INTRODUCTION — Valgus malformation of the great toe, commonly known as a bunion, is a very common and potentially painful, debilitating condition of unclear etiology. This topic will provide an overview of the anatomy, pathophysiology, diagnosis, and management of hallux valgus (HV) in adults. Toe and foot injuries are discussed elsewhere. (See "Toe fractures in adults" and "Metatarsal shaft fractures" and "Overview of foot anatomy and biomechanics and assessment of foot pain in adults".)
ANATOMY AND BIOMECHANICS
Definitions and basic forefoot anatomy — By convention, toes and their respective metatarsals are numbered from one (great toe) through five (little toe). The great toe has two phalanges, while the second through fifth toes typically have three (figure 1 and figure 2 and figure 3). Tendons and ligaments insert at the bases of each phalanx. The digital artery and nerve pass together along the sides of each toe.
●Ray – The forefoot consists of five longitudinal projections, called rays, which are comprised of the metatarsal and the bones aligned with and proximal to the metatarsal, such as the cuneiforms or cuboid bones. HV involves the first ray.
●Hallux valgus deformity – This deformity is defined as a lateral deviation of the hallux (great toe) on the first metatarsal (figure 4). The deviation of the hallux occurs primarily in the transverse plane. The deformity often also involves rotation of the toe in the frontal plane, causing the toenail to face medially (ie, eversion). These two deviations have led to the use of different terms to describe the deformity. In orthopedic texts, it is often called "hallux valgus," whereas some podiatry texts prefer the term "hallux abductovalgus." Patients are more familiar with the expression "bunion."
●Hallux abductus angle – The hallux abductus (HA; or HV) angle is created by the bisection of the longitudinal axis of the hallux and the longitudinal axis of the first metatarsal (figure 4 and image 1). Historically, an HA angle of >15 degrees was considered abnormal, but such deformities are not always symptomatic, and in some cases, an HA angle >15 degrees occurs naturally due to the shape of the articular surfaces involved [1,2]. Contemporary research suggests an HA angle of ≥20 degrees is abnormal .
●Intermetatarsal angle – The angle determined by the bisection of the longitudinal axes of the first and second metatarsals (figure 4). An intermetatarsal (IM) angle <9 degrees is considered normal.
●First ray anatomy – There are no muscles that originate on the first metatarsal to directly stabilize the first metatarsophalangeal (MTP) joint. The abductor and adductor hallucis muscles pass medially and laterally to the MTP joint respectively, but they are located nearer to the plantar surface (figure 5). Thus, any force pushing the proximal phalanx laterally, or the metatarsal head medially, lacks direct muscular constraint and can create a valgus deformity.
The first metatarsal is held in alignment by a splinting action of the abductor hallucis muscle medially and by the lateral pull of the peroneus longus acting at the base of the metatarsal . Movement at the first MTP joint in the transverse plane is prevented by collateral ligaments running from the metatarsal epicondyles, distally and plantarly, to the proximal phalanx.
Biomechanics of hallux valgus deformity — Increased pressure under the head of the first metatarsal (for example, due to increased subtalar pronation or a congenital plantarflexed first ray) will force the first ray to move medial-dorsally. This movement increases the HA and IM angles and places the metatarsal more medial relative to its proximal phalanx. When the muscles act to stabilize the joint during gait, the proximal phalanx is pulled against the lateral aspect of the metatarsal head, which pushes the metatarsal more medially, further increasing the HA angle.
As the first metatarsal moves medially and the hallux moves laterally, the medial capsule and medial collateral ligament come under chronic strain and eventually rupture. The medial movement of the metatarsal forces the abductor hallucis muscle beneath the metatarsal. From this position, it acts solely as a plantarflexor of the proximal phalanx and contributes to the valgus rotation seen with HV deformity. Eventually, without medial stabilizing structures, the lateral joint capsule and collateral ligaments tighten, and the adductor hallucis muscle acts unopposed, exacerbating the deformity .
