The Moy Technique: Named Concepts and Definitions

Several parts of Dr. Moy's approach are specific enough that they've been given names: a closure technique, a set of preoperative examinations, and a surgical planning calculation. This page defines each one in the same wording used everywhere else on this site, so the terminology means the same thing wherever it appears.

The Moy Corset Closure

The Moy Corset Closure is a sequential capsular and soft-tissue balancing technique performed after correction of the first metatarsal and restoration of the first metatarsophalangeal joint.

Its purpose is not simply to close the surgical incision. The closure is designed to help maintain the corrected relationship between the first metatarsal, great toe, sesamoid apparatus, flexor hallucis longus tendon, and surrounding capsular structures.

After the osseous correction is completed, the tibial sesamoid and flexor hallucis longus tendon are reassessed relative to the crista of the first metatarsal head. The great toe is held in the desired corrected position while the medial capsule is progressively tensioned and secured.

In larger deformities, the closure is performed sequentially rather than by tightening the entire capsule at once. Each pass is placed and tied individually, with the position of the great toe, sesamoids, joint motion, and soft-tissue tension reassessed between sutures.

The concept is similar to tightening a corset: correction is developed progressively and evenly rather than by applying excessive tension at a single point.

The objective is a balanced closure that supports the corrected alignment without overconstraining the joint or sacrificing postoperative range of motion.

Dynamic Preoperative Assessment of the First Ray

The Moy Technique uses several clinical examinations together to determine whether the deformity is flexible, where the deforming forces originate, and how much correction may be required.

Hallux Snapback Test

The Hallux Snapback Test evaluates the tendency of the great toe to return toward its valgus position after being manually placed in corrected alignment.

The examination may be performed with the patient seated and standing. The examiner manually corrects the hallux and then releases it while observing the direction and force with which the toe returns toward its original position.

A pronounced snapback suggests persistent deforming forces acting across the first metatarsophalangeal joint. These may include capsular imbalance, sesamoid displacement, tendon vectors, or structural malalignment of the first ray.

The test helps the surgeon anticipate the degree of soft-tissue balancing that may be necessary in addition to osseous correction.

Manual Reducibility Test

The Manual Reducibility Test determines how readily the first metatarsal and hallux can be returned toward normal alignment by manual manipulation.

The examiner stabilizes the foot and applies corrective pressure to the first ray and great toe while assessing both the amount of correction obtainable and the resistance encountered.

A deformity that reduces easily behaves differently from one that remains rigid despite manual correction. This distinction contributes to surgical planning and helps determine how much of the deformity is structural versus dynamically maintained by soft tissues.

First Metatarsocuneiform Joint Evaluation

The First Metatarsocuneiform Joint Evaluation assesses the proximal first ray for abnormal motion and, particularly, pain associated with movement of the first metatarsal at the first metatarsocuneiform joint.

The first metatarsal is stabilized and translated through its available dorsal and plantar motion while the examiner evaluates the amount of mobility and whether that movement reproduces pain.

Mobility alone should not automatically be interpreted as pathologic instability. In the Moy Technique, pain generated at the first metatarsocuneiform joint is an especially important clinical finding and is considered together with the radiographic examination and the overall biomechanics of the first ray.

Tendon Vector Assessment

The Tendon Vector Assessment evaluates the direction of muscular and tendinous forces acting on the great toe before and after manual correction of the deformity.

Particular attention is directed toward the extensor hallucis longus, flexor hallucis longus, adductor hallucis, and the relationship of these structures to the sesamoid apparatus and first metatarsophalangeal joint.

As the hallux drifts laterally, these structures may cease to act as neutral flexors and extensors and instead contribute to the deforming force. During examination and surgical correction, the surgeon evaluates whether restoring the structural alignment of the first ray also restores more favorable tendon vectors.

These four examinations are not interpreted independently. Together they provide a dynamic assessment of the deformity that cannot be obtained from a static radiograph alone.

Moy Dorsal Wedge Calculation

The Moy Dorsal Wedge Calculation is a preoperative radiographic method used to estimate the amount of dorsal bone that should be removed during the osteotomy in order to obtain the desired shortening and final position of the first metatarsal head.

The calculation begins by identifying the desired final distal position of the corrected first metatarsal head.

A longitudinal bisection of the first metatarsal is then established. From the most lateral proximal point of the base of the proximal phalanx, a perpendicular line is projected to the longitudinal axis of the first metatarsal. This provides a reference for the anticipated final relationship between the first metatarsal head and the proximal phalanx.

The distance from the distal tip of the existing first-metatarsal articular surface to the desired final position is measured along the longitudinal axis. That distance represents the amount of planned shortening.

The dorsal wedge is then designed so that closure of the osteotomy produces the calculated shortening while allowing the metatarsal head to translate laterally and, when indicated, slightly plantarflex.

Rather than removing an arbitrary wedge of bone, the technique uses the anticipated final position of the metatarsal head to determine the amount of correction required.

The calculation is a planning guide rather than an absolute intraoperative mandate. Final wedge thickness and head position are confirmed during surgery according to the actual anatomy, bone quality, joint relationship, sesamoid position, and stability of the correction.

See the Moy Approach for how these concepts fit into the overall procedure, and selecting a procedure for how the wedge calculation relates to choosing an appropriate technique.