during pronation subjects the first MTP to intense forces from which hallux valgus can develop.

If the foot is sufficiently hypermobile as a result of excessive pronation, the metatarsal tends to drift medially while the hallux drifts laterally, producing HV. If no hypermobility is present, hallux rigidus develops instead.

Arthritic or metabolic conditions that may cause HV include inflammatory arthropathies such as gouty arthritis, rheumatoid arthritis (see the images below), and psoriatic arthritis, as well as connective tissue disorders such as Ehlers-Danlos syndrome, Marfan syndrome, Down syndrome, and generalized ligamentous laxity.

The myriad neuromuscular diseases that may cause HV include multiple sclerosis, Charcot-Marie-Tooth disease, and cerebral palsy.

Traumatic conditions that may cause HV include malunions secondary to first-MT fractures with or without intra-articular damage, soft-tissue injuries of the hallux, and sequelae of dislocations.

Structural deformities that have been associated with HV include malalignment of articular surface or MT shaft, abnormal MT length, metatarsus primus elevatus, external tibial torsion, genu varum or valgum, and femoral retrotorsion.

In a case-control study assessing the role played by the morphology of the first tarsometatarsal (TMT) joint (TMT1) in the etiology of HV, Ji et al compared an HV group (82 feet) with a control group (79 feet).[2] The HV group had a significantly wider middle-facet width (MFW; 9.9 vs 8.7 mm), a lower inferior lateral-facet height (ILFH; 1.7 vs 2.5 mm), a smaller inferior lateral-facet angle (ILFA; 16.3º vs 24.5º), and a larger TMT1 angle (1.9º vs 0.9º). Four types of TMT1 morphology were identified: continuous-flat, separated-flat, continuous-protruded, and separated-protruded. The continuous-flat type was found to be associated with more severe HV and TMT1 instability.

Sovilj et al performed a study (315 feet with HV) aimed at determining whether the anatomic orientation of the first metatarsocuneiform (MTC) joint (oblique, 165 feet; transverse, 145; convex, 5) affected the size of the HV angle (HVA) and the first intermetatarsal angle (IMA) and whether it contributed to the dynamics of the development of HV.[3]  An oblique anatomic orientation of the first MTC joint was found to be associated with more severe HV and with faster development of the deformity. 

Although hallux valgus is a common condition that accounts for a significant number of office visits to foot and ankle specialists, its incidence has not been documented accurately. Relatively few studies have been published, and much of the information has consisted of empirical data with low levels of evidence.

The National Health Interview Survey conducted by the National Center for Health Statistics found that hallux valgus affected approximately 1% of adults in the United States.[4] Gould et al found that the incidence increased proportionately with age, from 3% in persons aged 15-30 years to 9% in persons aged 31-60 years to 16% in those older than 60 years. Gould et al also reported a two- to fourfold higher incidence in females than in males. Whether this finding indicates a true sex-based dimorphism or whether it reflects differences in footwear remains to be determined.

The role of genetic predisposition has also been noted, with evidence to suggest familial tendencies.

Hallux valgus is a complex deformity, and various approaches are available. To date, no satisfactory studies have been performed to compare the various procedures and their success rates. If the deformity and etiology are addressed successfully, the benefits of treatment far outweigh the risks.[5, 6]

Schuh et al studied changes of plantar pressure distribution during the stance phase of gait in patients who underwent hallux valgus surgery followed by multimodal rehabilitation.[7] The study included 30 patients who underwent Austin and scarf osteotomy for correction of mild-to-moderate hallux valgus deformity and began a rehabilitation program 4 weeks postoperatively (once weekly for 4-6 weeks). Plantar pressure analysis was performed preoperatively and at 4 weeks, 8 weeks, and 6 months postoperatively. Range of motion (ROM) of the first MTP joint was also measured.

The results of this study included an increased mean American Orthopaedic Foot and Ankle Society (AOFAS) score, from 60.7 points preoperatively to 94.5 points 6 months after surgery, as well as increased ROM of the first MTP joint at 6 months, with a significant increase in isolated dorsiflexion.[7]  In the first metatarsal head region, maximum force increased from 117.8 N to 126.4 N, and the force-time integral increased from 37.9 N⋅s to 55.6 N⋅s. In the great-toe region, maximum force increased from 66.1 N to 87.2 N, and the force-time integral increased from 18.7 N⋅s to 24.2 N⋅s.

Ciechanowicz et al assessed ability to resume physical activities in 79 patients who underwent scarf osteotomy for hallux valgus.[8]  After the procedure, patients' frequency of physical activity rose by about 21%, and the time they spent on sports (min/wk) rose by about 19%. Their satisfaction with the results of scarf osteotomy averaged 8.2 on a scale of 1 to 10. A majority of the patients (67%) were able to maintain this amount of physical activity postoperatively, and a minority (24%) were able to increase it.

A number of the surgical procedures performed to treat hallux valgus are potentially capable of reducing the increased forefoot width commonly associated with this condition. Panchbhavi et al reported an 8.7-mm reduction in the metatarsal span in 52 patients who underwent distal chevron osteotomy and Akin osteotomy.[9]  Conti et al reported mean decreases of 8.9 mm in bony foot width and 6.9 mm in soft-tissue width on radiography in 30 patients (31 feet) who underwent a modified Lapidus procedure combined with a modified McBride and Akin osteotomy.[10]

Patients with hallux valgus (HV) can present initially in several ways; therefore, evaluation of the history is extremely important. A patient may present with a nonacute onset of deep or sharp pain to the first metatarsophalangeal (MTP) joint during ambulation, with exacerbation during particular activities. This presentation warrants further examination, including radiologic evaluation, to determine whether articular degeneration of the first MTP joint is present.