Since not all cases of HV deformity become severe, there may be a threshold up to which the forces deforming the joint can be opposed by other anatomic structures. When forces greater than the threshold occur, the joint becomes deformed. It is possible that such progression occurs rapidly rather than worsening steadily over several years [1,2,6].
EPIDEMIOLOGY — The prevalence of HV deformity varies but is widely prevalent among adult populations. According to a systematic review of 78 studies involving almost 500,000 subjects, the prevalence of HV is approximately 23 percent among adults aged 18 to 65 years, 36 percent among adults over 65 years, and 30 percent among all adult females . The prevalence is greater among shod (wearing shoes) compared with unshod (barefoot) populations; however, the condition is twice as common among females than males in unshod populations [8-10].
ETIOLOGY — Although many theories have been proposed, the precise etiology of HV deformity is unknown [11,12]. HV deformity is likely multifactorial in origin and includes such factors as abnormal foot mechanics affecting the first ray [5,13-17], abnormal first metatarsophalangeal anatomy [18-21], joint hypermobility [22,23], and genetic influences . HV is also associated with conditions such as inflammatory joint disease [24-26].
Since HV deformity occurs primarily in shod populations, affecting females in particular, poor footwear has frequently been cited as a cause. The fact that some females wear footwear that compresses their toes significantly without detrimental effects, while some males suffer from marked HV deformity despite the use of nonconfining footwear, leads many to think that footwear probably exacerbates underlying bony or mechanical abnormalities rather than acting as a primary factor.
Case reports describe HV development in athletes after a first metatarsal injury, such as in valgus stress to the hallux and collateral ligaments [27,28].
While many studies have reported that HV is associated with a change in weightbearing pressures under the hallux and in other areas of the foot, these studies have all been observational, and therefore, causal relationships cannot be determined. It remains unclear whether changes in loading are a result of the HV deformity itself or related to an underlying mechanical dysfunction that contributes to the development of the HV deformity .
However, it seems clear that weightbearing pressures under the foot change as HV develops, since pressure lesions (eg, calluses) develop, which were not present before the deformity and may not be present on the unaffected foot. One study has suggested that changes in weightbearing pressures might lead to further injuries within the foot or limb . However, the precise relationship between plantar pressures and specific injuries remains unknown. There is no evidence that general gait parameters are affected by HV, but there is some evidence suggesting that severe deformity does disrupt gait and balance, particularly on uneven surfaces and among older adults, who may be put at increased risk of falling [29,31].
CLINICAL PRESENTATION — Patients with HV typically present with foot pain and/or slowly progressive deformity of the first metatarsal joint (picture 1 and picture 2). Patients typically present with pain over the prominent medial eminence of the first metatarsal head, which may first present as discomfort while wearing shoes. Patients may also present with pain or calluses along the lateral great toe or medial second toe, as these digits abut each other. Given its prevalence, clinicians may also note its presence on routine physical examination. Pain severity and functional limitation can range from asymptomatic to severe.
EVALUATION AND DIAGNOSIS
Diagnosis — The diagnosis of HV is made clinically, as it is easily recognized on physical examination (picture 1 and picture 2). The HV deformity is a lateral deviation of the hallux (great toe) on the first metatarsal in the transverse plane, with the hallux abductus angle greater than 20 degrees and the intermetatarsal angle greater than 9 degrees (figure 4). The deformity can also involve rotation of the toe in the frontal plane, causing the toenail to face medially (ie, eversion/valgus). Prominence of the first metatarsal head on the medial forefoot is a common finding that results from the increase in the intermetatarsal angle.
Identify associated conditions — Several associated conditions around the first metatarsophalangeal (MTP) joint may be clinically evident alongside HV. Identification of these associated conditions is important, as additional intervention may be indicated if they are present [32-34].
●Bursitis is common, caused by inflammation of a medial bursa protecting the joint. This arises from direct pressure from the footwear, or movement of the footwear, against the bony prominence of the metatarsal head. Wider-fitting footwear or padding can reduce the forces against the joint.
