Chapter 73 What Is the Best Treatment for Hallux Valgus?*
Theories on the pathology and appropriate treatment of hallux valgus have been extensively described in the orthopedic literature. The wealth of information on the surgical management of hallux valgus has been molded into frequently taught treatment algorithms and principles. Although these algorithms and principles aim to provide consistency in treating symptomatic hallux valgus, the wide variety of approaches to treating hallux valgus suggests that they are far from commonly accepted. The purpose of this current concept review is to provide a balanced representation of current thinking on the pathomechanics, assessment, and treatment of hallux valgus. Orthopedic management of hallux valgus remains challenging. Despite the appeal of establishing universally accepted treatment protocols and algorithms, a critical review of the literature suggests that the surgeon treating hallux valgus deformity should individualize management to the particular patient.
HISTORY OF THE CONDITION AND OVERVIEW OF CAUSATIVE FACTORS
Bunion, a term evolving from the Latin word bunio, meaning “turnip,” poorly defines the condition hallux valgus. To our knowledge, the first published reference to hallux valgus is by Carl Hueter in 1870.1 Hallux valgus is commonly thought to develop because of unaccommodative shoe wear. Some support this conclusion,2,3 but consistently sufficient evidence does not exist to confirm unaccommodative shoe wear as a causative factor in the development of hallux valgus. Conversely, the observation that many individuals do not experience development of hallux valgus despite wearing nonphysiologic shoe wear for many years implies that some individuals may have an incompletely defined predisposition to hallux valgus. Other studies report that hallux valgus develops in some unshod individuals, implying a congenital predisposition.4–10 Hallux valgus in juveniles, adolescents, or male individuals whose feet have not been subjected to shoes with narrow toe boxes supports a congenital predisposition. An association between hallux valgus and female sex is also suggested.11,12 It has also been proposed that there is a familial predisposition to development of hallux valgus.6,13–15 The exact cause leading to the development of a hallux valgus deformity remains unclear and may be multifactorial. However, as the bunion deformity tends to develop over time, it seems reasonable to conclude that repetitive forces applied to the first metatarsal phalangeal joint leads to hallux valgus.
CAUSATIVE FACTORS AND PATHOMECHANICS (PROPOSED THEORIES)
Anatomic Considerations
Repetitively forcing the hallux into a valgus position, particularly with weight bearing and ambulation, is believed to eventually result in a valgus deformity at the first MTP joint. The summation of ground reactive forces and dynamic muscular forces eventually leads to attenuation of the medial joint capsule, contractures of the lateral joint capsule and adductor tendons, with a resultant medial deviation of the first metatarsal head (“bunion deformity”).
Pes Planus and Hallux Valgus
Pes planus may lead to hallux valgus because of increased forefoot abduction that creates a nonphysiologic load on the plantarmedial aspect of the great toe during heel rise. The association between pes planus and hallux valgus is controversial. Although some authors suggest that patients with pes planus have a greater tendency to experience development of hallux valgus than patients with maintained arches,16–23 others fail to support this association.14,24–26 The combination of conflicting reports and consistently Level III-V evidence provide insufficient evidence (grade I) to prove or disprove an association between pes planus and hallux valgus.
Hypermobility of the First Tarsometatarsal Joint
Mobility of the first TMT joint is observed in the sagittal and transverse plane.27 The actual prevalence of medial column hypermobility continues to be controversial. It is theorized that hypermobility could lead to the development of hallux valgus in two ways. First, greater than physiologic dorsal subluxation of the first metatarsal could result in pes planus alignment, increased forefoot abduction, and a nonphysiologic load on the plantarmedial aspect of the great toe during heel rise. Second, greater than physiologic medial subluxation of the first metatarsal could result in increasing the 1-2 intermetatarsal angle (IMA), promoting metatarsus primus varus. Some foot and ankle surgeons maintain that hypermobility of the first TMT joint or lack of stability of the foot’s medial column contributes to the development of hallux valgus28–32 and resultant pain,33 a theory popularized by Morton.9,34–37 Lapidus38–40 supports this theory and suggests surgical correction with a first TMT joint arthrodesis. Although a convincing argument in theory, no evidence exists to support such a correlation, and in fact, other investigators have demonstrated that hypermobility of the first TMT joint is not directly associated with hallux valgus.37,41–45 Insufficient evidence (Level III-V) exists to support or disprove the contribution of first TMT joint hypermobility to the development of hallux valgus (grade I).