The patient may also describe aching pain in the metatarsal (MT) head secondary to shoe irritation that is relieved when the shoes are removed. This presentation is indicative of superficial bump pain. Often, both forms of pain are progressive and have been present for many years. The frequency or duration of pain may recently have begun to increase, and activity may exacerbate the pain. Patients may even describe a recent notable increase in the size of the deformity or medial bump.

Questions about limitation of physical or daily living activities are valuable for understanding the severity of the patient's pain. It is also important to ascertain what, if anything, relieves the pain and which treatments (eg, surgery) have been attempted previously. Occasionally, trauma or inflammatory arthritis is an associated finding.

Another possible presentation is burning pain or tingling in the dorsal aspect of the bunion, which indicates neuritis of the medial dorsal cutaneous nerve secondary to pressure either from the enlarged bone itself or, commonly, from footwear. The patient may also describe symptoms caused by the deformity, such as a painful overlapping second digit, interdigital keratosis, or ulceration to the medial MT head, without a complaint regarding the bunion deformity itself.

The physical examination should include a comprehensive assessment of the vascular, dermatologic, neurologic, and musculoskeletal systems.

The musculoskeletal assessment can be divided into two components: determination of the etiology and evaluation of the resultant pathology (or presenting deformity). Understanding both components is essential in determining the most satisfying and successful treatment plan, whether conservative or surgical.

The workup is tailored to the patient's history. If neurologic complaints, systemic arthritis, or collagen vascular disease are mentioned, they should be addressed further in detail. If none of these are present, the focus then turns to the biomechanical examination, which includes assessment of the following measures, any or all of which can contribute to hallux valgus:

• Hip internal/external rotation
• Genu valgum/varum
• Tibial torsion
• Ankle joint stiffness, especially decreased dorsiflexion
• Subtalar joint stiffness
• Midtarsal joint stiffness
• Neutral calcaneal stance position
• Resting calcaneal stance position
• Forefoot/rearfoot varus or valgus

Assessment of resultant pathology can be divided into weightbearing and nonweightbearing evaluations; both yield important information for determining the appropriate treatment protocol (see the image below).

Nonweightbearing evaluation

The position of the hallux in the transverse plane should be assessed relative to the second digit. The hallux can be overriding, underriding, abutting, or without contact. Lateral deviation of the hallux may result from subluxation of the MTP joint or structural changes to the hallux. The hallux may be rotated in the frontal plane, as noted by valgus or varus rotation of the toenail. Thus, hallux abductus indicates transverse plane deformity, whereas hallux abductovalgus indicates deviations in the transverse and frontal planes.

The medial prominence should be assessed. Most medial prominences are located dorsomedially and appear to be more severe in a metatarsus adductus foot type. Erythema or bursa indicates shoe pressure and irritation.

The first aspect of range of motion (ROM) to assess in the first MTP joint is maximum available motion. Normal dorsiflexion is 65-75°, with plantarflexion less than 15°. The next aspect is quality of joint ROM and whether pain or crepitation is present; such findings indicate intra-articular cartilage degeneration. Pain without crepitation suggests synovitis. The final aspect is axis of motion. The joint is considered track-bound if the hallux drifts laterally after being placed in a neutral position during ROM exercises. Degree of lateral drift indicates severity of lateral soft-tissue contracture.

First-ray ROM should be evaluated in two ways. The first is determination of the ROM and resting position. Normal ROM is 10 mm total, with 5 mm dorsiflexion and 5 mm plantarflexion (see the image below). Resting position should be neutral in comparison with the second MT head. The second evaluation is determination of mobility in the transverse plane. In the normal foot, there is little to no motion available; however, in the presence of HV, motion may be detectable.

Plantar keratosis at the interphalangeal (IP) joint of the hallux indicates excessive pronation at pushoff. If present underneath the first MTP joint, this indicates excessive pressure secondary to equinus, rigidly plantarflexed first MT, prominent sesamoid, rigid forefoot valgus, or cavus foot type. Keratosis underneath the second MT head can indicate a short first MT or long second MT, a dorsiflexed first MT with resultant transfer lesion, retrograde plantarflexion of the second digit from hammertoe deformity, or hypermobility of the first MT.

The entire first-MTP joint complex should be palpated for pain during passive and active ROM, including but not limited to the dorsal, plantar, or medial MT head; sesamoid; crista; proper digital nerves; and extensor hallucis longus (EHL) tendon.

Contracture of the EHL is present only in long-standing lateral subluxations of the first MTP joint or neuromuscular disease.

Associated deformities, such as a second-digit hammertoe (see the image below) and flexible or rigid flatfoot, are commonly noted. Instability of the second digit may allow a more rapid progression of HV, in that the second digit is unable to act as an adequate lateral buttress.