●Pain with limited range of motion suggests degeneration of the cartilage covering the metatarsal head. Treatment involves either trying to improve the range of motion through the use of orthoses or mobilization or controlling the range of motion with taping. The use of rocker sole footwear may be tried.
●Hammertoe and claw toe deformities of the lesser toes (picture 3) may be present, caused by destabilizing pressure from the laterally deviated great toe. Toe splints or deeper footwear at the toe box can be helpful. Severe, painful deformities may be managed surgically.
Increased pressure on the metatarsal head causes central metatarsalgia due to the patient's chronic shifting of weight from an unstable first ray onto the central rays. This is managed using insoles to redistribute the plantar forces or to add further cushioning.
●Synovitis (pain and swelling) of the MTP joint may be present due to active inflammation. This is managed with orthoses to improve the MTP joint function or rocker sole footwear. Steroid injections may be considered.
●Degeneration of the crista on the plantar surface (figure 5) may occur, caused by erosion as the metatarsal moves over the sesamoids. Insoles can redistribute the plantar forces or add further cushioning.
●Entrapment of the medial dorsal cutaneous nerve as it passes through the enlarged bunion area may lead to sharp or tingling pain across the dorsomedial side of the joint. This is typically caused by the pressure of footwear in the local area, so the fit of the footwear needs to be optimized. The bony prominence may need to be addressed surgically.
These interventions have been found useful in the author's experience.
Imaging in select patients — For most patients with HV deformity and nonsevere symptoms, radiography is not performed. However, for patients with severe or refractory symptoms, radiographs may be helpful to determine the presence and extent of damage to the articular surfaces of the first MTP joint. In addition, when surgery is being considered, radiographs are essential to assess the severity of the deformity and select the appropriate surgical procedure (algorithm 1 and image 1). Weightbearing dorsoplantar (also called anteroposterior) and lateral radiographs are typically obtained. In addition, an axial view can assist with assessment of the frontal plane deformity of the metatarsal and the sesamoid position.
Goals of treatment — The goal of both conservative and surgical management is to improve pain and function and slow progression of the deformity. Patients should be educated that, with both conservative and surgical management, the HV angle may improve somewhat, but cosmetic deformity is likely to persist.
Initial conservative management — Management starts with conservative therapies, and surgery is reserved for refractory cases (algorithm 1) . Because HV is due to structural changes, conservative therapy is unlikely to correct the deformity. However, it can be very effective in decreasing pain and improving function. While there is little published evidence that conservative treatments are effective for HV, in our experience, patients with mild symptoms can achieve symptomatic relief with footwear modifications, toe spacer orthoses, and other conservative treatments . Patients who do not improve after at least three to six months of conservative management and have pain that impacts their quality of life may be referred for surgical evaluation. Initial surgical management without a trial of conservative measures is rare and reserved for the more severe cases. (See 'Surgery for severe or refractory symptoms' below.)
There are few high-quality, randomized trials looking at conservative treatments for HV . Based on anecdotal evidence of efficacy, we suggest the following nonoperative treatments to alleviate symptoms and slow progression of HV deformity . The type of conservative treatment depends upon availability of specialists and anatomical and biomechanical features, such as degree of HV deformity and severity of symptoms.
Footwear selection and modification — We instruct all patients with HV to wear low-heeled shoes with a wide toe box or specially altered shoes with increased volume to accommodate the first metatarsophalangeal (MTP) joint (algorithm 1). Existing footwear can be modified with a shoe stretcher with bunion attachments to alleviate pressure and friction on the affected MTP joint. Shoe stretching is offered at shoe repair shops or via commercially available devices for home use. Commercially available bunion pads can be applied to the overlying skin to temporarily alleviate irritation due to pressure/friction.
Diabetic patients and patients with multiple deformities or other comorbidities warrant early referral to a podiatrist or footwear specialist for specialty shoe options.
