Proximal and Distal First Metatarsal Osteotomies for Hallux Valgus

Christopher B. Hirose, MD

Michael J. Coughlin, MD

Dr. Hirose or an immediate family member is a member of a speakers’ bureau or has made paid presentations on behalf of Arthrex, Inc. and serves as a paid consultant to or is an employee of Arthrex, Inc. Dr. Coughlin or an immediate family member has received royalties from Arthrex, Inc., Erchonia, Stryker, and Wright Medical Technology, Inc.; is a member of a speakers’ bureau or has made paid presentations on behalf of Arthrex, Inc. and Stryker; serves as a paid consultant to or is an employee of Arthrex, Inc., Erchonia, Integra, and Stryker; has received research or institutional support from Arthrex, Inc., Integra, and Stryker; has received nonincome support (such as equipment or services), commercially derived honoraria, or other non-research-related funding (such as paid travel) from Arthrex, Inc. and Stryker.

PATIENT SELECTION

Indications

We carefully consider performing a simultaneous proximal and distal first metatarsal osteotomy in a patient who has a symptomatic moderate to severe hallux valgus deformity with a congruent first metatarsophalangeal joint (Figures 1 and 2).

Radiographic findings include a first-second intermetatarsal angle greater than 13°, a distal metatarsal articular angle (DMAA) greater than 15°, and a congruent first metatarsophalangeal joint (Figure 3).

FIGURE 1 Preoperative AP radiograph of the foot of an adolescent shows a hallux valgus deformity with a congruent joint.

Congruent hallux deformities are uncommon: Piggott¹ noted a 9% occurrence (20 of 215 adult feet) of congruent first metatarsophalangeal joints, and Coughlin and Carlson² described a 2% prevalence (21 of 878) in adult feet.

Recognition of an increased DMAA angle is of utmost importance. In one study, higher hallux valgus recurrence rates were found in patients who had undergone distal soft-tissue realignment procedures but also had congruent first metatarsophalangeal joints.³ This is due to the fact that when one forces an already congruent joint to
become incongruent, the proximal phalanx seeks its original position of congruency on the first metatarsal head, re-creating the hallux valgus deformity. Stiffness and pain can result. In contrast, with the distal first metatarsal closing-wedge osteotomy, the hallux valgus deformity is corrected by correcting the DMAA, keeping a congruent joint congruent.

FIGURE 2 Postoperative AP radiograph shows proximal and distal first metatarsal osteotomies with correction of the distal metatarsal articular angle (DMAA).

FIGURE 3 AP radiograph shows a severe distal metatarsal articular angle (DMAA).

We perform a triple osteotomy (adding a proximal phalangeal Akin osteotomy to the double first metatarsal osteotomy) in patients with hallux valgus interphalangeal deformities, in patients with significant rotational deformities, or in patients in whom we have performed a double first metatarsal osteotomy but a residual hallux valgus deformity remains. Both adult and juvenile deformities are considered for surgical treatment.⁴ Although juvenile hallux valgus corrections have historically had high rates of failure, Smith and Coughlin⁵ believe that these failures may have been due to an under appreciation of deformity. When all of the deformities are addressed and the DMAA is corrected with a distal closing-wedge metatarsal osteotomy, success rates are significantly higher. Coughlin⁶ reported good or excellent results in 92% of 60 juvenile hallux valgus corrections.

PREOPERATIVE IMAGING

Three weight-bearing radiographic views of the foot are obtained: AP, lateral, and oblique. The radiograph tube is centered over the tarsometatarsal joint and angled 15° toward the ankle joint, with a 1-m separation between the radiograph tube and the radiograph. The hallux valgus angle (Figure 4, A), first-second intermetatarsal angle (Figure 4, B), distal metatarsal articular angle (Figure 4, C), and first metatarsophalangeal joint congruency (Figure 5) are measured and noted.

PROCEDURE

Room Setup/Patient Positioning

The patient is positioned supine on a standard operating room table. A small bump is placed under the ipsilateral hip so that the foot points toward the ceiling, and a mini C-arm fluoroscanner is positioned on the surgical side of the bed. An Esmarch tourniquet is wrapped around the ankle for exsanguination.

Special Instruments/Equipment/Implants

The following equipment should be on hand: a crescentic oscillating saw blade, a straight oscillating blade, a 3.5-mm solid small-fragment screw, 0.062-in Kirschner wires (K-wires), and a proximal first metatarsal plate.

VIDEO 94.1 Proximal and Distal First Metatarsal Osteotomy. Christopher B. Hirose, MD; Michael J. Coughlin, MD (6 min)

View Quicktime Video

Video 94.1

Surgical Technique

Distal Metatarsal Osteotomy

Attention is turned to the distal first metatarsal closing osteotomy to first correct the DMAA. We template hallux valgus deformities to resect a predetermined wedge of bone with the goal of correcting the DMAA to less than 6°. On average, a 4- to 6-mm wedge of bone is removed.² A longitudinal medial incision is made over the first metatarsal head, centered over the first metatarsophalangeal joint.

Skin flaps are raised, and the dorsal medial cutaneous nerve is protected. An L-shaped capsulotomy is constructed, with the horizontal limb placed dorsally and the vertical limb placed proximally (Figure 6, A). This keeps the strongest portion of the capsule—the attachment to the proximal phalanx—intact.

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