The Minimally Invasive Hallux Valgus Correction (SERI)

Hallux valgus is a deformity of the forefoot characterized by progressive lateral subluxation of the proximal phalanx of the first toe on the first metatarsal head. It is considered pathologic when the patient experiences symptoms associated with a valgus deviation (hallux valgus angle [HVA]) greater than 15 degrees (FIG 1).⁸

Hallux valgus is more common in adult women. It is often bilateral, and in many cases it is associated with other foot deformities, such as lesser toe or hindfoot or midfoot deformities that may exacerbate the pathology.¹⁴

Hallux valgus is often a progressive disease that compromises the physiologic function of the first metatarsophalangeal (MTP) joint and potentially the entire forefoot.

The technique described in this chapter—known as SERI for “simple, effective, rapid, inexpensive”—can be applied to congruent and incongruent hallux valgus deformity.

ANATOMY

The first metatarsal is the broadest and shortest of the five metatarsals, and the distal condyle of the first metatarsal head articulates with the proximal phalanx of the great toe. In addition, the plantar aspect of the first metatarsal head articulates with the sesamoids, which are contained in the flexor hallucis brevis tendon.

The relationship of the medial and lateral sesamoids is maintained by the intersesamoid ligament. In association with the ligaments of and muscle balance about the first MTP joint, the sesamoid complex contributes to stabilizing the first MTP joint.

When functioning properly, the first MTP joint optimizes push-off of the hallux during gait.⁴

Although physiologically the first MTP joint has a wide motion arc in the sagittal plane, it exhibits very little flexibility in the coronal plane. Hallux valgus occurs with greater than physiologic coronal plane motion of the first MTP joint.

The first metatarsal head receives its main dorsal blood supply from the first dorsal metatarsal artery, a major contributor to an extracapsular anastomosis at the first MTP joint. On the plantar aspect of the first metatarsal head, the blood supply is from a combination of capsular arteries, branches of the first plantar metatarsal artery, and the first dorsal metatarsal artery.^15,16

PATHOGENESIS

The pathogenesis of hallux valgus is not fully understood.

In some patients, hallux valgus deformity may be due to congenital malalignment, neurologic conditions, systemic disease (such as rheumatoid arthritis), connective tissue disorders (with greater than physiologic ligamentous laxity), valgus deviation of the lesser toes, or trauma.^3,4,12,13

Several factors that may compromise the normal biomechanics of the foot have been implicated in the development of hallux valgus, including hereditary factors, shape of the first MTP joint, shoe wear, pes planus, and metatarsus adductus.^{1–3,10,18,19}

Controversy remains over the greatest primary cause leading to hallux valgus: valgus deviation of the hallux or metatarsus primus varus.^5,8–11

PATIENT HISTORY AND PHYSICAL FINDINGS

With loss of the physiologic balance of the first MTP joint, dynamic muscle function leads to progression of hallux valgus deformity in the majority of cases.

Progressive hallux valgus may create other forefoot problems, including bursitis of the first MTP joint (FIG 2), callosities, and onychocryptosis (between the first and the second toe).

Advanced hallux valgus may diminish first MTP joint function to the point that it leads to lesser toe deformity (claw and hammer toes) and associated transfer metatarsalgia (FIG 3).

For ideal decision making in the management of hallux valgus, the following factors must be considered: pain, mobility and stability of the first MTP joint, and associated deformity.

The site of the pain should be evaluated. The pain is often localized at the prominent medial eminence. At times, an inflamed bursa, a site of tenderness, overlies the prominent medial eminence. In advanced hallux valgus, the pain should be referred to the lateral metatarsal head.

Hallux mobility at the first MTP joint should be evaluated. Range of motion of the first MTP joint should be checked both in its resting valgus position and its correct neutral position. Any limitation may be a sign of first MTP joint incongruency or arthritis and should be evaluated radiographically.

Stability of the first MTP joint should be assessed. Severe instability of the first MTP is a contraindication for use of the SERI technique.

Associated lesser toe deformities, such as claw toes, result in metatarsal overload and callus formation, often creating symptoms that exceed those directly related to the hallux.

IMAGING AND OTHER DIAGNOSTIC STUDIES

A standard radiographic examination, including anteroposterior (AP) and lateral weight-bearing views of the forefoot, allows the assessment of arthritis and congruency of the joint; measurement of the HVA, intermetatarsal angle (IMA), and distal metatarsal articular angle (DMAA); and calculation of the metatarsal formula,^17,20,21 especially the relation between the length of the first and the second metatarsal.

Preoperative planning is performed using the preoperative weight-bearing radiographs of the foot. In particular, we assess the radiographs to determine the desired obliquity of the bone cut and the amount of mediolateral and dorsoplantar shift of the metatarsal head required to reduce the metatarsal head over the sesamoid complex and correct an increased DMAA (FIG 4).

NONOPERATIVE MANAGEMENT

Comfortable shoes with a wide toe box and sole may reduce the pressure on the first metatarsal head’s medial prominence. In severe deformity, custom-made shoes or insoles with a metatarsal support may relieve symptoms attributable to transfer metatarsalgia and associated plantar callus formation.

Nonoperative treatment of hallux fails to correct the deformity; it only accommodates to it. Given that hallux valgus deformity tends to progressively worsen, probably due to muscle imbalance about the first MTP joint, symptoms may abate only with surgical correction when conservative treatment proves inadequate.

SURGICAL MANAGEMENT

In our experience, the SERI technique is effective in correcting mild to moderate hallux valgus, with HVA and IMA not exceeding 40 degrees and 20 degrees, respectively.^6,7

The operation is indicated in case of hallux valgus presenting with any degree of DMAA and a mild degenerative arthritis of the first MTP joint.

Specific contraindications to the SERI technique are severe degenerative arthritis, stiffness, or severe instability of the first MTP joint.

In our experience, the SERI technique can be performed as simultaneous bilateral procedures or combined with concomitant correction of associated foot deformities.⁷

Preparation and Positioning

Before surgery, the patient’s foot or feet (simultaneous bilateral procedures) are scrubbed using disinfectant soap solution.

Several anesthetic techniques can be used. We usually prefer a sciatic nerve block using ropivacaine hydrochloride monohydrate 7.5 mg/mL.

The patient is placed in a supine position, with the lower extremity externally rotated with the foot’s lateral border contacting the operating table.

After the foot is exsanguinated, an Esmarch elastic bandage is used as an ankle tourniquet with adequate padding.

The SERI technique does not require a lateral soft tissue release, particularly with a flexible hallux valgus deformity, because the lateral soft tissues relax with lateral translation of the first metatarsal head. Even with slight stiffness of the first MTP joint, we do not perform a lateral release, instead applying an intraoperative manual stretch to the adductor hallucis by forcing the hallux in a varus position.