Pretest

Introduction

Hallux valgus can occur at any age.¹ Patients with onset of the condition before the age of 10 are referred to as juvenile hallux valgus, and those with an onset between the ages of 10 and 18 are referred to as adolescent hallux valgus. The spectrum of the condition will be referred to as juvenile and adolescent hallux valgus (JAHV).

Definition

Juvenile and adolescent hallux valgus is described as 14° metatarsophalangeal angulation of the great toe and is a complex of deformities. The growth plates of the first metatarsal and the proximal phalanx are open at onset. Other features of JAHV that differ from adult-onset hallux valgus include milder bursal thickening over a relatively small medial eminence and almost a full range of motion of the metatarsophalangeal (MTP) joint without any evidence of degeneration. The term JAHV should be applied to any case with an above-defined onset regardless of the patient's age.²

Epidemiology

In a screening survey, the incidence among children between 9 and 10 years of age was found to be 2%.^3,4 There is often a female preponderance, with girls accounting for >80% of cases.² Juvenile and adolescent hallux valgus has a tendency to occur bilaterally.

Etiology

The cause of JAHV is unknown. In contrast to adult-onset hallux valgus, constricting footwear has not been found to be a major factor in JAHV.² In an article by Coughlin,⁵ constricting footwear was noted only by 24% of patients to play a role in the development of JAHV. Pes planus and ligamentous laxity might be associated with JAHV.² The shape of the first metatarsal might play an important role, as may the orientation and flexibility of the first metatarsocuneiform (MTC) articulation.²

Genetics

More than 70% of patients have mothers with a history of JAHV. Virtually all modes of transmission have been proposed.²

Clinical Features

Children and teens with JAHV are initially asymptomatic. As they grow, some patients report pain over the bunion and redness generally develops. Patients often have discomfort wearing fashionable, narrow shoes. The foot, including midfoot and hindfoot, should be thoroughly evaluated in weight bearing when looking for hindfoot valgus. Examiners should also look for an Achilles contracture. A motor and sensory physical examination should be performed to check for spasticity or neuromuscular diseases. Shoes should be evaluated for the wear pattern. All patient and family concerns and expectations should be clarified.⁶

Pathophysiology

The sesamoids often undergo lateral subluxation under the effect of the adductor and short flexor muscles. The medial collateral ligament and the medial capsule are lengthened with a corresponding contracture of the same structures on the lateral side of the MTP joint. The great toe pronates, and the abductor moves plantarward because it is unable to counteract the effects of the adductor. Long extensor and flexor tendons displace laterally to act as bowstrings across the joint. The MTP joint is subluxated, and the articular surface is angulated in relation to the long axis of the first metatarsal.^7,8 The lesser toes are also affected during the course of the disease.³ Although metatarsus primus varus has been associated with the deformity,⁹ evidence suggests that the second metatarsal is moving laterally away from the normally placed first metatarsal.^8,10

Associated Conditions

Pes planus and ligamentous laxity might be associated with JAHV2, but there has not been any correlation found between the height of arch and the hallux valgus deformity.² Severe valgus deformity of the hindfoot plays an important role in the development and progression of JAHV.¹⁰ Neuromuscular conditions and spasticity can accompany JAHV. Achilles tendon contracture should be sought, which may influence the success rate of the therapy. Metatarsus adductus can be present in some patients.¹⁰

Imaging and Radiographic Measurements (Slide)

Standing anteroposterior and lateral radiographs of the foot are required for evaluation. The overall foot alignment should be assessed along with evaluating the midfoot and the hindfoot. The forefoot measurements are as follows: the hallux valgus angle, or the MTP angle, is accepted as normal if <14°; the intermetatarsal (IM) angle, or the angle between the 1st and 2nd metatarsal, is considered as normal if <8°. The distal metatarsal articular angle (DMAA) is formed between the shaft of the first metatarsal and the line perpendicular to the articular surface of the MTP joint. The DMAA is expected to increase in JAHV. Nevertheless, it does not have a high interobserver reliability because the identification of the extent of the metatarsal head cartilage is difficult in many children and adolescents. In addition, the MTP joint congruity, relative lengths of the metatarsals, MTC orientation, proximal phalangeal articular angle, and lesser metatarsal orientation should also be assessed.² In comparison with the adult-onset hallux valgus, the MTP angle is less and the magnitude of deformity of IM angle is increased in JAHV.¹⁰

