Akin Osteotomy

The primary indication for an Akin osteotomy is hallux valgus interphalangeus or in cases in which residual hallux valgus causes pressure on the second toe on the load stimulation test.

The Akin osteotomy is most commonly used to accompany a scarf or chevron osteotomy.

An isolated Akin is contraindicated in the treatment of hallux valgus.

We use a proximal medial closing wedge osteotomy that is fixed by a varisation screw (Depuy, Warsaw, IN).

The osteotomy is fashioned within metaphyseal cancellous bone, ensuring excellent cancellous healing. The osteotomy, by being close to the apex of the deformity at the interphalangeal (IP) joint, allows for more powerful correction.

Preoperative Planning

Surgery is performed on an outpatient basis.

Anteroposterior (AP) and lateral weight-bearing radiographs of the foot are evaluated for metatarsal length, intermetatarsal angle, hallux valgus angle, distal metatarsal articular angle, and IP angle for cases that may require a proximal phalangeal osteotomy to obtain complete correction.

Congruency of the joint, presence of osteophytes, the size of the bony medial eminence, and position and condition of the sesamoids are noted.

Preparation and Positioning

Prophylactic antibiotics are administered.

A thigh tourniquet is applied.

The patient is positioned supine with a sandbag under the ipsilateral buttock so the big toe points to the ceiling.

TECHNIQUES

Akin Osteotomy

Exposure

The exposure is performed usually as an extension to the midline longitudinal incision from the metatarsal osteotomy. If performed as an isolated procedure, the exposure must allow visualization of the metatarsophalangeal (MTP) joint proximally and the shaft of the proximal phalanx distally. The exposure of the shaft of the phalanx may require excision of overlying fatty tissue.

After dissecting directly onto bone, the exposure is completed by periosteal elevation above and below the phalanx. Two small pointed retractors are placed above and below the phalanx to protect the extensor and flexor tendons (TECH FIG 1).

Kirschner Wire Placement

A 1-mm Kirschner wire is placed in the midportion of the phalanx in the sagittal plane approximately 3 mm distal to the phalangeal flare (TECH FIG 2A).

Traction on the big toe allows us to visualize the joint to ensure the wire is not intra-articular (TECH FIG 2B).

The Kirschner wire is removed and the hole marked (TECH FIG 2C).

Osteotomies

Make the proximal cut parallel to the phalangeal base (TECH FIG 3A).

To maintain control of the osteotomy, the lateral cortex is scored but not penetrated with the saw blade, thus allowing it to act as a hinge.

The second osteotomy is created to produce a wafer of bone with the apex laterally (TECH FIG 3B). When removed, it should look like a fine slice of lemon.

The wedge is closed with direct pressure. This “greensticks” the intact but weakened lateral cortex.

Staple Placement

The varisation staple (usually 8 mm; 10 mm in larger feet) is selected, and the tip of the distal end is marked with a pen (TECH FIG 4A).

The staple is placed with the osteotomy compressed.

It should be on the midportion of the phalanx in the sagittal plane (TECH FIG 4B).

The distal staple leaves an ink mark. This mark is drilled with a 1-mm Kirschner wire (TECH FIG 4C) and then the hole is marked. The position for the staple can then be identified by the two bone marks.

While maintaining compression, the staple is inserted in the predrilled holes.

The stability of the fixation is checked (TECH FIG 4D), and axial traction confirms the staple is not in the joint.

Wound Closure

The wound is closed in layers with continuous Monocryl to skin, and a forefoot bandage is applied to maintain the correction.

Case Example (Courtesy of Mark E. Esley, MD)

Background, Surgical Approach, and Preoperative Planning

A 30-year-old woman with symptomatic left hallux valgus had increased intermetatarsal and hallux valgus angles.

Radiograph suggests congruent (symmetric) hallux valgus deformity that may be indicative of an increased distal metatarsal articular angle (TECH FIG 5A).