Weightbearing evaluation

Often, the pathology or severity of deformity is not as apparent when the patient is not bearing weight as it is when the patient is bearing weight. Therefore, weightbearing examination is an important part of the physical evaluation. In this examination, the following aspects should be assessed:

• Positional increase of hallux abduction in the transverse and frontal planes
• Increase in medial prominence
• Increase in EHL tendon contracture
• Dorsiflexion of the first MTP joint, characterized as decrease, increase, or no change
• Hallux purchase, noted as good, fair, poor, or absent; this should be normal preoperatively and serves as a baseline for postoperative examination
• Metatarsus adductus; the greater the adductus, the greater the deformity appears

Generally, laboratory studies are not required for a routine assessment of hallux valgus (HV). However, if systemic or metabolic disease is suspected, the following studies can be of value in determining etiology or disease activity:

• Uric acid ^[11]
• Erythrocyte sedimentation rate (ESR)
• C-reactive protein (CRP)
• Antinuclear antibody (ANA)
• Rheumatoid factor (RF) ^[12]

Radiography continues to be the standard means by which joint pathology is assessed and angular deformity measured. However, weightbearing (standing) computed tomography (CT; see below) is increasingly being used in the management of HV. If ulceration is present and if the radiographic findings are inconclusive, radionuclide imaging[13]  may be considered as a possible adjunct study to rule out osteomyelitis.

Radiographic views

Weightbearing anteroposterior (AP), lateral oblique (LO), lateral (LAT), and sesamoid axial views should be obtained in the angle and base of gait (see the images below). Nonweightbearing radiographs may reveal the osseous relationships differently, causing an improper selection of surgical procedure. Weightbearing radiographs demonstrate the structural status of the foot.

The AP projection is used to determine the intermetatarsal angle (IMA), metatarsus adductus angle (MAA), hallux abductus angle (HAA), proximal articular set angle (PASA), and hallux abductus interphalangeus angle (HAIA), as well as the first metatarsal length, sesamoid position, condition of the first metatarsophalangeal (MTP) joint, bone stock, first metatarsal base, hallux rotation, and medial metatarsal head enlargement (see the images below).

The LAT projection is used to determine first metatarsal sagittal plane position and dorsal exostosis and/or osteophytes.

The LO projection is useful in evaluating bone stock and presence of dorsomedial exostosis. Because the bunion is located on the dorsomedial aspect of the metatarsal head, the prominence may be appreciated fully only in an oblique view.

In the sesamoid axial view, the sesamoids are observed for any lateral subluxation out of their respective grooves. As well, the crista is evaluated for erosion created by this subluxation. The joint sesamoid-metatarsal joint space is also examined for degenerative changes.[14]

Radiographic angular relations

Various angles, structures, and positions are assessed as listed below.

The normal IMA is 8-12° in a rectus foot and 8-10° in an adductus foot type. This angle is the relation between the longitudinal axis of the first and second metatarsals. If the angle is increased, the condition is termed metatarsus primus adductus.[15]

The normal MAA is less than 15°; more than 15° is considered adductus. This angle is the relation between the longitudinal axis of the lesser tarsus and the second metatarsal. This angle indicates whether the forefoot is in a rectus or adducted attitude in reference to the rearfoot. The rectus foot has an MAA of less than 15°. An angle larger than 15° causes the hallux valgus deformity to appear more severe than it actually is.

The normal upper limit for the HAA is 15-20°. This angle is the abduction of the longitudinal bisection of the proximal phalanx and first metatarsal; it is also known as the first-MTP angle. This is the primary method for quantification of the hallux abductus, either positional or structural.

The normal upper limit for the PASA is 7.5°. This is a measurement of the structural position of the first metatarsal head cartilage. It is used in determining whether the joint is congruent, deviated, or subluxated (see the image below).

The upper limit of normal for the distal articular set angle (DASA) is 7.5°. This angle detects structural abnormalities of the proximal phalanx base. Abnormalities may indicate the need for proximal phalanx osteotomies. The angle is determined by longitudinal bisection of the proximal phalanx of the hallux with reference to a line that connects the medial and lateral extents of the proximal phalangeal articular surface. The degree of abduction of the phalangeal bisection away from 90° determines this angle.[16]

Sesamoid positions 1-3 are normal, and the range is 1-7 (see the image below). In pathologic hallux valgus, the crista often is eroded as a result of the laterally deviated position of the sesamoids. The sesamoid position represents the degree of lateral subluxation of the sesamoid apparatus.

The normal range for the first metatarsal declination angle is 15-30°. This angle is determined by bisection of the first metatarsal shaft in reference to the weightbearing surface. This is a useful evaluation for selection of a procedure that includes plantarflexion of the metatarsal in the sagittal plane.

The upper limit of normal for the hallux valgus interphalangeus angle (HVIA) is 10°. A larger angle indicates a structural deformity of either the proximal phalanx head or the distal phalanx base, which gives the hallux an abducted appearance that is occasionally confused with a hallux valgus deformity. Inability to detect an abnormal angle may lead the surgeon to overcorrect a hallux abductus. The angle of abduction is determined on an AP view from longitudinal bisection of the proximal phalanx compared with longitudinal bisection of the distal phalanx.

In a study aimed at assessing the intraobserver and interobserver reliability of radiographic methods used to measure the hallux valgus angle (HVA) and IMA and determining the most reliable method for making those measurements before and after a proximal crescentic osteotomy of the first metatarsal, Shima et al found the most reliable method to be one in which a line connected the centers of the first metatarsal head and the proximal articular surface of the first metatarsal to define the longitudinal axis of the first metatarsal.[17]

Radiologic pathology

Radiographs may be useful in evaluating the condition of the first MTP joint. Two main aspects should be evaluated.

The first aspect is the width and uniformity of the joint space (see the images below). Normally, the joint space appears uniform. An increase or irregularity is indicative of degenerative changes. Therefore, if the osteoarthritis is severe enough, a joint-destructive procedure should be entertained.[18]

The joint should also be evaluated for osteophytes at the articular margins. The normal joint is free of osteophytes. Osteophytes are yet another indication of the severity of degeneration.