Distal Metatarsal Articular Angle
Hallux valgus may exist with a congruent/symmetric relation between the first proximal phalanx and the first metatarsal head, suggesting a congenital predisposition in select patients with an increased distal metatarsal articular angle (DMAA).46–48 Richardson and colleagues49 note that the DMAA ranged from 6.3 to 18 degrees; as the angle increases, so does the propensity for hallux valgus, albeit congruent/symmetric. Coughlin14 adds that the DMAA tends to be greater in patients with juvenile hallux valgus younger than 10 years when compared with those older than 10. Although Richardson and colleagues49 suggest that the DMAA can be reliably determined radiographically, others have reported poor interobserver reliability.50–52
Medial Capsular Integrity
Uchiyama and investigators53 demonstrate, in a cadaveric model, that feet with hallux valgus have a different organization of collagen fibrils than that observed in normal feet. These findings may be in response to abnormal stress repetitively applied to this part of the joint capsule. Alternatively, abnormal mechanical properties of the medial capsule such as those seen in patients with conditions such as rheumatoid arthritis may increase the propensity to develop hallux valgus.
CLINICAL MANIFESTATION/TYPICAL PRESENTATION
Physical Examination
The severity of hallux valgus deformity and pes planus are assessed with the patient weight bearing. To illustrate appropriateness of shoe wear, the physician may wish to contrast an outline of the patient’s foot with nonphysiologic shoe wear. Medial eminence tenderness, first MTP joint range of motion, and first TMT hypermobility may be evaluated with the patient seated.43 Limited first MTP joint range of motion with or without crepitance should alert the physician to potential first MTP joint degenerative changes.
Because physiologically normal values of first TMT joint mobility have not been defined, first ray hypermobility remains a controversial finding and a diagnostic challenge, despite some authors providing methods to objectively quantitate first TMT joint motion.54 Even though a validated Klaue device exists to measure first ray mobility,55,56 it is not particularly practical in the clinical setting. Moreover, first TMT joint hypermobility may not only occur in the sagittal plane but also in the transverse plane.27 Clinical evaluation may not be adequately specific to isolate the first TMT joint, and therefore may assess only medial column mobility. Physical examination should also include the evaluation of the second MTP joint for presence of synovitis, metatarsal head overload, and/or second toe deformity, all of which are often associated with hallux valgus.
Imaging Studies
Radiographic Measurements Pertinent to Hallux Valgus.
Several parameters measured from AP radiographs aid in the basic characterization of a hallux valgus deformity. The hallux valgus angle (HVA), defined as the angle formed by the intersection of longitudinal axes of the diaphyses of the first metatarsal and the proximal phalanx, quantifies the malalignment of the first MTP joint. Several authors have suggested that the upper limit of normal for this measurement is 15 degrees.6,57–59 The IMA represents the angle formed between the diaphyses of the first and second metatarsals. This measurement quantifies the extent of metatarsus primus varus. The upper limit of normal for the IMA is 9 degrees.6,57–59 The interphalangeal angle, which measures the angle between the metaphysis and diaphysis of the proximal phalanx, determines the amount of hallux valgus interphalangeus (HVI). The physiologic upper limit of normal for this parameter is 10 degrees.51,58, 59 The DMAA assesses the angular relation between the articular surface of the head and diaphysis of the first metatarsal. The upper limit of normal DMAA is 10 degrees.37,49, 51 The literature suggests that, although preoperative intraobserver and interobserver reliability for the HVA and IMA is excellent (<5 degrees, 95% confidence interval),51,59–61 assessment of the DMAA remains a diagnostic challenge, with poor intraobserver and interobserver reliability.47,49–52
Radiographic Measurements Purported to Suggest Hypermobility.