Pain management — For patients with persistent pain, we advise the use of nonsteroidal anti-inflammatory drugs (NSAIDs) or acetaminophen if tolerated and there are no contraindications (eg, ibuprofen 400 to 600 mg orally every eight hours as needed or acetaminophen 325 to 1000 mg orally every eight hours as needed). Diclofenac gel may also be used if a topical preparation is desired (table 1). These medications should be taken at the lowest effective dose and for the shortest period of time (algorithm 1) (see "Nonselective NSAIDs: Overview of adverse effects" and "Acetaminophen (paracetamol) poisoning in adults: Pathophysiology, presentation, and evaluation"). Topical ice can also be helpful, especially when pain seems secondary to bursitis.
Orthoses — For patients with persistent symptoms, we recommend a trial of orthoses, which may be used alongside the above measures. Both prefabricated and custom-made orthoses improve foot mechanics by reducing abnormal subtalar joint pronation and preventing abnormal forces from acting on the first ray complex (picture 4). Orthoses may also prevent further deterioration of the HV angle. Orthoses are most effective when worn in a low-heeled, well-fitting, fastening shoe (ie, non-slip-on shoe).
There is limited and somewhat conflicting evidence to support the use of orthoses for HV. A randomized, controlled trial of 209 patients with HV demonstrated improved pain scores at six months and improved global assessment at one year in patients who received orthoses compared with no treatment; however, these improvements were not maintained at a later time point . In a meta-analysis of 16 observational and randomized studies including 1026 patients, foot orthoses did not improve HV angle or pain . In a smaller meta-analysis of 285 patients from nine studies of orthosis design, various orthoses showed modest benefit, especially designs that promote first ray alignment such as orthoses with a toe separator .
Indirect support for the use of orthotics in HV comes from a randomized, controlled trial of 102 patients with active rheumatoid arthritis; orthoses were shown to prevent development of HV deformity compared with controls (adjusted odds ratio 0.27, 95% CI 0.08-0.92) .
The limited evidence comparing custom and prefabricated orthoses for HV suggests both have similar efficacy and emphasizes the importance of adjustment and proper fit, regardless of type . Because custom orthoses are significantly more expensive than prefabricated orthoses, patient preference, resources available, and mechanical correction achievable are primary factors guiding orthotic selection.
If the above conservative measures are effective, they may be continued indefinitely; though, caution should be exercised with long-term use of NSAIDs. Patients should be counseled that symptoms may return if the above interventions are discontinued.
Other conservative treatments
Physical therapy — We do not routinely recommend physical therapy for HV, as there is little evidence to support it and access to this therapy is limited. Physical therapy for HV involves mobilization, stretching, and manipulation by trained professionals, typically physical therapists, chiropractors, and podiatrists. Mobilization involves slow repeated movements within the range of motion. Stretching involves applying sustained pressure to take the joint to its end of range of motion. Manipulation involves the rapid movement of the joint beyond the current range of motion. These are undertaken in a supervised clinical setting and then maintained by the patient at home through specific exercises.
A randomized but unblinded trial including 56 females with moderately symptomatic HV compared mobilization, exercise, and toe splinting with no treatment . At 12 months, the treatment group had improvements in pain, functional, and strength scores compared with the control group. In addition, the HV angle improved by approximately seven degrees in the treatment group at 12 months follow-up compared with the control group, where the deformity remained static.
Splinting — We do not routinely recommend splinting because there is little evidence that such interventions improve long-term outcomes . Splints can be used to place the toe in a corrected position to enable soft tissue adaptation and delay rupture of the medial joint capsule and collateral ligament. The most commonly used devices are night splints (prefabricated/over-the-counter devices), which realign the hallux while nonweightbearing, typically during sleep (picture 5). For daytime wear, nonorthotic foam wedges can be placed between the first and second toe to achieve a similar realignment effect.
Management of associated conditions — Some conditions associated with HV deformity (eg, bursitis) may benefit from specific management as discussed above. (See 'Identify associated conditions' above.)
Surgery for severe or refractory symptoms
Indications for surgical referral — Patients with severe pain or dysfunction (eg, significant difficulty with ambulation) and those with refractory symptoms despite conservative treatment should be referred to a foot surgeon (algorithm 1). Guidelines suggest a trial of at least three to six months of conservative treatment before referring for surgical evaluation . Neither the clinical nor radiographic appearance of the deformity plays a significant role in the decision to pursue surgery.