Radiographic bone stock assessment

Radiography is an excellent method for determining the quality and density of bone. In general, bone density should be uniform and trabeculation should be fine. The head of the metatarsal should be evaluated for cysts. In the normal metatarsal head, cysts should not be observable. Cysts indicate structural adaptation of the bone to function and load, or systemic arthritis.

Severe osteopenia or cysts may preclude the use of various forms of internal fixation or osteotomy. Note any increased density of the second metatarsal, which indicates excessive forces on the second metatarsal due to instability of the first metatarsal. Stress fractures of the second metatarsal commonly occur in this setting (see the image below).

Other radiographic findings

The hallux valgus, the medial eminence, and the soft tissue are evaluated as follows:

• Hallux valgus - No valgus rotation, as noted by the symmetrical concavity of the borders the medial and lateral shafts, should be evident. Asymmetry indicates the need for a procedure to the proximal phalanx to derotate the hallux
• Medial eminence - The normal metatarsal head is free from excessive bony proliferation; bony proliferation indicates an the imbalance of the joint with excessive medial tension
• Soft tissue - The soft tissues are evaluated for edema, bursae, calcification, or other signs of chronic inflammation

Root et al divided the pathomechanical development of hallux valgus into four stages as follows[19] :

• Stage 1 - Excessive pronation causes hypermobility of the first ray, causing the tibial sesamoid ligament to be stretched and the fibular sesamoid ligament to contract; lateral subluxation of the proximal phalanx occurs
• Stage 2 - Hallux abduction progresses, with the flexor hallucis longus (FHL) and flexor hallucis brevis (FHB) gaining lateral mechanical advantage
• Stage 3 - Further subluxation occurs at the first MTP joint, with formation of metatarsus primus adductus
• Stage 4 - The first MTP joint finally dislocates

The use of weightbearing CT (WBCT) has become increasingly relevant in the workup of patients with HV. Siebert et al compared WBCT with sesamoid-view weightbearing radiography (WBR) for the assessment of the metatarsal pronation angle (MPA) of the hallux in patients with and without forefoot pathology.[20]  Measurements obtained with WBCT did not differ significantly from those obtained with WBR, suggesting that either sesamoid-view WBR or WBCT can be reliably used to measure the first MPA.

In a study by Welck et al, standing CT (ie, WBCT) scans from 50 feet with symptomatic HV (n = 43) were compared with scans from a control group comprising 50 normal feet (n = 50).[21]  The standing CT assessments of sesamoid position, rotation, and metatarsosesamoid joint space were found to be reliable and highly reproducible; highly significant difference in these parameters were noted between the two groups. The authors used these results to propose a novel standing CT–based classification of hallucal sesamoids that considers the degree of displacement and wear, suggesting that this classification may help elucidate the effect of relative sesamoid displacement and chondral wear on surgical outcomes.

Kim et al described the use of a semiweightbearing coronal CT axial view for evaluating first-MT pronation and sesamoid position in 138 patients (166 feet) with HV as compared with 19 patients (19 feet) with no HV deformity.[22]  Four types of HV deformity were defined on the basis of the alpha angles and the tibial sesamoid grades on axial CT.

Indications for repair of hallux valgus (HV) include the following:

• Painful joint range of motion (ROM)
• Deformity of the joint complex
• Pain or difficulty with footwear
• Inhibition of activity or lifestyle
• Associated foot disorders that can be caused by this condition

Associated foot disorders include the following:

• Neuritis/nerve entrapment
• Overlapping/underlapping second digit
• Hammer digits
• First metatarsocuneiform (MTC) joint exostosis
• Sesamoiditis
• Ulceration
• Inflammatory conditions ( bursitis,  tendinitis) of the first metatarsal (MT) head

Contraindications for surgical treatment include the following:

• Extensive  peripheral vascular disease
• Active infection
• Active osteoarthropathy
• Septic arthritis
• Lack of pain or deformity
• Advanced age
• Lack of compliance
• Myocardial infarction within the previous 6 months
• Comorbid conditions that place the patient at significant cardiovascular or respiratory risk

In the future, surgeons and patients will benefit from prospective randomized studies designed to compare various procedures, their indications, and their success rates. The surgeon must continually search for the most stable procedure that offers the greatest degree of correction with the fewest complications. To avoid the mistakes of the past, it is essential first to be familiar with what has been attempted previously.

An adequate physical examination to determine the etiology and specific deformity is necessary for treatment planning. Medical therapy can be used to address the etiology, but it cannot change the irreversible cartilage, bony, and soft-tissue adaptations of the deformity. Therefore, most medical therapies are aimed at assuaging symptoms.

Adaptation of footwear

Spot-stretching shoes or using shoes with wider and deeper toe boxes may be considered. Padding and strapping have limited success in long-term management, other than to relieve footwear or digital pressure. However, in the elderly population, padding and strapping may be the best options if surgical correction is medically contraindicated.

Pharmacologic or physical therapy

Nonsteroidal anti-inflammatory drugs (NSAIDs) and physical therapy can be offered to relieve acute, episodic inflammatory processes. Corticosteroid injections can also be useful for acute inflammatory conditions in the first metatarsophalangeal (MTP) joint. No evidence supports prolonged physical therapy for HV.

Functional orthotic therapy

Functional orthotic therapy may be implemented to control foot biomechanics.[23] This approach can relieve symptomatic bunions, though the foot and first MTP joint must maintain some degree of flexibility.[24] For example, the joint cannot be laterally track-bound on clinical examination, and the sesamoid position cannot be greater than 4 on radiography. These two findings indicate a deformity that is nonreducible or that cannot be manipulated to a neutral, pain-free position.

