Supramalleolar Osteotomy with External Fixation Perspective 2

Ankle arthrodesis remains the gold standard for ankle arthritis.

Ankle arthrodesis is indicated for painful arthroses, instability, malalignment, and joint sepsis.

Regardless of the method of arthrodesis, complications are not uncommon and include nonunion, malunion, infection, osteoarthrosis of contiguous joints, neurovascular injury, wound healing issues, and limb-length discrepancy.

Rates of nonunion and other complications alone have been reported to be as high as 30% and 60%, respectively.

Malunion may be among the most consequential and detrimental complications because of its effect on functional outcome.

Sequelae of a malaligned ankle arthrodesis include subtalar degeneration, reduced foot flexibility, compensatory foot deformities, and pain with ambulation. Correction of malaligned ankle fusion is thus critical to preserve the functional mobility of neighboring joints.

Revision of a malaligned ankle arthrodesis can be both technically demanding and traumatic to previously operated bone and soft tissue.

Preservation of compromised soft tissue structures, including the periosteum, is also a critical consideration when revising the failed ankle arthrodesis.

The amount of bone resection required to obtain apposition of viable bony surfaces can create an even greater limb-length discrepancy (larger than the expected 1 cm).

Malunion ankle deformities are typically multiplanar and therefore are not easily corrected acutely.

The literature is sparse in regard to rates and management of the malpositioned ankle fusion. At our institution, we address these complex deformities through a minimally invasive osteotomy with gradual external fixation correction.

In addition to presenting our technique and results, we will objectively define the optimal clinical and radiographic position for an ankle realignment arthrodesis.

SURGICAL MANAGEMENT

Our minimally invasive technique uses a four-incision percutaneous Gigli saw osteotomy with gradual external fixation correction of the ankle malunion.

The subperiosteal Gigli saw osteotomy through a prior malaligned fusion site limits soft tissue compromise while optimizing soft tissue and bone healing.

External fixation provides gradual accurate multiplanar (rotation, angulation, and translation) realignment while simultaneously correcting limb length. In addition, obtaining proper alignment of an ankle fusion is paramount.

Positioning

Under general anesthesia, the patient is positioned supine on the radiolucent table with an ipsilateral hip bump to place the foot in a foot-forward position.

A nonsterile thigh tourniquet is placed, and sterile prep of the entire leg to the level of the tourniquet is performed.

Under video fluoroscopy, a marking pen is used to indicate the desired level of the osteotomy on both the anteroposterior (AP) and lateral views. The thigh tourniquet is then inflated.

TECHNIQUES

Percutaneous Osteotomy

The first incision is made transversely, just medial to the tibialis anterior tendon (TECH FIG 1 A–C).

Subperiosteal dissection with a periosteal elevator is performed across the anterior tibia.

This subperiosteal dissection creates a subperiosteal tunnel that protects the tendons and neurovascular bundle along the anterior aspect of the ankle.

Along the desired level of the osteotomy, the periosteal elevator is then maneuvered in a rocking motion against the bone and across the entire anterior ankle to the lateral aspect of the ankle malunion.

A vertical second 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 medial incision to the lateral incision (TECH FIG 1 D).

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

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

Through the lateral incision, the periosteal elevator is passed posterior subperiosteally to exit just on the posterolateral corner of the ankle malunion.

A vertical third incision is made posterolaterally, where the elevator tents the skin (TECH FIG 1F).

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

Again, the elevator is extended from the third incision subperiosteally posterior to the ankle malunion deep to the flexor tendons to exit medially at the level just anterior to the posterior tibialis tendon (TECH FIG 1H).

A transverse fourth incision is made where the elevator tents the medial skin.

From the fourth incision to the third incision, the curved tonsil is used to grasp the suture attached to the Gigli saw and pull them through the fourth incision.

The Gigli saw is now circumferentially around the ankle malunion (TECH FIG 1I).

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 ankle is cut from lateral to medial.

To avoid injury to the medial skin, cutting is stopped just before the medial 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 1J).

When the cut is complete, the elevator will block further progression of the saw, thereby preventing medial soft tissue damage (TECH FIG 1K,L).

The completion of the osteotomy is confirmed with the image intensifier.

Then the Gigli saw is cut and removed (TECH FIG 1M,N).

The tourniquet is deflated, and the incisions are closed.

External Fixation Application

The tourniquet is inflated only while passing the Gigli saw but is released before the fixator application.

External fixation allows for gradual correction of deformity and lengthening, which can be accomplished by using the Ilizarov external fixator or the Taylor spatial frame (TECH FIG 2).