Second metatarsal diaphyseal hypertrophy, a medially oriented first TMT joint, and first TMT joint obliquity have been suggested to indirectly determine hypermobility of the first ray. Diaphyseal hypertrophy of the second metatarsal, particularly the medial cortex, has been suggested as a sign of hypermobility of the first ray.28,29, 31, 62, 63 No investigation has demonstrated a correlation between radiographic changes in the second metatarsal and hypermobility.37,44, 64 However, one study demonstrated a marginal correlation between the IMA and dorsal mobility of the TMT joint in patients with hallux valgus.65 A medially oriented obliquity of the first TMT joint has proposed as an associated sign of a hypermobility, but Brage and colleagues66 demonstrated that changing the inclination of the x-ray beam relative to the floor created wide variation in the measurement of the first TMT joint obliquity. Based on these findings, Brage and colleagues66 concluded that first TMT joint obliquity was not a reliable indication for first TMT arthrodesis in the management of hallux valgus. An investigation observed significant dorsal translation and dorsiflexion of this joint in a series of patients with moderate-to-severe hallux valgus compared with normal control subjects.67 The appearance of plantar gapping at the TMT joint has been attributed to radiographic projection and discounted as an indication of hypermobility.33,71 Currently, no investigation has correlated these presumed radiographic abnormalities of the TMT joint with clinical hypermobility.
Correlating Physical and Radiographic Findings.
Thordarson and coworkers68 evaluated 285 women, with an average age of 49 years, scheduled for corrective surgery for hallux valgus. Validated AAOS foot-specific outcomes data collection questionnaires were used. Preoperative radiographic data (HVA and IMA) were stratified into degree of deformity. The data were stratified into age groups consistent with those reported for the 36-Item Short Form Health Survey (SF-36), and the results were compared with the SF-36 for the general population. The global foot and ankle score and the shoe comfort score were compared with the general population, and the severity of the preoperative deformity was correlated with the baseline scores. Bodily pain scores were uniformly worse for hallux valgus patients compared with the general population, with significantly lower global foot and ankle and shoe comfort scores, a finding that suggests that the bodily pain score from the SF-36 represents a sensitive measure of the difficulties experienced by patients undergoing corrective hallux valgus surgery. The preoperative radiographically determined severity of deformity failed to correlate with any scores measured.
CLASSIFICATION
NONOPERATIVE TREATMENT
Symptoms of pain are best treated with shoe wear and activity modification. Shoes with a wider toe box and a comfortable upper are often helpful. Padding over the medial eminence or adjustments to the shoe to create more space medially can be helpful. However, nonoperative management cannot reverse hallux valgus deformity, and successful surgery may lead to an improved functional outcome. A randomized, controlled trial in 209 consecutive patients with symptomatic hallux valgus treated in four Finnish general community hospitals demonstrated that, although orthoses provided short-term symptomatic relief, surgical management of hallux valgus led to superior functional outcome and patient satisfaction as compared with orthotic management at a minimum follow-up of 12 months.69 Surgical correction also led to better functional outcome and patient satisfaction than observation (“watchful waiting”), suggesting that the natural history of symptomatic hallux valgus deformity, at 12 months, is not one of improvement (Level I evidence). Although this prospective, randomized study demonstrates benefits of surgical correction of hallux valgus when compared with nonoperative treatment, insufficient evidence exists to support that corrective bunion surgery should be favored over nonoperative management (grade I).
MILD-TO-MODERATE DEFORMITY
Distal Procedures
Incongruent Hallux Valgus.
Simple Bunionectomy.
Few recent orthopedic articles report on simple bunionectomy (medial eminence resection with medial capsular plication). In a retrospective review of simple bunionectomy, Kitaoka and coauthors70 note high recurrence and high patient dissatisfaction rates. Given the limited Level IV evidence for simple bunionectomy, no specific recommendation (grade I) can be made for medial eminence resection in hallux valgus correction.
Modified McBride Procedure (Distal Soft-Tissue Procedure).
The McBride distal soft-tissue procedure, although common as an adjunct procedure in many hallux valgus corrective surgeries, has also been described as an isolated procedure for hallux valgus correction. In 1923, Silver22 reported the combination of medial eminence resection, lateral capsular release, adductor hallucis tendon release, and medial capsular plication for the treatment of hallux valgus deformity. The modified McBride procedure includes medial capsulotomy (and subsequent plication), division of the ligament between the lateral capsule and fibular sesamoid, adductor hallucis release, lateral capsular fenestration, and a controlled varus stress to the first MTP joint.71–73 A concern about hallux varus after the original McBride procedure74 prompted the preservation of the fibular sesamoid in the modification.