Slide 1

Natural History

The natural history is not clearly defined, yet Kilmartin³ reported that progression of hallux valgus occurs in adolescents despite the use of well-fitting comfortable shoes with a wide toe box. Piggott¹¹ stated that congruous MTP joints are stable and less likely to require surgical correction.

Treatment

The aim of conservative treatment is to find a shoe that matches the foot. High-heeled shoes should be avoided. The preferred shoes should have an adequate toe box, a soft upper, and a low heel. When buying a pair of shoes, it is advised to try on the shoes toward the end of the day when the foot reaches its maximum size. It may be helpful to draw the outline of the weight bearing foot and compare it with that of the shoe.¹⁰

Although pads for bunion protection and arch supports can be used,⁹ there are some conflicting reports of the success of orthotic devices.^1,3 Surgery is indicated only when significant pain continues despite conservative treatment.¹² Surgery for JAHV does not have the high success rate of other elective procedures. Complications may include stiffness of the MTP joint, persistent pain, avascular necrosis of the metatarsal head, and a high rate of recurrence.¹⁰ Therefore, surgery solely for cosmetic purposes is discouraged.¹⁰ The postoperative recurrence rate of JAHV has led to the recommendation that the surgery should be postponed until skeletal maturity. The recurrence rate is also high in cases with hyperelasticity and significant pes planus. The surgery should be aimed at maintaining a flexible first metatarsophalangeal joint, preserving the normal weight bearing pattern of the forefoot, and retaining a reasonable means of salvage should a complication occur.

A surgeon should address all of the components of the deformity: the pronation of the hallux, the increased hallux valgus angle, the increased IM angle, and hypermobility or obliquity of the metatarsocuneiform joint.¹⁰ Because the pathologic components of every patient are different, surgeons must be able to tailor the procedure to the patient rather than strictly following a fixed procedure. The following are basic recommendations:

In a mild hallux valgus deformity with a hallux valgus angle <25°, the surgical options include distal soft tissue realignment (intraarticular) or one of the distal metatarsal osteotomies (extra-articular) (eg, chevron osteotomy or Mitchell osteotomy). A chevron osteotomy is performed in the distal metaphysis of the first metatarsal together with a medial eminence resection. Zimmer¹² noted that an average correction of 8° is achieved with a chevron osteotomy in adolescents. A Mitchell osteotomy is a lateral displacing angulation osteotomy that is performed more proximally than a chevron osteotomy.

Distal metatarsal osteotomies are aimed at correcting the DMAA. If the first MTP joint is congruous, then it is wise to avoid inta-articular methods of correction. Distal soft tissue realignment (or the modified McBride procedure) consists of freeing the lateral sesamoid from its attachments (but no excision); releasing the adductor conjoint tendon; leaving the distal adductor attachment to the phalanx intact; incising the transverse intermetatarsal ligament; performing a lateral capsular release, medial eminence resection, and medial capsulorrhaphy; and suturing the adductor conjoint tendon back to the lateral metatarsal capsule.¹⁰

Performing a distal metatarsal osteotomy (eg, chevron osteotomy) and distal soft tissue realignment for the same first metatarsal increases the risk of resultant avascular necrosis. If the IM angle is >8°, then it is better to move proximally and perform a proximal metatarsal osteotomy or a medial cuneiform osteotomy. In a patient with an open physis of the base of the first metatarsal, it is best to select an open-wedge osteotomy of the medial cuneiform, especially if the MTC joint is deviated medially and the first metatarsal is shorter than the second.¹⁰ Proximal metatarsal osteotomy or a medial cuneiform osteotomy is aimed at correcting the increased IM angle or the metatarsus primus varus.