Procedures — Both orthopedic and podiatric specialist foot surgeons, as well as nonspecialists, perform operations to repair HV deformity. No study has compared the results of surgery based on surgical specialty. We typically refer patients to a foot surgery specialist with experience repairing HV deformity.
Approximately 150 surgical procedures for the correction of HV deformity have been described. The most common techniques are described below. Selection of surgical approach is determined by surgeon experience and patient factors, including severity of the deformity, presence of arthritis in the MTP, age, and level of activity.
●Bunionectomy (Silver procedure) involves removing the most prominent portion of the metatarsal head. Bunionectomy is rarely performed alone and instead is performed alongside one of the following procedures.
●Osteotomy entails cutting the first metatarsal and realigning the bone in a less adducted position. Although a greater degree of correction is possible through proximal osteotomies, these procedures require larger dissections and have higher complication rates.
●Tenotomy/soft tissue procedure involves reconstructing the soft tissue (eg, tendons) to pull the bones into a corrected position. The McBride procedure, an example of such a procedure, involves detaching the adductor tendon from the proximal phalanx and transferring it to the neck of the first metatarsal. These procedures can be performed in conjunction with a bony procedure such as an osteotomy.
●Arthrodesis involves fusing the MTP joint or the metatarsocuneiform joint in a corrected position. Arthrodesis of the MTP is usually performed on patients with severe joint degeneration at the MTP or for revision bunion surgery. Arthrodesis of the metatarsocuneiform joint (Lapidus procedure) is used commonly currently, as it focuses correction at the apex of the deformity.
●Arthroplasty involves removing either just the metatarsal joint surface or both the metatarsal and proximal phalanx joint surfaces and replacing the joint surface(s) with a prosthetic joint implant. This is not performed often and, when performed, is often in an older patient population with arthritis present in the MTP.
Small observational studies suggest these procedures can improve pain and function for patients with HV; though, outcomes are varied and do not suggest uniform benefit [38,43-49]. Therefore, the decision to pursue surgery, as well as the type of procedure, risks, and expectations for outcome should be thoroughly discussed between the surgeon and the patient. (See 'Postoperative recovery, return to work, and patient expectations' below.)
Minimally invasive, or percutaneous, surgery is used with increasing frequency. One small, prospective study comparing minimally invasive surgery with open scarf osteotomy found no difference in the degree of correction of the deformity, but the minimally invasive approach resulted in a shorter scar and reduced surgical time . In a randomized control trial comparing traditional osteotomy with a minimally invasive procedure involving a distal V-shaped osteotomy, no differences in pain, functional, or radiographic outcomes were found . Patient satisfaction was greater for the minimally invasive procedure in the first nine months following the procedure, but there was no difference in satisfaction after this time . These results are consistent with those of other studies included in a systemic review of minimally invasive HV surgery .
Postoperative recovery, return to work, and patient expectations — Recovery from surgery and return to work depends upon the procedure undertaken. If a bony procedure such as an osteotomy is performed, healing requires bony union, which typically occurs at six to eight weeks postoperatively, even when early weightbearing is allowed. External factors such as smoking and other comorbidities may impair healing and increase the time required .
In a study of 89 patients who underwent osteotomy for HV, the average time to return to work was six weeks, whereas the return to sport was eight weeks . Functional and cosmetic improvement continue after surgery for at least one year. In a separate study of 59 patients who underwent osteotomy for HV, measures of postoperative patient satisfaction showed continued improvement from 6 to 12 months .
Managing patients' surgical expectations is important. Patient satisfaction does not necessarily correlate with surgical outcome as determined by radiographic parameters (ie, hallux abductus and intermetatarsal angles) . Patients should be educated that the hallux will not be straight after the operation. Ten to 25 degrees of valgus angulation is expected at the MTP joint after surgery. Resolution of postoperative pain and swelling may require several months .