Flexibility is necessary, as it allows the orthotic to manipulate the joints and foot and reduce the deformity, providing stability and thus relief. A rigid deformity can only be corrected surgically because it can no longer be manipulated.

If orthotics are to be manufactured for a patient, the physician must be familiar with the orthotic prescription form to control the patient's deformity, though this form varies among different manufacturers. A sufficient understanding of the patient's requirements may enable the physician to use simple over-the-counter devices instead of more costly custom-molded devices.[25, 26, 27]

The physician should be aware of the following issues: the patient's activities and weight, the top cover of the orthotic, the rearfoot/forefoot post, the biomechanical examination, and the possible modifications. These are discussed in more detail below.

Activity

When prescribing orthotics, the physician should ask questions such as these: "When will the patient primarily be using the orthotics? In dress shoes? During sports activities? During the day at work?"

Generally, dress shoes afford the patient the option to wear smaller devices, but these lack the control of larger orthotics. Patients participating in sports require more shock-absorbing capability from the orthotic; therefore, a more pliable material should be used.

Furthermore, the material used for the shell or orthotic can vary. A rigid material (eg, graphite) is thin and lightweight, does not deform, and is durable. However, graphite has a tendency to crack and therefore should not be used for sports applications. Another option is polypropylene, a durable, flexible plastic that resists breakage. It can easily be altered by grinding or heat molding in the office, whereas graphite cannot. A disadvantage of polypropylene is its tendency to deform over time and with use. Some physicians use leather or cork with success.

Weight

The material used can be ordered in varying thicknesses. The heavier patient needs a thicker material that will not bend, crack, or deform under the patient's weight. Moreover, the bulkier the patient's shoe, the thicker the shell material that can be used without causing the orthotic to fit uncomfortably. A thicker material can add control.

Top cover

Orthotics generally have liners on top of the shell, either to provide shock absorption or cushioning or to act as the shoe liner. Choices include, but are not limited to, leather, vinyl, Spenco, ethylene vinyl acetate (EVA), Poron, and Pelite. Top covers do not contribute to the control of the orthotics and are not functionally necessary.

Rearfoot/forefoot post

Applying a post, or exterior material, of a different material that is either molded with the shell or added on later can increase the stability and control of the orthotic. A rearfoot post is under the heel cup, and does not extend into the midfoot region.

A forefoot post may be added for biomechanical control for a patient with a rigid deformity (eg, rigid forefoot valgus) that cannot be controlled satisfactorily or comfortably with the orthotic because of the nonmaneuverability of the patient's foot. Therefore, the patient with rigid forefoot valgus requires a piece of material added extrinsically, or under the orthotic on the lateral aspect, to balance the forefoot to the rearfoot.

Biomechanical examination

The physician must determine the type of deformity the patient has and obtain angular measurements to prescribe the correction.

A plaster nonweightbearing mold is made of the foot in a neutral position (rear foot neither everted or inverted), with the forefoot loaded to simulate weightbearing. From this cast, the orthotic manufacturer creates an orthotic with built-in corrections. For example, if the patient has a 4° flexible forefoot varus, the rear foot likely compensates for this deformity, thereby allowing the forefoot to bear weight evenly across all MT heads.

A well-built orthotic allows the foot to stand in a neutral position, both in the forefoot and in the rear foot, removing increased pressures and deforming forces caused by the compensation.

Modifications

Possible modifications include measures such as the following:

• Increasing the height of the heel cup (for more control)
• Creating a wider medial arch (for a collapsed, flat foot)
• Providing a plantar fascial groove (for a tight, painful plantar fascia)
• Using a metatarsal pad (for pain under the second MT head from overloading due to inadequate weightbearing by the hallux)

If the etiology is determined to be a metabolic or systemic condition, it is best to work with a rheumatologist, neurologist, or primary care physician to stabilize, manage, and slow the progression of disease and to choose therapy for the HV deformity.

Surgical treatment can be offered when conservative therapy is impractical or fails to relieve the patient's symptoms. The goals of surgical treatment are to relieve symptoms, restore function, and correct the deformity. The clinician must consider the patient's history, physical examination, and radiographic findings (see the image below) before selecting a procedure. On occasion, the final procedure is determined intraoperatively when the physical appearance of the joint, bone, and tissue can be observed directly.[28, 29, 30, 31, 32, 33]

The following features of the surgical repair allow successful correction of the deformity:

• Establishing a congruous first MTP joint
• Reducing the intermetatarsal angle (IMA)
• Realigning the sesamoids underneath the MT head
• Restoring the ability of the first ray to bear weight
• Maintaining or increasing the first MTP joint's range of motion (ROM)
• Realigning the hallux to a rectus position
• Correcting or controlling etiologic factors

The specific procedure selected in a given case varies, depending on the surgeon's preference, the nature of the deformity, and the particular needs of the patient, though the surgeon can follow a simple algorithm based on clinical and radiographic findings to determine the procedure of choice (see image below).

