Percutaneous Midfoot Osteotomy with External Fixation

The midfoot extends from the midtarsal joint to the Lisfranc joint and connects the hindfoot and forefoot.^2,3 Normal gait requires complex synergetic actions between the joints of the hindfoot and midfoot.⁷

Midfoot deformities can be either stiff or flexible and can present as uniplanar or multiplanar deformities.

Midfoot deformities have a severe impact on the pedal biomechanics by altering weight-bearing forces and pedal alignment.

PATIENT HISTORY AND PHYSICAL FINDINGS

Preoperative clinical examination and radiographs (FIG 1) are used to determine the degree and location of deformity.

Clinical examination is critical with midfoot deformities for assessment of the joint range of motion, flexibility, and the degree of rotation deformity (supination and pronation).

SURGICAL TREATMENT

The goal of surgical intervention is to restore pedal alignment, to allow proper transfer of weight from hindfoot to forefoot during gait, to decrease pain, and to reestablish functional gait without affecting adjacent joint motion.²

Conventional midfoot osteotomies are limited, as acute deformity correction can cause neurovascular compromise and requires extensive exposure, retained hardware can increase risk of infection, and wedge resection can sacrifice normal joints and alter anatomic realignment.⁵

In the literature, many types of osteotomies have been described for correction of midfoot deformities, each one designed to correct a specific deformity or condition.^2,3,8,9

Cavus: Cole, Japas, and Akron osteotomies

Relapsed clubfoot and metatarsus adductus: medial opening cuneiform wedge and lateral closing cuboid wedge osteotomies

We present a percutaneous midfoot Gigli saw osteotomy technique for correction of uniplanar and multiplanar midfoot deformities.

This unique percutaneous saw technique was first described in 1894 by Italian obstetrician Leonardo Gigli.

A Gigli saw is a twisted stainless steel cable that is a very effective cutting surface when used in a reciprocating fashion against bone.¹

Our technique has several major advantages:

It is minimally invasive, which decreases the risk of soft tissue injury and infection and improves osseous healing by preserving the periosteum and soft tissues. It minimizes the soft tissue insult, which is essential for the multiply operated foot.

It is not limited by the magnitude of the deformity, spares joints, and growth plates and allows for ease of uniplanar or multiplanar deformity correction.

Gradual correction with external fixation produces regenerated bone, which is preferred to bone resection.⁴ The bone resection can increase foot stiffness.

Gradual correction with external fixation also allows for accurate anatomic realignment of the foot, which reestablishes normal ligament and muscle function.^4–6

Preoperative Planning

Radiographic planning determines the center of rotation angulation (CORA) of the midfoot deformity.⁶

The level of the CORA, together with clinical examination and radiographic assessment to determine the degree and location of deformity, determines the correct osteotomy level.

Positioning

The patient is placed in a supine position on a radiolucent table.

The leg is prepped just below a nonsterile thigh tourniquet, which allows for bending of the knee during surgery. The ability to flex the knee 90 degrees intraoperatively is advantageous in obtaining anteroposterior (AP) fluoroscopic imaging of the foot.

A hemisacral bump is placed to obtain a foot-forward position.

The patient is prepped and draped, and the tourniquet is elevated.

Approach

Various levels of midfoot osteotomies can be performed (talocalcaneal neck or cuboid-navicular or cuboid-cuneiform bones) based on preoperative planning.

The talocalcaneal neck osteotomy is used when the subtalar joint is stiff or fused.

When the subtalar joint is mobile, the level of the midfoot osteotomy is across the cuboid and navicular or cuboid and cuneiform.^5,6

TECHNIQUES

Technique 1: Midfoot Osteotomy and then Gradual Correction with External Fixation

The midfoot osteotomy is performed before external fixation application or screw insertion.

With the aid of fluoroscopy, the level of osteotomy is identified and marked (TECH FIG 1A).

A 1.8-mm Ilizarov wire is placed on the foot under fluoroscopic guidance, and a marking pen is used to mark the exact level of the osteotomy on both the AP and lateral views.

All midfoot osteotomies require four percutaneous transverse incisions.

The first incision is made transversely at the plantar lateral border of the foot, and subperiosteal dissection with a periosteal elevator is performed across the plantar vault of the foot. This subperiosteal dissection creates a subperiosteal tunnel that protects the tendons and neurovascular bundle along the plantar aspect of the foot.

The periosteal elevator is then maneuvered in a rocking motion against the bone and across the entire plantar arch to the plantar medial foot (TECH FIG 1B).

A second transverse incision is made where the skin is tented by the extension of the periosteal elevator, and the elevator is removed.

A no. 2 Ethibond suture is clasped with a curved tonsil hemostat and passed through the previously created subperiosteal tunnel from the lateral incision to the medial incision (TECH FIG 1C).

Once the suture is passed, the Gigli saw is tied to the suture and pulled from lateral to medial through in the same subperiosteal tunnel (TECH FIG 1D).

The position of the Gigli saw is checked by image intensifier to ensure that the level of osteotomy has been properly maintained.

Through the medial plantar incision, the periosteal elevator is passed across the dorsum of the foot subperiosteally below the tibialis anterior tendon to exit just lateral to this tendon.

The third transverse incision is made lateral to the tibialis anterior tendon, where the elevator tents the dorsal skin.

The curved tonsil is then passed subperiosteally from the third incision to the second incision to clasp the Ethibond suture, which is pulled with the Gigli saw through the third incision (TECH FIG 1E).

Again the elevator is extended from the third incision across the dorsum of the foot laterally and subperiosteally below the extensor tendons to exit at the level just dorsal to the cuboid and the first incision.

The fourth transverse incision is made where the elevator tents the lateral skin (TECH FIG 1F).

From the fourth to third incision, the curved tonsil grasps the suture attached to the Gigli saw and is pulled through the fourth incision.

The Gigli saw is now circumferentially around the bones of the midfoot (TECH FIG 1G). Care must be taken during the passage of the Gigli saw to maintain the correct level of the planned osteotomy.

The two Gigli saw handles are now attached, and, using a reciprocating motion, the midfoot is cut from medial to lateral (TECH FIG 1H). The Gigli saw handles may need to be crossed while making the reciprocating cut to avoid lateral soft tissue injury.

To avoid injury to the peroneal tendons and lateral skin, cutting is stopped just before the lateral bone is exited. A periosteal elevator is placed between the fourth and first incisions crossing the Gigli saw, and then the cut is continued (TECH FIG 1I).

When the cut is complete, the elevator will block further progression of the saw.

After completion of the cut, the osteotomy is checked with the image intensifier.

The Gigli saw is then cut and withdrawn from the foot (TECH FIG 1J).

The tourniquet is deflated, and the incisions are closed.^5,6

External Fixation Application

External fixation allows for gradual correction of deformity and lengthening, which can be accomplished by the Ilizarov external fixator or the Taylor spatial frame.

Stirrup wires placed just proximal and distal to the midfoot osteotomy are used.

As a rule, forces tend to take the passage of least resistance, which in the foot are the joints and growth plates, so it is essential to add these two stirrup wires adjacent to each side of the osteotomy. Each wire is carefully inserted on either side of the osteotomy under fluoroscopic guidance (TECH FIG 2).