Patients must also understand that they may not be able to fit into narrower shoes postoperatively; otherwise, they may be dissatisfied if this expectation is not met. One study found that only 2 of 52 patients could wear smaller shoes after their procedure, despite a postoperative reduction in foot width .
TREATMENTS OF UNPROVEN BENEFIT — There are a variety of treatments for HV of unclear or unproven benefit that we do not recommend.
●Botulinum toxin – One randomized control trial compared botulinum toxin type A injections with saline injections and found no difference in outcome for hallux abductus (HA) angle, function, or pain at six months posttreatment .
●Marigold ointment – In a single, small trial, marigold ointment was effective in reducing pain, soft tissue swelling, and the HA angle when applied to the bunion area over an eight-week period . However, the trial had methodologic limitations that limit the applicability of the results.
INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5th to 6th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10th to 12th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.
Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)
●Basics topic (see "Patient education: Bunion (The Basics)")
SUMMARY AND RECOMMENDATIONS
●Anatomy and pathophysiology – Hallux valgus (HV) deformity (bunion) is defined as a lateral deviation of the hallux (great toe) on the first metatarsal (figure 4). The deviation of the hallux occurs primarily in the transverse plane. The deformity often also involves rotation of the toe in the frontal plane, causing the toenail to face medially (ie, eversion). Since not all cases of HV deformity become severe, there may be a threshold up to which the forces deforming the joint can be opposed by other anatomic structures. When forces greater than the threshold occur, the joint becomes deformed. (See 'Definitions and basic forefoot anatomy' above and 'Biomechanics of hallux valgus deformity' above.)
●Diagnosis – The diagnosis of HV can be made clinically, as it is easily recognized on physical examination (picture 1 and picture 2). For most patients, radiography is not performed. However, for patients with severe or refractory symptoms, radiographs may be helpful to determine the presence and extent of damage to the articular surfaces of the first metatarsophalangeal (MTP) joint. In addition, when surgery is being considered, radiographs are essential to assess the severity of the deformity and select the appropriate surgical procedure (algorithm 1 and image 1). Two weightbearing views, including a dorsoplantar plus an additional projection such as an axial view, are typically obtained. (See 'Clinical presentation' above.)
●Initial conservative management – For most patients, we advise selection of footwear that are low heeled and have a wide toe box, along with analgesics for pain as needed. In our experience, most patients with mild symptoms can attain good symptomatic relief with interventions such as footwear modification and analgesics.
For patients with insufficient relief from such measures, we suggest the use of orthotics (Grade 2C). The limited evidence comparing custom and prefabricated orthoses for HV suggests both have similar efficacy and emphasizes the importance of adjustment and proper fit, regardless of type . Because custom orthoses are significantly more expensive than prefabricated orthoses, patient preference, resources available, and mechanical correction achievable are primary factors guiding orthotic selection (algorithm 1). (See 'Initial conservative management' above.)
●Surgical referral for severe or refractory symptoms – The decision to consider surgery is based primarily on severity of symptoms, including duration, pain, and difficulty with ambulation. Neither the clinical nor radiographic appearance of the deformity plays a significant role in the decision to pursue surgery. Limited evidence does not suggest uniform benefit of surgery; therefore, we recommend a trial of conservative therapy for at least three months before surgery is considered. (See 'Indications for surgical referral' above.)
●Recovery and patient expectations – Recovery from surgery and return to work depend upon the particular procedure undertaken. If a bony procedure such as an osteotomy is performed, healing corresponds to the time to complete bony union; this occurs at around six to seven weeks postoperatively even when early weightbearing is allowed.
Patients should be educated that the hallux will not be straight after the operation. Ten to 25 degrees of valgus angulation is expected at the MTP joint after surgery. Resolution of postoperative pain and swelling may require several months. Patients should also be informed that they may not be able to fit into narrower shoes postoperatively; otherwise, they may be dissatisfied if this expectation is not met. (See 'Postoperative recovery, return to work, and patient expectations' above.)
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