Minimally invasive surgery (MIS) for HV is gaining popularity.[34] Arthroscopically assisted correction of HV is an attractive option, in that it is minimally invasive; however, there remains a need for further study of criteria for patient selection, as well as long-term outcomes.[35]

The procedure is chosen with the aims of reducing the patient's symptoms most effectively and preventing recurrence. The choice is based on particular components of the HV, which can include positional and structural deformities of the MTP joint, adaptive changes of the first MTP joint, and the position and condition of the sesamoid apparatus. Classes of surgical procedures include the following:

• Capsulotendon balancing or exostectomy
• Osteotomy
• Resectional arthroplasty
• Resectional arthroplasty with implant
• First MTP joint arthrodesis
• First MTC joint arthrodesis

Capsulotendon balancing or exostectomy

This procedure can be performed independently, but it is usually performed in conjunction with an osteotomy. It is designed to restore the integrity of the first MTP joint and reduce the medial osseous prominence of the MT head. Indications include the following:

• Painful osseous medial prominence of the MT head
• Deviated or subluxated first MTP joint
• Adequate, pain-free ROM
• Reducible deformity

The postoperative course includes limited-to-full weightbearing in a surgical shoe immediately following the procedure. 

Osteotomy

Osteotomy (see the images below) is performed to correct structural deformities associated with the cuneiform, metatarsal, and phalanges of the first ray and typically includes a lateral release and capsulorrhaphy. These procedures should be performed at the level of the deformity.[30, 36]  (See Hallux Valgus Osteotomy.) Minimally invasive approaches to osteotomy have been devised and are being studied (see below).[34, 37]

Akin first proposed osteotomy of the hallux in 1925 for the correction of HV. However, experience has shown that this is not a primary procedure for HV repair; it does not directly restore the sesamoid position, address adaptive changes of the cartilage of the MTP joint, or correct MT deviations. Instead, it is used to address deformity of the proximal phalanx and correct an abnormal hallux abductus interphalangeus angle (HAIA), long proximal phalanx, abnormal distal articular set angle (DASA), or frontal plane rotational position of the hallux.

The proximal phalanx osteotomy commonly performed is the Akin procedure, in which a medial wedge is removed from the proximal phalangeal shaft. This procedure often is performed concomitantly with a procedure that addresses HV, should deformity of the proximal phalanx be present. Its use is best considered intraoperatively once the primary surgical procedures have been performed.

If an Akin operation is performed independently for correction of HV, the surgeon should anticipate even greater lateral subluxation of the first MTP joint that leads to rapid recurrence of the original condition despite the initial clinical improvement.[38, 39]

MTC osteotomies address deformities along the MTC complex. Indications include an increased IMA, metatarsus primus elevatus, or an increased proximal articular set angle (PASA) with articular adaptation of the first MT head. The levels at which these osteotomies are performed include the distal, diaphyseal, and proximal levels along the MT shaft.

Distal osteotomies are performed in the metaphyseal region and achieve only a relative correction of the IMA. They are inherently stable and are associated with fewer occurrences of head displacement/rotation or shaft elevation. The joint congruency is corrected primarily with this osteotomy. They may be performed for both a congruent joint and an incongruent joint with an IMA of less than 15°.

After a distal osteotomy, the patient typically has 2-6 weeks of limited weightbearing in a surgical shoe. Common complications include shortened first MT, second metatarsalgia, restriction of motion, and recurrence of deformity.

Common distal or head osteotomies include the following:

• Reverdin-Laird procedure, a medially based wedge resection with lateral transposition of the MT head
• Austin or chevron procedure, a horizontally directed V-shaped displaced osteotomy with lateral transposition of the MT head
• Mitchell procedure, a lateral transpositional transverse osteotomy with preservation of a lateral cortical block of bone

In a prospective randomized trial comparing Mitchell osteotomy (MO) with chevron osteotomy (CO) in 120 female patients with hallux valgus, Buciuto found that patients treated with CO had significantly better results with regard to American Orthopaedic Foot and Ankle Society (AOFAS) Clinical Rating System (CRS) scores, number of postoperative complications, patient satisfaction, and length of sick leave (for employed patients).[40] The results suggested that in female patients, CO should be regarded as the first-line procedure for treatment of mild and moderate HV.

A study by Seo et al found that despite concerns about aggravation of osteoarthritis and fixation failure, distal chevron osteotomy with lateral release for moderate-to-severe HV was safe in patients aged 60 years or older.[41]

In a cadaveric study, Chen et al described an alternative approach to Kirschner wire (K-wire) fixation in distal chevron osteotomy of the first MT whereby a tricortical technique was used rather than a unicortical technique.[42]  They found tricortical K-wire fixation to be biomechanically superior to unicortical K-wire fixation and not significantly different from single-screw fixation.

Diaphyseal osteotomy is associated with a decreased blood supply and is less stable than a distal procedure, but it can achieve a greater correction of the deformity and address a true PASA deviation.[43] It can lengthen the first MT after rotation or translocation to correct the IMA; therefore, it is a procedure of choice for short MTs.

The midshaft osteotomy is performed for mild-to-moderate HV deformities, with an IMA greater than 15° but an HV angle (HVA) smaller than 40°, though large degrees of correction can also be achieved with greater rotation of the fragments. In addition, this can be performed as an alternative to a base procedure. This procedure is best used in patients with good bone quality (ie, without significant osteopenia).

Common midshaft or diaphyseal osteotomies include the following:

• Scarf procedure, in which a Z-shaped osteotomy in the transverse plane extends from the MT head to the base with lateral rotation of the distal fragment ^{[43, 44]}
• Ludloff procedure, in which an oblique osteotomy is oriented dorsal-proximal to plantar-distal from the head to the base with the distal bone fragment transposed laterally

The proximal osteotomy is considered to be the least stable, with the greatest risk for MT elevation and fixation failure, but it achieves an actual instead of relative correction of the IMA. Base osteotomies are considered for HV deformities with an IMA greater than 15° and an HVA smaller than 40°, in which the first MTC joint does not demonstrate hypermobility.