Few recent orthopedic articles report on isolated modified McBride procedures for the correction of hallux valgus deformity. In a retrospective review, Mann and Pfeffinger72 note acceptable patient satisfaction rates and improvement in hallux alignment (Level IV evidence). However, a selection bias to patients with mild and flexible deformities was suggested.75 Johnson and coworkers71 retrospectively compared the modified McBride procedure and distal chevron osteotomy, with the two groups matched for age, severity of deformity, and length of follow-up (Level III evidence). Although postoperative satisfaction rates were not significantly different, the distal chevron group exhibited significantly better correction of alignment. Given the limited Level III and IV evidence for the modified McBride procedure, no specific recommendation (grade I) can be made for the McBride distal soft-tissue procedure when used in isolation for hallux valgus correction.
Distal Chevron Osteotomy.
The distal chevron osteotomy is a V-shaped osteotomy of the first metatarsal, described by Corless,76 Johnson and coworkers,77 and Austin and Leventen.78 The capital fragment is shifted laterally to narrow the forefoot. An anatomic study suggested that the capital fragment can be safely shifted laterally 6.0 mm in men and 5.0 mm in women, and still maintain greater than 50% bony apposition of the fragments.79 The procedure has been performed with or without fixation of the shifted capital fragment.80–85 The symmetric orientation of the distal chevron osteotomy78 has undergone several modifications to accommodate fixation.77,80 The combination of a medial closing wedge osteotomy of the first proximal phalanx (Akin) and a distal chevron osteotomy has been described when hallux valgus with metatarsus primus varus is associated with HVI.86,87 The distal chevron osteotomy also has been combined with a lateral capsular or adductor tendon release, or both.83,85,88–90
For mild-to-moderate hallux valgus correction, the effectiveness of the distal chevron osteotomy in providing favorable outcomes and patient satisfaction, regardless of fixation method, addition of lateral soft-tissue release, length of follow-up, or patient age, is supported by numerous retrospective reviews (Level IV evidence).80–85,90–97 The average preoperative IMA was less than 15 degrees in all studies. DeOrio and Ware81 report satisfactory outcomes and patient satisfaction with a low complication rate with bioabsorbable fixation (Level IV evidence). Crosby and Bozarth93 and Gill and colleagues82 note no significant differences in favorable outcomes or patient satisfaction and minimal complications in case series comparisons of screw, Kirschner wire, and no fixation and Kirschner wires versus bioabsorbable fixation, respectively (Level IV evidence).
Although the addition of a lateral release to a distal chevron osteotomy may improve global correction of hallux alignment, patient satisfaction is similar in patients who have distal chevron osteotomies with or without lateral release. Resch and investigators’89 Level I evidence investigation compares distal chevron osteotomy with and without adductor tenotomy. Although the clinical appearance and radiographic alignment were significantly improved in the group with adductor release, patient satisfaction was not. Mann and Donatto,80 in a small case series (Level IV evidence), note satisfactory outcome for distal chevron osteotomy without lateral release: similar to results of Level IV evidence studies of distal chevron osteotomies with lateral release.92,95, 97
Two recently published Level IV case series of distal chevron osteotomies with lateral release83,85 note that the results were maintained with longer follow-up: Trnka and coworkers’83 follow-up period was 2 to 5 years, and Schneider and colleagues’85 follow-up period was 5.6 to 12.7 years. Furthermore, both studies suggest that results were equal for patients older and younger than the arbitrarily chosen age of 50 years.
Congruent Hallux Valgus.
Although subject to poor interobserver reliability,47,50–52 the DMAA47,49 can be decreased by combining the distal chevron osteotomy with Akin osteotomy80 or by making a biplanar distal chevron osteotomy in mild hallux valgus deformity46,98 (Level IV evidence). Whereas the goal of a combination of distal chevron and Akin osteotomies is to improve clinical alignment through extra-articular correction, the biplanar distal chevron osteotomy aims to simultaneously correct hallux valgus and decrease the DMAA. In the biplanar distal chevron procedure, two different osteotomy configurations can be used. With the conventional, symmetric pattern of two osteotomy limbs of equal length, a second oblique wedge resection for each cut allows a reduction in the DMAA in combination with the lateral shift of the metatarsal head46 (Level IV evidence). With a short, relatively vertical dorsal limb and long, horizontal plantar limb, a second wedge resection dorsally permits redirection of the metatarsal head simultaneous with the lateral shift98 (Level IV evidence).
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