In some patients, the Akin procedure is preferable if the majority of the deformity is in the proximal phalanx. The Akin procedure consists of medial eminence resection and a medial capsulorrhaphy, combined by closing-wedge medial osteotomy at the base of the proximal phalanx. This procedure provides extra-articular correction. Thus, in addition to being used in hallux valgus interphalangeus, it is indicated in severe cases where there is a significant deformity at the MTP joint and an increased IM angle. It is used in combination with a proximal metatarsal or medial cuneiform osteotomy. Akin osteotomy in an immature skeleton requires a meticulous surgical plan to avoid iatrogenic injury to the physis of proximal phalanx.¹⁰

In a moderate hallux valgus deformity with a hallux valgus angle >25°, it is better to perform a proximal first metatarsal osteotomy with or without distal soft tissue realignment according to the congruity of the MTP joint. A proximal metatarsal osteotomy provides better fulcrum in correcting an increased hallux valgus angle and IM angle. Intraoperative localization of first metatarsal physis helps in placing the osteotomy just inferior to the physis. Considering the length of the first metatarsal, the type of the osteotomy can be an open-wedge, closing-wedge, or a crescentic type to increase, decrease, or maintain the final length, respectively. Alternatively, an open-wedge medial cuneiform osteotomy can be performed as well. As other choices, a Mitchell osteotomy or a combination of a chevron osteotomy with Akin procedure can be performed when the MTP joint is congruent.¹⁰

In a severe hallux valgus deformity with a hallux valgus angle >40°, a number of procedures can be combined accordingly. In cases of hypermobility or an oblique orientation of the first MTC joint, MTC arthrodesis may be applied, which has been popularized as Lapidus procedure.¹⁰

Lastly, arthrodesis of the MTP joint is the most reliable way of hallux valgus correction in patients with cerebral palsy.⁸

References

Groiso JA. Juvenile hallux valgus. A conservative approach to treatment. J Bone Joint Surg Am. 1992; 74:1367-1374.

Morrissy RT, Weinstein SL, eds. Lovell and Winter's Pediatric Orthopaedics. 5th ed. Philadelphia, Pa: Lippincott Williams and Wilkins; 2001:1200-1202.

Kilmartin TE, Barrington RL, Wallace WA. A controlled prospective trial of a foot orthosis for juvenile hallux valgus. J Bone Joint Surg Br. 1994; 76:210-214.

McDonald MG, Stevens DB. Modified Mitchell bunionectomy for management of adolescent hallux valgus. Clin Orthop Relat Res. 1996; 332:163-169.

Coughlin MJ, Roger A. Mann Award. Juvenile hallux valgus: Etiology and treatment. Foot Ankle Int. 1995; 16:682-697.

Helal B. Surgery for adolescent hallux valgus. Clin Orthop Relat Res. 1981; 157:50-63.

The Core Curriculum. Adolescent bunion.
http://www.posna.org/resources/coreCurriculum/pdf/adolescentBunion.pdf

Weiner BK, Weiner DS, Mirkopulos N. Mitchell osteotomy for adolescent hallux valgus. J Pediatr Orthop. 1997; 17:781-784.

Houghton GR, Dickson RA. Hallux valgus in the younger patient: The structural abnormality. J Bone Joint Surg Br. 1979; 61:176-177.

Coughlin MJ. Juvenile bunions. In: Mann R, Coughlin M, eds. Surgery of the Foot and Ankle. 6th ed. St. Louis, Mo: Mosby; 1993:299-338.

Piggott H. The natural history of hallux valgus in adolescence and early adult life. J Bone Joint Surg Br. 1960; 42:749-760.

Zimmer TJ, Johnson KA, Klassen RA. Treatment of hallux valgus in adolescents by the chevron osteotomy. Foot Ankle. 1989; 9:190-193.