Proximal procedures necessitate the use of a nonweightbearing cast for 4-8 weeks until complete ossification occurs in order to prevent elevation of the MT.

Common base or proximal osteotomies are as follows:

• Crescentic procedure, in which a crescentic blade is used to transect the first metatarsal, resulting in a dome-shaped osteotomy; the distal segment can be rotated in the transverse and sagittal planes for correction of the deformity
• Closing abductory wedge (Loison/Balacescu type) procedure, which is a transverse osteotomy with the lateral wedge removed and the medial hinge kept intact
• Closing abductory wedge (Juvara) procedure, which is a long, oblique osteotomy extending from proximal-medial to distal-lateral with the lateral wedge removed and medial hinge left intact

Resectional arthroplasty

Resectional arthroplasty (see the images below) is a joint-destructive procedure that most commonly is reserved for elderly patients with advanced degenerative joint disease (DJD) and significant limitation of motion.

The typical resectional arthroplasty that is performed is known as a Keller procedure. It is performed when morbidity might be increased with the more aggressive osteotomy that would otherwise be selected. The procedure includes resection of the base of the proximal phalanx with reapproximation of the abductor and adductor tendon groups. The technique is inherently unstable and should be used judiciously.[45, 46] The postoperative course includes limited-to-full weightbearing in a surgical shoe immediately after the procedure.

Resectional arthroplasty with implant

Resectional arthroplasty with implant (see the images below) is the same procedure as the resectional arthroplasty, with similar indications, but stability is markedly improved with the addition of the total implant. However, this operation is not without the complications inherent to implants, which include foreign-body reactions, synovitis, lysis of the bone, and implant failure.

First metatarsophalangeal joint arthrodesis

Arthrodesis of the first MTP joint (see the images below) is a joint-destructive procedure that offers a higher degree of stability and functionality. It is considered the definitive procedure for DJD. It results in complete loss of motion at the first MTP joint and is reserved for patients with high activity levels and functional demands.

This is a difficult procedure to perform in elderly persons because of the need for nonweightbearing status for 4-8 weeks postoperatively. Indications include the following:

• Painful or severely limited ROM in the first MTP joint
• Significant degenerative arthritis
• Revision or repair of prior arthroplasty with implant or osteotomy (salvage procedure)
• Extensive trauma to the first MTP joint that is not reparable with osteotomy
• Ligamentous laxity
• Neuromuscular disease

First metatarsocuneiform joint arthrodesis

Significant and/or hypermobile hallux abductovalgus may be reduced with arthrodesis of the first MTC joint[47] (see the images below). Indications include the following:

• Metatarsus primus varus
• Hypermobility of the first ray
• Metatarsalgia of the lesser MTs
• Degenerative joint disease of the MTC joint

Minimally invasive surgery

MIS techniques for HV surgery have been the subject of increasing interest. (See the images below.)

A 2009 study by Lin et al found minimally invasive distal MT osteotomy to be associated with good satisfaction, functional improvement, and a low rate of complications, suggesting that this could be an effective, safe, and simple means of treating mild-to-moderate HV.[36]  

In a 2020 randomized controlled trial, Kaufmann et al compared minimally invasive with open distal metatarsal osteotomy for treatment of HV over a 5-year study period.[48]  Follow-up included assessment of the AOFAS Forefoot Score, a visual analogue scale (VAS) pain score, and a patient satisfaction score at 6 weeks, 12 weeks, 9 months, and 5 years; radiographic outcomes (HV correction, joint degeneration) and ROM were also evaluated. At 5 years, no significant differences between the two surgical approaches were noted.

A retrospective study by Merc et al examined the initial experience (100 cases) of a single surgeon with the minimally invasive chevron Akin (MICA) osteotomy in an effort to define the learning curve associated with the procedure.[37]  For operating time, the learning plateau was reached after 29 cases; for proficiency in fluoroscopy application, after 30 cases; for complication rate, after 42 cases. Thus, there was a lag between the point after which the surgeon felt comfortable with the procedure and the point after which complications decreased.

In a prospective single-surgeon series of consecutive patients (50 feet; minimum follow-up, 12 mo) undergoing fourth-generation MIS in the form of the metaphyseal extra-articular transverse and Akin (META) osteotomy for HV, Lewis et al assessed clinical and radiologic outcomes.[49]  The primary outcome measure was the Manchester-Oxford Foot Questionnaire (MOXFQ) score; secondary outcomes included radiographic deformity correction, clinical assessment, and EuroQol-5D-5L patient-reported outcome measures (PROMs). The META procedure yielded significant improvements in both clinical and radiographic outcomes.

A 2023 systematic review and meta-analysis by Alimy et al addressed the question of whether MIS for HV, as compared with open surgery, resulted in (1) improved AOFAS scores and VAS scores for pain, (2) better radiologic outcomes, (3) fewer complications, or (4) shorter operating times.[34]  The authors found no significant differences in clinical or radiologic outcomes between the two approaches. In view of the methodologic shortcomings of some of the source studies and the absence of confirmed advantages for MIS, the authors were unable to recommend MIS over traditional approaches to HV surgery.

