Chevron osteotomy is indicated in patients with symptomatic mild to moderate hallux valgus deformity with no significant arthritis. Mild to moderate deformities are those with an intermetatarsal (IM) 1-2 angle of 16° or less in a weight-bearing anteroposterior radiograph of the foot (Fig. 1.1). More severe deformities may not be adequately corrected with this operation. It is preferable if the patient has a painless, mobile MTP joint that may be passively corrected to anatomic alignment. The chevron osteotomy is occasionally indicated in patients who have failed hallux valgus operations, such as simple bunionectomy with medial capsulorrhaphy.

Chevron osteotomy is not indicated for patients who have general or local conditions that preclude operative treatment, such as skin ulceration, local or remote infection, or dysvascular foot, or for patients who are unable to comply with required postoperative immobilization and protected weight bearing. Operating on patients with asymptomatic hallux valgus deformities is generally not advisable, nor is surgery because of anticipation of difficulty at some uncertain time in the future. Patients must understand that the consequence of returning to fashionable, constrictive footwear is a higher rate of recurrent deformity and symptoms. Significant MTP arthritis and severe hallux valgus with
an IM 1-2 angle of more than 16° are also contraindications for the operation. Neuropathy is a relative contraindication. The patient’s chronologic age is not as an important factor as physiologic age in considering this procedure. Although it was previously believed that the operation was not indicated in patients older than 50 years of age, this concept has been challenged by favorable clinical results in these patients. An MTP joint that is rigid, is tender, has painful motion, has crepitus with motion, and is not passively correctable to anatomic varus-valgus alignment has a worse prognosis.

Planning for a chevron osteotomy includes a history, examination of the foot, general health evaluation, radiologic interpretation, and consideration of expectations. An ideal patient for a chevron osteotomy describes the symptoms in realistic terms and has appropriate expectations. When the pain is excruciating, involves areas of the foot and ankle other than the bunion, or is present even without the use of shoes, a chevron osteotomy may not be the answer.

Besides noting the presence of the hallux valgus deformity, the foot examination should include measurement of MTP joint movement in dorsiflexion and plantarflexion relative to the plantar foot. Many patients with hallux valgus are unaware of their restricted MTP motion preoperatively, but they may recognize the limitation after the operation. It is also useful to determine flexibility of the hallux in the varus-valgus plane and notice whether the toe deformity is easily correctable. A deformity that is not passive correctable may be an indication of an arthritic joint or a laterally facing distal articular surface of the metatarsal (i.e., increased distal metatarsal articular angle) that is not effectively treated with a conventional chevron osteotomy. The neurovascular status of the foot should be documented. If posterior tibial and dorsalis pedis pulses are not palpable, additional investigation is warranted, such as a Doppler examination or noninvasive vascular studies.

The foot should be examined for any difficulties with lesser toe deformities or callus formation beneath the second metatarsal head, because they may be a source of symptoms after hallux valgus surgery. An adjunctive procedure for a lesser metatarsal is occasionally indicated with a chevron osteotomy of the first metatarsal. However, restoring the hallux alignment and first metatarsal head in an improved weight-bearing position with the chevron osteotomy may decrease the overloading of the second metatarsal and reduce in callus formation and pain.

A general health evaluation is important to anticipate difficulties that may occur. The presence of diabetes mellitus, peripheral vascular disease, peripheral neuropathy, and selected medications such as prednisone all have specific implications.

Radiologic evaluation should include weight-bearing anteroposterior and lateral views. The IM 1-2 angle is measured as the angle between lines drawn from the center of the head to the center of the base for the first and second metatarsals. This angular measurement may in some instances underestimate the magnitude of deformity, as occurs in feet with metatarsus adductus. The hallux valgus angle measured between the first metatarsal axis and the shaft of the proximal phalanx is also determined. Degenerative arthritis at the MTP joint can be evaluated on the anteroposterior and lateral radiographs.

A chevron osteotomy is usually performed under ankle block anesthesia as outpatient surgery. Patients who are particularly anxious can still tolerate an ankle block anesthetic with some degree of parenteral sedation. An ankle block can be performed bilaterally, although occasionally patients may prefer general anesthesia.