Preparation for surgery

A complete history and physical examination are required for surgical correction of HV. The history should include allergies, complications with anesthesia, bleeding disorders, use of anticoagulants, immunocompromised status, and tobacco use. Preoperative evaluation may include the following:

• Electrocardiography (ECG)
• Chest radiography
• Laboratory workup, including a complete metabolic panel, complete blood count (CBC), coagulation studies, and urinalysis if warranted

The patient should be well informed of the etiology, course, and prognosis of the deformity, as well as the risks and benefits of conservative and surgical options.

HV can generally be corrected surgically on an outpatient basis.[50] Situations that may warrant hospital admission include the need for parenteral medications, perioperative complications or anesthetic complications, an inability to function independently, and coexisting medical conditions. Patients undergoing complex surgical procedures may also require hospitalization.

The choice of anesthetic techniques for the surgical procedure depend on the surgeon's, patient's, and anesthesiologist's preferences. These choices include general anesthesia, spinal anesthesia, and monitored anesthesia with local blocks. The block typically is performed with a short- and/or long-acting local anesthetic. For maximum benefit and preemptive analgesic effect, it is administered prior to the initial incision.[51] A pneumatic ankle tourniquet is generally used to achieve hemostasis for better intraoperative visualization.

Prophylactic antibiotics generally are not warranted unless the surgery is anticipated to last longer than 2 hours, the patient is immunocompromised, or an implant is being inserted.

Procedure

A linear dorsomedial longitudinal incision is created, extending from the midshaft of the first MT distally to the midshaft of the proximal phalanx medial to the extensor hallucis longus (EHL) tendon. The incision is deepened through skin and soft tissue, with care taken to identify and retract all vital neurovascular structures. Cauterization is used for bleeding as needed.

The lateral release is then performed in stepwise fashion to achieve release of lateral contractures, with the hallux able to reduce without restriction (see the image below). (A systematic review and meta-analysis by Izzo suggested that in percutaneous HV surgery, lateral soft-tissue release does not appear to reduce the risk of recurrence at a mean follow-up of 4 years, nor does it improve clinical or radiologic outcomes.[52] )

Capsulotomy is then performed and the periosteum is reflected to expose the MT head.

The initial goals of the anatomic dissection are to provide access to the surgical area, to establish hemostasis, to identify and release any soft-tissue contractures, and to prepare the site for the osteotomy. Once this is accomplished, the predetermined osteotomy is performed. Fixation is achieved by using the lag technique described by the Arbeitsgemeinschaft für Osteosynthesefragen–Association for the Study of Internal Fixation (AO-ASIF).

Once fixed, the capsule, subcutaneous tissue, and skin are reapproximated, with capsulorrhaphy[53]  performed if warranted. Dressings consist of nonadherent gauze with dressings to splint the hallux in its newly corrected position.

The type of procedure performed and its inherent stability determine postoperative management of the osteotomy. Dressings applied at the time of the surgery should supply corrective forces (eg, derotation, plantarflexion, adduction) while the soft tissue remodels, with mild compression to control postoperative edema. Orthotics may be employed for postoperative immobilization.[54, 55]

Pain should be well controlled postoperatively. The patient's weightbearing status is determined on the basis of the procedure performed but generally is limited during the first 2 weeks to prevent deviation or displacement and to minimize edema. The patient may begin ROM exercises on a daily basis after the sutures are removed, and weightbearing is advocated to prevent limitation of joint motion from excessive scarring.[7]

Radiographs to assess alignment, fixation, and progression of ossification are obtained immediately after surgery and when a change in activity level is anticipated.[17]

Complications that may occur after surgery include the following[56, 57, 58, 59, 60] :

• Delayed healing of the incision
• Osseous malunion or nonunion
• Numbness or tingling
• Hematoma
• Hardware failure
• Displacement of the osteotomy
• Delayed suture reaction
• Cellulitis
• Osteomyelitis
• Avascular necrosis (AVN)
• Elevation of the MT
• Transfer lesions
• Limitation of joint motion
• Hallux varus
• Recurrence

These complications can vary, depending on the surgical technique and procedure. Preoperative education and realistic patient expectations can help in minimizing or managing these sequelae.

Sieloff et al performed a systemic review and meta-analysis (25 studies; 1583 procedures; mean follow-up, 26.4 mo [range, 12-168]) examining complications and associated clinical outcomes after scarf osteotomy for HV.[61]  The following complication rates were noted: recurrence, 5.1%, troughing, 3.5%; AVN, 1.0%; nonunion, 1.8%; malunion, 2.7%; infection, 2.4%; complex regional pain syndrome (CRPS), 5.3%; and hallux varus, 3.4%. The IMA decreased by an average of 6.3º.

A systematic review and meta-analysis (17 studies; 18 data sets) by Lalevee et al assessed long-term (minimum follow-up, 5 y) outcomes and HV recurrence rates for four categories of distal first-MT osteotomies: chevron, Mitchell, Bösch, and "others."[62]  The pooled HV recurrence rates were 64% for an HVA threshold of 15º or greater, 10% for a threshold of 20º or greater, and 5% for a threshold of 25º or greater. Mean weighted postoperative HVA was significantly higher for Mitchell osteotomy than for the other three categories, but there were no significant differences in recurrence rates for the three different HVA thresholds.

Once the immediate postoperative period has passed, it is important to take steps to ensure that the deformity does not recur. Therefore, the etiology must again be considered and addressed properly. If the practitioner can control such factors, he or she should do so at this time to optimize surgical results.

Patients may require functional orthotic control. Several studies have shown that orthotic devices are beneficial, especially in patients with diseases such as rheumatoid arthritis, in which excessive forces accelerate degeneration. Control of these forces may postpone further destruction to the joints and provide the best long-term results after surgery.[63]